460 thrust bearing problem

[65venom]

I installed a 460/485hp crate motor with a tremec 5 speed in my superformance cobra. The timing gear sheared off the cam after 300 miles. After another
500 miles I cut the filter and noticed a bronze dust in the oil. I tore it down and found the thrust bearing worn. I machined the crank and replaced the bearings. After a great dyno session, I got another 160 miles on the engine and it started a severe knocking. Another wiped out thrust. This time the pressure plate
has grooves like a record. The clutch assembly is the standard shipped from Snakebite Performance. Whats my problem!!!

[blykins]

What's the end play on the crank?

[Mr.Fixit]

You have to check input shaft distances and compare them to the stack height of the clutch, PP, and pilot bearing. Just takes a piece of dowel or welding rod, a magic marker, and a straight edge.

The input shaft could be puting a heavy thrust load on the crank at either the pilot bearing or by shoving the disk into the flywheel due to a too-deep installation.

[Mr427]

Agree with Mr. fixit. There is severe forward pressure on the crank, enough so that it is not even getting the chance to oil itself properly. Remeber this is truck size, strength and quality that you have. Measure it before you grind down that expensive gearbox. That is clearly next in line, literally !!

[wiroto]

Contenued positive pressure on the throwout bearing can have the same results
wiroto

[Mr.Fixit]

Agreed, he should also make sure that tehre si a little bit of freeplay betweeen the TO and the PP.
.100"- .125" should be OK