E30 M50 Swap Flywheel Machining

[MaxBell]

Hey, I've been searching like a mad person and I can't figure out how much I have to machine off my M20 flywheel to put it on my M50.

I've heard that it hits the back of the M50. The best (only) person who posted anything gave a measurement of "around 3/16ths" but I want exact numbers.

Anyone know how much (in thousandths) should be machined off the M20 flywheel?

[scottinAZ]

most people have the back shaved down to the level of the ring gear, Not too many take measurements for this work.

[Tico Frank]

There is a decent pic of this on an m50 swap some dude in Newfoundland or somewhere like that did. I wish I could remember more since I want to get my flywheel lightened before I install soon too.

[MaxBell]

Anyone got specific measurements?

If I was to get the outer ring machined down to the back of the teeth, would I get the area that the bolts go through machined as well?

[scottinAZ]

Anyone got specific measurements?

If I was to get the outer ring machined down to the back of the teeth, would I get the area that the bolts go through machined as well?

You do NOT want to change the mounting pad where the bolts go through. the offset on the M20 flywheel is different than the M50 fly (its nearly flat). If you were to get that area machined, it would negate any gains from getting the back shaved.

[5KWattson]

shaved the back off three I M20 flywheels down to the ring gear all three are in use currently in my car and two of my friends cars, nothing bad has ever happened due to taking off material from the back side, as for exact measurement...1/8" is about all it needs to clear but if you are shaving it down why not go on a diet while your there

[Wanganstyle]

This was done by my preferred local shop that handles engine work; they do full surfacing and balancing of flywheels, lightening also if you ask the right way nicely!

Stock flywheel:



Shaved backside and balanced flywheel:

[A_Whelan]

I don't know the exact measurement, I took it to them and just guessed and we measured what would be left at the shop and it sounded good. It's in post #6 and note that the flywheel is facing a different direction in each picture.

http://www.r3vlimited.com/board/showthread.php?t=207322

[MaxBell]

Thanks all, I had it machined down to about 1/16th from the teeth. It clears fine.

[Jand3rson]

Thanks all, I had it machined down to about 1/16th from the teeth. It clears fine.

That's what I had them do with mine, you don't want it flush to the ring gear.

[Tico Frank]

That's what I had them do with mine, you don't want it flush to the ring gear.

Did you have yours balanced? And what was the cost of the shave, if you don't mind my asking.

[Jand3rson]

Did you have yours balanced? And what was the cost of the shave, if you don't mind my asking.

Mine actually was not balanced at the time, because the Napa machine shop didn't have the proper mounting capability, but the tech said he has done several flywheels on his machine, and taken them to another shop for the customer to be balanced, and they didn't need it.

I think I paid $95 for the shave, and they resurfaced the other side, too.

[zer0_paint]

sorry to bring up an old thread, but im getting this done today and need to know exactly where and how much to shave off??? thanks

[mpowerful]

[justin_l_]

I went off this picture when I did mine. I think it weighed around 12 lbs when done. I machined it myself.