The guy that is building my TH400 puts flex plates in a brake lathe and watches them spin. If they wobble to the naked eye or appear oblong while rotating, he won't use them.

He says they will be real hard on the pump gear.

We looked at one, a scat flex plate and it wobbled badly. I mean really bad.
Then another one was obviously oblong.

I have another one now and we'll rotate it tomorrow.

I'd never heard of this stuff before. I don't know tranny's but this I hadn't heard of.
This guy is putting together this tranny like its a swiss watch. He is photograghing it as he goes and is going to put the pics on a cd for me. I think that is cool.

So anyone heard of flex plates that wobble before?

It's rare to find one that doesn't move a little. .050" is often seen. And it usually won't hurt anything. The critical thing is to have 1/8" to 3/16" converter clearance. Push the converter fully back into the pump and then measure distance from the converter mount tabs to the flexplate. If you have less than 1/8" make sure the converter is fully seated in the drive gear. If so, then you need to take it apart and find out if it was built wrong. If over 3/16" you need to use parallel ground washers/shims to tighten it up to the proper range. Also, the center pilot on the converter must engage the crankshaft enough to keep it concentric.

Would that spacing be the same on a TH350? Thanks

Would that spacing be the same on a TH350? Thanks

yes

Mike,
I have yet to see one that does not move some, including some of the best and most expensive SFI ones made. The external balance ones seem to be worse, probably because of the weight welded to them. If you really think about it, once the converter is bolted to it, it has to be flat. I have never seen it cause a problem.

He, He!!

Just like BillK say's!!

Once tight, it's gotta be flat!

But that said, 350's w/ TH400's in 'Burb's tend ta crack the flexplate right around the OD of the crank flange... At least a friend of mine had two crack on him in his junk 'Burb....

pdq67