700R4 Automatic PITA

[Zombie86]

Ok so for the past 6 months I have become completely stuck on my transmission. I have an '86 Camaro Z28 305 MFI G code with the 700R4 Automatic 4 speed. At first it would be stuck in 1st and then hit 30 and redline, I'd back off the throttle and get on it again to try and manually shift it and it would just catch back up to redline. I replaced the governor yesterday as it appeared I was correct and it was stuck. Replaced the cap and test drive it and it shifted all 4 just fine. I go to take it back home and after about 5 miles it down shifted to second and then first for a red light and once I took off again it was stuck in 1st once again. Any suggestions besides a rebuild I'm on disability and cant afford it currently.

 

[jthomas]

There are a number of things it could be but if I was faced with this I would pull the valve body and take all the valves and springs out and give it a thorough cleaning with brushes, brake clean and compressed air. Make absolutely sure you lay all the parts out in the order they came out and use great caution taking end caps off as the springs will causes parts to fly out and get lost. Also use caution using picks or small screwdrivers to get valves out so you don’t damage the edges of the valves or the mating surface of the valve body.

Also when lowering the valve body and separator plate, keep it level to see what check balls are where so you can put it together the same way.

I would bet money your valves are sticking. If you have any miles on your trans this is a good maintenance procedure anyway.

Another thing to check is your trans pressures and TV setup to be sure you have the right pressures at the right throttle positions. When retrofitting these trannys to our cars the TV cable setup often has the wrong geometry, but, that does not typically cause the shifts to “stick”. It will cause them to be late or early, but not stick; unless your TV cable is sticking in the cable sheath. It could also be the TV valve sticking and that would be fixed when you clean the valve body.

 

[Zombie86]

Thanks Jthomas. I'm gonna drop the pan and pull the valve body today and see if I didnt wear anything out. Also gonna completely flush the system and pretty much set it all back to factory. I dont know if they did any modifications before I got the car I just know a lot was messed up on it.

 

[CorkyE]

I had that issue with my 700R4 - googled the problem and found a utube video where a small clip falls off the TV cable to piston inside the valve body. That wasn't my problem, but it's something to check. I called TCI, who made my modified valve body and tech guy said to add a bottle of Lube Guard, jack the rear up and run through gears several times and this would free that piston. It worked for me. Good luck with yours.

 

[Zombie86]

I had that issue with my 700R4 - googled the problem and found a utube video where a small clip falls off the TV cable to piston inside the valve body. That wasn't my problem, but it's something to check. I called TCI, who made my modified valve body and tech guy said to add a bottle of Lube Guard, jack the rear up and run through gears several times and this would free that piston. It worked for me. Good luck with yours.

Appreciate the advice, I'll try this also and see what's not working correctly.

 

[Zombie86]

Ok so the major changes I made. Replaced, trans filter, 1-2 accumulator, cleaned valve body, pan gasket, and cleaned all debris from pan. Reassembled everything and as soon as I noticed a fatal flaw in my trans I ordered a replacement TV Cable as well. The lever inside the trans that controls the pressure was about 1/2 inch away from the piston. Over time the cable stretched and moved away from the piston causing little to no pressure in the system. Outside of the Carb this is not noticeable and I seen fit to completely replace it. So that's were I sit at the moment getting ready to install the new cable and hopefully get up and going again. Will let you know the result.

 

[Twisted_Metal]

How much debris was in the pan?
Clutches can be badly burned if the TV valve wasn't working properly.

 

[Zombie86]

No debris. The trans cooler was blown.

 

[jthomas]

I’d suggest you replace the TV spring while you’re at it. If you need one PM me your address and I’ll mail you one. I had to buy a bunch to get one so I have extras I’ll never use.

 

[Zombie86]

I’d suggest you replace the TV spring while you’re at it. If you need one PM me your address and I’ll mail you one. I had to buy a bunch to get one so I have extras I’ll never use.

Appreciate it, got the cable in yesterday night gonna run it around the block today and see is she is working. Cable feels good, motor is running good idle, RND all feel good.