Mopar thrust bearing failure

[devo340]

I keep killing the thrust bearing in my 360 Stocker after 10 passes.
Last time, had the thrust repaired on the crank, freshen the convertor, changed to another 904 trans, did away with the quik disconnects on the trans cooling lines.
After the thrust repair, I had .002 endplay.
The time before, had .010 endplay.
All the bearing look great.
Anyone else have this problem?

[Lee Valentine]

.002 is too tight it will cause a failure.

[jims5600]

I agree with Lee,that is rather snug. Out of curiosity,what is your stall
speed? I have seen a real high rpm stall causing early thrust brg.
problems but I would think a stocker wouldn't hit all that hard.
All your end play etc is within specs I assume.
Good luck devo

[jmcarter]

Originally Posted by jims5600

I agree with Lee,that is rather snug. Out of curiosity,what is your stall
speed? I have seen a real high rpm stall causing early thrust brg.
problems but I would think a stocker wouldn't hit all that hard.
All your end play etc is within specs I assume.
Good luck devo

And along the same lines, sure the converter isn't ballooning? Might want to ask whoever freshened it about that. Had a "other brand" that caused me some problems before changing to ATI

[devo340]

I though .002 might be too tight, I checked the service manual & it had .002-.010 for range.
It is a ATI convertor, sent it back to them. Asked about it ballooning, no concerns found. It was freshened up at that time also.
It is footbraked to 3K to leave.
Another racer was having the same problem with a 340 Stocker.
He recommended me to a guy at Pro Trans.
They have a piece called the "destructor" that goes into the convertor charge hole.
I haven't disassembled the engine from this last failure to inspect the bearing yet. Just cut the oil filter open, found bearing material & the crank has excess movement.
I checked the crank during the last race, it didn't kill it until the last two passes. Also lost a tenth at the same time.

[Greenlight]

0.002" is way too tight for a race engine.

0.007" is more typical for a race engine. I lot of flexing occurs under the high stresses in a race engine.

Also, please check the end play with JUST the upper bearing in place, then again with JUST the lower bearing in place to confirm the alignment of the upper to lower bearing halves.

You know the saying, "If you have too much bearing clearance you are the only one who knows. If you don't have enough bearing clearance, EVERYBODY knows."

It's best that you are the only one who knows.

[Dean Feiock]

Most likely to much cooler/lube circuit pressure. Good converters don't really balloon, but excess pressure will force them forward off the stator support. A common problem on some transmissions with a high fixed line pressure.

Tee a pressure gauge into your cooler lines. You'll want no more than 50 PSI at stall speed. Anything over that needs a restrictor installed. With a fixed line pressure in the 150-175 range, a restrictor with a .094" hole is a great place to start.

[ss3011]

It is also important that you have at least .080" pull up on the torque converter . All converters will balloon a bit depending what the charge pressure is , and how many rpm's it is spun to . Having pull up will help keep the converter from binding up on the splines and damaging the engine thrust bearing .

[Gregg Luneack]

Also check the hole in rear of the crankshaft
to be sure its bigger than the hub on the converter.

[Ed Wright]

You can slide the converter back from the flex plate when unbolted, right?