Machining m20 single mass fw

[bimmer630]

Apologies on advance if this has been covered.. my internet is down and my phone won't let me use the search forums bar for some reason (droooooiiid)

I had my fw machined and I told the guy to maintain the step up.. because I've read somewhere that the clutch will slip if the proper height isn't there.
Well.. he said it was warped and he had to machine it all the way.

Question is has anyone had the outer edge machined down to re-create the "step "? It looks like the dowel pins are either part of the ring gear or held in by the ring gear. Is this one of those deals where the fw has to go in an oven b4 the ring gear will press off?

Does anyone know the spec of the step?

[jlevie]

The dowel pins are removable. The shop that I use always machines both of those surfaces to maintain the step.

[frankie591]

^ Exactly. The dowel pins have to be removed, and however much they machine off the clutch surface they also have to remove off the outer ring where the pins sit.

[bimmer630]

Cool thanks. He was telling me it looked like the pins werent removable, but we only looked at it quickly.

[jlevie]

Find a shop that knows what there are doing. It sounds like this guy doesn't have a clue.

[bimmer630]

Hes actually very good.. he just doesnt normally deal with flywheels and such. And he is french canadian so there is a slight language barrier. Im taking it back tomorrow to have the outer edge cut.
does anybody know the spec?

[jlevie]

A good machinist he might be, but cutting on a lathe isn't how you surface a flywheel. That operation is done by grinding with a form of a Blanchard grinder. Any good automotive machine shop can do this.

[bimmer630]

I never said that he did use a lathe. he grinded it. Does anybody know the specs of the step up on the flywheel?

[jlevie]

That depends on the clutch used, but I believe stock is 0.010".

[bimmer630]

Got my FW today, He put a .010 step down where the press plate attaches, and also shaved the front of it off.. I havent weighed it yet but it he went down to 1/16" from the ring gear which from what people say takes about 4 lbs off (?)


I used a LUK stock replacement (e30) clutch set. got if for 175.00