Lotus Europa Community
Lotus Europa Forums => Garage => Topic started by: JeffBatt on Friday,March 11, 2022, 02:07:02 PM
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I’m trying to rough in the rear toe on my special.
Spec seems to be 1/8” to 1/4”. Can anyone confirm if this is per wheel, or total?
Thanks! (Seems like I need to used a ton of spacers. Seems wrong…)
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Those specs in the workshop manual are for the total toe. A lot of guys here have tended to use a toe toward the smaller toe measurement.
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So, spec is 1/4” total max for a twincam? (i.e. 1/8” per wheel)
Thanks!
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Right.
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Thank you!
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Having just gotten new bushings for the trailing arms, and needing to reduce my toe from a recently measured 5/16 total, I would be interested to hear how much of a difference a single pair of "normal" washers would make to the toe.
I unfortunately don't have the washers here to measure. I'd like to minimize the number of iterations required to complete this.
Thx!...Vince
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Having just gotten new bushings for the trailing arms, and needing to reduce my toe from a recently measured 5/16 total, I would be interested to hear how much of a difference a single pair of "normal" washers would make to the toe.
I unfortunately don't have the washers here to measure. I'd like to minimize the number of iterations required to complete this.
Thx!...Vince
I'm thinking that you'll need 2 iterations; frequently toe on the rear is reduced when new bushings are installed, in my experience, since the bushings have a tendency to sag inward as they age. Bolt up with what you have, take the reading, and you'll know where you need to either leave alone, add, or remove. But, predicting beforehand is hard without knowing your starting point with fresh metalastic units in place.
Just a suggestion.
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I would say there really is no “normal” washer thickness. AN washers come in two thicknesses in that size bolt (0.032” and 0.062”). Alignment shims which should be available at parts houses or even Harbor Freight have specified thicknesses and are handy because you don’t have to unbolt the joint to put them in.
I think in the past, someone has posted the change in toe from a certain sized washer. Maybe he can remind us again.
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1/4" seems excessive, I would have thought 1/8" total toe in, 3/16" absolute max, so 1/16" per wheel, 3/32" per wheel max
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I'd be cautious as you really don't want it to go to toe-out during cornering. You have track time to dial it in? Great! Setting up for the road? I'd keep to at least the minimum spec. Also, don't forget to check your rear thrust angle.
As an aside, Tim Engel checked with the factory back in the day and was told the rear toe spec was not across the axle but for each individual wheel. Certainly the S1/2 spec seems that way. The TC/S spec less so.
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Thanks for the advice. I'll check the manual, and then ask some expert(s) before finalizing things.
I did my very first run over 60mph the other day. 70 for a short period, then 75 briefly. There was a truck in front of me. I didn't really want to pass him. One step at a time, if you catch my drift.
I didn't sense that there was really anything wrong, but just going straight certainly demanded my attention.
I'm not exactly sure what's to be expected, but some reading tells me that handling could be very sensitive.
-VI'd be cautious as you really don't want it to go to toe-out during cornering. You have track time to dial it in? Great! Setting up for the road? I'd keep to at least the minimum spec. Also, don't forget to check your rear thrust angle.
As an aside, Tim Engel checked with the factory back in the day and was told the rear toe spec was not across the axle but for each individual wheel. Certainly the S1/2 spec seems that way. The TC/S spec less so.
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I’m going to need about 12-15mm of spacers per side to even hit 1/4” total toe-in.
Bought some of the Esprit spacers because I don’t want to stack that many washers. I also have some very thin shim washers from McMaster, but I’m not sure if I’ll need to fine tune quite that much.
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1/8 - 1/4” per wheel for a TC, measured at the wheel (not tire)? Wonder if I should start there rather than total..
This kinda makes sense in that I’m shocked how many spacers I need to hit spec.
I'd be cautious as you really don't want it to go to toe-out during cornering. You have track time to dial it in? Great! Setting up for the road? I'd keep to at least the minimum spec. Also, don't forget to check your rear thrust angle.
