CSR owners check your rear suspension mounts

[Shortshift]

Err - so am I having a bad day or is the bolt reversed in one picture, relative to the other?

James

[PlastererPete]

I thought that when fitting my new ones. One side will have the bolt head toward the rear of the car, the other will have the bolt head towards the front of the car. The orientation of the spacers/washers is the same on each bolt as per the picture. Just the direction will change. 

[SamC]

Oh blimey, yes! Sorry James! Just noticed that! I was looking at the spacer orientation.

The one in your photo (#173) is correct - the bolt head should sit inside the ally bracket slightly so the one in #167 is incorrect as you say. Like Pete says the bolt head direction is different left to right owing to it being the same bracket for both sides.

[David aka Blue7]

Interestingly I will be meeting Richard graham tomorrow at Nairn car show. He was a member of the CSR design team. I met him here last year and after he left i spoke to another person who told me about the suspension problem.  

David 

[SamC]

Send him our regards! 

[Shortshift]

Replying to #178:

So, would the incorrect assembly of the clevis pin and through-bolt arrangement have been a contributory factor in the failure on Steve Marsh's car?

And can Steve shed any light on whether the car might have been assembled in that incorrect condition from new (assuming his car is a factory build) or whether that corner might have been subject to 'servicing' at some time after initial build?

James

 

 

[SamC]

Not sure to be honest James. With my Multimatic dampers it wouldn't have clamped through the damper top hats properly. It looks like it might do on the Bilsteins (?) in Steve's photo?

[sjmmarsh]

The car was factory built and the only thing that has been touched was one of the rear dampers that was replaced when the top lug seized in the steel collar resulting in one of the lugs breaking off, which would have necessitated replacing the lot - but that was a long time ago. I'll find it in the paperwork. 
 

I have now caught up with the Article in LF - I need to contact CC to let them know my incident could have been way more serious than a broken spring, had the sidewall been cut all the way through (the tyre lifted a piece of the side skin at the join between the side and rear skins) as it would possibly have spat the car across the middle and outside lanes of the M11 at 70mph!

Does anyone have an email address so that I can let them know (with photos)?

[sjmmarsh]

Dug my receipts out - both rear dampers were replaced on 9/4/11 by Caterham Midlands - the mileage then was around 18k.

[sjmmarsh]

I was getting the CSR ready for collection by Nick Potter tomorrow, so took some photos of the near side Clovis - it looks OK to me, apart from some witness marks on the bottom of it. 

I also noticed on the offside rear part of the clevis (attached to the upright) that there was a loose piece of the clevis, still just attached but it came away when I touched it. One (smaller) face looks discoloured and so may have been a pre-existing crack, but the other size looked fresh (the bright bit is where it was still attached) - I presume that this was damage after the clevis gave way as the damper flew around. I can't see how it would have otherwise broken.

Yes, I do need to get under the car and give it a good clean when I get it back!

[David aka Blue7]

What intrigues me is the pitted surface of the broken areas, they have all been rough and pitted and this one looks even worse almost as if the casting was contaminated in some way.

[SamC]

It's pretty normal for that kind of failure. It'll be a relatively high strength ally with low strain to failure.
 

It's just failed with very little elongation along the grain boundaries.

[OldAndrewE]

From #178 "the bolt head should sit inside the ally bracket slightly" . The first photo in #185 does not show that, does that mean the work done by Caterham Midlands was done incorrectly?

[SamC]

If that's who did it, yes.

Bolt head should face the front on the LHS and the rear on the RHS. 
 

Assembly order should be the two conical washers onto the bolt, then fit the bolt through the clevis.

[sjmmarsh]

The photo in #185 shows the LHS clevis. I can't be sure which way round the RHS was assembled until I get the bits back as I may have swivelled it round to get the grease off it to take the photo. 

[Shortshift]

As this thread continues, it becomes increasingly clear that the design appears to be poor in so many respects, including that it can be assembled with the through-bolt, collets and washers in the wrong order without any indication that this is incorrect.  Assuming that this is a critcal assembly process then it should have been made error-proof.

From what I've read on here, the specified alloy is also an incorrect choice (prone to failure at low strain, effectively insufficiently ductile and correspondingly too brittle), there could be some dimensional issues (for instance, possibly allowing the damper body to contact the upright and act as a leverage-increasing fulcrum on full rebound and) and the general concept of the expanding collect and washer arrangement (promoting high levels of hoop stress in the lugs) are all also points of concern.

Furthermore, it has to be recognised that the probable failure mode can be far more serious than the usually benign failure of a coil spring in a 'normal' road car - which often goes undetected by the driver until the failure is spotted on inspection or during a service.  From posts above it looks likely that a failure of one lug (it seems that it's usually the cap-head and collet end that fails first) may go completely undetected, with the remaining lug carrying all loads until it, too, fails without warning.  The consequences of a sudden failure along these lines could well be serious indeed - the yellow car in Scotland that ended up in a field below the road reinforces the point.

Having kept quiet on this for quite some time, I do hope there's a resolution underway that will be made available for all factory-spec CSRs to reflect the magnitude of problem, concern and possible consequences.  And I don't just mean fitting Luke's brackets without an appropriate degree of engineering assessment and validation work having first been carried out on that design; the offered solution has to be fit for purpose in all respects.

James

[SamC]

#190 Your photo in #167 shows the collets on the RHS incorrectly under the nut not the bolt head. 
 

#191 Agreed with everything James, let's hope there is a satisfactory resolution.

[David aka Blue7]

I had a long chat with Richard Graham (ex Multimatic), at a car show on Saturday.  It is 20 years ago that he worked on the design of the CSR so specific details about components is not easy to recall but he couldn't recall a "clevis bracket" and thought the upright assembly was one unit but regardless of that, he couldn't recall using any aluminium components, just steel.  It could be that CC tweaked the design to save on component cost but we will never know unless Multimatic still have original drawings.  Neither of us could think why aluminium was used instead of steel unless it was somehow cost related.

I came across a good photo of the rear suspension setup from my archives.  It is taken from the Evo magazine article at the launch of the CSR is 2005, some good information about the design and this photo (click on the top photo to see all 9 photos).  To add more intrigue, the photo looks like the near or left hand side?  In which case the clevis bolt head is facing to the rear, when it should be facing forward but it could be just a CAD error.

David

[SamC]

This is the CSR assy guide page for the bracket. The one in the CAD doesn't look like the final design to me? (Ref where the vertical bolts to the upright sit.)

 

[ScottR400D]

Any updates on this? Or is everyone just fitting the Team Leos units and forgetting about it?

 

 

[SamC]

Radio silence from Caterham. Not heard a stitch since the follow up questionnaire.

 

[PlastererPete]

Same here. Not heard a thing since I dropped my old clevis’ to them and filled in both the questionnaires. They are in the middle of “the big move” from Gatwick though. 

[ScottR400D]

They are rather good at can kicking………

[Midas]

I contacted Bob Laishley on 5th November and asked him if there was any update we could share with Club Members.

Bob's reply was that Caterham are currently heavily involved with the DVSA regarding a fix for the problem. That was as much as he could say at this time.

I plan to meet up with Bob before Christmas, and I will ask again if there is an update - assuming a more public statement has not been released beforehand.

Regards

Richard

Chair

[ScottR400D]

I wonder what significant involvement DVSA might have other than asking what the remedy was.