Lotus Elan and Lotus Elan Plus 2 Forums

I have a 3.5 diff that I have been waiting to fit to may S4 elan. Recently while working to install CV drive shafts, i decided to install the 3.5 diff. Now i have it in place, i find out the prop shalt end bolt spacing is larger (the newly installed 3.5 diff has smaller bolt spacing) than the diff I removed.

I good freind 'Prezoom' has suggested th change the back portion on the prop shaft. This sounds like the easiest fix, however i need to source the smaller prop shaft to diff piece
Any ideas I have looked at the TT site in UK and he has a PINION FLANGE drilled for both size props.
Does anyone have a spare small bolt spacing part of the prop that connects to the diff? or have any other suggestions?

Thanks
James

I recently had exactly same experience when reverting back to a 3.77.

The new diff unit has a different PCD on the flange. I ended up swapping the flange from the existing diff onto the new unit. I was worried about the preload as I'd already built up the new diff with new bearings and seals but I just torqued it to the factory setting, checked it for 'feel', and all was fine.

Personally I would keep the prop as it is in case you alter the balance/phasing by changing the rear flange.

Until then I never realised there are different flanges on the diffs

Jon

If you decide to change the prop flange I have an 86mm O.D. one. I think S4's originally came with a 92mm one though so it all depends on originality of your car. I guess you've got a 108mm one that is causing you the issue?

The other issue may be that I'm in UK and that I'm looking for ?35 for the flange + postage.

No worries if you're not interested. Just a thought.

Regarding the TTR diff flanges they don't come with a seal shield and need modifying if you want to use one - I did this recently - please see here : lotus-gearbox-f37/gearbox-and-diff-rebuild-recommended-suppliers-t39157.html

James, I have one from an MGB shaft. I believe its the one you need. PM me with your address

Hi James

If you reside in a biggish city just check out the local specialists- propshaft work is still big business despite the proliferation of front drive cars.

Should cost you around ?30 or so inc fitting.


Regards

John

I did exactly as Jono did. Installed the correct flange after setting up with the incorrect flange-everything worked out fine-the diff is quiet and the oil was relatively clean when I changed it last night after 1200 odd miles.

Hi James,

I have the small prop shaft flange fitted to a diff flange drilled for both the small and large bolt patterns.

I'd be willing to do an even swap if that is of interest to you.

Bill

Thanks for all the replies.
I think I have a solution that will work.
I do appreciate all the offers
James