lsd differential questions?????

[tim s]

hi,
i have a 1995 540i/a & i am looking to install a lsd. i have been looking at changing it to 3.64:1 ratio. is this a good ratio to change it to? will a lsd from a 1990 735i fit?
thanks for any help you can provide.
tim s.
1995 540i/a
1987 325e

[gale]

e32/e34 diff's will interchange but I believe M5's are different. You may have to swap the input hub and/or axle output hubs depending on the year and whether the diff is from a manual or auto. I believe only lsd to lsd axle hubs can be swapped, open diff's have a different arrangement for how the hubs attach and are attached internally? Lsd hubs come off really easy, just pry on the outer flange lightly with a screwdriver and it pops an internal snap ring out of a groove. Just be careful to put them back in lightly and rotate them slightly to register the splines before tapping them in with a rubber hammer. Replace the seals if the hubs have to be removed.

The diff is really easy to remove from the car. The socket head screws on the axles are a pain to break loose the 1st time. They have serrated binder heads on the underside of the head which bites into a metal washer plate that spans 2 bolts. Clean any dirt out of the sockets with a small screwdriver & compressed air & use a breaker bar on a hex bit or a pipe on an allen wrench. The diff drops out by removing the 2 bolts on the rear bracket and the single bolt on the front of the stamped sheet metal plate. The plate stays on the diff. The diff is heavy, it weighs approx. 92# so be ready with a floorjack.

It might get a little dicey if you have to swap the input hub, the preload on them is factory set and establishes the clearance between the ring & pinion gears. If merely removing the hub to replace a seal, and putting the same hub back on, one can scribe a mark on the nut & hub & retorque it to the same position. You might be able to successfully swap them if you scribe a mark and measure the torque required to line the mark back up, and apply that torque to the swapped hub & neglect the mark. If the preload isn't set correctly, the diff can fail within 1000 miles.

[Rigmaster]

6 cyl E34's (525i, 535i) and 530i all use the same diff (configuration and bolt-in wise), the 540i and M5 use a different type of diff (i.e- will NOT bolt into the 6 cyl E34's or 530i's).

So, if you have a 540i, you need a diff from another 540i OR an E34 M5 to fit.

That's my story and I'm sticking to it.

ps- I have a couple of E34 diffs on Ebay right now- including a NICE 3.46 LSD for 6 cyl cars or 530i- just search under "E34 differential"

Thanks, Bret.

e32/e34 diff's will interchange but I believe M5's are different. You may have to swap the input hub and/or axle output hubs depending on the year and whether the diff is from a manual or auto. I believe only lsd to lsd axle hubs can be swapped, open diff's have a different arrangement for how the hubs attach and are attached internally? Lsd hubs come off really easy, just pry on the outer flange lightly with a screwdriver and it pops an internal snap ring out of a groove. Just be careful to put them back in lightly and rotate them slightly to register the splines before tapping them in with a rubber hammer. Replace the seals if the hubs have to be removed.

The diff is really easy to remove from the car. The socket head screws on the axles are a pain to break loose the 1st time. They have serrated binder heads on the underside of the head which bites into a metal washer plate that spans 2 bolts. Clean any dirt out of the sockets with a small screwdriver & compressed air & use a breaker bar on a hex bit or a pipe on an allen wrench. The diff drops out by removing the 2 bolts on the rear bracket and the single bolt on the front of the stamped sheet metal plate. The plate stays on the diff. The diff is heavy, it weighs approx. 92# so be ready with a floorjack.

It might get a little dicey if you have to swap the input hub, the preload on them is factory set and establishes the clearance between the ring & pinion gears. If merely removing the hub to replace a seal, and putting the same hub back on, one can scribe a mark on the nut & hub & retorque it to the same position. You might be able to successfully swap them if you scribe a mark and measure the torque required to line the mark back up, and apply that torque to the swapped hub & neglect the mark. If the preload isn't set correctly, the diff can fail within 1000 miles.

[Anton CH.]

Can you post a link to the ebay auction?

6 cyl E34's (525i, 535i) and 530i all use the same diff (configuration and bolt-in wise), the 540i and M5 use a different type of diff (i.e- will NOT bolt into the 6 cyl E34's or 530i's).

So, if you have a 540i, you need a diff from another 540i OR an E34 M5 to fit.

That's my story and I'm sticking to it.

ps- I have a couple of E34 diffs on Ebay right now- including a NICE 3.46 LSD for 6 cyl cars or 530i- just search under "E34 differential"

Thanks, Bret.

[DrewZ]

Look for a diff from an E32 750iL. Early 750s had a big-case 3.15 LSD. Later ones had either a 3.46 or 3.64 (I'm not sure which). The only other diffs that will fit are from the E34 M5 (either 3.73 or 3.91) or an E31 (2.65).

Drew Zacharda
6-speed Touring with 3.15 LSD

hi,
i have a 1995 540i/a & i am looking to install a lsd. i have been looking at changing it to 3.64:1 ratio. is this a good ratio to change it to? will a lsd from a 1990 735i fit?
thanks for any help you can provide.
tim s.
1995 540i/a
1987 325e

[Bill R.]

7/90 has the 3.15, from 7/90 on its has the 3.64.... and thats US, Canada and Japan only..

Look for a diff from an E32 750iL. Early 750s had a big-case 3.15 LSD. Later ones had either a 3.46 or 3.64 (I'm not sure which). The only other diffs that will fit are from the E34 M5 (either 3.73 or 3.91) or an E31 (2.65).

Drew Zacharda
6-speed Touring with 3.15 LSD

[tim s]

7/90 has the 3.15, from 7/90 on its has the 3.64.... and thats US, Canada and Japan only..

[DrewZ]

7/90 has the 3.15, from 7/90 on its has the 3.64.... and thats US, Canada and Japan only..

[DrewZ]

With your stock diff (2.93) in 5th gear (.79): 2500rpm=83mph
3.15: 2500rpm=77mph
3.64: 2500=66mph
3.73: 2500=65mph
3.91: 2500=62mph


Drew Zacharda
Touring with .83 top gear, 3.15 LSD and 2500rpm @ 73mph