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anyone know which BMW the caterham BMW diff comes from
timbo7 - 10/1/14 at 04:23 PM

As the title - anyone know which BMW model Caterham use for their new BMW diffs?

Cheers

sdh2903 - 10/1/14 at 04:31 PM

Iirc it's off an e46/z4 and they are usually 3.62 or 3.64 ratio. They are fitted I think to some of the auto models 2.5l and 3.0 petrols.

sdh2903 - 10/1/14 at 04:44 PM

Have a look here:

Bmw diffs

Is the caterham not using the diff with an adapter to mount the same as the Sierra diff? If so then there's a pretty good choice of ratios to choose from.

timbo7 - 10/1/14 at 06:02 PM

Reason I ask .. Is I need a longer ratio than 3.6... A 3.07 would be pretty close.

But need the higher ratio diff casing, dimesions, bearing shaft splines and bearing race dimensions to match the Diff caterham supply.

So for example will the E87 118d diff be identical bar the cwp internals?

sdh2903 - 10/1/14 at 06:14 PM

Have you tried realoem website? You should at least be able to get the bearing dimensions etc.

I'm not that familiar with the later stuff but if the crown wheels are all the same then I suppose you could cherry pick your ratio. I know the none evo m3 3.0 lsd uses a 3.15 ratio and uses a 188mm crown wheel but guessing that wouldn't fit the caterham mounts. Iactually have a spare 3.15 crown wheel and pinion lying spare somewhere if you could make any use of it for the cost of post.

ettore bugatti - 10/1/14 at 07:13 PM

I thought they used an E87 1-series diff. Or is that the same as the E46/85 diff?
E46s (the six cylinders) can be found with 3.07 and 2.93

As far as Im told the LSDs from earlier BMWs E30/E34/E36 doesn't go into housing of the later ones (as used on the E46)
http://www.bokchoys.com/differential/

mackei23b - 10/1/14 at 09:01 PM

Caterham use a Titan Lsd in the BMW diff.

cr500dom - 15/10/15 at 11:07 AM

quote:
Originally posted by timbo7
Reason I ask .. Is I need a longer ratio than 3.6... A 3.07 would be pretty close.

But need the higher ratio diff casing, dimesions, bearing shaft splines and bearing race dimensions to match the Diff caterham supply.

So for example will the E87 118d diff be identical bar the cwp internals?


Sierra Diesels had 3.14 ratio, which would be a much easier swap than the BMW Diff

Ajoasika - 7/6/17 at 12:32 PM

BMWs with X-Drive have front diffs with alloy cases, and about 25 kg less weight. Same ratio range as rear diffs, all the way down to 2.47:1. Diffferent sort of mini sub-frame required to hang it on the Sierra-sized mounts on Caterham/Westfield though. This is important to allow retro-fitting of higher ratios.

And the drive shaft holes are different from side to side.

Note the BMW diff on the Caterham has had some machining done to the case - those front ears are gone, replaced with bolt-holes. But they are sooooooo heavy, especially with LSD. Colin Chapman would not have approved.

Does anyone tried fitting a BMW CWP to a Sierra case? What we need is someone to start casting alloy Sierra-type casings that take BMW internals, which I suspect are not very interchangable.