Which diff?

Hi guys,

To summarize, I have an E30 with an S52 that's receiving a major power upgrade this season. I currently have an E28 3.25 in there and I'd like to change it out to something nicer. I'll be going with a custom unit from diffsonline but I'm curious what you guys would recommend. This is a track only car.

I'm going to change to a 2.93 gear and for the carrier, I'm thinking: 1) Quaife 2) OS Giken 3) custom 30/90 ramping

Any input, especially based on first hand experience, would be very appreciated.

Thanks! D

Wanna sell the old diff?

I would but he'll want it as a core.

Thanks anyway. I just noticed the whole "Canada" thing and realized that it would probably be a customs hassle.

Yeah, shipping + customs would probably be close to the diff price. Actually when I bought it, I had it shipped to a parcel place in Niagara Falls. It wasn't until I got there that I realized what I'd done. It's run by a pair of little old ladies. Thankfully they just left it where the poor UPS guy dumped it by the door, hah.

Hey, Jeff. Do you want an E30 diff....?

My brother is pulling the 2.73 out of his car and putting in a 2.93 LSD. I'd expect him to be throwing out the old diff.

A 2.93!? What trans are you running?

I have a track-only S52 with a ZF from an E36 M3 (1:1 5th) that I run a 3:46 LSD w/ 50% lockup squeezed in. It is an almost perfect combo for strong acceleration everywhere but with enough top end to pull all the way to the brake zone on the back stretch at the Glen or the front straight at Summit with a 7250 rpm redline.

A 2.93 would be awful IMO unless you had 500lb/ft of torque - and then it would break the axles.

If everything pans out then it should be putting down 550-600 ft lbs to the wheels. My 3.6 M5 topped out at 230-240 at MoSport, I can see this car running out of gearing long before the end of the straight with the ZF (about 250). Axles hold up fine unless you're a drag racer/power shifter. But an MZ3 rear end will be joining the diff, although that's mainly for the wider wheelbase for the bigger meat, with fatter axles as bonus.

GRM (actually Ian Stewart) did a diff article last year on an S2000. Not sure, but I think the OS Giken was the one they chose. Somebody with a better memory than mine recall that one?

I remember that write up, which is what made me think OS Giken is the only way to go. But a very respectable birdie told me that they're really not all that great and they all come with the same setup, regardless of model, so they need further development to work best in a given application. So now I'm not sure again. The same person told me that a stock carrier with a 30/90 ramping is actually best. So I'm curious what others think that take their cars to the track? If you chose a quaife or another torsen over a clutch pack, or vice versa - how come? (esp if you've tried both)

If you have the money you can't go wrong with OS Giken!