Mopar 904 trans pressure - Page 2

devo340 · 07-30-2018, 07:19 PM

The only constant is the convertor.

I will be doing some comparasion & taking mearsuments when the engine comes out.
I do have a spare Turbo Action convertor to compare it to.

ss3011 · 07-30-2018, 08:22 PM

Quote:

Originally Posted by devo340

The only constant is the convertor.

I will be doing some comparasion & taking mearsuments when the engine comes out.
I do have a spare Turbo Action convertor to compare it to.

The two 904 transmissions are built the same ? Do they happen to have aftermarket bellhousings ?

devo340 · 07-31-2018, 06:10 AM

Quote:

Originally Posted by ss3011

The two 904 transmissions are built the same ? Do they happen to have aftermarket bellhousings ?

No, stock cases.
One came out of my bracket car that has 10 seasons on it & the other is the one that came in the Stocker.

Tom Goldman · 07-31-2018, 09:02 AM

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.

CMcAllister · 07-30-2018, 08:38 PM

I don't do these things everyday, but I know some guys who have fought this with a high RPM Torqueflite combination. I would ask someone about those cooler line pressures. 50PSI at 2k - hard to tell what it is as the RPM go up. I do remember that some people were using a pressure relief system to dump fluid from the cooler system directly to the pan to limit that pressure. Flexplate to crankshaft bolts leaving marks on the front of the converter? Verify the clearance there for reference before unbolting everything. Converter snout not bottoming or jamming in the crankshaft flange bore? Front trans pump chewed up?

07-30-2018, 07:19 PM	#1
devo340 Junior Member Join Date: Apr 2016 Location: Sapulpa, OK Posts: 92 Likes: 129 Liked 168 Times in 30 Posts	Re: Mopar 904 trans pressure The only constant is the convertor. I will be doing some comparasion & taking mearsuments when the engine comes out. I do have a spare Turbo Action convertor to compare it to.

07-31-2018, 09:02 AM	#4
Tom Goldman VIP Member Join Date: Jan 2003 Location: Allentown,PA Posts: 2,479 Likes: 900 Liked 889 Times in 239 Posts	Re: Mopar 904 trans pressure 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. __________________ Tom Goldman 1500 SG , 1506 STK

07-30-2018, 08:38 PM	#5
CMcAllister Senior Member Join Date: Sep 2006 Location: Fulton County, PA Posts: 625 Likes: 18 Liked 931 Times in 265 Posts	Re: Mopar 904 trans pressure I don't do these things everyday, but I know some guys who have fought this with a high RPM Torqueflite combination. I would ask someone about those cooler line pressures. 50PSI at 2k - hard to tell what it is as the RPM go up. I do remember that some people were using a pressure relief system to dump fluid from the cooler system directly to the pan to limit that pressure. Flexplate to crankshaft bolts leaving marks on the front of the converter? Verify the clearance there for reference before unbolting everything. Converter snout not bottoming or jamming in the crankshaft flange bore? Front trans pump chewed up?