I have a Caterham chassis (narrow bodied) that I wish to try out an IRS with.

Before I start bracing the rear chassis to take the wishbones, etc, I thought I'd better firm up on my Sierra Diff / Driveshaft knowledge...

I'm using a 7" 3.62 LSD. It has Lobro's so the Caterham driveshafts are a no-go. I thought I'd keep it (relatively) simple and use Sierra shafts. This should extend the original rear track width by about 10cm - hopefully this will not uspet things too much.

So...

I know b*gger all about Sierra shafts. Are there any differences that I should know about? I'm looking for the lightest suitable shaft with disc capability.

Cheers

Scootz

[Edited on 20/6/07 by scootz]

The lightest possible would be the push in type that caterham use, theses are obviously shorter than Sierra parts, thus lighter. Use these with a set of disc adaptors from any of the Locost suppliers.

HTH

John

Hi John.

I already have Caterham push-in shafts - the problem is that the Sierra LSD doesn't take a push-in shaft.

[Edited on 20/6/07 by scootz]

If it is the earlier type of Caterham chassis ie the same as the Lotus Seven S3 you will have to do major structural work in the cockpit area to take the loads from the IRS. The modifications to recent Caterham chassis are so extensive that little is left of the original Chapman designed frame.

see
http://www.mycaterham.com/mediac/400_0/media/DIR_39305/DIR_121116/22.jpg

http://www.mycaterham.com/117516/117447.html

Going de Dion with a Caterham style A frame lower link is a better option as is retaining the Escort or Marina rear axle.

In contrast a late Lotus Seven S2 chassis (almost identical to the early Lotus S3)

http://www.georgecushing.net/Lotus7.html


Not a lot of it !!!!!

Hi BT.

It's a De-Dion chassis I have - I just fancy trying something a bit different.

A while ago I found some pictures of what was referred to as a Lotus 37. This was a Lotus seven with IRS using trailing arms as used to locate a live axle to feed the loads into the chassis sides. This was combined with lower wishbones for lateral support. The arrangement is similar to that used on many old formula 1 cars like the Lotus 25
This would seem to be a better approach for a S3 style Caterham

[Edited on 21/6/07 by JonBowden]
Rescued attachment l737ag9.jpg

Another pic of the same car
Rescued attachment l737ag3.jpg

It would be easy to do, only fault is a small ammount of roll steer.

Len Terry used an alternative version with two parrallel lower links in place of the reversed wishbone.

Just been looking at the De-Dion set-up. Sure the tube is a substantial b*gger, but there's not a great deal of engineering connecting it (and therefore the wheels, etc.) to the chassis...