As an aside, Tim Engel checked with the factory back in the day and was told the rear toe spec was not across the axle but for each individual wheel. Certainly the S1/2 spec seems that way. The TC/S spec less so.
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I have heard, in the foggy past, that occasionally the front bushing is mounted inside out. That is, mounted such that the attachment is sifted inboard by the thickness of the bushing witch is around 15 cm. Could this be the issue?
Ron
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I have the bushings bolted to the outside of the frame, with the thick rubber sections facing inward.
I think this is how they’re supposed to be? With the thick rubber section facing out, I’m not sure if there would much room for adjustment?
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On the first production S1s, the bushings were bolted with the flange on the outside and bulk of the bushing facing inwards. This led to a situation where the rear wheels were toed out with no adjustment left. The factory did a production change and issued a bulletin to fit the bushing flange on the inside of the chassis to provide enough adjustment (still with bulk of bushing to the inside). I believe this is true for the TC/S as well.
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Jeff- how much toe (in or out) do you have now?... and can you recommend a specific supplier for the Esprit shims? I may buy them, but I'm reluctant to buy a bunch of them without having some idea what I really need.
-Vince
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This is how I have the bushings attached right now.
Vince - looks like sjsportscars has them, found them cheaper but in 5mm thickness here, looks like they also have 2mm:
https://www.pnmparts.co.uk/lotus-shim-4052
My plan is to use 10mm of Esprit spacers on each side and then fine tune with a few washers. I could be more simple if I reversed the bushings but that might make them stick too far out.
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Thanks;... but what did you measure for toe before you start shimming?
-V
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Is the body removed, Jeff?
If so, check to make sure you can get the long bolt out with the body in place.
On the S2, the bolt head needs to be on the inside of the chassis - don't know if this applies to the TCS so hopefully, someone will chime in on that.
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:I-agree:
I'm almost positive it also pertains to the TC. In any case, it's better to put the bolt in from inside the frame if you don't know.
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Yep, the body is off but I will flip the bolts around, there will be no way to easily get them out like this with the body in place.
It isn’t actually shimmed yet, but I aligned it with toe plates and a string referenced to the center of the backbone to figure out about how many shims I’d need. It’s just sitting loose.
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With no shims, there is a ton of toe in, think it was around 1” total measured at the tires but didn’t have my string in place yet to know more exact.
Was shocked it was that much.
Thanks;... but what did you measure for toe before you start shimming?
-V
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It isn’t actually shimmed yet, but I aligned it with toe plates and a string referenced to the center of the backbone to figure out about how many shims I’d need. It’s just sitting loose.
What's a "toe plate" ? . . a plate attached to the hub face to measure toe, presumably?
JB mentioned checking the thrust angle and this is probably an ideal time to do it while you can see the chassis centreline and are playing around with shims & string etc.
I've often wondered how precise this was when they came out of the factory.
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Toe measurement plate:
I'm new with this, but it seems quite good. I believe that most of them just lean against the tire. I like that these rest against the wheel, using standoffs; seems like better precision to the measurements.
-Vince
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I would wait until the body is on. That will lower the suspension and alter things considerably.
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Toe measurement plate:
I'm new with this, but it seems quite good. I believe that most of them just lean against the tire. I like that these rest against the wheel, using standoffs; seems like better precision to the measurements.
-Vince
The problem with that sort of device is that it's hard to get a true centreline and as JB posted, it's easy to get the thrust angle wrong because you're only measuring overall toe relative to the wheels, not centreline. Having said that, I often use a similar device for front toe because it's easy to set up & very quick to do.
For DIY alignment my personal preference is for the basic string box method. Time consuming to set up but very low tech and you can even do the maths to allow for some error in aligning the "box" with the centreline. That gives a good indication of toe per wheel which is what you need at the rear otherwise the car's never going to feel right.
Shims - I also use the Esprit style shims and also needed far more than I expected to get within spec, I can't recall off hand but something like 8mm comes to mind and that was why I moved from washers to the Esprit style. If you need more than the odd one or two (like I did) then you can easily make them up from Aluminium plate with thinner ones to get the final setting if you can't get the right plate thickness.
