Swapping Diff???? shafts aswell?? Bid to small Case diff...

[mrfuzzyfelts]

When swapping from a small case to a big case diff, do u need to change the shafts???

As the diff is wider??

or will it still fit the same shafts?

[Chris-W]

Straight swap - the output shafts on a big case have shorter flanges than on a small case.

[jmc330i]

Change the diff only. As Chris said the difference is on the diff not the shafts, so its a straight swap.

[Brianmoooore]

Propshaft length and preload should always be set up after a diff change though.

[jmc330i]

Good point Brian - I always forget to mention that

[tomtomiS]

aaaaaah, i wonder! i replaced the diff on my iS ages ago and after, it still made the awful whining noise as if its about to pop. i diagnosed the noise as rear beam bushes on their way out as an mot tester pointed them out as maybe needing doing soon. is it possible that the length/ preload thing might be why it still whines? i am confident that its not a dodgy diff as i bought it from a zoner a few years ago

[mrfuzzyfelts]

Propshaft length and preload should always be set up after a diff change though.

HOW DO I DO THIS

[Brianmoooore]

All done at the prop centre bearing.
Slacken the fixing bolts for the centre bearing mount, and then mark with a pencil behind the bracket where it naturally sits. Slide the bracket 4 - 6mm forwards, then re tighten the bolts.
The prop length adjustment is achieved by a sliding spline arrangement that is obvious when you see it. Secured by a sleeve nut; slacken it off to adjust the length, then tighten to 7.4 lb. ft., or 10Nm if you prefer totally meaningless new measures. Pipe grips are the tool usually used on this nut.

[Dr Firefly]

I know this is an old thread, but was interested. What happens if you don't do this? Only just found out about it now 2 years after I swapped on a 318i diff onto my 320i - only one I could find at the time. All running fine still, is it worth doing?

Cheers,
Ian