Best diff

[alpinescott]

OK....I have the s52 in and purring. first drive today and the 4.10 diff is way to obnoxious for me, plus 7k on the tach at only 80mph will not cut it. I would like some ideas from the experts.

[cabin]

Depends largely on the transmission you are using...

[alpinescott]

^^zf tranny off 98 m3

[giantkeeper]

^^zf tranny off 98 m3

3.15, 3.23, 3.25

I personally am running a 3.15

[e30rapidic]

i have a zf with 3.46....too much on the highway. 3.15 is probably the best

[matthugie]

i have a zf with 3.46....too much on the highway. 3.15 is probably the best

You need a 6 speed ;)

OP, it does greatly depend on your transmission. If you're ZF, I agree with 3.15, maybe 3.23. If 260, the 3.73 works very well, but does leave a bit to be desired on the highway. I'm considering a 3.64 down the road for that very reason.

[Wanganstyle]

currently 3.15, have done 3.23 and 3.38 also with that driveline but in an e30 3.23/3.15 or lower would be more suited for traction

[alpinescott]

What ya'll think about a 2.93?

[scottinAZ]

What ya'll think about a 2.93?

2.93 is about a 10% change over a 3.25, similar to changing from a 4.10 to a 3.73. If you still have the 4.10, you are looking at a nearly 30% change in gearing.

Expect to lose pickup and off the line performance with a 2.93, but also expect your mileage to increase.

I currently have an M50TU with G260 combo, feeding a 3.73. Defintely feel the difference over the 4.10 I had, Mileage is up, happy fun tail out is down. Probably going to get a 3.25, due to being a DD, but keep the 4.10 if I feel the need to hoon it up a bit.

[kalib0y]

2.93 is great for acceleration and fwy cruising. I chose to go with 3.25 though.

[ACHTUNG]

I'm running a 3.07 LSD with the ZF trans.

[MattM]

i love my 2.93... 95% of my driving is freeway

[alpinescott]

Thanks for all the input guys! 3.15 sounds like a good compromise...anybody got an extra laying around?

[RobertK]

Check BF.c. Best bet is to buy one from an E36 M3 and swap into your E30 diff case.

[giantkeeper]

Look for a Z3M diff, my 3.15 came from a Z3M and only needed the output flanges swapped to plug and play.