Lotus Europa Community
Lotus Europa Forums => Garage => Topic started by: literarymadness on Tuesday,January 26, 2021, 04:14:54 PM
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I finally did what I have been wanting to do for a while: have Steve Smith over at Twin Cam Racing (Sarasota, FL) upgrade my rear drums to disc brakes and my front discs to vented ones. I ordered the Banks' ones from Lotus Supplies Ltd. and had Richard at Banks groove both the front and rear discs. In the spirit of "While already down there," I went for aluminum hubs to save future labor costs. I drove my TCS back from Sarasota down I-75 on the West Coast of Florida, then across Alligator Alley (about 200 miles) back to back home just outside Ft. Lauderdale on the Southeast Coast of Florida. The braking was very intuitive and modulation was easy. It felt like a modern car. Average speeds on I-75 are 75-80 mph and on Alligator Alley, 80-85+ mph. Even at those speeds, you still get passed or tailgated till you move over. Keeping up with those speeds and braking at those speeds felt very normal. Does anybody else have rear disc brakes and how do you like them?
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When I built my car, I put Richard's rear disc kit on it. When I got it on the road, the brakes seemed great! The reality was that it had been SO long since I drove it stock that I had no frame of reference. I think they are a lot better than the stock drums. I haven't needed to (nor do I ever want to) but I suspect that I could lock up four wheels even though I'm running 195/50-15 in the front and 205/50-15s in the rear. So, I'm very happy with them!
BTW - I'm running the stock M/C size with dual Lockheed boosters.
Edit: fixed the rear tire size!
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Originally put rear sliding Wilwood calipers on. Definite improvement over drums. But you can never have too much in the way of brakes so later went to vented rotors with 4 pot Wilwoods up front and 4 pot Wilwoods at the rear as well. Have 2 MC on balance bar. Notice huge improvement on track days.
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@SwiftDB4: Now those are some serious brakes! :beerchug:
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Hi literary,
If I recall, the Banks kit uses Sierra rear callipers, correct?
It looks like you've changed the front callipers as well?
Could you elaborate on those, please?
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You can't see from the photo but the front are the Vented Disc Kits that include Aluminum Hubs from Banks/Lotus Supplies and I had Richard add the grooves for me. I thought the rear calibers were from a Vauxhall but I don't know for sure. Maybe someone else on the forum knows.
https://www.lotus-supplies.com/parts/brakes/disk-kits/disc-kit-front-vented-incl-new-alloy-hubs/
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Rear calipers are from a Ford Sierra, same calipers as used on Caterham’s for many years (lots of different pad materials available for similar weight vehicles).
The Front calipers used to be from a Peugeot 205 GTI (same calipers where fitted to other Peugeot/Citroen vehicles) but they appear to be a different model (same brake pad, probably a newer Peugeot/Citroen model) as the area that the pads sit into is a different shape to the 205 ones. - Again, quite a range of different pad materials readily available for those calipers.
There used to be a couple of options on those front calipers that would allow for non vented or vented discs, the piston etc was the same but the area that the pads sit in was bolted on and came in different sizes to span the thickness of different discs.
Have raced, trackday’d and now road driven on the same front and rear setup (with twin master and balance bar) for 21 years now and they are more than capable.
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@JR73: Thanks for the info! Makes me even happier for doing the upgrade.
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Firstly, thanks Literary & JR73.
Richard's front vented kit is all the better for including the alloy hubs.
When I built my car, I put Richard's rear disc kit on it. When I got it on the road, the brakes seemed great! The reality was that it had been SO long since I drove it stock that I had no frame of reference. I think they are a lot better than the stock drums. I haven't needed to (nor do I ever want to) but I suspect that I could lock up four wheels even though I'm running 195/50-15 in the front and 205/50-15s in the rear. So, I'm very happy with them!
BTW - I'm running the stock M/C size with dual Lockheed boosters.
BDA,
Are you using the stock front brake set up with Richard's rears?
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Thanks for reminding me, Gavin. I forgot to describe the front brakes in my previous post. No, I have Richard’s vented front brake kit but I saved money and used the iron hubs. I also don’t have grooved discs.
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Thanks, BDA.
The next question is; was there a noticeable improvement with Richard’s vented front brake kit?
I'm trying to nail down if vented fronts are worth it when considering the un-sprung weight penalty.
I'm not sure what the Lotus 47 used but wasn't it pretty much a stock Europa set up on the front?
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Thanks, BDA.
The next question is; was there a noticeable improvement with Richard’s vented front brake kit?
I'm trying to nail down if vented fronts are worth it when considering the un-sprung weight penalty.
I'm not sure what the Lotus 47 used but wasn't it pretty much a stock Europa set up on the front?
I believe it was. Hard to tell from this photo but it might have the thicker gt6 rotors https://www.fantasyjunction.com/sold/1966-lotus-47/photos#photos-134 (https://www.fantasyjunction.com/sold/1966-lotus-47/photos#photos-134)
I opted not to go front ventilated for that very reason. Wilwood makes the powerlite caliper in two widths so I could go bigger without much trouble if the solid rotor has trouble handling it.
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It's hard for me to compare because it was twenty five years between when I drove my stock Europa and I rebuilt it. I have to say that I was impressed by the braking when I put my car on the road so I suspect it brakes significantly better than a stock TCS. Literarymadness would have a better comparison than I. My car should brake significantly better in the rain (rear discs work better than drums in the rain) and in extended braking such as a track day or going down a mountain because it should handle heat a lot better. I don't plan on competing in my car so the real reason I upgraded my brakes is because I had significantly more horse power than a stock TC.
Is it worth the added sprung weight in the front? I can't answer that. I didn't think the added expense of the aluminum hubs was worth it because I doubted I'd be able to notice the difference. If you're planning on competing in your car and you can afford it, I would get the aluminum hubs and vented discs.
BTW - according to this site (https://www.ultimatecarpage.com/spec/5814/Lotus-47-GT.html), the 47 had vented discs all around.
Edit: after checking Chuck's link, it could be that the brakes were upgraded on the one I liked to.
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I really like the stock brakes. They work very well.
BUT
They have limited thermal capacity. They will fade down long hills and on the track. I'm experimenting with pad materials (green stuff doesn't cut it) but I think vented front rotors are in my future. Presently I have no plans to change from the rear drums, which I find work very well.
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@JB Your S1 is about 300 lbs. lighter than a TC/TCS; that makes a difference too.
I also think the grooved slots also reduce brake fade and prevent glazing. Here are a couple of interesting videos about brake types.
https://www.youtube.com/watch?v=78wbht355R8
https://www.youtube.com/watch?v=5OWM1wttWA8
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Cross-drilled rotors are very common in motorcycle applications where they do provide a some of the effect of an internally vented rotor. There is no room for traditional internal venting such as cars use due to space and weight considerations. Like a motorcycle, the Europa's stock rotor is too thin for normal internal venting. I think that careful cross-drilling can provide a benefit. Others have found it so. No doubt a a normal vented rotor is better, 100%. However, space is at a premium if you want to stick with stock wheels.
Track days? Racing? Fit traditionally vented rotors, no contest. (regulations permitting).
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It’s worth bearing in mind that whatever the 47’s had fitted was relative to the time -1960’s.
Disc brakes where still a fairly new technology back then and things have certainly moved on somewhat since, if vented discs where available (and affordable) then I don’t doubt that they would have been fitted - check out the discs fitted to F1 cars from that time.
The kit that literary has fitted was designed to replace the originals without the need to change wheels, give an improvement in performance whilst maintaining a good balance. - yes all sorts of other options are possible, have seen vented discs and bells with 6 pot AP front and 4 pot AP rears fitted under 15” wheels on a Europa that was running over 350bhp - it was used solely as a race car though and the development of other parts of the car went hand in hand with the brake upgrades.... running slicks it actually bent a set of tubular front lower wishbones under braking - the design and manufacture of these was changed as a result. It also ended up having completely different front uprights because the original trunnions then started to fail......worked fantastically in a race environment but in all honesty would be complete overkill for a road driven Europa. - seriously, how hard can you drive on the road to require that sort of braking setup?!
