M70 into an e34 swap.

[rahim2]

I did a search for "M70 e34" and nothing came up. I have a 1990 525 with the ol m20 engine in it, bad transmission. I also have a 1990 750il with the m70 in it, bad transmission. I bought the 4hp24 rebuild kit and was considering doing a m70/e34 swap. I wanted to go manual, but the 6 speed transmission for the v12 is, well, pricey at best. I've heard of one person using the trans out of a e30 and used an adapter plate, this doesn't sound like a good match to me, sounds like me changing trans after trans. I'm starting this project in the next few months after I get this customer's "civibushi" (94 civic/4g63 turbo) project out of my hair.

Anybody that had done this pass me any insights or bumps in the road I can look forward to?

Yes, there will be pics...



Web Design

[Richard454]

The v12 in the E34 has been done a bunch- The first one I saw was in like 90-91....

Here's one-
http://www.dtmpower.net/forum/m5-5-s...4-project.html
Go to the E34 forum and search V12 there- Some guy has a thread on a build...




As far as the transmission....Depending on your access to the right stuff (machine shop/getting-having the parts to measure) - "the" 6 speed would really be you cheapest cash outlay -upfront...By the time you make an adapter figure out the clutch-flywheel- etc you'll save money in the long run- even if you do most of the work yourself and the labor is free.

The v12 has a lot of torque off idle ( I think 80% of max torque output at 2000 RPM) so that lightweight E30 trans will be spitting metal- your gonna have to go w/ something more substantial. I saw a swap w/ a T-5 transmission- but the last I heard from the guy -the T5 had mulched up its gears...But there are companies that will build the T5 to handle more torque...but you are back up to $2K easy...I've got a T45 ( a little better than a T5) but I abandoned the idea because I didn't want to pull it back out after i broke it...

NO other BMW engine uses the same bellhousing bolt pattern- the V-8s and I think the V-10s (haven't actually test fitted one on it) have the same crankbolt pattern.

In my swap w/ a M70 - the BMW 6 speed (about $2-2.5k used w/ most of the parts) was NOT an option because of the gear ratios. First gear would have been useless. I went w/ a Richmond 6 speed overdrive ($3K new) and milled down the auto bellhousing to fit the Richmond- that's the Reader Digest version- as I had to do a lot of homework figuring out the disc height/throw out travel and the inputshaft w/ pilot bearing...BMW E31 flywheel drilled and doweled to fit a Chevy 10.4 clutch...

Richard