Big block chev thrust bearing problems

I have started to damage my thrust bearing on my big block 469 cui engine after 4 years of racing and 168 runs . It's a 750 HP 469cui with a power glide trans , the car runs 9.1s at 149 mph and weighs 2825 lb. I caught the problem before it damaged the crank so I just polished the thrust while still in the engine fitted new bearings and put it on the Dyno. Everything checked out good so I raced and won the next meeting . It did it again, went through the same process again but this time I lowered the cooler line pressure from 150 psi to 95 psi , pressures were taken while on the trans brake . Raced the car did well but wore the thrust again . Can anyone help ?

 

I would check your converter for ballooning. This happened to me on a blower motor years ago.

 

or possibly a cracked flexplate, but i'd go with the convertor issue

 

Converter still measures ok but some times I wonder if it could balloon and then retract back again.