Like I have mentioned, pretty much the same setup as literary has fitted is on my own Europa with the aluminium front hubs - whilst I was racing it I used a variety of race compound pads (Mintex 1122 and 1144 predominately from memory) and never had any fade, didn’t warp/cook any discs (had temp paint on them to monitor) and certainly didn’t find anything lacking in performance or feel. When I retired it from competition it was then solely used for track days, initially I continued using the race pads but found that good quality road pads where more than up to the job when only at 7 tenths with a passenger (extra weight!) and now run exactly the same on the road (have now connected the handbrake) - they are never close to any sort of track temps but have plenty of stopping power and good initial bite, even without a servo.
As a side note, if you are buying aluminium front hubs then be aware that there are some cheaper ones available that I have seen fail - the outer bearing lands broke into the centre of the hubs...wheels go a bit wobbly when that happens! So buy from a reliable and trusted source.
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Speaking of racing brakes, I thought it might be of interest to see documentation on a race prepared Europa back in the ‘70s. The car was prepared for a production category car meaning most modifications were limited to what was available in production cars at the time so the brakes were very similar to stock brakes. Engine mods were allowed but I would guess it produced less than 200 hp. (A very different animal than what JR73 described.) The races were 50 mile sprints.
http://lotus-europa.com/manuals/misc/jensen.pdf. (See page 11)
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I inquired about the Jensen rear upgrade previously and no one thought it was worth pursuing....
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The Jensen document is about building a race car to meet regulations. They used twin leading shoe rears because regs forbad the changing of brake type. For their purposes, it worked well. For street use? Not a good idea as you would lose your handbrake and the parts to do the conversion are now hard to find.
Also note they changed the rears to match changes at the front. Important to maintain overall balance when modifying the brake system.
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It’s worth bearing in mind that whatever the 47’s had fitted was relative to the time -1960’s.
Disc brakes where still a fairly new technology back then and things have certainly moved on somewhat since, if vented discs where available (and affordable) then I don’t doubt that they would have been fitted - [...]
Intuitively, I'd agree.
But for the sake of the exercise, the devils advocate may consider what underlies this.
I'd accept that a calliper like the much acclaimed Wilwood would be seen as superior. It's made from billet material so can be lighter and more compact without sacrificing rigidity. It also houses four pistons for more even pad wear and better modulation/feel.
Pad material and it's composition has also improved over the years.
Similarly, I expect rotor metallurgy has likely improved, too.
But I don't think there's any getting around the physics. The devils advocate might say those improvements have been incremental but not night and day.
350HP Europas?
Sure, but if we're considering a bell curve of braking performance the tails are invariably substantially different from the mean. 350HP Europas are definitely residing on a tail of the bell curve.
Fr'instance, I'd think the Lotus 47 is a reasonable aspirational standard - somewhere to start.
From BDA's previous link:
Lotus 47GT - 565 kilo / 1,246 lbs with 165 bhp / 123 kW @ 7,000 rpm.
I'd suggest there won't be many road going Europas around with a better spec. and most will be heavier.
I've not heard widespread complaints around the braking performance of a 47.
So, in my mind, if we accept the general notion that brakes should be purchased relative to the HP they're attempting to arrest, the question becomes a little easier.
Certainly, a rotor with a higher mass will absorb more heat. A vented rotor will shed heat better than a solid one.
So, how much quicker would a 47 be with vented front rotors given they have no history (as far as I know) of exceeding the performance envelope of the factory spec?
I suspect there'd be very little in it.
As a caveat, there are, of course, other variables and I'm certainly not any sort of brake engineer so would be happy to be educated on all this.
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Please understand that I brought up the Jensen race car only for comparison purposes to the race car JR73 described. As I attempted to make clear and JB reiterated, that Jensen car was constrained by the rules. If they were allowed rear discs and vented discs, they certainly would have used them. It was the best method available to skin that cat and they actually did skin the cat.
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A friend of mine took up vintage racing with a nice Sunbeam Tiger. By god he was fast out of the blocks! Holy Doodle, leading by a wide margin only two laps in. Third lap, approaching the hairpin with limited run-off, the brake pedal hit the floor. Boiled his brake fluid inside 3 laps and 10 minutes. He and the car survived but he was never as fast again. Brakes, particularly thermal capacity, can make a huge difference.
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3rd lap? . . join the club
Other tracks were OK, but at Calder raceway in Melbourne, my brakes would consistently last only three laps till I really had to nurse them. The very long front straight and the longish back straight & not much in between is what I put it down to.
Between heats, I'd have to adjust up the rear shoes each time. Being play racers, I don't have enough data to be 100% sure of things. We used DS11 pads for a long time and when they became rare we changed to something called "Black Flash" front pads and they were fine too.
It's all anecdotal but I recall an event at Sandown raceway. The wife of a club member was running their Elan. Don't be misled, she'd done lots of racing and was a good steerer. The Elan had similar performance so always a fun dual.
Up over the hill we went and down towards the left hand corner. I braked for the corner and she sailed past me on the inside. Dammit . . four wheel disks are impressive, I thought.
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47’s did indeed evolve over time, the factory uprated the front brakes whilst they where still in production - the front upright was specially cast in common with the F2 version of Lotus 41 to accommodate a larger Girling brake for the later 47A model and I’m sure you are aware that they had rear discs from the outset along with a balance bar pedal box. - they may look similar to the standard Europa equipment but they aren’t the same.
Pretty much any 47 you see now is likely to be restored back to ‘as was’ spec from when it was new in order to compete in the historic race series’ that they qualify for so anything that may have developed over time would have to have been undone. - I’m not saying that the originals where poor in any way but racers are always looking for small improvements in all areas so it’s likely that vented discs where fitted on some cars as time and technology moved on in order to gain the next small advantage... Historic racers have their hands tied somewhat and have to make the most of what was originally fitted regardless of if it could or needs to be improved.
The reason I mentioned the 350bhp Europa was just to show that anything is possible - and relatively easy to engineer but it then generates the need to further improve other areas as well. Would make for great bar room bragging rights but ultimately it’s unlikely that many (if any) would need anything like that for road use and occasional track days.
The question seemed to be more about the kit that literary has recently fitted and whether it was a noticeable improvement - I would personally say it is a good upgrade that fits easily, gives a good balance, performs well and the parts are readily available to be sold as a kit. - is it increasing the unsprung weight?
You could fit the 47 brakes but I reckon it would cost you more in time and money to source and then some more of both to fit (a bit of modification required to the front and extensive modification to the rear suspension for certain - questionable as to if it’s even possible?) and once again it’s likely that the unsprung weight will alter from the original - possibly weighing more with the larger calipers and stronger uprights etc...
There are endless options, it really depends on what you are actually after and how you intend to use your car?
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I called Steve Smith over at Twin Cam Racing in Sarasota who did the install and he told me that in addition to the aluminums hub that the new calipers seemed lighter than the factory ones so those two factors combined should more than offset the weight increase of the vented discs. He saved my original parts for me and said he would weigh them in the next day or so. His place is about 200 miles from me; otherwise, I would do it myself. I will post the weight when he gets back to me. Does anyone know the weight of the ones that come in the kit or lives in the UK (to save me an overseas phone call) and could call Richard to find out. The brakes already seem significantly better and that was with driving less aggressively in order to properly break-in the Mintex pads. My TCS is running about 125+ hp at the rear wheels and the weight is about 1450 lb. (sans petrol, spare, or rear tub).
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Here are the weights of OEM parts in grams - lbs
Cast iron hub (no studs) 2034 - 4.48
Front Brakes
Rotor 2546 - 5.60
Caliper 3140 - 6.91
Caliper bracket 323 - 0.711
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Thanks for posting that Chuck! The aluminum hub W/O studs is 2.2 lbs.
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The question seemed to be more about the kit that literary has recently fitted and whether it was a noticeable improvement - I would personally say it is a good upgrade that fits easily, gives a good balance, performs well and the parts are readily available to be sold as a kit. [...]
