TimOk1

E code tranny 4R100, 78000 miles. Fluid level right.Not sure if fluid and filter has been changed how ever it looks and smells very clean. EX DOT fleet truck used at D/FW airport, still has flight line clearance permit in owners manual.
Here's what it does.
Cold it shifts smooth and quiet all 4 shifts.
Warmed up it shifts smooth and quiet in 1 2 3 then 3 to 4 shift it makes a sound like a rumble strip and shifts to OD. Some times very faint ,others very noticeable

Not a good sound I'm sure My guess is clutch shutter or clutch glaze.

I'll do a filter and fluid change and see what that does.
Any thoughts from the 4R100 techs?

Thanks Tim from Southern Oklahoma

xmustangloverx

sounds like a torque converter shutter is what you're experiencing. I'm not a tranny tech, so don't quote me, but what you're describing sounds right.

TimOk1

thanks xmustang. sounds right. It does it on final shift event which is , I assume, the TC locking up. In your opinion is it terminal ? Pressure switch malfunction? We just bought this truck AS IS of course. Guess a trip to tranny guy is in the near future. Later TIM

xmustangloverx

Again, I don't do auto trans repairs, but I believe the torque converter would have to be replaced.

AFSOCSGT

I have read on here previously that a fluid and filter change should clear that up.

Cain64

Possibly a filter change and fluid. DO NOT HAVE THE TRANS FLUSHED!!!!! Just change the filter and drop the pan that will get out enough old fluid if you want flush the cooler, but DO NOT FLUSH THE TRANS ITSELF. If problem persists swap the torque converter they are cheap statting around 80$ ithink maybe a low milage used for 50$.

TimOk1

Thanks to all , Ill give the 7700 a fluid and filter change and see what happens. If it persists guess I'll get to replace a TC . Thanks again Tim