Powerflite problem...

The powerflite trans in my '55 Desoto needs about 15 minutes of driving time before it will shift into drive from low. After that it shifts great all the time I am driving! There is no slippage, and the shifts are firm. The trans fluid is red and clear. Any ideas? I have never worked on an auto trans (scary) but am willing to try!

Any help is appreciated!

Thanks, Dusty

 

Sounds like a sticking governor. When cold it won't open. When warmed up it functions properly. If it shifted sloppy when warmed up, I would also suspect the direct drive clutch plates and piston seals.

If you are inclined, you could check the direct drive clutch apply port pressure with an oil pressure gauge. Lift the rear wheels off the ground and attach the oil pressure gauge to the port (1/8th inch pipe plug, driver side of transmission) and with the oil pressure gauge visible, start the vehicle and while in DR, slowly accelerate up to where the shift should take place. If the gauge goes up and the shift does NOT take place the direct drive clutch is bad. If the gauge never goes up, the governor or valve body are the problem areas. (this test should be done with the engine cold, as this is when the shift has the problem.