Brian
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Aligning the string to the center of the chassis is (obviously) much easier with the body off.
I’ve got Avo coilovers, so I will do this alignment with them lowered all the way down and then raise them slightly before putting the body back on. I imagine it will end up pretty close.
Anyway, my goal with the Esprit spacers is to just keep the washers to a reasonable number of about 5 or less per side.
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Nice toe plate!
I truly think you can get as good, or better, an alignment than you would at most shops that use lasers just by taking your time and being diligent with your measurements.
Toe measurement plate:
I'm new with this, but it seems quite good. I believe that most of them just lean against the tire. I like that these rest against the wheel, using standoffs; seems like better precision to the measurements.
-Vince
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The problem with that sort of device is that it's hard to get a true centreline and as JB posted, it's easy to get the thrust angle wrong because you're only measuring overall toe relative to the wheels, not centreline. Having said that, I often use a similar device for front toe because it's easy to set up & very quick to do.
Brian
Understood, Brian.
I got the toe plates most specifically because I was doing front suspension work and wanted to check alignment there after replacing the tie rod ends. I know that using them I won't get a full reading on the condition of the rear, but figured it would be a good idea to get a baseline reading on the rear toe anyway, with thrust angle to be determined later.
I want to update the brakes (no boosters present) with a Spitfire master cylinder, and while I'm at it figured I should replace the 40 or 50 year old rear brake hoses. So that leads to also replacing the trailing arm bushes (maybe original) while I'm working there... Which leads to dealing with rear alignment. So as you see, the plot thickens!
I appreciate the info from Brian and Jeff to give me an idea about what I might need for shims. I'll try to get a rough measure of how far the trailing arms are set from the frame presently and work from there I think. I'd rather not bite off all this at once (It's a lot to chew), but maybe it's the right way.
It was interesting and revealing, doing the measuring / adjusting / driving / re-adjusting on the front. Initially I had way too much toe. I was surprised to find that it made handling very squirrely, but it was about about 1/2 in., so a lot!
-Vince
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While I'm thinking about it, I'll say: information from Tim Engels, who seems to be very knowledgeable, is that at the rear, anyway, toe specified in the shop manual is measured at the outer diameter of the wheel rim, and is for one side, not both.
So, looking at the maximum toe of 1/4 in. specified for a TC, and measuring it on my 185/70-13 tire, about 23.2 in. diameter, with the stock Lotus steel wheel rim of 14.25in. I would get:
23.2/14.25 x .25in. x 2 (across both wheels), giving a max toe at the rear of .814 in., measured at the outer diameter of the tires.
One of the Engel references is here: https://groups.io/g/LotusEuropa/message/164808 . The other, about one vs. both wheels, is elsewhere :)
I'm not the expert! If anyone has other ideas, feel free to chime in.
-V
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I used what Elise guys use as their weight and wheelbase are nearly the same. S1 Elise is 1550 lbs.
I just went out and measured and I am 5/32" total toe in on the rear using 24" long toe plates. My car is one hand, stupid steady over 100 mph. I was 120 last Sunday for a second, 80-90 the rest. Too much toe in will make a car wander too.
https://wiki.seloc.org/a/Geo_Setups
https://trakkrats.com/technical-info There's a alignment pdf download
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Fotog, I would think toe at the rim would be less than toe measured at the tire edge, given the same angle. And .814 is more than .5. If you invert the tire/rim ration, it gives 0.307 total toe between wheels. I might be way off. I'm just trying to understand what you're all doing for when this comes up for me.
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1/8” per wheel is 1/4” total - think that would be in spec however it is supposed to be defined.
So, I’m shooting for just under 1/2” total measured at the tires.
While I'm thinking about it, I'll say: information from Tim Engels, who seems to be very knowledgeable, is that at the rear, anyway, toe specified in the shop manual is measured at the outer diameter of the wheel rim, and is for one side, not both.
