Automotive Forums

trans is behind a 400 SBC in a chevelle. Just installed after trans had set for about 18 months. At first it seem to respond to cable adjustment and was shifting good for about 20 miles. Now it goes into forward or reverse and shifts fine when cold but after about 2 or 3 miles when it gets warmed up, the motor revs up trying to start off and slowly goes into gear and the motor is overreving for the speed the car is moving but the trans will eventually shift thru the gears to overdrive.  

I have the same problem with my 89' Pontiac Firebird, i sure hope someone has an idea to whats wrong because i'm about to pull the tranny and start overhaulin it.  

I'd take a hard look at the TV cable. The symptoms indicate slow pressure rise. Check this website out - http://www.tvmadeez.com/article/index.php

This is one of the best write ups I've seen on the TV cable and adjusting it.

If the Trasmission is a transplant from a different model vehicle, the throttle bracket is likely to be incorrect.  

well heres the deal, i did do a motor swap, and when i put it all back together i used the throttle mount that was on the new engine, the shift points were all jacked up and stuff. Anyways a did a little reading, traced it to the throttle bracket and i compoared the two, big surprise, they were different. So i changed them out, and afterwards the transmision worked totally perfect and normal. The day after i changed the brackets, i went to leave school, had to back out, had no reverse. So i shut it off, popped the hood, checked the fluid (I started it to check the fluid) and it was fine, tried reverse again, and it worked. About three days later i was on the highway and it shifted out of overdrive into 3rd and ever since its been acting up. It works fine until it warms up, then it slips like a big dog.  

The bad thing about low pressure problems is that it does damage to the tranny in a hurry. I burned my forward clutches and broke the spring in the 1-2 accumulator when it did finally slam into second gear - all due to my misadjustment of the TV cable.
The only common component in action to reverse and slipping out of 4th into 3rd is the pump.
You are probably looking at a rebuild. One remote possibility is that the gasket on the filter is missing. The only reason I mention this is that I had a transmission service done years ago and the mechanic left the O ring off the filter. It would run fine for a while, then start slipping and or dropping out of gear. I do my own trans fluid changes now. Messy job, but at least I know it got done right.  

Hi Steve, you might try servicing the trany. It may be a low fluid problem but droping the pan will give you a better idea if something more serious is going on. If you have a bunch of fine iron it can get stirred up after the fluid starts to warm up and thins out.
Good luck and let me know if it works.
The trany man  

I talked to a tranny guy and he told me the problem was heat related, obviously, he was thinkin that the valve body is possibly warping, causing pressure loss when it warms up. There is also a strange noise coming from in between the oil pan on the engine and the front pump, i was thinking that the torque converter is possibly falling apart? But the tranny deffinatly works fine untill it is all warmed up, then it starts slipping, and i have asolutely no reverse  

66, I lay money down that the pump is bad. Could very well be a result of the converter dumping.
The trany man.