Oh, no, I'm certainly not looking to criticise Literary's kit nor his (or your) experience with it.
I've already said the kit looks good and both your experiences are appreciated.
My curiosity was to consider a more fundamental point which goes beyond any particular brand of kit.
To reiterate, I expect few would disagree that a larger vented rotor would out perform a smaller solid rotor, but that's beside the point.
The assumption seems to be that the existing Europa front solid rotor is under-performing, but, as far as I can see, there's no broad evidence to support such an assertion.
There's also no broad acceptance that Lotus 47 front brakes under perform and we know they aren't entirely comparable to a stock Europa. My consideration of using the 47 as a reasonable benchmark also accepts that.
I hope that clears up where I'm coming from.
Rear disc conversions are noted on these forums in many shapes and sizes.
Richard's kit seems well regarded all round. There's also many home brew conversions using a variety of different components. The consensus seems to be that converting to rear discs provides a definite improvement.
Based on that, a vented rear rotor should out perform a solid one, right?
I reckon the same logic should be applied to the front rotors but that doesn't seem to happen.
Perhaps it's because we're all human. I expect Chunky would be OK with challenging our own assumptions . . . while adding lightness.
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Vented brake rotors simply provide better cooling and are less likely to warp and fade. Colin Chapman wasn't worried about the longevity of his cars nor its components. I on the other hand don't have that luxury. I live in Florida where people drive stupid fast over the Interstate 70 MPH Speed Limits and seem to be overly brake-happy even in semi-dense traffic. I drive occasionally from South Florida to the Smoky Mountains of Tennessee and downhill mountain-driving is murder on your brakes and I will take any advantage I can get. And the last thing you need is brake fade going downhill. I live in a really flat topography (South Florida) and am not a particularly good mountain driver like some of the guys on this forum who live in those type of regions. I need my vehicle to occasionally be a better car than I am a driver. This is something I wanted to do and am not telling anybody to do it.
Back in the day, I was the guitarist for a band in the '80s that had a number of hits. Those were the days when I really pissed my money away on things I didn't need LOL. ;)
But it made me happy. :beerchug:
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The assumption seems to be that the existing Europa front solid rotor is under-performing, but, as far as I can see, there's no broad evidence to support such an assertion.
I'd go with that statement as well. As someone else has posted, vented discs weren't that common back in the 1960s so there's no surprise that Lotus kept with the solid 232mm disc. But if heat soak was a problem for them, they always had the option to move to the thicker & larger 245mm disc/caliper of the GT6 as they had those on the Elan+2 and IIRC the later Elite/Eclats. So cost wise it wouldn't have made a massive difference, in fact the added volume might have got them a better deal ?
They added a servo(s) so they obviously had an eye on how the braking effect felt for the driver, or it might just have been marketing, who knows ? But they stayed with the 232 solid disc, so I think that means they thought it worked well enough for a road car.
Rear disc conversions are noted on these forums in many shapes and sizes. Richard's kit seems well regarded all round. There's also many home brew conversions using a variety of different components. The consensus seems to be that converting to rear discs provides a definite improvement.
Based on that, a vented rear rotor should out perform a solid one, right?
I reckon the same logic should be applied to the front rotors but that doesn't seem to happen.
Personally I think rear discs are an improvement. I still have the OEM drums and could easily revert but frankly there's more chance of me flying to the moon and back. However even on the second round of "upgrades" where I changed the front from 232mm to 260mm discs and the rear from 240mm to 258mm, I've stayed with solid discs all round.
I could easily have fitted vented discs as there are plenty of options but as I only ever drive on the road and either I don't drive fast enough or brake hard enough, I've not had brake fade even with the OEM setup. So I figured the lighter solid discs would be fine for me. I just wanted a bigger diameter for less pedal pressure.
Even so, I can see the extra security margin with vented fronts, I'm just not so convinced about vented rears. I know Lotus fit them on the Elise (S1 at least) but I suspect that's because they use the same disc at all 4 corners and adjust the balance with the piston size, so they're saving cash on buying in stuff.
When I did the 2nd conversion I used one of those infra red thermometers to measure the disc temperature after a run and not surprisingly the fronts were considerably hotter than the rear. I forget the numbers and in any case they would only be comparative F/R rather than absolutely accurate temperatures, but I seem to recall the fronts were roughly double the rears.
You'd expect something like that anyway, but for me it says "vented rears aren't required" (just yet ;) )
Brian
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I have largely stock brakes. Slotted rotors, green stuff pads and braided brake lines are the only mods. in normal driving the brakes work GREAT: plenty of power with lots feel. No complaints there.
Driving from Pemberton to Whistler, I experienced significant brake fade on the steep, winding descent. The pedal stayed firm, just the braking power went away. Pretty classic case of heat overload. My first step is to try Mintex 1144 pads. So far, they work great but no mountain passes like the Pemberton run have come my way yet. Next option will be to space the calipers and fit vented rotors.
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I've used those Mintex pads for a while now on both the Elise and Europa. There are no mountain passes around here (Lincolnshire is like a billiards table) but the pads worked very well when we were in Yorkshire. Again no mountain passes where we lived but quite hilly with no speed cameras and I did drive a bit more enthusiastically in those days.
On such a light car as your S1, they might just be enough to do the trick. Before the Mintex I also used Greenstuff and with the benefit of hindsight I don't think they are as good a material although they did have a better initial bite/lighter pedal from cold.
Brian
.....of course the true hero would say "if you've got brake fade then you're obviously using them too much....." ;)
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Vented brake rotors simply provide better cooling and are less likely to warp and fade. [...]
Cheers, agreed and no dispute from me.
But have you ever warped a Europa disc?
Know anyone who has?
I don't recall any posts reporting warped discs.
Regarding fade, the stock pads don't really handle the heat under arduous conditions. As I say, we switched to DS11 or Black Flash pads. They were well regarded back in the day and while sometimes squealy, performed fine on the road as well.
On my S2, it was always the rear drums that left the party early. When that happens, you tend to push harder on the pedal but that just means you're working the fronts more. Don't recall ever boiling the fluid, though.
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You'd expect something like that anyway, but for me it says "vented rears aren't required" (just yet ;) )
Yes, that was my point, of course.
It's interesting to observe that since the Europa community started delving into rear disc conversions, people then recognised the need for an appropriate rear calliper size so as to avoid the rears locking before the fronts.
I don't recall anyone being concerned the stock rear drums might lock up first!
That tells us something.
[...] But if heat soak was a problem for them, they always had the option to move to the thicker & larger 245mm disc/caliper of the GT6 as they had those on the Elan+2 and IIRC the later Elite/Eclats.
Regarding the GT6 discs, I've read that one needs to swap the whole upright, rotor and calliper in order to upgrade. I've never had cause to question this but is it possible to bolt just the GT6 rotor to the Europa hub?
My thinking here is that if it's the calliper bracket dictating the swap and one is looking to install different callipers anyway, then a custom calliper bracket isn't much of an issue?
Thanks . . I'd also forgotten about the Elite/Eclat using the GT6 stuff.
From Googling around other Lotus forums, apparently there's some 265mm discs that fit in place of the 245mm ones on some variations of Eclat/Elite. Interesting, but more research needed.
Here's a (stolen) pic of a GT6 245mm disc on an Eclat upright that's supposed to take a 265mm disc.
I presume that means, apart from the diameter differences, they're interchangeable. Maybe?
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Banks Europa Engineering only sells one disc kit for the front brake and that is the one I had put on. My original front rotors were in bad shape and one of my calipers questionable. So by the time I added up the price for all the individual parts (including the aluminum hubs), the complete kit was cheaper, but not enough to sway me one way or the other. So I called Richard and asked his advice and he talked me into the complete disc kit saying it was track tested and time proven and that was the best option for stock wheels. The aluminum hubs save me 2.3 lbs. per wheel. The difference in weight between a stock Spitfire rotor and a vented one is less than I thought (a little over a pound increase). Supposedly, the new calipers are slightly lighter. Even if they're not, I still have shaved at least a pound of unsprung weight per wheel. So in the end I wound up with Better Calipers, Cooler Brakes, and Less Unsprung Weight. Works for me!
