for all those who changed their rear diff or chip

[derick]

I was woundering if anyone could tell me about how much of a diffrence it has made? Actual #'s would be nice but i just wanted some feed back before i go out and do the same thing.

rear diff from 3.91 to 4.26(i think)

[mholbrook]

I changed my diff from 3.46 open to 3.64 LSD on my last 535. Best thing I ever did for that car. I also chipped with Conforti Chip. Second best thing. I think you need a few more replies to make your decision. I would certainly chip it however. Cheap and easy. Diff is a good days work unless you have a lift available or pay for the R&R.

[calmloki]

I changed my diff from 3.46 open to 3.64 LSD on my last 535. Best thing I ever did for that car. I also chipped with Conforti Chip. Second best thing. I think you need a few more replies to make your decision. I would certainly chip it however. Cheap and easy. Diff is a good days work unless you have a lift available or pay for the R&R.

Mike,
If I'm figuring that correctly, that translates to about a 5% increase in engine RPM to over the ground speed. Leaving aside the open vs. LS change, derick could try out that change by changing tire size. Yes, it will be a bit uglier to look at, but could be a cheap quick way to try that diff difference. Are you sure you didn't have a 3.25 open? The 3.91 to 4.26 change is about an 8% difference, again, something one could achieve with a smaller diameter tire. Only suggested for low buck trial and testing.
Tom Walrod

[gale]

I was woundering if anyone could tell me about how much of a diffrence it has made? Actual #'s would be nice but i just wanted some feed back before i go out and do the same thing.

rear diff from 3.91 to 4.26(i think)

If yours has a 3.91 in it stock from the factory, then I'm assuming it's an 89 or 90 535i automatic? In 91-93, they changed to a 4.27 for the 535i/735i(til 92). In retrospect, when my 92 was an automatic, I would have gone from a 4.27 to a 4.45 if they weren't so expensive, it certainly felt like it was good for it & never felt the 4.27 was too high & the extra punch out of hole would have been nice.

As for the chip, definitely one of the best bangs for the buck. Can't provide specifics, but you'll definitely notice a difference.

[grave77]

i simply don't recommend it. already the 535 with the 3.91 is not comfortable at high speeds. i found that changing to 3.64 is much better with an EAT chip on.

[DanDombrowski]

My best 1/4 mile time was 16.1 stock, 15.6 with a chip