I have a 4.10 diff. Should I re-build and install or go wit

[Guest Anonymous]

(nt)

[Guest Anonymous]

Like what car do you have? 4 spd or 5 spd? If 5 spd cr or overdrive....etc etc etc. Is it a road car or do you spend time on the track? Etc

[Guest Anonymous]

(nt)

[Guest Anonymous]

and sell the other diff (or just the pinion and ring gear) to a track minded individual (assuming it is in good shape)

You can probably pay for your 3:91 LSD or at least offset the cost.

[Guest Anonymous]

(nt)

[Guest Anonymous]

(nt)

[Guest Anonymous]

URL: http://www.geocities.com/karlkarlb/BMW.html

I loved that diff. Did not decrease street driveability at all. It was great.

[Guest Anonymous]

3.64/4.10 = .89 (The 3.64 is about 11% taller or 11% taller top end and 11% less revs, and less torque and acceleration)

3.64/3.90 = .93 (3.64 is about 7% taller or 7% taller top end and 7% less revs, and less torque and acceleration.

3.90/4.10 = .95 (3.90 is roughly inn the middle between 3.64 and 4.10, but closer to 4.10.)

The 5th gear in the OD5 speed is .80 while 4th is 1/1 ratio like in the 4 speed.80 is a huge jump and when used with the 3.64 it just about renders this gear useless. Acceleration and torque in 5th with 3.64 is lousy (3.64 x .80 = 2.9). Your 3.64 final drive effectively would become 2.9 (Lousy)That is why most people use the 3.90 or 4.10.

The effective final drive ration in 5th with these diffs would be:

3.64 x .80 = 2.90

3.90 x .80 = 3.12

4.10 x .80 = 3.28

3.28/3.64 = .90

using the 4.10 ratio will therefore cut down the overdrive jump from 20% to 10%. This is optimum, and your motor will come close to or still be able to redline in 5th gear.

3.90 LSD is easy to obtain and most cost effective. You can turn the 4.10 into a 4.10 LSD by incorporating some of the 3.90 LSD guts into the 3.90. ($600 - $1,000)

You guys can check my math. I'm not an engineer.

Slavs

[Guest Anonymous]

This car has a straight cut gear, close ratio, dog leg 5 speed with a 4:10 diff. I remember that 120 mph (VDO electronic) was like 7200 rpm.

John

[Guest Anonymous]

John