Yet another Tandem Master Cylinder installation

[EuropaTC]

Ok, yet another tale of someone installing a non-OEM master cylinder in their Europa. This probably won't be of great interest to you guys on the left of the pond, but for anyone with a UK or European car it might be of help. So here goes. 

The standard system consists of a single circuit m/cyl of 0.7" bore with servo assistance. I replaced the m/cyl with a 0.75" one several years ago and thus had a slightly higher pedal pressure with less travel.  The single servo is located in the engine bay & brake pipes convey fluid from the front to rear servo & then back again for the front brakes.

The plan is to replace the single circuit m/cyl with a tandem m/cyl at 0.7" bore, to remove the servo assistance and replace the front pads with Greenstuff pads in the hope that this alleviates the lack of servo assistance. If pedal pressures are unacceptable then to re-install the original & a second servo unit as per the US spec Europa Specials.

The OEM m/cyl as used on the Export Spec Europas is now very difficult to source and appears to be only available via specialists  at appropriately high prices. (£180 seems to be the going rate if you can find one). However there are more affordable options available if you are prepared to do some modifications and as such I purchased a tandem m/cyl intended for the Triumph Spitfire 1500, part GMC226 for approximately £75. This has the same bore and flange pattern as the existing single circuit m/cyl although the actuating rod will need to be swapped over for the Lotus one.

Image01

However this will not be a straightforward installation. Firstly the reservoir is a push-fit & sloping wedge-shaped item because the m/cyl is mounted at an angle on the Triumph bulkhead. This isn't a big deal because the Europa needs a remote system anyway whatever cylinder is used.

The second problem is that the brake pipes exit on the LHS of the cylinder. On a LHD car this isn't an issue as they exit towards the wheel arch where there will be plenty of room, but with RHD I found that the secondary circuit pipe was a very tight fit against the fibreglass floor of the front compartment.

I decided to modify the bodywork underneath the radiator to give more access for the front brake pipe outlet. Although not essential, this will make installation and maintenance easier in the future and there will be no significant impact on the radiator mounting or front boot space.

Image02

So a small cut-out was made as shown in the photograph, using a combination of dremel & hacksaw blades from either above or below. A repair section was moulded by the simple process of making a cardboard template, lining this with tin-foil & then laying up 2/3 layers of matting. I removed this from the mould in a plastic state which allowed me to offer it up to the hole & trim where necessary using a pair of scissors - much easier than when the resin has full hardened !

Image03

Then it's simply bonded into place as shown in the photographs, finished off with surface tissue, left overnight & then given a coat of matt black paint to tidy it up. It's not the world's neatest job but it looks on a par with the rest of the boot interior and is certainly fit for purpose.

Right, the next stage is to remove the OEM part & bolt in the new one. As can be seen from the next picture, the actuating rods need to be changed over, or at least the Tandem push rod needs modifying & threading to accept the Lotus extension. I decided against modification because the diameter of the new one is slightly less than the OEM rod and hence the resultant thread didn't look strong enough to me for a critical item.

Image04

New m/Cyl modified and it's installation time, a simple bolt in job.

Points to note - the new cylinder has metric threaded fittings for the brake unions so you'll need some modern couplings. I used new brake pipes rather than modify the old ones, the cost is minimal and although it takes more time, it's much easier to work with new materials than old. The primary circuit goes to the front brakes, the secondary to the rear brakes on a front/rear split.

Image05

The reservoir now needs to be remote, and as with the OEM installation, it is all very close to the steering rack bellows. I used 90deg plastic elbows coming out of the first chamber and a straight connector for the second (forward) chamber. In truth the new installation is fractionally lower than the OEM m/cyl & brake pipe but I still decided to fabricate a small aluminium cover, as shown in the photograph, to isolate the rack bellows and the filler pipework.

Image06

The two filler pipes go through the original hole into the front boot with the new 2 chamber reservoir mounted on a new bracket in the same place as the OEM single reservoir. I might change this at some point to include a low level switch, but for now it's acceptable. (You can also see the yellow dust and overspray from last summer’s respray still hanging on in the radiator, fan and other places you don’t normally see from the driving seat ! )

Well, how different is in practice with no servo and a smaller m/cyl bore ? Hmm, now this is a strange one. I know the servo was working properly and as expected the reversion to a 0.7" bore has restored the pedal travel to it's original design, but the overall impression is that removing the servo has had very little impact on the braking performance in terms of pedal pressure. It's still very easy to lock the front wheels with a deliberate stab to the brake pedal, and if you brake normally with a gradual increase in pressure then basically there's nothing to choose between the systems in terms of usability.

