I'm currently running a powerglide with an 8" ATI converter behind my LS7427. The motor ran great for 2 years with an 4L65E. When I converted to the powerglide I lost the engine thrust bearing in less than 20 passes. Figured it was just a simple failure. The crank was replaced with a new one and the motor was freshened up. Crank end play was .0025".. Now it looks like it has eaten another thrust bearing in less than 20 passes again. Converter is spaced according to ATI's specs...pull from trans at least 1/8" but no more than 3/16". It was a brand new converter both times also.

What could be causing it to push on the crank? Anyone else had this problem?

 

Excessive converter charge pressure pushing the converter into the crankshaft.

It can be the way the trans is built, the way the converter is built, or a combo of both.

 

sounds like your converter ant right im sorry to hear that

 

I think I have found the problem. Looks like the converter hub bottoms out in spacer pilot hole and then pushes on the crank. I'm using a 4L80E flexplate and spacer. The spacer needs about .100" machined off.
Little things like this can cost you a ton!