Stan944

Here is my next question: I had the flywheel machined out, and I'm not fully happy with the result. They used a grinding stone (I though this would be done on a leight), and due to a kink on the flywheel, they left about 1 mm -wide "ring" of untouched surface (at the outer diameter of the clutch disk). In other words, the clutch disk stays flat on the flywheel, but if it's off-center more than about 1.5 mm, it would rest on the uneven surface, and possibly crack the disk lining, etc.

The question is do I have to worry about it? I'm thinking that there is no way the disk could be shifted by 1.5 mm off center during regular operation, as the pilot bearing wouldn't allow for it. On the other hand, will I be able to position the disk properly during tightening of the pressure plate? I mean no more off center than 1.5 mm. Keep in mind that I have a plastic clutch alignment tool.

P.s. I don't think I have stepped clutch discussed in the other thread, i.e. I don't see any steps at the contact of the disk lining with the flywheel nor the pressure plate.

I think I'm safe, but would like to hear your opinions, especially if somebody had a similar experience.

David Floyd

Here is some info I dug up

http://www.tomorrowstechnician.com/tt/tt40260.htm

http://www.babcox.com/editorial/bf/bf100372.htm

Now to find someone local to resurface correctly.

Sam Lin

Centering cones are not the ideal way to mount a flywheel for cutting, ideally you go to a more specialized shop that can make a custom adaptor to fit your flywheel. Using a custom adaptor gives a more solid surface and makes for a far more accurate cut.

Sam

David Floyd

Sam, you know a good machine shop that can do this correctly ?

Sam Lin

I know in AZ, we've got a couple, but I'd just look in your phone book and call around or ask a local race shop/race engine builder. Pick a place that you feel comfortable with, ask about the step and if they use centering cones or if they make adaptors. There's no reason to go shipping a flywheel around, it's about as elementary a machining operation as they come.

Sam

David Floyd

Will do, thanks Sam

KuHL 951

Ditto on the machine shops that cater to the racing set. I've taken so many flywheels to one shop that they do it while I wait; $35 and they always machine to the edge if the flywheel was designed that way.

Stan944

Thanks for the replies. I understand it would be best to have it redone for perfect condition, but can anyone comment if I have a problem or not?

David Floyd

So do you have 18mm or so of unfinished flywheel at the outer edge ?? If so it sounds like the machine shop do not surface the step where the pp sits.

Your clutch disk will not shift because it sits inside the pp

Can you post a picture ?

Sorry, I did not intend on hijacking your thread

Stan944

David, judging by your reply, your flywheel is completely different that mine, and I have no clue how you came with 18 mm ? Keep in mind that I'm talking early (1983) 944.

To refraze my question, the clutch disk stays flat on the resurfaced section of the flywheel when its exactly where it should be, or up to about 1.5 mm "radially-away" from the rotation axis. More accidental offset than 1.5 mm would make the disk to rest on the not-properly-machined section of the flywheel, and posibly crack.
I think it's OK like this, as the clutch disk is not supposed to move radially on the drive shaft, but can someone experienced with early 944 confirm it?

Unfortunately, I don't have access to a camera now...

Sam Lin

It's fine, won't move that much.

Sam

David Floyd

Ok, sorry I dug out my Haynes manual it has the early flywheel in it and they are not the same.

Are both early and late flywheels stepped ? you can clearly see a step on the early but not on the late ?

Stan944

Thanks Sam, this is good news.
Now if only I could understand how to mount the shims at the throw out bearing for proper clutch engaged and not operation (my other thread)...

83na944

Stan,

I had my 83 flywheel resurfaced. The machine shop told me before they started that they would not be able to grind up to the raised part of the flywheel. The result was a radius instead of a perfect 90 degree angle between the raised part and the surface that the clutch bolts up to. It was not a 1 mm ring, but there was a definite radius at that point.

I don't know how a machine shop could grind the surface all the way to that edge. They could do it with a lathe, but I don't see how they do it with a grinder.

Anyway, when I assembled the clutch there was no problem, and there was no problem with performance after the install.

Stan944

Thanks Steve, this is good news for me.