[cheezehead69]

Ok i have a 1997 4l60e with a fresh rebuild that me and a friend did. New clutches, plates, band, tourqe converter, shift kit and so on. it works great in all gears, shifts nice but in 3 and 4th it bump shifts. so anywhere from 60 to 120 kmh it will do this. But only at slight acceleration or if you let off and let the tranny freewheel and then apply a light amount of gas. if you get into it it down shifts and works like normal. I have changed the fluid since the rebuild as well as check all the selinoids. Does any one have any advice. Thank you Jayson.

[Crosley]

Welcome to Hotrodders.com. We do not use the "please help" in thread titles , we know why you are here.

How did you check the solenoids? Did you check them hydraulically and the electric?

Please describe this bump shift. I am not sure I understand. Does the trans jump around gears from 3 to 4th , back and forth?

What was the original failure problem?

[cheezehead69]

I checked the solenoids with an ohm meter. They where all within the peramaters that the manual showed. It never jumps from gear to gear. The tranny doesnt hunt for gears what it does it when you apply slight throttle it revs up about 500 to 800 rpm and then drops into gear. and it dosent slowly drop in it hits and almost jumps the truck forword. you can feel it. now it only does this when the rpms are around 1000 to 1600. if you are cruzing at a constant speed it dosent have the problem only when you slow dow and the lightly accelerate to maintain speed or slowly increase speed. the original failure was about 300 000 km of abuse and slipping in 1st, 4th and a huge hesitation from park to anygear.

[cheezehead69]

I am stumped i have talked to guys and tested parts. i dont know what is wrong. what a wierd problem. does anyone have any suggetions.

[Crosley]

Solenoids can fail hydraulically and test fine with ohm meter.

Sounds like you have a internal leak. Perhaps mis installed parts during your parts replacement on this trans?

Perhaps you missed a bad worn area for the sealing rings or cut a sealing ring during the parts replacement?

[cheezehead69]

thanks ill o ome more tests an some deeper digging.

[oldbogie]

Originally Posted by cheezehead69

Ok i have a 1997 4l60e with a fresh rebuild that me and a friend did. New clutches, plates, band, tourqe converter, shift kit and so on. it works great in all gears, shifts nice but in 3 and 4th it bump shifts. so anywhere from 60 to 120 kmh it will do this. But only at slight acceleration or if you let off and let the tranny freewheel and then apply a light amount of gas. if you get into it it down shifts and works like normal. I have changed the fluid since the rebuild as well as check all the selinoids. Does any one have any advice. Thank you Jayson.

Are you getting any codes with this?

There's lots of reasons, but off hand given that line pressure does follow the depth your foot is in the throttle, I'd suspect a leaky valve such as the 3-4 Relay/4-3 Sequencer. A leakage induced pressure loss here would let 4th drop to 3 rd on a light cruise throttle. Stepping on the pedal would bring line pressure up and snap the valve back into the 4th gear position. However, wear, being wear, eventually you won't get 4th at all. This is a pretty nervous valve so it wears on its bore pretty hard which lets oil out. There's fixes for it.

Keep in mind these are complicated beasts and I'm shooting in the dark. But I bet something in that valve body circuit isn't as good as it needs to be and this is one of several common problems with that circuit.

Keep in mind that the master control is these computer controlled solenoid valves, but they just replace the old governor versus throttle control valves. The rest of the old stuff that sequences and times the shifts is still in there. Along with a bunch of what always becomes leaky check valves

Bogie