Hi, first post, hoping to get some help as I am stumped.

Rebuilt transmission in 2011, no problems until last week. Now it will shift 1st and 2nd no problem, sometimes 3rd, but after that the engine will race and rpms go up very high until I take my foot off gas pedal. it will then sometimes find the right gear, sometimes it will wind right back up. This does not happen every time, and shifting is smooth and no clunks/bumps/noises even when it seems to slip or not find right gear. It seems that every now and then the engine hunts for the right gear? Fluid is at correct level, filters were replaced when transmission was rebuilt....seems almost electronic in nature as mechanically everything seems fine. Any help or feedback would be appreciated.

 

Anyone?

 

Pulled the pan yesterday, clean fluid, no clutch material. Flushed and refilled, got it back on the road and same thing, this time went into 4th no problem, went to accelerate to pass a truck on the highway and she raced up again, had to jimmy the pedal to get her to settle back in.

Really weird. Any tech out there seen anything similar?

 

do you have a 4l60 or a 4l80E

 

Hi, I have the 4l60

 

Oh boy i haven't been back here for a while, i hope you got your trouble figured out. It sounds to me like a worn out front sprag or you have a lack of line pressure.