Edit to add:

PDF file with the pictures  inline with the relevant text, plus an update from 2016. The same m/cyl but with different pads (Mintex M1144) and pedal leverage ratios.

[LotusJoe]

Nice documented modification. 

[3929R]

Nicely done.  Thanks for posting the write up.

Well, how different is in practice with no servo and a smaller m/cyl bore ? Hmm, now this is a strange one. I know the servo was working properly and as expected the reversion to a 0.7" bore has restored the pedal travel to it's original design, but the overall impression is that removing the servo has had very little impact on the braking performance in terms of pedal pressure. It's still very easy to lock the front wheels with a deliberate stab to the brake pedal, and if you brake normally with a gradual increase in pressure then basically there's nothing to choose between the systems in terms of usability.

  I never got to drive my car when it had servos.  I am happy to hear another testimony that I'm not missing anything.

[EuropaTC]

Hi, thanks for the comments guys.

Incidentally I don't want to give the impression that the servo doesn't do anything at all, just that there are other options available.  I think if you want to remove a servo you need to look at pad materials because the OEM spec was for a harder pad if a servo was fitted. The EBC Greenstuff pads I've fitted are known to have a good "bite" on non-servoed systems although over here folks use them on both.

Brian

[YellowS4DHC]

Europa TC,
Your write up was very, very helpful to me - and timely too. 

I just acquired a Federal TC that, for some reason, didn't have a tandem M/C; the PO modified it back to a single M/C configuration and without the servo.

After reading your article, I bought and installed the Spitfire M/C and replaced all the front bundy lines.  All very easy since my car is LHD.  You even forewarned me about the metric fittings on the M/C.  I got motivated and went on to rebuild both calipers (pistons were crap).  All I need now are some EBC pads.

Thanks for taking the time to document and post your work, you made life easier.

Rick

[EuropaTC]

Hi Rick,

You're welcome, I'm glad it was of some use.  In practice it's a fairly easy swop, I'm sure others have gone the same route before and I'm surprised it's not a more popular option because these parts are readily available. (actually the metric threads caught me out the first time I used this m/cyl, it was one of those "doh" moments  )

Brian

[Bainford]

Thanks for the info Brian. Very interesting. Did your car have a remote reservoir from new? The reservoir on my car is not remote, though the m/c is mounted so low in the car that it almost seems as though it is no higher than the calipers. I am planning some improvements to my braking system, including  redoing all of the brake lines to get rid of the mess in the engine compartment. The boosters have been removed from my car by the original owner, but the brake lines are a mess as a result. Fluid for the front brakes goes all the way to the rear to the 'brake fail' switch and boosters (when they were there), then forward to the calipers. My plan is to get rid of all this mess and mount the fail switch up front near the master cylinder. I may consider fitting a remote reservoir at that time to make brake service more convenient. The m/c is so low that I can't see how it works, and will be even worse when I fit the 1" lowered springs on the front.

For the record, my car is fitted with a .7" bore master cylinder from a Lotus 7, or some variant thereof.

[EuropaTC]

Did your car have a remote reservoir from new?

Yes, I thought they all did ? The new dual chamber reservoir is mounted pretty much in the same place as the original single chamber was, just on a new bracket.

I think 0.7" is the correct bore. Mine was originally that but at one point I fitted a 0.75" to see how the car felt with less pedal travel. In junking the servo I decided to revert to a smaller one just in case I couldn't press the pedal hard enough to stop 

I haven't installed a fail switch circuit. Yes, I know, only doing half a job......    But seriously I don't see why it's needed if you install a brake fluid warning system, which is the next part of the change, it just seems to complicate matters to me. I don't really need to know if the front or rear circuit has failed, a drop in fluid level is enough to panic me anyway !

Brian
 

[Bainford]

I haven't installed a fail switch circuit. Yes, I know, only doing half a job......    But seriously I don't see why it's needed if you install a brake fluid warning system, which is the next part of the change, it just seems to complicate matters to me. I don't really need to know if the front or rear circuit has failed, a drop in fluid level is enough to panic me anyway !

Brian

I wonder if the m/c mounted reservoir is a federal thing.

