TH350 Problem
 

60's pretty good first pass off of trailer. second pass will slow about 3 on 60. Third pass will slow even more. Will slow as much as a tenth on 60. Everything has been pulled a part and check by several people. New valve body. New clutches (several times) Only thing that has not been replaced is the case. Can take the convertor and put it on another (spare) trans and it is very consistent on 60's. Any suggestions? Need to add. I can put spare trans in and use same dipstick on both trans so fluid level is the same.

Re: TH350 Problem
 

do you have a pressure gauge for the trans?

Re: TH350 Problem
 

Do you have a temp gauge on the trans?

Re: TH350 Problem
 

160

Re: TH350 Problem
 

Good Morning Terry,
I had a similar problem a few years back with a GM/Chevrolet PG case.
I had changed over from "sleeve type bushings" to Roller Bearings and followed the recommended clearance tightening and the trans would slow the car down as we started hot lapping the car. I loosened the "end play" about .003 to .005 overall and the problem stopped.
My spare Glide ( also a GM case) was set up with the recommended tighter clearence's and wouldn't slow down as it got hotter.
So is the case growing and tightening up or is it the front pump, maybe its an alum. drum or hub, sorry I don't have a exact answer, but I found running a little more end play clearence did "fix" my problem at the time.

Respectfully,
Henry Kunz 1534 H/SA

Re: TH350 Problem
 

It does have the aluminum stuff in it and also a new pump.

Re: TH350 Problem
 

I don't know about the 'glide but you don't want to loosen a T 350 up much. Keeping them snug helps them in the direct drum area.
I asked about the temp, because, if the converter is already on the loose side of things, the warmer fluid could hurt it.

Re: TH350 Problem
 

You probably have a seal that is leaking , which is causing a clutch to drag . The hotter the fluid gets the greater the leak that is causing the clutch to drag . What type of ring seals do you have on the pump tower ? Typical types are cast iron with a locking feature or two types of plastic seals one solid , or the second type with a diagonal cut end . The best seal is the solid teflon .

Re: TH350 Problem
 

Teflon and front pump has been out a zillion times. Not sure on temp but don't think that is the problem. Deep pan so it has an extra 2 qts. Sharver originally done trans yrs back. He plugged the coolant lines and did some drilling on pump to redirect fluid. The pump has been replaced and wondering if maybe that could be problem?

Re: TH350 Problem
 

I have talked about this before , but deep pans are not designed to increase the cold fill volume , but to lower the fluid level away from the rotating parts . As fluid gets hotter it expands and if that expansion gets the fluid up into the rotating parts it will mix up like a milk shake . That is bad for windage and will also hurt pressure stability , lubrication , and cooling . A deep pan with 2 extra quarts of fluid in the trans will be even worse . Typically you need a re-calibrated dipstick which compensates for the deeper pan .
Since you have a problem with one trans and no problem with another , I still believe a leaking seal is more likely .