What diff with an M30 e30?

[MrK]

I just swapped in an M30 from a 1992 535i along with its gearbox into my touring, but the 3.73lsd I have on there seems to have made the final gearing a little too short, in fact short enough that first gear has become useless. Is that a common problem?

What diff would be best for this application?

[DarkWing6]

I'm not an M30 swap expert, but if the 3.73 is making things that short go with a 2.93 or 3.25 depending if you would like shorter gearing on longer.

[JoeMadoo]

I'm going to run a either my 3.23 or go back to stock (2.91). When i turbo the m30 i'll use a 2.79.

[bmw335isturbo]

I just swapped in an M30 from a 1992 535i along with its gearbox into my touring, but the 3.73lsd I have on there seems to have made the final gearing a little too short, in fact short enough that first gear has become useless. Is that a common problem?

What diff would be best for this application?

This is just Me.
4:10lsd drag racing
3:91lsd drag racing
3:25lsd -good in town gear
2:93lsd -ok, intown gear and hwy driveing good on gas
2:79lsd -good tall gear would not use unless you want to modifi the m30 good on hwy

[MrK]

Thx bmw335isturbo, that's all the info I need. I'll probably try a 3.25 lsd on for size.

[Axxe]

3.25 will be great. I don't see how the 4.10 would be good for drag racing, first is useless, second is like first with a 3.25, etc.

[JoeMadoo]

3.25 I think is perfect for the eta, especially a chipped one. With an much higer revving M30 it might be a good idea to stay the same ratio, for increased acceleration and top speed.

[george graves]

Yea, I have a 3.73. I also use to own a e21. This set up reminds me ALOT of that car. First is only good to get you going, all the fun is in second (much like a track car no?)

I offten times start out in second, and carry that gear all the way to the speed limit. I'm amazed at how fluidly the m30 throws that car WAY past everyone else on the road.

That being said, I'll swap to a 3.25(3.4x???) someday (maybe)...I just love second gear with this set up way too much...

And yes, a 4.10 would be a good diff - if your day job is pulling stumps.