BMW E30 diff question

So what is the best OE diff/final drive to go for. The car is a late 80's E30 325 2 door rally car of a friend.

From what I can find, there were a few models that came with a 4.1 LSD, though I can't find out the type of LSD. 325ix, which was the AWD model, apparently had a clutch type rear LSD, though that's not verified, nor is any info about if it is easily swappable with RWD applications.

Owner was thinking of just putting an OBX helical in with the stock 3.73 final drive, but I convinced him (I think) that he should find a 4.10 with the stock LSD and save the money for the Kaaz clutch diff in the future.

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Grant Hughes

One of my customers has us throw a 3rd member he found online (apparently from a BMW parts retailer) into his short-bumper 325i. He said it was from a late (still E30) 325is. The ratio was 3.73 and it was definitely a clutch type diff. He only paid mid-$200s as I recall, and the one he got still had a lot of breakaway torque left in it.

Not sure if 3.73 would be worth it on its own, but for a diff that's fairly cheap, if you can get a good one. The diff made about as much difference in handling/drivability as when we tok out the ancient crusty worn out factory dampers and put in some nice beefy Bilstein HDs.

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Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.



Edited 1 time(s). Last edit at 05/16/2007 07:46PM by Pete.

IIRC the stock LSD's are onlly a 25% lockup - not much but better than nothing

the 4.10 is out of the e30 M3's

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-Jason

The stock ones are a 4-spider ZF unit, like those used by Ford for the Sierra motorsports program only tiny... like 6" ring gear. All forged though. I used to have one sitting on the shelf, was thinking of trying to use it on the XR, but it's too small. Cool looking.

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Scott Manley
Spokane, WA
86' XR4Ti
37

As a full time rear end shop owner..There aways a mess of BMW diff on ebay..Theres a mess of cheap ones on there now...