540 Diff question

[dbals]

Ive got a 95 540 6speed. Ive found a 3.64 lsd out of a 88 735 locally and was wondering about what you guys thought on the ratio. Is this to high? I dont know the final drive ratio is so whats this going to do rpm wise in 6th cruising at 85?
thx

[632 Regal]

ratio aint anything, that case wont fit in your car

[dbals]

Well damn it....thought it would. Are flanges wrong or is it totally wrong? I know your the diff master (read your rebuild) What do I need? I have a supercharged 540i/6 and the open diff is driving me crazy.
thanks for the help regal
-drew

[632 Regal]

you need a rear end from a 540/M5/740 etc, theres a write up in brunos site about what goes where. you'll want a better gear ratio like a 3:43/3:64 (or whatever)

[dbals]

you need a rear end from a 540/M5/740 etc, theres a write up in brunos site about what goes where. you'll want a better gear ratio like a 3:43/3:64 (or whatever)

Ive look at bmwe34.net and didnt see anything....Iam I blind?

[motuman]

Your least expensive option is a S3.15 diff out of a e32 750i. Make sure the metal tag has an S in front of the ratio (3.15), otherwise it will not be a limited slip. You should be able to find one for around $300.

The members of the M-Sport message board have tried have tried many different ratios report that the 3.15 (or 3.23, which is custom and very expensive) is the correct ratio for a 6-speed. If you go with a 3.64 it will make first gear useless, especially with a s/c.

BTW - I can also confirm that the 735 case size is too small for your car.

Good luck!





Well damn it....thought it would. Are flanges wrong or is it totally wrong? I know your the diff master (read your rebuild) What do I need? I have a supercharged 540i/6 and the open diff is driving me crazy.
thanks for the help regal
-drew

[BillionPa]

3.15 for supercharged.

[632 Regal]

3:15 from what he has is not much of a change, a lower 1st gear even tho it wont run long before a shift will really get these sleds going fast in the city range.

[632 Regal]

3:15 from what he has is not much of a change, a lower 1st gear even tho it wont run long before a shift will really get these sleds going fast in the city range. Believe me I thought the 3:64 was way way too big bit 1st still runs til 40mph.

[BillionPa]

well, a stock 540/6 has a 2.85 or something, 3.15 would increase engine speed by 10%, 3.25 (supposedly optimal for stock engine 540/6) by 13%

[Paul in NZ]

i have heard that the LSD diffs wont work with the traction control.
Why not?Or is it a myth.

[632 Regal]

correct at 1:1 ratio but you have to figure overdrive numbers.
well, a stock 540/6 has a 2.85 or something, 3.15 would increase engine speed by 10%, 3.25 (supposedly optimal for stock engine 540/6) by 13%

[Dr. Frank]

I have 3.64LS with a powerdyne S/C. 1995 540ia. With the auto, I love the 3.64, it is not too high a ratio. When floored it holds first until 40 km/h and will spin the tires at both the 1/2 and the 2/3 shifts. (245/45/17 on 9" bbs rims)
P.S. I have traction control and the LS works fine with it. However I turn it off if I plan on really pushing the car.