E30 subframe swap thread???

[HeathMO]

I know there is a thread where some one swapped an e30 subframe into an e21 and just added the strut mount and shortened it. If I believe correctly its pretty similar to the e28 swap you just have to add the strut mount.

If any one knows where I can find this thread please let me know cuz I've searched for hours!!

[bassboy3313]

front or rear subframe? Haven't heard of the front working, but the rear takes lots of modifying to make work.

[HeathMO]

the rear sorry. I'm just trying to find out how to get a stronger diff and keep the 4x100

[amarino]

Check this out for an upgraded diff: https://www.bmw2002faq.com/articles....tial-build-r74

[bassboy3313]

^^^ that is an ok upgrade, but it's still just a small case. Small case diffs can't handle much power. Just google "e30 diff in e21" and you will find pics and info on whats involved with what you are looking for. Lot's of fabrication and modifying.

[pofo]

You can swap internals from a e36 318 that has lsd into a e21 lsd case

[amarino]

^^^ that is an ok upgrade, but it's still just a small case. Small case diffs can't handle much power.

Well then we need to know how much power OP is looking to get out of their M20 swap. Of course bigger diff can handle more power reliability but no point in going through all the work when you're still within the range of your stock diff. You have a Turbo M20 swap, what diff are you using?

I found this random thread that claims the E36 small case can handle up to 300 fl-bs.
https://www.bimmerforums.com/forum/s...36-Diff-Thread

The E36 came with three different differentials. All E36 318i/is/ic came with a "small case" diff. This featured a 168mm ring gear. These diffs can hold up to anywhere between 200 and 300 ft-lbs of torque (specific to ratio).

Also here's another good discussion on E30 diff in an E21, straight from the FAQ/DIY thread:
https://www.bimmerforums.com/forum/s...n-e21-subframe

[HeathMO]

Sorry for the late reply its been a busy week end. So Ive got the m20 swap and I plan on going turbo when the time and finances all allow but before I can do that I need all the weak spots fixed I'm hoping to make 300whp but I also want room to move up. I have a e30 rear subframe and diff I am just debating on if its worth all the fabricating or if i should hunt down a e28 subframe which would be pretty difficult there aren't many older bummers up here in east idaho.

[Tom D]

not sure why an E21 needs 300, but if you're going through the trouble then weld the E30 diff support into the E21 subframe, bolt up a medium case diff and call it a day!

[m60b30530i]

My blue e21 has a full e30 rear sub frame swap. About the same as the e28 swap, need to make mounts for the shocks.

Centering the sub frame was a pain on jack stands.

Also I have a e28 sub frame with trailing arms and axles. Already cut to except the e21 mounts.