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But have you ever warped a Europa disc?
Know anyone who has?
I don't recall any posts reporting warped discs.
The two HSCC TC’s that we looked after did.
They where built to 5 speed special spec and included the wider rear drums to give them the best of what was possible within the rules. The pads and shoes were race compounds along with the fluids.
The quicker of the two guys used to constantly report that he had ‘run out of brakes’ by the end of a race, both used to consistently finish high up in the results though.
Pads and shoes had to be replaced after each round - qualifying session and a race (front pads had seen a LOT of heat and where generally cracked or starting to break away from the backing plates on both cars), front discs every two/three rounds (dependant on the tracks) and the rear wheel cylinders had to be changed at the same intervals as the seals appeared to cook and fail (sudden loss of fluid was much worse than ‘fade’ or ‘judder’ as they used to report and after a couple of failures it wasn’t worth the risk - both drivers where Barristers!)
Neither driver was particularly interested in doing much maintenance other than getting in and driving the car so double headers where a major concern as changing rear shoes was completely out and they would reluctantly get their hands dirty and change the front pads before the second race (its easy isn’t it?!) - generally all of the above was replaced prior to a double header weekend to give them a chance of making it through safely...
Again, not your average bit of road driving but they certainly weren’t doing any sort of endurance events either.
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I don't recall anyone being concerned the stock rear drums might lock up first!
Absolutely no chance ! From memory they were about 25-30% braking effort on the rears and would never lock before the fronts had. I suppose wet roads might swing it, but you'd have to be trying very hard.
Regarding the GT6 discs, I've read that one needs to swap the whole upright, rotor and calliper in order to upgrade. I've never had cause to question this but is it possible to bolt just the GT6 rotor to the Europa hub?
My thinking here is that if it's the calliper bracket dictating the swap and one is looking to install different callipers anyway, then a custom calliper bracket isn't much of an issue?
and
Here's a (stolen) pic of a GT6 245mm disc on an Eclat upright that's supposed to take a 265mm disc.
I presume that means, apart from the diameter differences, they're interchangeable. Maybe?
I have also read the same on LotusElan.net, Elans with bolt on wheels had the same uprights as the Europa but the knock on wheels had the heavier versions. Both have 232mm discs with type 14 calipers and I've seen posts saying you need to swap the lot.
On mine (k/o wheels) I swapped the discs/bracket & caliper for the 245mm/type 16 calipers and it's a bolt on job. Unless it's a concern about the smaller stub axles I'm not sure why folks say you need the heavier set-up, it looks to me as if they'd just bolt on either upright. The later Triumph uprights had the caliper bracket cast in place so perhaps that's the reason for the statement ?
I don't know if the Eclat discs are interchangeable. I used Citroen BX 265mm discs on my car but you need to re-drill the mounting holes. The BX comes in both solid & vented versions and once you've re-drilled the mounting holes for the hub, they fit very well, the offsets are very similar. If the Eclat discs look to have been modified then I bet that's what they use.
But 265mm discs won't fit with standard wheels, not even a steel one.
Brian
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You can't just bolt on the larger rotor (GT6) to the europa, its all larger bits.....bearings, etc. IIRC that is. Besides the larger axle, etc. gives better stability and longevity/reliability if you want to go racing.
I've got Mintex 1144's front and rear with a banks clone kit in the rear. Sierra (Scorpio) rear calipers and Integra disks. The braking power improvement on track days is very noticeable. I took my infrared temp gun to a track day at PIR and measured 320F front and 300F rear after a 15 minute session. No fade with these pads, at least on a track day (go as fast as you dare). Just a mostly stock TCS but very happy with the stock front brakes and the Banks design in the rear.
Jerry Rude
4005R
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Nice write up about brakes.... https://www.gglotus.org/ggtech/europa-brakeinfo/brakeinfo.htm
Discusses the difference in "response" between drums and discs among other things.
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All Lotus Elise including the least powered S1 to the 2020 current one have rear discs brakes and vented disc brakes upfront. If Lotus in 1995 had felt the 1972 Twin Cam Special brake set-up was a better setup, the 1650 lb Elise (same weight as Fed-spec TCS) would have had that setup. While the TCS has slightly larger drums than previous models, they are basically the same design as on the S1 when the car was introduced in 1966. I am not criticizing the original factory brakes in any way or questioning the ability to stop. But brakes have improved since 1966 and I believe that the Banks Kit (Peugeot 205 GTi vented brakes with aluminum hubs) are an upgrade. The same goes with the Ford Sierra discs I now have in the rear vs. the old drums.
@Turboforce: The article also says "Small, light weight disc brakes sized to be balanced with the stock fronts would be fine. The main advantage won't be more braking "power" as much as matched response times. Matched response times would make it "easier" to apply the brakes rapidly with less risk of locking up the fronts pre-maturely... and therefore easier to use the full braking potential."
I am not a trained driver nor do I race. But I do drive for long periods of time at fairly high speeds in semi-dense traffic, where other drivers occasionally do really stupid maneuvers usually at night (Hey it's South Florida). In a panic stop, a few feet can make a huge difference and not the time to find out how I should have braked. I'll take any advantage I can get.
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Not disagreeing! I will probably add rear discs to mine at some point ;)
Just thought it was an interesting article......I thought the point of the different responses was enlightening.
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All Lotus Elise including the least powered S1 to the 2020 current one have rear discs brakes and vented disc brakes upfront. If Lotus in 1995 had felt the 1972 Twin Cam Special brake set-up was a better setup, the 1650 lb Elise (same weight as Fed-spec TCS) would have had that setup. While the TCS has slightly larger drums than previous models, they are basically the same design as on the S1 when the car was introduced in 1966. I am not criticizing the original factory brakes in any way or questioning the ability to stop. But brakes have improved since 1966 and I believe that the Banks Kit (Peugeot 205 GTi vented brakes with aluminum hubs) are an upgrade. The same goes with the Ford Sierra discs I now have in the rear vs. the old drums.
@Turboforce: The article also says "Small, light weight disc brakes sized to be balanced with the stock fronts would be fine. The main advantage won't be more braking "power" as much as matched response times. Matched response times would make it "easier" to apply the brakes rapidly with less risk of locking up the fronts pre-maturely... and therefore easier to use the full braking potential."
I am not a trained driver nor do I race. But I do drive for long periods of time at fairly high speeds in semi-dense traffic, where other drivers occasionally do really stupid maneuvers usually at night (Hey it's South Florida). In a panic stop, a few feet can make a huge difference and not the time to find out how I should have braked. I'll take any advantage I can get.
My thoughts exactly! in DFW it is a miracle if you don't have some one pull out right in front of you on a daily basis. I nearly creamed someone with my M3 who pulled across 2 lanes of service road traffic the other day. He went from a dead stop leaving a parking lot straight to the merging lane of the highway without even looking!! The cost of upgrading to disc all round is negligible compared to to the damage it might prevent in a worst case panic brake scenario. I am not planning to run my car in any vintage racing which would require period correctness.
When my '66 chevy truck was running (all drum manual brakes) it was truly terrifying how little room people give you. I have since upgraded to disc on that...it still doesn't run yet though :)
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When my '66 chevy truck was running (all drum manual brakes) it was truly terrifying how little room people give you. I have since upgraded to disc on that...it still doesn't run yet though
That reminds me of my tow vehicle when I was racing - a Ford Econline 150 (I think... was there a 100?) van. It had a 302 with a two barrel and four wheel drum brakes(!). My trailer and car were pretty light and it towed pretty well. I even got about 13mpg on the highway which is really good for towing a race car.
What you reminded me of is when going to Texas World Speedway near College Station, Texas, there was a stretch of about 10 to 15 miles where every few miles, there was a stop light. If I hit the first one wrong, I hit them all. By the time I got up to speed, there would be another light. The drum brakes were fine for the first four or five lights but those brakes were gone by the time I got to the last two or three lights and it was a struggle not to blow past a red light!
