Caterham Seven CSR Important Information

[Gabriel]

Might be interesting for some of you guys:

https://caterhamcars.com/de/news-eu/calling-all-csr-owners

[Croc]

 

Thank you for posting.  Its about time Caterham got off their ass and did something on this.  The long running thread on Blatchat says they should have reacted a long time ago to a glaring safety issue.

 

This had been a known issue in the racing community for a while but only recently had it migrated into road cars as their mileage got significant.  Despite what Caterham says on their website, I would not want to be dealing with this part failing while at speed. 

 

There have been two or three CSRs in the US with cracked mounts.  I replaced mine earlier this year using a replacement part designed by Team Leos UK as Caterham were uninterested in providing support.   Replacement parts are available by order in the USA via Josh at Rocky Mountain Caterham and should he not be able to assist, then I know a back up source. 

 

Caterham-CSR-Rear-Clevis-Inspection-Guide-SL1-v2.pdf

[MV8]

IMHO, it is decent design, but I can see how the floating sleeve side of the mount could seize in the mount ear if not lubricated and crack if the sleeve has to move during reassembly. The sleeve could be separated with a 1/2 x six inch threaded rod, washers and nuts, a couple inches of pipe or thick walled dom to slip over the sleeve and sit against the mount ear, a socket the slightly less than the sleeve od on the opposite side, and a hand torch and/or wd40. Then the ear bore and sleeve can be cleaned with emory cloth and a good copper anti-seize applied to both. Should work better than new.

Edited September 9, 2023 by MV8

[Croc]

31 minutes ago, MV8 said:

IMHO, it is decent design, but I can see how the floating sleeve side of the mount could seize in the mount ear if not lubricated and crack if the sleeve has to move during reassembly. The sleeve could be separated with a 1/2 x six inch threaded rod, washers and nuts, a couple inches of pipe or thick walled dom to slip over the sleeve and sit against the mount ear, a socket the slightly less than the sleeve od on the opposite side, and a hand torch and/or wd40. Then the ear bore and sleeve can be cleaned with emory cloth and a good copper anti-seize applied to both. Should work better than new.

 

 

I have a bundle of these on the work bench - the old broken plus some new milled replacements for future spares since this now looks to be turning into a consumable for track cars.  The original failure on the outside surface of the ear (not the side) seems to be poor casting/raw material, then corrosion, into which the inevitable metal fatigue sets in.  The failure crack seems to be mostly from the outside to the in from what I have seen in the Blatchat threads, offline photos and the various CSR email chains I am a part of. 

 

As you rightly point out, it definitely needs lube on assembly as the there is movement through the suspension articulation. 

[MV8]

If the sleeve does not float on the mount, when the bolt is tightened to clamp the coilover to the mount, instead of the sleeve sliding in the mount to take up the clearance between the sleeve and the coilover, the mount ear is pulled toward the coilover by the bolt, causing the fatigue and cracking on the outside.

 

Usually, one side of a flanged mount is fixed/rigid to ensure the coilover is located in the right position where the other flange is either flexible (enough to move as needed to take up the clearance needed for R&R of the coilover) or has a floating sleeve like this one does.

 

Here is an example. One side floats while the other side locates: https://www.speedwaymotors.com/Speedway-Weld-On-Lower-Mount-for-Bearing-End-Shocks,3530.html

Edited September 9, 2023 by MV8

[11Budlite]

The latest entry from this thread must have been an exciting ride: https://www.pistonheads.com/gassing/topic.asp?h=0&f=101&t=2035620

[MV8]

If the floating sleeve is not rusted to seizing in the housing to cause the failure I described, it could be that the floating sleeve to bore fit is not as close as it should be or the bolt is not as tight as it should be, allowing the sleeve to move vertically in the housing bore with every bump. I see the wall thickness of the housing is less than a 1/4 inch. The floating sleeve od could be reduced enough to make room to fit a fixed liner to the housing. The liner could be flanged to provide more leverage, surface area for the load, and prevent the liner from sliding when tightening the bolt. The bolt would likely need to be longer flanged or not, to move the socket head out of the housing or the od reduced/ground for clearance to the reduced housing bore.

[Croc]

 

8 hours ago, MV8 said:

If the floating sleeve is not rusted to seizing in the housing to cause the failure I described...

 

No, its not that in mine and the two others I am aware of.  Mine was clean.

 

8 hours ago, MV8 said:

....it could be that the floating sleeve to bore fit is not as close as it should be or the bolt is not as tight as it should be, allowing the sleeve to move vertically in the housing bore with every bump.

 

No, not that either in any of the three cars I am personally aware of.  Bolt is snug.  It was regularly torqued and paint marked as part of my maintenance schedule. 

 

8 hours ago, MV8 said:

I see the wall thickness of the housing is less than a 1/4 inch.

 

I think this is getting close.  Engineer analysis on my failed part shows poor cast material, some minor corrosion (not visible to naked eye inspection) and metal fatigue at fail point.  1/4 inch would not be sufficient with this fact pattern.   Would like to do a full NHTSA analysis but there is no need for my purposes.

 

Paraphrasing the engineer who did the analysis, fix the materials and prevent corrosion, then the fatigue may never have happened.  

 

8 hours ago, MV8 said:

The liner could be flanged to provide more leverage, surface area for the load, and prevent the liner from sliding when tightening the bolt.

 

I think your idea of liner has merit but I would not reduce the wall thickness.  I suspect this part may get more loading under actual use than Multimatic (the original designers) CAD modeled back in 1998-99.  I would love to see the results of the modeling.  I attached the original design summary.

 

The upgraded part from Team Leos has not failed in racing conditions potentially showing that using quality materials with the same part design works. 

 

 

Multimatic CSR engineering suspension.pdf

[MV8]

Understood. I've no doubt that replacement with an improved part is the best way to go, using better quality materials and/or increased wall thickness/support/gusseting. My suggestions are only for improving the safety margin and service life of original mounts found to be serviceable as-is or repaired if possible to standard specification. To clarify, I've included a crude drawing. The wall thickness is effectively increased and the liner is steel. I don't know all the oem dimensions or how practical it would be.

 

[mccasksl]

Thanks for sharing. Caterham folks were readily encouraging / offering visual inspections of all CSR’s in attendance at the 50th Anniversary Celebration at Donington. FWIW no apparent cracks or deficiencies found in the 4-5 cars I watched them inspect. They had several offending (failed) parts on the bench to show what they were looking for. Upon my return stateside, visual inspection of my 2005 CSR w/ 11,600 kms did not show any cracks etc. but I plan to disassemble mine for a closer inspection and proper reassembly w/ lube etc. I received two new “clevis blocks” with purchase of the car. 
 

Cheers!

Steve

Austin

[Croc]

It definitely needs disassembly to check properly.  I thought mine were good just by looking but once disassembled, the crack was obvious.  Mileage is not always the driver here - Josh at Rocky Mountain had a CSR with a broken clevis block with only 6000 miles on it. 

[TurboWood]

Wow, good it’s great to see this information shared. I guess it’s time to look!

 

Daniel