Ruining wishbone bushings, possibly due to bent wishbone(s) ?

[BDA]

I'm not convinced they are bent. First, they don't look bent. The TC/TCS workshop supplement says the lower arms for the S1/S2 are the same as for the TC/TCS and it is incorrect. It might be that dimensionally, they are equivalent, but I would need confirmation. The TC/TCS have the tube for the shock bolt that yours has but the S2/S1 does not. Without going through a long story, my car ended up with a pair of S1/S2 lower arms and whether it was because of them or something else, I could hardly move the suspension at all. It was a long time ago and as I say, there were other variables so it is possible that they are interchangeable but as I say, without confirmation I wouldn't do it.

According to the parts manual, there are two different arms for the TC/TCS. It's possible that you have two leading arms on one side and two trailing arms on the other or maybe some even more complicated combination. For that matter, I may also! Yikes!

If someone can give the proper dimensions, that would be a big help.

[Grumblebuns]

Peter, your little problem got me thinking on the straightness my control arms. After I get my electrical issue fixed, it looks like I'm going to have to go back and visit my front suspension again, and I thought I was done with the mechanicals on 1098R. I also have a TCS with it's front end up in the air for brake work. I'll have a look at it's control arms and see what it measures. All this will be in a few days, I need to get the blinkers and brake lights working on 1098R first.

On the S2, to compensate for the huge gap between the control arms and the mounting holes in the uprights and shock, I used washers and I offset the bush slightly on the inner sleeve of the control arm where it pivots on the chassis point. Probably not recommended but I was out of options at that point.

Joji Tokumoto

[pboedker]

BDA, as far as I read the parts manual, the lower arm pairs ar interchangeable, i.e. the trailing on the one side becomes the leading on the other side ande vice versa. That's why it needs 2 of each of the CA20 and CA21. These have parts numbers from the type 65, so they could very well be different on earlier models. I will dismantle the left side now, to make sure that they aren't bent too, but I believe they should measure 59mm as the workshop manual says.

The upper arms are 4 different ones, the leading two with a S1 part numbers, the trailing two with type 65 part numbers. The trailing ones are those that moved from 'inside the chassis' to 'outside the chassis' during production run. So only the leading arm measurements from the workshop manual can be valid, since the manual is showing early S2 dimensions. Yes, measurements that are definitely TC/TCS valid, could be really nice.

Thanks, Joji, I appreciate all the measurements I can get. And if nothing else, this might be a heads up to others to measure the parts properly on reassembly before pulling the bushings apart as I did.

[BDA]

Oops! Sorry for the brain fart about the two different parts!  But it is a relief that I didn't put my front suspension together wrong! 

From your measurements, Peter, I would think that something that far off would be obviously bent. I don't see that from your pictures. Hopefully Joji's measurements will shed some light on this.

I know I remember posting about this issue to the yahoo group and finally found my post and an explanation of what was happening. Here it is:

Jim Grunewald wrote:

> I found
> driver's side leading lower A-arm was pushed toward the rear about a
> 1/2". The interior metal sleeve is proud of the rubber part which is
> proud of the outer metal sleeve. The outside metal sleeve is properly in
> the A-arm (I took some pictures that hopefully show what I'm talking
> about in an album entitled "Interesting bushing failure").

This is a relatively well-known issue, and there are two independent
possible causes. The first one was documented in an early issue of ReMarque.
I've brought it up on the list in the past. This problem is most often
caused when aftermarket dampers are fitted. Typically the lower mounting
bushings of the replacement dampers are shorter than those on the OEM
dampers, the result being that there is a clamping force that tends to
deform the inner bushings. Konis are known offenders here. The solution is
to add spacers to the damper lower mount bushings. I measured the space that
had to be filled with the suspension fitted less dampers, then added the
necessary spacing to the lower damper mounting bolt during reassembly.

The second issue is caused by reaction to braking force. If this is the
cause of the problem, you will see both halves of the lower A-arm shift
rearward at the inner pivots, with associated deformation of the bushings. I
placed washers at the rear of both inner bushings to prevent this motion,
and it has worked very well.

