3.91 lsd from a 1984 work in my 91 318is?!? help guys

[bsturman92]

Hey so i came across a 3.91 lsd from a 1984 e30... will it fit.my 91 with no problems? Or do i have to swap out the flanges??? Im going in a few hours to pick it up so i would appreciate any help..... thanks guys

[Bearmw]

It's a good diff for your car but I can't remember if the flanges need swapping. It is also a good performance upgrade for a basically stock 325i as well IMO.

[reelizmpro]

It should fit but it's a small case diff with the long flanges. No need to swap the flanges, if you do then they will be too short, IIRC. I'm not sure but I think your 91 has the medium case diff like the 325's.

[MR 325]

It's a direct swap. You'll just need to change over your speed sensor.

Barry the 84-85 318 and 91 318 both had small case diffs.

[Boltspeedman]

sorry to jump in on this old thread, but since on the topic I figured I'd ask a couple questions..

I'm debating on 4.10 or 3.91 lsd in to my 318is, currently has a 4.10 open. As far as performance, Am I loosing any acceleration with a 3.91 vs. 4.10? I know at this point either would be an upgrade.

[ELVA164]

You will lose a little acceleration, but it will also help you on the highway. A fair trade in my opinion.

[drummerchubbs]

Will 1991 325i directly work with a medium case 2.93LSD???

[reelizmpro]

Yes, they all will work. It's just a matter of size difference. small case diffs will have longer flanges.