E30 Zone

hey guys need some help my m8 has a 1990 325i sport he was running a 4.10 small case welded diff and has bought a S3.91 LSD out of a 325i it is quite larger then the 4.10 but it wont fit.

when trying to fit it the drive shaft cups will line up and fit but the 4 main bolts wont line up at all has any one come across this problem before is there any way to get it to fit...

TBH there a pain in the ar*e to fit.. firstly are you sure its been removed from an E30? any pictures? have yous sat both diffs side by side to see if the holes are in the same place? could it just be a case of needing to muck around a bit more with it..

the 4 19mm bolts are a real pain to get in , make sure he 'starts ' the 2 very top bolts first !

I have found this way to be the best,

Dont tighten any of the bolts untill all four have been wound in a few threads.

wel lads tha fella says he ligned 2 bolts in the prop first but the very top the holes are a little bit out of line the diff came outta sport he bought it a while ago is ther any other way of tellin it came outta a sport i took a pictre on my camera but have mis layed my lead so will put up as soon as i can

if he's changing from a small case diff to a medium case diff, the prop length will need to be adjusted to suit. there's a large 'nut' halfway down the prop, loosen this and it slides in and out.

push it all the way in, fit the diff then slide it back, bolt up to the diff, then tighten the length adjuster thingymajig.

gareth wrote:if he's changing from a small case diff to a medium case diff, the prop length will need to be adjusted to suit. there's a large 'nut' halfway down the prop, loosen this and it slides in and out.

push it all the way in, fit the diff then slide it back, bolt up to the diff, then tighten the length adjuster thingymajig.

I never even gave that a thought.. boy is changing from a 4.10 to a 3.64 so theres a good chance that is the problem

my m8 has a 1990 325i sport he was running a 4.10 small case welded diff and has bought a S3.91 LSD out of a 325i it is quite larger then the 4.10 but it wont fit.

pay attention at the back

gareth wrote:

my m8 has a 1990 325i sport he was running a 4.10 small case welded diff and has bought a S3.91 LSD out of a 325i it is quite larger then the 4.10 but it wont fit.

pay attention at the back

at least im not the only one..

oh the other thing to add regarding swapping small to medium case:
the diff output flanges are different - you need to get the flanges with the new diff and fit the lot complete.