The comprehensive DOHC engine swap thread.

[Brew]

130k on the motor when I bought it, about 137k now.

I had to replace the alternator last week, but other than that its been very reliable.

[bmwe3]

what is all needed to swap a m20 flywheel into a s50?

[Brew]

what is all needed to swap a m20 flywheel into a s50?

Should bolt right up as long as you have the m20 starter and clutch/pressure plate.

You may also have to shave down some castings on the rear of the oil pan, I did.

[Jason89i]

Should bolt right up as long as you have the m20 starter and clutch/pressure plate.

You may also have to shave down some castings on the rear of the oil pan, I did.

I tried to use the m20 flywheel, but the back side of the flywheel needs to shaved down. it would not mate to the block. the raised portion of the backing did not clear by about 1/2". i ended up getting frustrated and ended up going the easy route. I used the e36m3 flywheel / pressureplate / slave cyl. cheers

[bmwe3]

i have a brand new sach cluctch kit in my car s50 but the flywheel is no good so im just thinking of putting a m20 flywheel since its lighter and i have one sitting and a s50 flywheel is going to run 500 for a ltw one.

Factory Sachs clutch, less than a year old

is that a normal m20 clutch can it hold the power of a s50?

[Brew]

Factory Sachs clutch, less than a year old

is that a normal m20 clutch can it hold the power of a s50?

Yup, normal M20 clutch. It does fine with my chipped non-vanos, don't know how well it would handle an S50 though. I have heard people say that it can handle 300hp....

[JGood]

Hey guys...

I just did a five speed swap a few months ago, with all brand new parts. The only used part is the tranny/driveshaft, so I'm deciding when it's m50 time if I should just keep the m20 trans, or go with the m50. If I use the m20, does anyone make a crossmember or would anyone be willing to make one? I can't weld. If I go with the m50 one, what is the deal with the m20 clutch, because I'd like to reuse my clutch that has less then 15,000 miles on it. Can I use my 85 325e's single mass flywheel/starter/clutch or not? The info on this is somewhat contradicting I found. Basically, I don't want to spend all the money for a m50 trans setup when I JUST did a five speed swap with all new parts that cost me $1500.

Justin

[bmwe3]

hey BREW are you using a e36 trans?
i know when i went to put on my s50 clutch the m20 clutch alginment tool didnt work i had to use a toyota one. so doesnt that mean that the m20 clutch wont slip on the s50 trans input shaft

[Brew]

hey BREW are you using a e36 trans?
i know when i went to put on my s50 clutch the m20 clutch alginment tool didnt work i had to use a toyota one. so doesnt that mean that the m20 clutch wont slip on the s50 trans input shaft

Nope, e30 transmission.

[Brew]

Should bolt right up as long as you have the m20 starter and clutch/pressure plate.

You may also have to shave down some castings on the rear of the oil pan, I did.

I tried to use the m20 flywheel, but the back side of the flywheel needs to shaved down. it would not mate to the block. the raised portion of the backing did not clear by about 1/2". i ended up getting frustrated and ended up going the easy route. I used the e36m3 flywheel / pressureplate / slave cyl. cheers

Sorry, didn't see this post before.

Where did your flywheel hit the block? Mine hit some raised castings on the back of the oilpan, which were easily removed by the die grinder, but cleared the block fine.

[Jason89i]

Where did your flywheel hit the block? Mine hit some raised castings on the back of the oilpan, which were easily removed by the die grinder, but cleared the block fine.

I was told by a good meaning individual (without actual experience) that the single mass m20 flywheel would bolt directly to the m50 and there was no additonal modifications necessary........NOT SO. I would love to see a writeup on the lightweight m20 flywheel install for the m50/getrag265. blackforest has an awesome writeup ( http://www.blackforestindustries.com/m20flywheel.htm ) on the m42/m20 flywleel conversion. does the m42(getrag 240) use a similar flywheel / clutch as the m50(getrag 265).......ANYONE?

on the block side of the m20 single mass flywheel there is a raised portion on the outer edge. it sticks up maybe 1/2' past the mating surface of the crank / flywheel. that is where my trouble was. that raised portion was hitting the block. I could have had it shaved off (read lightened) but then i would have needed a taller throw out bearing....flywheel would be closer to the block.

i was using the e36 5speed and i had an e36m3 flywheel.....so i just used that with a new e36m3 clutch pack. the pressure plates on the e30-325, e36-325 and e36m3 are all different. THEY WILL NOT INTERCHANGE. What ever you use for a flywheel, you will need that clutch pack. the mounting tabs / hole locations are all different.

This was the biggest obsticle i faced with the e30m50 conversion......well the silver label ews ecu took a while to figure out too. :oops:

[Brew]

Which M50 do you have? Maybe the block is different from year to year.

I know for a fact that I have the single mass m20 flywheel bolted directly up to the m50, no spacers, no mods to the block, and no lightening of the flywheel.

[Jason89i]

i have the 95 vanos m50. the flywheel i used was the single mass off an 89. i just measured the m20 single flywheel. the "hump" where most people lighten the flywheel protrudes a little over 3/16" from mounting face of the flywheel. If memory serves me correctly....the m50 dual mass mating surface is flush with the farthest protruding point.....(see blackforest pic 6)

thanks for responding. its nice to discuss in depth stuff with experienced others.

what throw out bearing did you use?

[Bryson]

I've done a few 24v swaps with m20 flywheels and on ZERO of those cars have I had block clearance trouble. The only place it rubs is the oil pan
done on non-vanos and vanos motors

edit: whatever flywheel you use means you have to use the accompanying clutch, I was under the impression that everybody was aware of that. The throwout and pilot bearings are the ones that match the transmission used

[JGood]

I've done a few 24v swaps with m20 flywheels and on ZERO of those cars have I had block clearance trouble. The only place it rubs is the oil pan
done on non-vanos and vanos motors

Even with m20 transmissions? So the m50 would bolt directly to my existing setup without and problems (besides trans mount)?