Big block chev rear thrust problems

I have suddenly started wearing out the rear thrust on my 469 cui big block chev after 4 years of racing and 168 runs . My monza runs 9.1s at 149 mph and weighs 2825 lb . I managed to catch it early so I just polished the crank thrust while still in the motor and changed the bearings, put it on the Dyno and everything checked good so I went racing. Well I won the meeting but wore the thrust again, went through the whole process again but this time I lowered the cooler line pressure to 95 Psi went and raced bloody done it again. Convertor has plenty of clearance. Has anyone got any ideas please am at my wits end , it's a powerglide and I sit on the trans brake at 5300 rpm.

 

Something is obviously pushing the crank. What is your convertor clearance? How about the driveshaft yoke pushing forward, how much clearance is there, not just at rest but dynamically? Is the rear housing thrusting forward?

 

The converter has plenty clearance , I can't imagine the rear shaft putting any force on the front shaft as in a manual . Have done some research over here in Australia and apparently others have had the same problem . So far the consensus is the pressure going into the converter is not the same as the pressure I measured in the cooler line , I was hoping some on on this site could come up with an obvious answer . Will let you know if we find it thanks anyway.

 

sounds like your convertor may be "ballooning". does it have an anti ballooning plate welded on it? When it balloons, it takes up the clearance and pushes on the crank.

 

What is plenty of convertor room if you don't mind sharing?
I recently checked my bearings and found I had a touch of push in the radius, Bryant crank, twin turbo Hemi with a Bruno Lenco, I double checked it and it was at .140. I normally run a little more and have never before seen the issue. FYI, I opened it back up to .185.
Good luck