Along the way, I also found this post to the yahoo group:

jcpeters1@shaw.ca
Date: Wed Feb 25, 2009 9:30 pm
Subject: Banks on Poly - Nylon front bushings

This thread was interesting as I considered going with these bushings last year.
I have modified suspension and my decision was made to stay with stock when I
spoke to Richard Winter (who happens to also sell hard nylon/brass ones). He
indicated that on his team cars he is finding the hard bushings are leading to
too much chassis damage and is not recommending them any more. As someone else
noted the Europa wishbones and chassis are not robust enough to justify the
minor reduction in deflection gained especially on a street driven car. Just my
2 cents worth.

Chris.

[pboedker]

OK, so the left side were also bent: The leading arm was 71mm (+12mm) and the trailing arm was 54mm (-5mm). Of course these measurements are not very precise being done with a ruler on the kitchen table. But they do indicate some difference.

It's not possible to see anything wrong or bent with any of the suspension arms, however holding the mounting plane to the table top the measurements speak very clearly and it is also easy to compare two arms next to each other to see the difference. Inserting a 1mm shim under either hole at the mounting end is multiplied to 4-5mm at the bushing end due to the length of the arm.

Now, when I overhauled the suspension in the winter, the lower arms might have been mixed left/right or diagonally. They can be combined in 4 ways as they should measure the same. One combination of my bent ones gives almost the correct inner width 118mm at both sides with the right side almost within spec. but the trunnion position of the left side appr. 10mm to the rear. My theory (speculation?)  is that the suspension arms were originally combined like this, but the left side hit a bump and got bent. I don't know. Pot holes are everywhere.

I've decided to replace the one ruined bushing, and refit the arms, using the 54mm and 57mm ones as trailing arms and with a washer on EACH side of the bushing. This should locate the trunnion at about the correct place, and since the top arms appear OK (I will loosen the nuts and check that the bushings aren't clamped together) the wheel alignment should be OK. Then I will shim the trailing arms at the trunnion/damper to make sure that the bushing in the two 48mm and 71mm arms are not stressed.

[BDA]

Great work, Peter!! I wonder if this is just a case of poor quality control... In any case, it seems like you have a pretty reasonable solution.

[Grumblebuns]

If I find that mine are bent, I will probably order replacements and I'm still not too clear on which arms are interchangeable with which car, S2 vs. TC.

I'm still trudging along on my S2 electrical issue. I finally got the two relays in the DB10 relay box freed up so they now operate. Now need to move on to the individual lights one by one.

Joji Tokumoto
Fallbrook. CA

[BDA]

Joji,
I'm not sure if there are any dimensional differences - from Peter's measuring, it seems they are similar - but the TC arms have a tube for the bolt at the lower shock mount where the S1/S2 arms are flat there and don't use a tube for the lower shock mount. To my knowledge, this is not shown in the workshop or parts manual. It seems odd that they would make it more expensive to make a TC arm unless there was a reason for it. It could be that the the lower shock bushing was a bit wider on the TC or something similarly benign. I thought I had spare S2 and TC lower arms, but so far I've only found the TC ones.If I find the S2 arms, I'll try to take some measurements and post the results.

Congratulations on your progress on the electrical front!

[Grumblebuns]

When I get to attacking the suspension of both the S2 and TCS, I'll try to get some photos posted for comparison and measurements. In the meantime, I'll check the KB later on in the week.

By the way, Ray at RDEnt. has new and used wishbones listed on the website.

[Grumblebuns]

This afternoon, I managed to remove and measure the lower right side suspension arms for one of my non running TCS. These are the dimension #4 measurements of both arms.

lower trailing half: 44 mm
lower leading half: 89.7 mm

Just by visual observation, it's obvious that both arms are bent. The front (leading) arm being the more severe. I'm assuming that both arms on one side are suppose to be mirror opposites with the centerline of the holes being parallel to each other. Look closely at the pictures of the inner bushing with the 1/2" bolt hanging off of them. It's obvious that both are bent from the angle of the bolt from vertical. I need to measure a new undamaged front wishbone set to validate my measuring technique. I'll check the right side suspension over the weekend and report my results.

