catherham build quility

[Norman Verona]

The de-dion tube issue was covered. It was a batch of tubes that failed when under extreme pressure, like going over kerbs on track. They weren't a risk on normal road use. The tube was modified as soon as the problem became apparant and is now history.

[oioi]

The de-dion tube issue was covered. It was a batch of tubes that failed when under extreme pressure, like going over kerbs on track. They weren't a risk on normal road use. The tube was modified as soon as the problem became apparant and is now history.

im not sure that is the full story.  A mate recently had his de-dion tube fail - car was a road car and it was not part of the dodgy batch.  Caterhms do have an ongoing issue with dedion tube failures and they are a weak point in the design.

[James]

The de-dion tube issue was covered. It was a batch of tubes that failed when under extreme pressure, like going over kerbs on track. They weren't a risk on normal road use. The tube was modified as soon as the problem became apparant and is now history.

Sorry but I would disagree with that statement, the problems have seemed to have occured since the original inception of the de-dion back in 1985 and alot of the problems mentioned in the thread on blat chat are from 2004 on, with eight versions of the de-dion ( you dont redesigns something unless you have a reason)

There have also been a suprising number of faliures at low speeds one guy was driving home after his MOT and it suddenly failed and yet there were no cracks that were seen by the MOT inspector. and then there's also this poor guy I think you will agree a little more than simply a bad batch.

Version 1 – SERIES 3 - 85-89. Part Number 79011

Original dedion tube.

ERW 12swg

Claw type centre mounting

Damper through-tube mount

The early tube was lightweight and could fail by jacking the car on it.

Damper mount was through the centre of the tubes diameter.

Most common failure was the small central buttress tearing away from the tube.

Version 2 – SERIES 3 - 90-96. Part Number 79016

90-94: Centre mount changed to buttress type. ERW 14swg and 12swg

94: Buttress widened

Tube seemed to be more substantial than V1, and the car could be jacked up on it OK.

Damper mount was through the centre of the tubes diameter.

Most common failure seems to be cracking around the circumference of the tube, at the end of the central buttress.

Version 2a – SERIES 3 - ?/07 replacements. Part Number 79016*

A more substantial version of V2 but with thicker 10 swg material appears to have been supplied later (eg in 07) as a replacement for earlier cars with through tube damper mounts, where the original tube has failed by cracking near the centre buttress). *These have the same part number 79016 as V2, but are described as "H.D. 10 GAUGE" on CC invoices.

Version 3 – SERIES 3 - 96> Part Number 79028

96: Lower damper mount added to allow use of increased gas volume dampers.

Damper through-tube mount retained for retrofit

End plate gusset gauge increased to 3mm (running change during production)

97: Indent for Watts link bell crank added

00: Buttress ends bronze welded

Still believed to be 12swg

A second (lower) Damper mounting for progressive dampers was added by welding on a sleeve to the bottom of the tube.

This version seems to have had many failures, mainly of the weld, or the metal immediately around the weld area, tearing away from the tube.

Version 4 – Series 3

02: (retrofit only) CDS 10swg

About twice the weight of V3 as the tube wall thickness has been increased.

‘Spare’ Through the tube mounting not fitted (except I believe on request from Arch).

Version 5 – Series 3 Still Part Number 79028

01: Holes added for brake pipe fixings

Damper bush gusset added

Damper bush length increased by 4mm

Not heard of any failures of this version.

Version 6 – Series 3

02: Overall width increased by 8mm

CDS 10swg to harmonise with SV tube production (Understood v5 was 10swg already?)

Version 7 – Series 3

04-present

Damper through-tube mount deleted