Turbo 350 3rd gear/reverse issues.

[newtongtz]

Hello, I have a 75 c10 with a 350/t350. I have seen a few threads with similar symptoms, but not exact, so I’m starting a new one.

When the truck is cold, everything works as it should. However, once it warms up I lose 3rd gear and it’s also very slow to find reverse. If it happens to find 3rd, and once it’s in reverse everything is nice and tight, no slipping. I know reverse and 3rd use the same clutch pack so I’m thinking it’s rebuild time, but I thought I would throw this out here before I remove the greasy pig.

I should mention that the fluid is all new, filter is new, modulator is new, and I removed and cleaned the Governor. The Governor was a little sticky so I cleaned that up and got it functional before reinstalling(No change). Also when I dropped the pan there was some clutch material obviously, but not as much as I was expecting to find.

The whole transmission is covered in 50 years worth of dirt and grease so I’m hoping someone has an easy idea I’m missing before I set out to pull this thing out.

Thank you!

 

[NickTransmissions]

Hello, I have a 75 c10 with a 350/t350. I have seen a few threads with similar symptoms, but not exact, so I’m starting a new one.

When the truck is cold, everything works as it should. However, once it warms up I lose 3rd gear and it’s also very slow to find reverse. If it happens to find 3rd, and once it’s in reverse everything is nice and tight, no slipping. I know reverse and 3rd use the same clutch pack so I’m thinking it’s rebuild time, but I thought I would throw this out here before I remove the greasy pig.

I should mention that the fluid is all new, filter is new, modulator is new, and I removed and cleaned the Governor. The Governor was a little sticky so I cleaned that up and got it functional before reinstalling(No change). Also when I dropped the pan there was some clutch material obviously, but not as much as I was expecting to find.

The whole transmission is covered in 50 years worth of dirt and grease so I’m hoping someone has an easy idea I’m missing before I set out to pull this thing out.

Thank you!

Hey man welcome to the forum!

Unfortunately, it's time for an overhaul so need to pull it and throw it on the bench for teardown and inspection.

I have a TH350 Info thread you can refer to for video instructions, parts, mods and other info.

Main pointers:
- Install a heavy duty intermediate outer one-way-clutch race (sprag race) which is one of the two most common failure points in these transmissions - I use the Sonnax HD race
- Install a good-used 4L60E center support - it's a drop in deal with no machining/modifiations necessary and addresses the other common failure in these units
- Ensure you use a wide direct drum bushing (replace all bushings)
- You can dual feed the direct clutch for increased longevity - my 'TH350 Beef Up on a Budget video covers the procedure - it can be found in my TH350 Playlist

Let me know if you have any questions once you have a chance to take a look.