Mopar 904 trans pressure

[Tom Goldman]

I just recently saw this problem on a customers 360 Drag Pak engine.
It was caught in time before the crank was damaged.
The root cause was not the converter but the converter pilot hub not having adequate clearance and bottoming in the crankshaft .030" before the converter reached the flexplate .
I was able to increase the clearance by using a .125" mid plate as a spacer and then using .125" spacers between the converter and flexplate .
The proper fix will be to machine the pilot hub deeper when the engine is apart for freshening . In this case the crank was a Scat crank , but I checked the depth against a stock 360 and it was within .020".
Converters do not actually balloon with modern shells and reinforcements ,but rather they try to push out of the pump .Excessive line pressure can be a factor, but the key word is excessive
Usually this movement is absorbed by the flexplate ,,but when there is no free movement in the crank pilot hub ,the thrust takes the load.

[devo340]

Originally Posted by Tom Goldman

I just recently saw this problem on a customers 360 Drag Pak engine.
It was caught in time before the crank was damaged.
The root cause was not the converter but the converter pilot hub not having adequate clearance and bottoming in the crankshaft .030" before the converter reached the flexplate .
I was able to increase the clearance by using a .125" mid plate as a spacer and then using .125" spacers between the converter and flexplate .
The proper fix will be to machine the pilot hub deeper when the engine is apart for freshening . In this case the crank was a Scat crank , but I checked the depth against a stock 360 and it was within .020".
Converters do not actually balloon with modern shells and reinforcements ,but rather they try to push out of the pump .Excessive line pressure can be a factor, but the key word is excessive
Usually this movement is absorbed by the flexplate ,,but when there is no free movement in the crank pilot hub ,the thrust takes the load.

Update; Found the ATI convertor that is in the car is bottomed out in the crankshaft. Have a spare Turbo Action convertor & checked it & had .102 clearance between the convertor snout & the crank. Real close to the problem identified in this thread.

[Bill Grubbs]

Originally Posted by devo340

Update; Found the ATI convertor that is in the car is bottomed out in the crankshaft. Have a spare Turbo Action convertor & checked it & had .102 clearance between the convertor snout & the crank. Real close to the problem identified in this thread.

Call ATI...their pilots are screw on, and can be bought in differing lengths.

Bill

[340Cuda]

Originally Posted by devo340

Update; Found the ATI convertor that is in the car is bottomed out in the crankshaft. Have a spare Turbo Action convertor & checked it & had .102 clearance between the convertor snout & the crank. Real close to the problem identified in this thread.

Mike that is great news.

[devo340]

Originally Posted by Bill Grubbs

Call ATI...their pilots are screw on, and can be bought in differing lengths.

Bill

Talk with ATI, they will have to move the lugs on the convertor to get the Clearance that I need.

[sugar1366]

You should inspect the front pump in the trans. If it was pushing forward on the thrust bearing, then it was probably pushing back on the inner gear of the pump.

Eddie Bolton