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I think the last few comments here illustrate the difference between what we'd like to think (Lotus brakes are great) and modern reality. This thread has sparked my interest so I did a quick search around for "what's good today ?" and came up with this page
https://www.consumerreports.org/car-safety/best-and-worst-braking-distances/ (https://www.consumerreports.org/car-safety/best-and-worst-braking-distances/)
It's not a specialist report, just some simple facts. Sporty cars are the top of the list, as you'd expect, and 60-0 comes in around 120 feet in dry conditions. Now I know some cars will do better, the Top Gear trio of Clarkson/Hammond/May did some stunning numbers with high powered BMWs, etc, but the thing we all face in modern traffic is the average saloon (because that's what we're going to run in the back of !)
I was surprised to find numbers in the 130-140 feet range, but that underlines how good modern brakes are. It seems the best cars are under 100 feet, which is pretty impressive (https://www.motortrend.com/news/20-best-60-to-0-distances-recorded/ (https://www.motortrend.com/news/20-best-60-to-0-distances-recorded/))
And now for our cars. Well, we all know the cars were praised on every road test so I pulled out my Brooklands books and looked up the numbers. Not an easy comparison because most UK tests seemed to concentrate on 30mph as the target speed and they came in around 31-32 feet.
Road & Track, Nov '73. TC Special, Min. stopping distance from 60mph.... 171ft. Yes, I read it twice and unless it's a misprint, that's the numbers. The S2 fared better, lighter car, similar brakes so you'd expect better and you S2 owners will be pleased to know you can brake almost as well as the average small car today and you can probably outbrake a pickup.
I was surprised. I never considered the OEM brakes as bad but I didn't realise just how far modern systems have come. Sobering really.....
Brian
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Europa TC Thanks for posting that!!! I screenshot the Consumer Reports Chart from that link. Those numbers reiterate my concerns with "How good are the driver in front of me's brakes?
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I wonder how much the improvement is due to anti-lock braking. I suspect a lot.
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Wow!
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You can't just bolt on the larger rotor (GT6) to the europa, its all larger bits.....bearings, etc. IIRC that is. [...]
That's what I recall, too.
Have you offered up a GT6 disc to a Europa hub? Some one must have done it.
I took my infrared temp gun to a track day at PIR and measured 320F front and 300F rear after a 15 minute session. [...]
Those are pretty low temps for a track event, aren't they?
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[...] If Lotus in 1995 had felt the 1972 Twin Cam Special brake set-up was a better setup, the 1650 lb Elise (same weight as Fed-spec TCS) would have had that setup.
Well, Lotus produced the Elite (Type 14) in 1957 and the Elan in 1962, both of which had four wheel discs.
Sometimes it not 'what's better' that makes it through to the final product.
I am not a trained driver nor do I race. But I do drive for long periods of time at fairly high speeds in semi-dense traffic, where other drivers occasionally do really stupid maneuvers usually at night (Hey it's South Florida). In a panic stop, a few feet can make a huge difference and not the time to find out how I should have braked. I'll take any advantage I can get.
Me either. I'd be a play racer at best.
Back in the early days, a group of us attended what was then known as an 'advanced driving course' conducted by a quite successful local racer. These courses were aimed at drivers needing to qualify for a race licence from an accredited organisation. There was an assessment as part of the course.
Apart from the more intuitive stuff like regulations, theory, cornering lines & apexes etc., the most helpful practical exercise by far was learning brake control.
The setup they used was simple. They hosed down the car park, and placed cones which represented the back of a stationary vehicle. As you drove by at a constant 60kph (35mph), the instructor would clap his hands and you'd hit the brakes and hopefully not hit the cones.
Later variations included a scenario where you'd need to swerve into the next lane and stop behind an imaginary vehicle placed one car length further forward. Needless to say, just slamming on the brakes doesn't really work.
I reckon brake control is something we can't readily practice on our own. Probably the best money I ever spent, so highly recommended.
If there's nothing like this in South Florida, perhaps this is a business opportunity ripe for the picking. ;)
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I wonder how much the improvement is due to anti-lock braking. I suspect a lot.
For the average, non-enthusiast driver, your typical mom taking kids to school, flooded roads, etc, I suspect it's a life saver. But I think the main advance is that virtually every car has a brake servo to reduce effort & thus can use higher pressures/clamping forces and harder pads more resistant to fade. Plus the trend for bigger wheels which allows bigger discs with more leverage, that makes a big difference to the maths.
On the topic of driver skill regarding braking, there was a DVD produced in the early days of the Elise by Andy Walsh called "Bending the Rules". He covers braking and shows how you could drastically reduce the stopping distance of the Elise, (no servo, no abs) with your style of cadence braking and what he terms as "threshold braking". (basically something very similar but clearly more effective)
I've taken a screenshot which is a bit blurry (old TV format) but does show the results in terms of car lengths stopping distances. Well worth a view if you can find it on Amazon, etc.
Brian
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In the interest of science I may sacrifice some tires to the gods of brake testing once my discs are in...
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Got that dvd. Did some driver training with Andy Walsh a few years ago in my Westfield. Made me realise the skill a good driver has in the whole feel of the car including braking. He got in my Westfield and first time did a perfect high speed stop. I couldn’t get anywhere near
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Braking on cars with light front ends is an interesting problem. This is the same with EVERY rear and mid engined car out there, not just Europas. If you mash the brakes hard, the fronts lock and you slide with no steering control. A locked sliding wheel does not slow you down anywhere nearly as quickly as a wheel held close to the point of locking but not quite locking (threshold braking). You might think increasing the rear brake force is therefore the answer. Not really, weight transfers to the front under braking. Just increasing the rear brake force may lead to the rear brakes locking first as this weight transfer occurs. As any fan of 70s cop shows can tell you, this leads to loss of control due to the rear of the car slewing around.
The key to safe short stops is squeezing the brakes to the threshold braking point. Squeezing allows time for the weight transfer to occur. Once the weight has transferred to the front, you can apply a lot of force before the brakes will lock.
This same issue arises with motorcycles and bicycles. Nail the front brake hard and the front locks every time. Squeeze, get the weight transferred, and stopping distances can be very short.
Yes, today's vehicles have phenomenal brakes, but that's not the reason modern cars stop so quickly. Your average driver would simply lock the wheels and slide out of control with just giving them "better" brakes. The difference is ABS. Now your average idiot driver can still know nothing and stop within fractions of foot as quickly as the best race drivers. Worse, the wee b@st@rds, who can't normally find their way out of a bathroom if you spin them round twice, somehow "know" their brakes are good and follow so #$%& close there is zero (or less) margin for error.
What can we do? Same as old school racers, motorcyclists and cyclists. We have to practise threshold braking until it becomes instinctive. Not once and pat yourself on the back. Practise repeatedly until you're good and then maintain weekly brush-ups so you do it automatically. Also:
- leave a little more room in front of you than you do in your modern car. That extra room is for the idiot behind you so you have the space to brake a little less hard and give the be-hinders more time to not do the wrong thing.
- look ahead! If you can anticipate things, you can react slower and improve your chances of getting out unscathed.
Brake improvements are useless, and probably counter-productive, without practising threshold braking and being more aware of your driving environment.
If you want to improve your brakes, great! Nothing wrong with that. Make sure you improve the whole brake system in a balanced way, not just one end and not the other. Then practise threshold braking as you will still get into trouble no matter how good your brakes are unless you practise!
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If you want to improve your brakes, great! Nothing wrong with that. Make sure you improve the whole brake system in a balanced way, not just one end and not the other. Then practise threshold braking as you will still get into trouble no matter how good your brakes are unless you practise!
Great advise. I mash the brakes in every new car I drive to find what I can get away with and find where they lock or don't and to get the feel.
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I just tried looking for bending the rules by andrew walsh. Found one in the UK. But Amazon.UK wouldn't ship it to California. It's probably the wrong DVD zone anyway. One in Canada was ~$130. Seemed a bit pricy.
Does anyone know where I can get a copy in the USA?
