[Mark Laczo]

A fellow racer has a 4.5" bore x 4.25" stroke, Crower crank large short snout, BME 426 rods, A460 block, blown alky BBF that had a thrust bearing failure. Estimated HP was 1600+. Using a slipper clutch. What could cause the thrust bearing to fail ? Improper crank end play ? Something to do with the clutch assembly ? Looks as though the crank could be toast as the thrust surfaces are quite bad. Any experiences or ideas on why this could happen ? This is just for my own knowledge as the racer has already built another engine(BBC) and moved on and is not really interested to know why this happened.

Thanks Mark

 

[crittersf1]

Which side of the thrust is worn?

 

[Mark Laczo]

thrust

I think it was the rearward side towards the flywheel, but I'll have to call/look at it to make sure.

Mark

 

[tall69]

It was probably caused by some sort of fitment issue between the transmission input shaft and crank. Maybe the bell housing was too short. Maybe something was binding. Thrust surfaces don't live long when the crank is forced forward.

 

[crittersf1]

If it is the side towards the flywheel, something to do with the transmission is shoving the crank forward, have seen it many times with automatics having too much line pressure.

 

[Mark Laczo]

thrust

Those ideas make sense because this engine only lasted 10 - 2.5 sec passes and then low oil pressure and was shut down.

Thanks Mark