How is a flywheel resurfaced? Need expert help!!

[Timothy B.]

Who knows how a flywheel is resurfaced? I have had my flywheel resurfaced twice now by a place that came highly recommended, who does them for many area shops. I had chatter after the first time (see other threads from me about that) and found I had some non-uniform runout of about .004". I took the flywheel back and they redid it and claimed they did see a problem and made sure it was good this time. Now on the car I have more runout than I did the first time, something like .010" now! At least this time I checked it before the tranny went it! Since I know someone will ask, I checked the crank flange and I measure no noticeable runout at all on the flange. I marked the high and low spots on the flywheel and they are 180 deg opposite, and if I remount the flywheel 180 opposite on the flange the same high and low spots remain. This confirms that the flywheel surface is out of plane with the center where it bolts to the crank.

I was thinking that maybe the machines they use to support the flywheel uses the center hole to attach rather than the actual bolt holes? Anyone know how this is done? The tech said their machine uses some sort of stone that spins. The finish has been nice and uniform, but something isn't right. Should the flywheel be cut with a cutter like how brake rotor is turned??

[David B.]

How is a flywheel resurfaced? Need expert help!!

Tim,

I had mine resurfaced recently and they used a large stone that revolves like a record player. The flywheel sits on top of it. I did not pay attention to the mounting method, so I can't advise on that part. The flywheel came out beautifully with this machining method and there is no chatter.

You probably have done this already, but I suggest you check the mating surfaces between the flywheel and the crank carefully for dirt, or burred surfaces that can cause the flywheel not to be seating properly.

Also, you may want the machine shop to check to see that your crank is straight. Cranks must always be stored on end or hung vertically. And of course cannot be allowed to fall over or they can be damaged (bent).

Hope this helps.

Dave

[John M.]

Re: How is a flywheel resurfaced? Need expert help

Tim,
It sounds like its ground flat just not true to the crank flange. It needs to be trued up on a lathe and then ground flat again. You'd think those guys would check that.

[Timothy B.]

Re: How is a flywheel resurfaced? Need expert help

John,

I am reaching the same conclusion as you. I know a guy at a local machine shop and I think I might get the flywheel to him and have him put it on a lathe. I can have him check the trueness of the face of the flywheel relative to the flange mounting surface, and if necessary true it up like you would a brake rotor.

I guess after that I will have to get it surfaced using the rotating stone technique also so that the face has the typical swirl pattern? Is that necessary or would a turned surface from the lathe be acceptable? Thanks for the comments.

So, can I conclude that the normal flywheel resurfacing process only creates a flat face, but doesn't do anything to true it up to the flange?

[John M.]

Re: How is a flywheel resurfaced? Need expert help

Tim, I don't know if that is the normal technique but it sounds like what's happening because the crank connection is recessed. You can get a pretty fine finish on a lathe but I don't know if this is good enough for a friction surface (it works for rotors). I think I would try to find another shop for a second opinion (or buy a new flywheel?)

[Jim L.]

Re: How is a flywheel resurfaced? Need expert help

Hi Tim

When I had my 63 engine rebuilt the shop owner said he would resurface the flywheel using a Laser to cut it. He said you can never remove the minute steel shavings that are invisible. He guaranteed that I would never have clutch chatter. I put 22000 miles on the car before I sold it and it never chattered. I woul recomend a new flywheel considering what you have been thru with your present wheel. I would also check the mounting surface stager the bolt tightening very carefully. Good Luck. Jim

[Timothy B.]

Update: Flywheel surfaced again......

Update: After talking to the machinist and deciding that turning the flywheel on a lathe was not a good idea, I found another machine shop to surface it on a grinder. I saw the machine this time. Flywheel was mounted on a platter from the center point where the crank flange mounts. The grinder clearly hit the high points that I had marked when I had it on my engine. When complete, it measured about maybe .002" total runout (max one way to max the other). When I put it on the engine I get about .004". Once again, the high and low points move with the flywheel when I rotate it on the crank. Apparently shops have real trouble getting closer to zero on runout as I have now been to two places.

This last place left a noticeably rougher surface on the face. It still has the typical circular pattern, but is much rougher due to a suppose courser stones. Is that a problem???

I have ordered a new flywheel from my local auto supply store and will see how good the runout is on it, and then decide which one I actually install on the car.

[Daniel C.]

Re: Update: Flywheel surfaced again......

Tim, I found a picture of a flywheel after it was ground if this helps. Also check your clutch disc springs and see if they are tight. Dan