pima.1971

Ok. So i know i will be taking down this 4l60e again and replacing at least the 3-4 clutch pack. I'm trying to find the cause of the failure ahead of time and fix it before taking the tranny out so i can verify the fix. Already replaced the force motor "eps solenoid" and that actually raised the pressure some, 5 psi or so. Unplugged the tranny to default to maximum pressure. It will reach 240psi at idle and drop to 190 at idle after a few minutes. If i put my foot on the throttle and raise it up to 1100 rpms it will hit 250+psi but then at 1300 rpm it will suddenly drop to 150 psi and finally 130psi the higher the rpms go. It seems the pump is capable of plenty of pressure. But why losing pressure above idle?

Codes reset and tranny plugged in pressure gauge reads:

Park idle 85 cold 65 warm
Nuetral 85 65
Reverse 125 95 but will see 130psi above idle
1st starts at 65psi and rises to 110 at 1/4, 1/2, wot and jumps to 120 right before the shift to 2nd
2nd starts at 120 and stays there until 3rd gear
3rd and 4th gears stay at 120 psi.

Now in any gear and letting off the gas coasting, slowing down at about 40mph, rpm just above idle, the pressure will quickly rise to 180-210. the pressure drops slowly (to 120) as the speed slows down more, rpm still just above idle.

Now I know the 3-4 is shot as there is plenty of clutch material in the pan and the 2-3 flare is getting bad above 3000 rpm.

Any ideas to fix this pressure issue so when the new clutches go in they will last longer than 15k miles?

Possible valvebody issues?

Thanks in advance

pima.1971

Pump had a new rings and slide spring from transgo put in during the last rebuild. Supposed to be good over 5800 rpm.

antoine

What about the boost valve

pima.1971

.490 boost valve.