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My main issue was never with the rear drums and dry weather braking. But more with wet weather braking in South Florida. Anyone in Florida will tell you that it go from clear blue skies to torrential downpours in a very short time. We are in the Sub-tropic Zone. When I said I had no training, I didn't mean I wasn't experienced. I have done heavy driving in 40+ states from the North to South, the East Coast to West Coast in all four seasons of weather and every type of terrain. I have pretty much driven in every country in Central and South America, from jungle roads in Colombia to mountain roads in the Andes of Ecuador and Chile. You can include some of Europe and a little in Japan. There are just certain things that you can't practice for.
The straw proverbial straw that broke the camel's back in wanting rear disc brakes happened a few months ago. I was driving back in my TCS from the other side of Florida on I-75 when I caught in a heavy rain storm with very poor visibility (100 ft at best). People in their big SUVs and pickup trucks somehow feel that it is still safe to drive fast in heavy rain. By the time I could see all the tail lights of twenty or so cars completely stopped on the interstate due to an accident, I had no choice other than to panic stop. My rear drums were no doubt water soaked-and completely useless at this point. My front brakes locked and the tail of my car was not behaving very well at all weaving in and out of the lane. The car hydroplaned for about 20 feet but somehow managed to stop about a foot or so from the next vehicle.
Had I not been going much slower prior than the other vehicles and keeping my distance, the ending would have been a little different. On the rest of the drive home, I made the decision to put disc brakes in the rear. The decision to get the new front kits came after speaking to Richard at Banks who told me the front and rear kits worked with each other very well and were time tested on the track for balance.
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^^ that's all too true. No matter how good we are, how far we look ahead or how often we practice, there will always be an element of human error when we react to an emergency.
I accept this is a personal hobby horse but anything that reduces my margin for error in modern day traffic is a good thing IMO. Increasing the rear braking effort will reduce my margin for driver error in locking up the front if only because it starts weight transfer earlier. The trick is not to get too much rear brake of course, we want them improved but not to the point of locking up first.
Using the same spreadsheet maths for the Elise S1 as the Europa, it works out that they decided 41% @ 1G was a good number for the rear brakes, which on that car has them locking up fractionally after the front at 1G. The S1 weighs around the same as the TC Europa but uses the 282mm (yes, 282) diameter discs F & R balanced by caliper piston diameter.
In comparison the Europa rear drum is around 23-25% which means the fronts can lock around 0.7-0.8G and when everyone else is 0.9G or better, we have a problem. It might feel like we're stopping quickly but the reality is that we're not as good as that shopping trolley driven by someone who only uses the mirror to put makeup on. (apologies for the MCP analogy ;) ).
But that's what we're up against in modern traffic.
Brian
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I hear ya, Literary.
I also live in a sub-tropical region and sometimes those downpours can be pretty intense.
I've been in lines of traffic where half the cars simply pull over and wait. Usually the really heavy part of the downpour only lasts a minute or two.
But also, the number of SUV's has increased markedly over the years . . and I suspect the sheer size of them is bigger in the US than here. The Toyota Hilux was announced as the outright best selling vehicle in Oz - for the last four years straight - crazy.
So, probably the danger has increased for little cars.
The eye level for the average Europa driver is probably three feet off the deck. By comparison, the big SUV's / trucks have a commanding view from perhaps six feet.
Add to that the 'confidence inspiring' ABS brakes means they probably aren't even looking for us, let alone seeing us.
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In the interest of science I may sacrifice some tires to the gods of brake testing once my discs are in...
I'd be really interested if you do that.
While I think it's no surprise that pretty much everyone is satisfied with their rear disc conversion, I don't recall any actual tests.
G-meters are cheap enough and you can even get free G-meter apps for a phone.
I accept this is a personal hobby horse but anything that reduces my margin for error in modern day traffic is a good thing IMO. Increasing the rear braking effort will reduce my margin for driver error in locking up the front if only because it starts weight transfer earlier. The trick is not to get too much rear brake of course, we want them improved but not to the point of locking up first.
Using the same spreadsheet maths for the Elise S1 as the Europa, it works out that they decided 41% @ 1G was a good number for the rear brakes, which on that car has them locking up fractionally after the front at 1G. The S1 weighs around the same as the TC Europa but uses the 282mm (yes, 282) diameter discs F & R balanced by caliper piston diameter.
In comparison the Europa rear drum is around 23-25% which means the fronts can lock around 0.7-0.8G and when everyone else is 0.9G or better, we have a problem. It might feel like we're stopping quickly but the reality is that we're not as good as that shopping trolley driven by someone who only uses the mirror to put makeup on. (apologies for the MCP analogy ;) ).
It's all a bit of a conundrum in some ways.
Presumably we agree the ability to lock the front brakes indicates they're satisfactory*. Basically this is because they've overcome the limitation of tyre traction.
If the rear conversions work well, do we know how well? . . . or how far they are from locking?
If I recall, the spreadsheet for the Europa suggests that a stock front disc is best paired with a 34mm rear calliper.
I've been tempted to go for a 36mm calliper and use an adjustable proportioning valve to trim the rears. One other advantage of this is that one could open the valve further for a wet track.
* with caveats of course.
https://race.parts/Catalogue/Braking/Proportioning-Valves/AP-Proportioning-Valves/AP-Racing-Lever-Type-Single-Bore-Proportioning-Valve
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If I recall, the spreadsheet for the Europa suggests that a stock front disc is best paired with a 34mm rear calliper.
I've been tempted to go for a 36mm calliper and use an adjustable proportioning valve to trim the rears. One other advantage of this is that one could open the valve further for a wet track.
Strangely enough, during our latest lockdown and prompted by the topic being raised here again, I took a fresh look at my set-up and came to the conclusion that a 36mm piston was certainly worth looking at. (that's with 266mmF, 258mm R discs) In theory it should have both locking around the same time but even if the sums are wrong then as you say a valve could trim it back a touch. But it's cold here and so I've done nothing other than idle thoughts and browsing Ebay.
Incidentally I tried the G force recording after a few guys on here told me that in the 20th century we had such things as phones & tablets which could do such things. I used a free app called "Physics Toolbox" (or something like that) which gave accelerometer graphs. The most impressive was off scale but I think that had something to do with the tablet flying off the passenger seat and ending up down the footwell..... :)
Brian
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My big complaint about my Europa TCS brakes is that the front brakes lock up way before the rears, if I can even get the rears to lock up at all. I have a standard TCS brake system (lockheed servos, front discs, rear 1.5" wide rear drums, standard master cylinder). I have never experienced brake fade in the Europa, although I have never had it on a race track.
So, does the rear brake disc conversion actually solve this issue? Do the rear brakes actually lock up? Any feedback would be appreciated since I would not consider changing to rear discs unless it did. If the rear disc conversions did this, I would consider it. However, I have not heard anyone claim that.
In my perfect world, with no bias valve, the rear brakes would lock up prior to the front brakes. A rear brake bias valve would be installed and then could be adjusted so the front brakes lock up slightly prior to the rear brakes. This adjustment would also be very much a function of the brake pad/shoe material and their temperatures, since the coefficient of friction of the brake material are not constant over temperature.
I have looked at this issue and have the following thoughts to improve the rear braking power and improve brake balance.
Install rear discs, but space and available calipers are limited with standard 13" wheels. Will they lock up the rears before the front brakes allowing the use of a bias valve?
Change pad and shoe materials. My experience is the greensuff pads really made the front lock up early. I currently run Mintex 1144 pads, which I really like except they squeal. There is not a lot of options for the rear shoes except if I want to rivet my own brake shoes. I run standard shoes.
Find a larger rear brake drum cylinder, which is difficult because of the self adjuster ratchet being part of the cylinder.
I have thought about installing a 3:1 servo in the rear circuit and keep the 1.9:1 servo in the front. They are currently both 1.9:1 servos. BP Northwest has the 3:1 servo for $159. Obviously, a rear bias valve would be needed for this.
Install a bias valve in the front brake circuit. This is not recommended by the bias valve manufacturers but I do not know why.
Install a residual valve in the rear circuit to improve the drum brake response time.
