i have a 1986 TH700R-4 that never would shift into overdrive it would rarely and then kick it self down and out of overdrive so i had decided to have it rebuild and the problem was the same and it would also rarly go into overdrive for a little bit and then kick down and out of overdrive....i know when ur car over heats a lot it can be bad for the transmission cause the cooler lines that run into the heat exchanger in the radiator help keep the transmission oil cool so this is deffenatly a factor on how it runs and shifts but if its something more and anyone has encounter this problem before or has or know how to fix this please help because my new engine replacement is coming prety soon

 

Do you mean it doesn't pull in the OD selection? Or the car doesn't shift into 4th gear?


If it doesn't pull with OD selected, this is a common problem with the 700r4. Take it out and get it up to about 40mph+ using Drive, and shift it to overdrive. Overdrive should engage, until you either cause a kick down or slow down below 4th gear speed.

Usually this means the forward sprag is shot, which is a common weak spot with this transmission especially prior to '87. It means a rebuilt unfortunately.

What happens is in 1,2,D, and only 4th gear in OD, there are clutches that overrun the sprag, meaning it will work even with a broken sprag. When you try to accelerate in a lower gear in OD, however, the sprag might hold for a little bit but then slips, (in my case causing a "clunk" and the car just to rev as if it were in neutral.

If you mean the car wont shift into it's 4th gear, then could be a number of things, but I would start by checking the TV cable adjustment.

 

Call Dana - 909-795-1876

He runs Pro-Built Automatics and builds them for a living. He also sells individual parts and is exetremely good with troubleshooting over the phone with properly descriptions. In the past he's never tried to push un-needed parts on me. He also helped me along with my cheap torque converter lockup vacuum switch.

 

it sounds like the sprag problem but but not really if i have it in the od selection there will be no loss of small RPM which is felt like another gearshift that leats u know that u have engaged OD which is about 40MPH+ and i had this transmission rebuilt before

 

ok ill give DANA a call