e30 differential swap options

[delt266]

Hey guys, I've been searching but cant seem to find a definitive answer. I have an 89 325i and a whole 95 M3 drive train. Can this M3 LSD be swapped into the e30 chassis? I was hoping there would be a writeup somewhere, but I cant seem to find anything. Any help would be greatly appreciated!

[bmwmech1]

Hey guys, I've been searching but cant seem to find a definitive answer. I have an 89 325i and a whole 95 M3 drive train. Can this M3 LSD be swapped into the e30 chassis? I was hoping there would be a writeup somewhere, but I cant seem to find anything. Any help would be greatly appreciated!

The answer is yes and no, Lol! It's not a straight swap, because the E36 diff uses a different diameter reluctor ring and a dual ear cover on the rear. I just modified my E30 LSD by adding the E36 dual ear cover and clearance'd the cover on the inside and machined a .300" spacer for the E30 speed sensor to fit without hitting the ring. You would have to do the exact opposite of what I did. Unless you're comfortable with doing these mods, look for an E30 LSD instead and sell the E36 one to offset your costs...

Garey

[delt266]

Wait I am slightly confused.. Why did you modify your e30 rear end? Maybe I am reading this funny.. Did you use a rear cover from an e30 rear end on a e36 rear end and then make the speed sensor fit?

[MR 325]

Just do yourself a favor and sell the E36 diff. Use the funds to buy an E30 diff.

[delt266]

Just do yourself a favor and sell the E36 diff. Use the funds to buy an E30 diff.

I mean is it really that much of a pain in the ass to make work? Shipping this bastard is more irritating to me than building or modifying something to work..

[Kershaw]

300 shipped for the diff to md?

:D

[jlevie]

With a bunch of work you could use that differential. But you'd be taking out a 3.73 (manual transmisstion) or a 4.10 (auto transmission) and replacing it with a 3.23. I suppose you'd get better gas mileage, but acceleration would suffer quite a bit.

[delt266]

300 shipped for the diff to md?

:D

It needs another rear cover as the mount arm is cracked. You arrange shipping.

[delt266]

With a bunch of work you could use that differential. But you'd be taking out a 3.73 (manual transmisstion) or a 4.10 (auto transmission) and replacing it with a 3.23. I suppose you'd get better gas mileage, but acceleration would suffer quite a bit.

Well the whole M3 engine, trans, and diff would go in, so the ratios would be from the 1995 car. The ratios that you mentioned, were you referring to the stock e30 differential that's already in my 89?

[jlevie]

Okay, if swap in the entire M3 drive train, then it would be worthwhile to convert the M3 differential.

[SpecM]

Really, just use an e30 or e24/e28 diff. There are 3.25 lsds available that are esay. Its more trouble than its worth to make an e36 diff work.

Sent from my Ally using Tapatalk

[nrubenstein]

You would have to modify your subframe to make the E36 diff work. The way the front case attaches is completely different.

[Wanganstyle]

The answer is yes and no, Lol! It's not a straight swap, because the E36 diff uses a different diameter reluctor ring and a dual ear cover on the rear. I just modified my E30 LSD by adding the E36 dual ear cover and clearance'd the cover on the inside and machined a .300" spacer for the E30 speed sensor to fit without hitting the ring. You would have to do the exact opposite of what I did. Unless you're comfortable with doing these mods, look for an E30 LSD instead and sell the E36 one to offset your costs...

Garey

This is a very extreme way to handle this.

Conversion to a dual ear diff is only needed for crazy power in a E30, done pretty often to E36/7 Z3........google search "randy forbes" dual ear z3 and you will find this common mod to the z3's that like to tear out their sheetmetal.

Garey; you could have just plugged in the E30 speed sensor or a newer e30/z3 speed sensor into the e36 cover and pnp into your harness. This is often done, easier than machining- just swap the sensor or the chopper wheel- you had them in your e30 diff!!!!

speedo gear presses right on to the lsd unit.



Someone with your skills should surely be able to swap a ring and pinion?

if you reference the OEM bmw TIS for e30 M3, there is full factory instructions on how to replace the gearing and set it. One can easily remove the guts of any USA side 188mm E36 M3 diff and install it into any E30 188mm case.

so if you have a E30

and you have a E36 LSD, and you want the ratio and the LSD in your e30:

1. gut e30 diff
2. gut e36 diff
3. install e36 guts into e30 diff shell with proper OEM BMW speed sensor ring (chopper wheel) and genuine proper length speed sensor.

then you can install it into your E30 :)


**************
How do you think my E36M3 has a 4.10 final drive gearing and TORSEN LSD in it :)

**************

[Wanganstyle]

With a bunch of work you could use that differential. But you'd be taking out a 3.73 (manual transmisstion) or a 4.10 (auto transmission) and replacing it with a 3.23. I suppose you'd get better gas mileage, but acceleration would suffer quite a bit.

Misconception:

the OP is installing a M3 entire driveline into his E30, along with the ZFsg310 transmission

5th gear in a e36m is = 4th gear in any 5 speed E30 with Original e30 factory gearbox.

3.15 is paired with a 1:1 SG310
3.73 is pared with a 0.81 (overdrive)

Doing the Math and Comparing the 2 with equal tires, redline, etc:

If running a ZF M3 gearbox the 1:1 5th gear, if you wanted to have a crusing rpm similar to the stock E30 5mt with 3.73, you would either want a 3.07 or 2.93 final drive

The stock BMW M3 5 speed e36's had 3.15 or 3.23 final drives; paired with a 1:1 5th gear both are shorter than the stock E30; would spin @ higher rpm on the freeway.


:)

[M-technik-3]

Just do yourself a favor and sell the E36 diff. Use the funds to buy an E30 diff.

Quoted for the truth.