Has anyone experienced premature wear on the cranshaft main thrust bearing in conjuntion with a 700 R4 when the converter is in lock-up mode?

Short story made long:

406 in an 89 GTA. Used original 400 crank turned .010. Speed Pro pistons, clevite bearings. New Comp cam and lifters. All machinining performed by reputable shop, same with assy. All tolerances checked and re-checked. Fired up without incident 60 psi oil press at speed. PLENTY of botttom end, car ran great for 50 miles or so. Then loss of oil pressure, pulled engine, disassembled to find 2, 3 and 4 main bearings worn to the copper and rod bearings getting close. Cam and lifters look new. Oil pump shows no wear or FOD with nothing in the screen. The trust bearing was worn .003 to .005 from the original spec which does not seem excessive.

The shop guy reassembled the engine and confirmed that all tolerances were within spec.

Rumor has it that in some instances the lock-up feature puts force on the crank and then induces excessive wear on thrust bearing which then contaminates the oil through-out the engine.

Anyone have any input?

Thanks for your time.
Paul

 

well i have put 450hp in front of a lock up converter with no wear whatsoever. i dont see a lock up converter putting that kinda wear on an engine at all. 50 miles and it was trashed. there was a machining error imho. the only thing i can see is if the converter didnt fit just right.

 

Only time I have known transmissions to cause trouble on thrust bearings, was the manual trans in the Z-34's back in the early 90's...... I would agree with the assembly error assessment, either at the machines shop, or, when installing the trans.

 

I was leary on the lock-up causing the problem also. Assembly was performed correctly. Still looking for a reason.

Others thoughts?

Thanks for your time.