flywheel
 

Do you think that a local machine shop should be competant enough to machine a 911 flywheel?

Possibly. But do a search either here or on the tech board. In the last month or so there was quite a discussion about how to properly machine a 911 flywheel. Apparently if done incorrectly with the wrong cutting tool it leave a ridge on the outer edge of the flywheel which means the clutch plate can't get a good surface to mate to.

Yep, a special "diamond" grinding stone is necessary to make the square corner. Do a SEARCH here.

If you are going to have a flywheel resurfaced, be aware that there are two common ways to do this. Most places will grind the flywheel with a blanchard grinder setup that uses a rotating abrasive to grind away at the top surface to renew it.

Another method is to chuck the flywheel up in a lathe and cut across the flywheel face with a toolbit.

The latter is a much better method.

The problem with having a flywheel ground is that when you get it back, it will look nice and new and fresh, but that is only on the surface. What happens with a flywheel during its service is that the running face will get heat treated due to the immense temperature from the friction of clutch operation. This will create hard spots in the flywheel that go much deeper that a grinder can remove. So once you get a ground flywheel back, install it, and do a few miles on the clutch, all of those hard spot will come right back up to the surface and the flywheel surface is less than optimum. All of those burn spots that look blue and black and brown all over the face on your used flywheel are those hard spots.

Turning the flywheel on a lathe will allow those spots to be removed because you remove material deep enough to get past them, thus resulting in a true fresh surface.

Sometimes the problem is that those hard spots go quite deep, and you must be careful not to exceed the spec of the flywheel with the material you remove.

Here is a shot of a flywheel surface that has the hard spots in it, so you can better see what I am talking about.
http://forums.pelicanparts.com/uploa...1078513971.jpg