So basically, I would like to be able to adjust the F/R braking bias which is not possible right now unless I install a bias valve in the front circuit to reduce the front braking pressure.
Any other ideas or thoughts?
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The correct way to adjust brake balance on the fly is with twin masters and a balance bar as adjustments remain constant. Adjustable bias valves are not consistent performers and need to be checked before each critical use. I would strongly recommend NOT using an adjustable bias valve in the way you describe. YMMV.
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I would agree with JB. Bias valve isn't as consistent as mechanical balance bar and dual MC. Yes you can get the rears to lock up with the right components. My S1 has Wilwood 4 pots all round (1.75" F and 1.375" rear). I have 13" wheels and I believe the rotors are 10" front vented, rear solid. With balance bar adjusted to rear I can lock up rears on track days. Of course it's preferable to have the fronts lock up slightly before rears for stability. Is all this necessary for street driving? Probably not.
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So, does the rear brake disc conversion actually solve this issue? Do the rear brakes actually lock up? Any feedback would be appreciated since I would not consider changing to rear discs unless it did. If the rear disc conversions did this, I would consider it. However, I have not heard anyone claim that.
Not completely, but then again you don't want the rears locking first.
I've added 2 screenshots below. The first is the OEM disc/drum TC, the rear brakes are the same as the S2 and not as large as the ones you have. This shows pretty much what everyone knows, you can lock the front brakes very easily at less than 1G and the rear drums never lock. (the lock is where the dotted line crosses the solid line, Front is black, Rear is red)
The next is 232mm F, 240mm Rear disc. I don't know what everyone else uses and that combination wouldn't fit with my 13" Cosmics but it was very close and I reckoned it could be made to work with minor adjustment. That will lock the rears in theory, but still after the fronts and at over 1G.
Whether these numbers are spot-on accurate or not I have no idea, but using the same data it does illustrate how you change the brake balance with rear discs. Larger discs don't really alter these ratios but they do reduce the pedal pressure significantly for a given brake force.
Brian
ps - actually I can confirm the rears will lock, I tried it on our gravel drive to see if I could get 4 skid marks ! ("you little kid" as my wife said)
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Is there anything you haven't measured or calculated on a Europa, Brian?!
I'm curious where your got all those numbers and calculations?
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Is there anything you haven't measured or calculated on a Europa, Brian?!
Fuel consumption, running costs and "hobby spends"....... never a good idea to have it written down. ;)
I'm curious where your got all those numbers and calculations?
Mostly from road tests. the manual. etc. I have been known to take bathroom scales to the workshop to weigh wheels/tyres, but only when the coast is clear (wife out shopping)
The original drum calcs/data were from Richard's original spreadsheet which I just copied over.
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JB
Many, many cars have adjustable rear bias valves. So, I respectfully disagree. If you are talking about my mention of putting the bias valve on the front circuit, I don't know and it is not recommended by any of the bias valve manufacturers.
I agree that twin master cylinders with a balance bar is best, but difficult to implement.
Also, would you agree the rear brakes lock up way before the front brakes?
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Banks balance bar pedal box with twin master cylinders (lid removed at time of pic). Hydraulic clutch option also available.
Fibreglass reinforced in area where pedal box is mounted.
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JB
Many, many cars have adjustable rear bias valves. So, I respectfully disagree. If you are talking about my mention of putting the bias valve on the front circuit, I don't know and it is not recommended by any of the bias valve manufacturers.
I agree that twin master cylinders with a balance bar is best, but difficult to implement.
Also, would you agree the rear brakes lock up way before the front brakes?
Forgive me for butting in.
In general, the thinking is that if the fronts lock and the rears don't, limiting the front brakes to match the rears via a bias valve likely leads to an overall reduction in braking.
More to the point, it doesn't address the actual issue which is insufficient rear braking.
From a short trip around the inter-webs, I didn't find complaints with adjustable proportioning valves but I did for the fixed OEM 'combo' variety. Happy to be educated on this.
It may also be that there's undoubtedly tons of OEM fixed valves travelling the countryside and a stark minority of aftermarket adjustable valves presumably used by enthusiasts.
Yes, difficult to implement twin masters.
There are a number of 'hanging pedal' kits around but I prefer the ergonomics of the floor hinging pedals - seems a more natural movement because it keeps the heels planted. I also want to retain the front plenum.
It's possible to buy the balance bar unit separately to install in, say, a replacement brake pedal, but that means rearranging the real estate on the front of the T section for the MC's. Not insurmountable, I'd guess, but I'd also want room for a clutch MC as well. That might get crowded.
Somewhere along the way we should discuss the stiffness of the various options. A stiffer pedal & MC mounting results in better feel under the foot and thus, easier modulation.
I suspect the Banks overhead pedals as per JR73's pic are mounted to the top of the chassis (?) and probably reasonably stiff.
The stock pedals bolted to the rear 'flap' of the chassis through the fibreglass floor probably less so.
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(that's with 266mmF, 258mm R discs)
Are these inside 13" wheels?
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Yes, difficult to implement twin masters.
There are a number of 'hanging pedal' kits around but I prefer the ergonomics of the floor hinging pedals - seems a more natural movement because it keeps the heels planted. I also want to retain the front plenum.
It's possible to buy the balance bar unit separately to install in, say, a replacement brake pedal, but that means rearranging the real estate on the front of the T section for the MC's. Not insurmountable, I'd guess, but I'd also want room for a clutch MC as well. That might get crowded.
A top hanging pedal follows the arc of your leg better than floor mounted (not my opinion). I kept floor mounted and used a dual master as I didn't want to cut out my frunk. If you want tandem masters you can make it work.
I wish someone would make a billet tandem adapter. I have seen them for other makes. It would solve many problems for Europa people.
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(that's with 266mmF, 258mm R discs)
Are these inside 13" wheels?
No Gavin, 13" would be very optimistic :)
I'm using 15" wheels. I haven't checked but would imagine that 245mm (GT6) and 240mm would be about the best you could get with 13" wheels. My Elan has the GT6 discs/caliper on 13" steels and it's a tight fit. I'd guess 245/240 would be the best you could hope for with standard rims.
Brian
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An article on proportioning valves:
https://centricparts.com/getmedia/d958a29e-4ebf-41fd-931f-bf7e4451801b/brake-proportioning-valves.pdf
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This is a very interesting debate which I follow closely. Valuable input from all sides. I had exactly the same problems with my first Europa which I restored some 30 years ago. The front brakes locked up very early especially in the wet. Very scary. I even tried to fix the issue by fitting a Tilton proportioning valve in the front circuit like suggested by Pfreen. With the bias forcefully shifted to the back it was indeed possible to lock the rears first even on a dry road. But the pedal force was really high and the deceleration not impressive. It felt like pulling the handbrake while driving. As we all know not much will happen in an Europa ;D. I kept the valve as the braking performance was slightly better with a some bias shift to the rear. But it was a far from ideal solution and I wouldn't do it again.
What puzzles me is that in all the old road tests no tester ever mentioned a bad brake balance on the Europa. They frequently achieved a deceleration of 0.9 g and had no complains concerning the braking performance. Of course back in the late 1960s the brakes were much worse in general but I can't imagine that the brake balance on a new Europa was as bad as we experience it today. My thought is that it must have something to do the friction coefficient of the older materials and the braking system being in a 'new' condition.
Now that I'm restoring another Europa I will face the same problems once more. I would really like to keep the drums so I need to get them working. First I will meticulously make sure that the whole system is setup 100%. The drums will be turned, balanced and the pads bedded in using emerald paper. I also may fit bigger slave cylinders to the rear if I think I need to shift the brake balance to the rear. That would have the same effect like adjusting a balance bar.
JBs comments concerning 'threshold braking' is very helpful. Especially as the response time of drum brakes is slower than disc brakes. It may have something to do that there is a spring that pulls the shoes away from the drum. As a resut there is more dead travel to overcome compared to a pad nearly touching the disc. That's where fitting of a residual valve could help by keeping the pad closer to the drum surface. I will give it a try as those valves are not very expensive.