The 'fail switch' is an integral part of the dual circuit brake system. The 'switch' (poor terminology, my bad) is a shuttle valve that isolates the failed part of of the system. In the event of a failure in one of the brake circuits, the shuttle moves within its housing blocking off the part of the brake system that has 'opened', thereby preventing further fluid loss and preserving the integrity of the remainder of the circuit. Of course, it also incorporates an electrical switch to illuminate the brake warning lamp on the dash.

I guess the problem with not incorporating this unit in the system would be uncontrolled fluid loss in the event of a system rupture. All of the fluid in the reservoir would be lost.

[EuropaTC]

Oh, I didn't realise that circuit isolation was it's primary function, from the instructions on bleeding the system I'd assumed it was primarily a warning system and that the primary and secondary circuits would operate independently from the master cylinder.   Again using that dangerous "assumption" I'd thought that a leak on a single circuit would empty all the fluid in that circuit, but as the reservoir has separate chambers for front and rear circuits, the losses would be restricted to the relevant chamber and highlighted by a drop in fluid level before it got down to the individual compartments.   That just shows what having a little knowledge and guessing the rest does for you.....      

I'd better sort one out then, thanks for the heads up 

thinking aloud - if your reservoir is mounted directly on top of the m/cyl and hidden in the wheelarch, how on earth do you manage to top it up or keep an eye on it ?

[LotusJoe]

to help add to the confusion I found this explanation on the Pantera site. 

http://www.panteraplace.com/page89.htm

I also found a picture of a shuttle valve.



Looks pretty close to the one used in our car.

[YellowS4DHC]

Brian, you asked:

thinking aloud - if your reservoir is mounted directly on top of the m/cyl and hidden in the wheelarch, how on earth do you manage to top it up or keep an eye on it ?

On my '72 LHD Federal TC, the tandem Spitfire M/C is directly beneath an access hole in the floor of the "trunk' right next to the spare tire.  It's pretty easy to see the fluid level if the tire is removed, and even easier to see by just looking in the left wheel arch.  I assume the access hole is original, and not something done by a PO.

Filling from above (through the access hole) will require a bit of dexterity and removal of the spare if you choose to decant directly from the can.  I used a turkey baster with a bit of tubing.  If you're careful, you don't spill or introduce bubbles into the fluid.  I've used this before on my other cars to draw off and refill clutch and brake reservoirs and it works pretty well.

Rick

'72 Europa TC

[EuropaTC]

Hi Rick,

Thanks for the photos, they explain things so much better ! 

As usual, it raises more questions - is your m/cyl mounted on a spacer to step it away from the chassis ?  If so, I can see how it all goes together and you have much better access to the brake pipes than I have on my car.  I wonder when that was introduced into the production line or if it's just fitted to LHD cars ?   

Mine was mounted directly onto the front cross member with threaded inserts in the chassis and I'm fairly sure it was OEM when I got the car. Even with the single circuit m/cyl this meant that the brake pipe was a tight curve and touching to the beginning of the rack bellows, although in practice it didn't wear the rubber. 

If yours does have a spacer block, I'm surprised there wasn't one fitted to the single circuit m/cyl as there is enough space and it would have made life so much easier. 

Brian

[Bainford]

I also found a picture of a shuttle valve.

Nice find, Joe, and it does indeed look similar to the units found on our cars. Looking carefully at the illustration, it does not support my suggestion of circuit isolation in the event of a line rupture. My explanation above is an attempt to pull a distant recollection from my auto shop days at trade school. I have just done a little quick online research and can find no evidence to suggest circuit isolation is a function of this valve. It appears to be merely a warning switch. All this time I've had the function of this component wrong.    Apologies all around for spreading false information, and especially to you, Brian.

[EuropaTC]

Apologies all around for spreading false information, and especially to you, Brian.

Absolutely no problem at all, that's what forums are all about.

Your comments made me sit back and think about the set-up and before Joe posted the schematic I did wonder if the valve shut down one circuit completely how you were meant to bleed the brakes. But I've never seen inside one of those valves so had no idea.   I couldn't work it out and so decided that when my new tandem reservoir arrives with it's low level fluid gizmo, I'd open up one circuit and keep pressing the pedal to lose all that circuit's fluid and see if the other circuit would still apply the brakes. 

Very crude, very simple and exactly the sort of experiment I can relate to.... 

Incidentally that's a very cool website you found Joe, we don't see many De Tomaso's over here. I've always liked the Pantera, a real sort of in-your-face supercar, totally impractical on our UK roads but I'm sure I'd struggle through with one.....

Brian