So, looking at the maximum toe of 1/4 in. specified for a TC, and measuring it on my 185/70-13 tire, about 23.2 in. diameter, with the stock Lotus steel wheel rim of 14.25in. I would get:
23.2/14.25 x .25in. x 2 (across both wheels), giving a max toe at the rear of .814 in., measured at the outer diameter of the tires.
One of the Engel references is here: https://groups.io/g/LotusEuropa/message/164808 . The other, about one vs. both wheels, is elsewhere :)
I'm not the expert! If anyone has other ideas, feel free to chime in.
-V
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All these numbers sound like a lot ….why so much toe?
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The spec for a TC is 1/8” to 1/4” inch toe-in when measured at the edge of the wheel, so almost 2x that when measured out near the tire edge.
There is some uncertainty if the spec is per side, or total. It is a lot of toe, but that’s the spec, so…
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Turbo: I don't know. I'm not generally knowledgeable about this stuff. I'm only trying to interpret what I read, either in the shop manual or on forums.
Kendo: you say: " I would think toe at the rim would be less than toe measured at the tire edge..." That's correct.
So, if Lotus says maximum 1/4 in. when measuring the toe across the diameter of the wheel, well, of course it would be greater measured at the outer edges of the tire. That's where I get 23.2 (tire diameter) / 14.25 (wheel diameter) x specification (1/4 in.) Make sense?
They say minimum is half that, so that would be ~.4 in. measured across both tires. That agrees with Jeff's goal.
And Clifton: That's interesting! At this point I can't imagine going over 100, much less 125. Crikey! But useful to hear your experience. Thanks.
I'm trusting what Tim Engel has said, but I think he's generally trustworthy. I believe he spoke to someone at Lotus to confirm where and how the measurements are made.
-V
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Tim also runs very little rear toe and actually a small amount of toe out at the front. He likes the quick turn in.
I stick to the minimum front spec and middle of the spec in the rear.
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And Clifton: That's interesting! At this point I can't imagine going over 100, much less 125. Crikey! But useful to hear your experience. Thanks.
I'm trusting what Tim Engel has said, but I think he's generally trustworthy. I believe he spoke to someone at Lotus to confirm where and how the measurements are made.
-V
The speed was just to say my alignment settings are good and stable at speeds higher than most Europa's can or will ever even go. 100 is reached quick and done often and the car is autocrossed monthly. The 1/2" rear toe in Jeff wants to try may work if it's a neighborhood driven car but it is not safe or optimal and will murder the tires. 1/2" in will not be a fun drive over 60 mph.
3/16" toe in on the front is way too much. 1/16" total in to a light 1/16" out feels much better.
The workshop manual for an S2, yes TC is heavier but it's the same car.
http://lotus-europa.com/manuals/s2work/c/index.htm#4
javascript:ShowWin3('../tech/index.htm#J',800,600,20,20,'S1/S2%20Technical%20Specifications.')
Front Toe - in 3/16 in. (4.76 mm.) to 1/16 in. (1.6 mm.)
Rear Toe - in Zero to 3/16 in. (4.76 mmm.)
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The 1/2” I’m talking about, measured at the tires, would be equivalent to 1/4” when measured at the wheels, as per the spec. I agree it will wear tires faster than less toe, but not sure why it would be dangerous? It is, after all, the spec for the TC.
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I agree with Clifton's recommendations. 1/2" total toe in is way too much. I also own a Superformance GT40 and have raced various formula cars over many years. All the cars had less than 1/4" total rear toe. I think your assumption that the toe spec is per wheel is wrong. "Too much rear toe in causes the car to feel light and unstable on corner entry" per Carroll Smith in his book 'Tune to Win'. Smith was a lead engineer in Shelby's GT40 team.
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A little under 1/2” total at the tire diameter is about the same as 1/4” total measured at the wheel diameter, that’s what I’m saying. By total I mean the sum of toe-in for both the wheels.
The spec is to measure at the wheel diameter. My toe plates are closer to the tire diameter, which is where I’m taking the measurement from.
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My previous toe figures are all at the tire. Despite all our advice you seem to be determined to have 1/2" total toe so try it.