Another reason for the slower response time of the drum could be that a drum brake has a 'self servo' effect. The leading shoe is forced by the rotating drum into the direction of the drum and increases the brake power. But this takes a short while so adds another small delay. I have no idea of how to overcome this effect except for fitting disc brakes to the rear.
Klaus
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It is possible to fit 3 MC in with original floor mounted pedals. This is on an S1 with S2 Spyder frame. Tight but works.
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First, I should mention that I have Banks vented front discs , Banks rear discs, std. dia. M/C, and dual Lockheed boosters. I also have a much bigger chin spoiler than stock.
I have really only noticed the fronts locking up severely (with a lot of accompanying tire smoke!) in panic stops at relatively low speeds. I don’t think I’ve had what you would call panic braking at high speed but I’m sure I have had a reason for heavy braking at relatively high speed and I don’t recall a lot of drama.
I have theorized that aerodynamics plays a part since at low speeds, the front would be “lighter” than at higher speeds. For TC road tests, aero could also play a role since I understand even the stock chin spoiler is effective and I would guess their braking test are probably from higher speeds (60mph+?).
Another factor could be that at lower speeds, you don’t get as much weight transfer to the front wheels.
Just a few thoughts on the issue of front wheel lockups under braking...
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It is possible to fit 3 MC in with original floor mounted pedals. This is on an S1 with S2 Spyder frame. Tight but works.
Is this your car? I would love to see more of how the balance bar was done.
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A couple of interesting observations from road tests back in the day.
Road &Track November Issue, 1973:
The brakes when used as Lotus engineers intended them (slowing for corner), are excellent: good control and easy to modulate. But in panic braking the rear end of our test car locked near the end of the stop, causing the back end to swerve. So stopping distances are only average. We had expected better, especially since the 70-series radials are one size larger at the rear.
Motor Sport February, 1972:
Quite Frankly we were disappointed in the wet weather handling of the car: the rear broke away much more quickly than one would have expected and sometimes the front caught us out and went first...we did not expect this from a Lotus
I can tell you first hand that a panic stop in the rain is not pretty which is why I went to rear discs to begin with.
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That would be with the 1.5" wide drums.
With my S1, I have driven in all weathers and made some strong stops -- I tend to drive so as to avoid full-on panic stops. I have not noticed any issues other than the need to "squeeze" the brakes just like I do on my motorcycles and bicycles.
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@JB: The Fed-spec TCS (1650 lbs.) is 20 to 25% heavier than your S1. Your car's lighter weight definitely has the stopping advantage over a TCS.
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My S1 has Wilwood 4 pots all round (1.75" F and 1.375" rear). I have 13" wheels and I believe the rotors are 10" front vented, rear solid.
That's a notable advantage of multi-pot callipers.
Because they're compact you can utilise larger discs for a given wheel size. Obviously they also increase the torque leverage, too.
It is possible to fit 3 MC in with original floor mounted pedals. This is on an S1 with S2 Spyder frame. Tight but works.
Thanks for the pic, Swift.
Three MC's doesn't look as crowded as I'd imagined.
I kept floor mounted and used a dual master as I didn't want to cut out my frunk. If you want tandem masters you can make it work.
Thanks for the pic, Clifton.
Can't quite figure it out but is the balance bar articulating on a pivot within that structure?
No Gavin, 13" would be very optimistic :)
I'm using 15" wheels. I haven't checked but would imagine that 245mm (GT6) and 240mm would be about the best you could get with 13" wheels.
Ha . . . I'm nothing if not optimistic.
Probably 15" wheels are the go, anyway.
Interesting link, JB.
I hadn't previously devilled into the finer points of twin MC's all that much. It takes very little travel on the balance bar to distribute pressures changes, so that's good.
Here's the notes on the Tilton adjustable prop. valve with some explanation of their workings.
Any glaring issues here?
https://tiltonracing.com/wp-content/uploads/2013/07/98-1261-Brake-Proportioning-Valve.pdf
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Got this article about brake biasing and performance from a site called Brakepedia sponsored by Brakes-shop.com
https://www.brakes-shop.com/brakepedia/general/brake-bias-and-performance
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The problem is that the brake bias we want on clean, dry pavement is entirely different from what we want on a slippery wet road. Other than converting to ABS brakes, there isn't a safe way to get both. The best method would be to fit an adjustable proportioning valve that works via rear suspension height, reducing the rear braking as the rear suspension rises. This would be very difficult to implement.
I think the best compromise is to set up the brakes for clean, dry pavement and use tires that perform very well in the wet.
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Thanks for the pic, Clifton.
Can't quite figure it out but is the balance bar articulating on a pivot within that structure?
https://tiltonracing.com/wp-content/uploads/2013/07/98-1261-Brake-Proportioning-Valve.pdf
Yes, the pivot is at the bottom.
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First, I should mention that I have Banks vented front discs , Banks rear discs,
For the record, I have just ordered spare disc pads for Banks for their ventilated front and solid rear discs.
The front pads are TRW GDB 327, from a Citroen Saxo or Peugeot 106
and the rear pads are TRW GDB 472, from a range of Ford cars.
Equivalent Part Numbers:-
Febi Bilstein: 16169, BELACO: BC398, BORG & BECK: BBP1302, BREMBO: P 24 018, DELPHI: LP507, EEC: BRP0537, FERODO: FDB398, LPR: 05P677, MINTEX: MDB1287, MOTAQUIP: LVXL520, PAGID: T5006, QUINTON HAZELL: BP364, TRW: GDB472, FORD: 1543375 .
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Clifton - is your balance bar adapter custom made?
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Clifton - is your balance bar adapter custom made?
Yes, custom. I used the factory pivot bushings and rod and kept the same ratio on the pivot that Lotus used. The balance bar part is off the shelf. Just the box that holds it all is custom. It bolts to the factory holes on the frame. I ended up adding a remote adjuster to make adjustments easier. If you can weld, it's an easy part to make.
The bias and feel is perfect. Slightly firmer than a vacuum boosted car. I may have had 3 or 4 front inside tire lock ups out of maybe 150 ish autocross runs trail braking into a low speed turn, common. Never both locking when pointed straight.
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I have been thinking about doing the same. I did not think there was room though. What is the pivot bushing? I have a push rod and the MC - what else is there?
What size MC bores did you use?
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First, I should mention that I have Banks vented front discs , Banks rear discs,
For the record, I have just ordered spare disc pads for Banks for their ventilated front and solid rear discs.
The front pads are TRW GDB 327, from a Citroen Saxo or Peugeot 106
and the rear pads are TRW GDB 472, from a range of Ford cars.
Equivalent Part Numbers:-
Febi Bilstein: 16169, BELACO: BC398, BORG & BECK: BBP1302, BREMBO: P 24 018, DELPHI: LP507, EEC: BRP0537, FERODO: FDB398, LPR: 05P677, MINTEX: MDB1287, MOTAQUIP: LVXL520, PAGID: T5006, QUINTON HAZELL: BP364, TRW: GDB472, FORD: 1543375 .
Great information! Thanks!
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I have been thinking about doing the same. I did not think there was room though. What is the pivot bushing? I have a push rod and the MC - what else is there?
What size MC bores did you use?
I thought I used the bushings from the factory but apparently didn't. I have bushings in there I got somewhere though.
I used a 5/8" front master and 3/4" rear. My piston areas are not the same as factory though. I have 4, 1.75" piston calipers front and rear. I do like smaller MC for better feel though. I also drilled a hole about .5" lower on the brake pedal arm for a better pedal ratio.
At least on an S2 the pushrod goes to a pivot then to the master. I used that same pushrod and made the pivot mount center to balance bar center the same as the factory distance.
To do again I would push the center point of the balance bar out further away from the frame as the remote adjuster mounted on the wheel side is very close to the lower control arm.
Second pic is the factory pivot sitting on the factory MC mount.
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I have a non-stock MC. So, have never seen the pivot. Maybe not on the TC?
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I have a Spydercars frame head on my S2.
Do you have a drawing or sketch of your mount?
Brand and numbers for the MC's?
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Twin Cam just has a normal rod that goes from the pedal to the master cylinder.