[pboedker]

Thank you for the update, Joij, your measurements show that something is clearly wrong with that side of the suspension. Sort of the same situation (bent backwards), that I think I had originally on the left side, before mixing the arms. The angles of the bushings can't be good to them either. Could be interesting to see the measurements from the left side arms too.

I owe an update myself, because since I refitted the suspension arms to my car and shimmed the trunnion/damper to try to better locate the outer ends, I have seen a very noticeable and better handling of the car. It must be the caster angle that does it, though I still need to confirm by measurement that it is now back within specs. The car is much better at high speeds, and where I before had white knuckles when driving 100km/h and above 120 wasn't really possible because it was all over the road, on the first test drive I now did 130km/h with one hand on the wheel and doing 150km/h was OK with two hands. Also slow speed handling, like e.g. through a roundabout is much more predictable than before. This is definitely something I will examine further, since it has 'put the fun back into motoring', as I think one of the contemporary road tests named it.

[buzzer]

Yep clearly bent, you last pictures shows that very clearly. and might be worth checking the chassis while you are at it, I would expect the arms to take all the hit, based on the amount of deformation,  but be worth checking out as you have everything unbolted.

Dave

[EuropaTC]

If poly is the answer, the Autobush poly bushes are not so costly - http://www.autobush.com/Lotus/Elan%20Twin%20Cam.htm

Resurrecting this thread, I've decided to try a set of these bushes and placed the order this morning. Cost for UK delivery was £45 for a set of 8 bushes with stainless inserts. I'm still bemused by the cost, I'm sure they were much more expensive in the past. My first thoughts were "cheap polymer" but reading their website it would appear not and to be an engineered product.

I'll post how it goes.......   good or bad.

Brian

[EuropaTC]

Hi folks,

A follow up post to the previous one above, as promised.

Well, the bushes arrived from Autobush, kit AUB5101 as for Lotus Elan.  You get 2 bags with 4 bushes plus stainless inserts,  a tube of grease and an instruction sheet in each bag. I've never used such things before so I don't know if these are good or bad, but they looked & felt quite solid to me. Inside the bore of each bush is a cross hatching which I tried to photograph but failed. Apparently this is to retain grease to reduce noise in operation and as the grease is white you can easily see when it's applied, which seems a neat idea. I had previously assumed such bushes would just have a plain bore, but these have clearly been engineered/designed.

As you might expect, they pop in easily enough. The instructions say "Apply grease, fit the bush into the wishbone then fill the bore and press in the stainless insert."  as they say once the insert is in place the bush will expand and then won't go into the wishbone.  It's a tight fit as it is so I think this is good advice.

And that's about it. It's an easy job and quite noticeable that you can tighten up the wishbones and still move them easily as the bush rotates on the stainless "crush spacer" as they call it.

I'm no driving god so I very much doubt I'll notice any difference when I get it out next week, but it does look like a reasonable alternative to the OEM rubber bushes, which in truth don't have that much rubber in them anyway.

Brian

Edit to add:

One thing I forgot in the original post, the stainless inserts / crush spacers were slightly different to the ones in the original bushes.  Now my wishbones are tubular Spyder ones and were supplied fitted with bushes so I don't know for certain that they were identical to OEM Lotus, but the length of the insert on the Spyder bushes was 34.9mm.  On the new Autobush kit, the length is 36.9, 2mm longer because the poylurethane bush is also fractionally longer

The way these are fitted doesn't make this a big deal, I only noticed it because I had thick washers on the upper spindle with the Roll Bar mount and when fitted I didn't get a full nut so I just used a thinner washer !  There wasn't any noticeable misalignment when mating up to the top ball joints, I suspect it's so little that it just slides into alignment on the insert.

[BDA]

Thanks Brian. Please give us your driving impressions when you get a chance.