Help! Transmission Problem ??

[401KVet]

I currently have about 48,900 miles on my car. When I bought it, it had 47,800. I had the transmission fluid and filter change right away, which has been about 6 months ago now.
I noticed when I drove it last week while going down the Interstate keeping it around 60-65 that there is a slight jerking/hesitation feeling going on. It is more noticeable with the AC on. If someone drove the car and was not use to how the car felt, they may have trouble even feeling it.
There is no change it the Tach, but you can see the speedometer needle jump back and forth so ever slightly.
Over a period of about 10 seconds you can feel it about 4 or 5 times, but very slight. It is less noticeable with the AC off.
The engine seems to be fine, but I had it looked at and the problem does not seem to be engine.
I haven't brought it back to the transmission place yet.

Any ideas??? ;help

Glenn

 

[petes74ttop]

Have you check the timing, could be to much advance. PG

 

[TimAT]

'80 (I think) had a TH350C. My guess is you're feeling the TCC locking up and releasing. Drive it again and get it doing the jerking.hesitaion, then just touch the brake enough to turn on the stop lights. If it smooths out, it's a TCC problem. If not, then very likely an ignition problem.

 

[Rodney Gold]

Dont think the 80 has a lock up TQ , at least mine didnt have one. Sound to me like a fuel problem , slight jerking at steady state sounds like lean , especially if the AC is loading the engine or there is some slight leak in the aircon vac operated controls ...rather difficult to diagnose.
Also check the vac lines going from carb or manifold to the vacuum modulator on the box , especially if you recently had box work.
Look at the tranny fluid , it should be clean red and not smell burned.

 

[401KVet]

Sorry guys, but I'm really not that much of a mechanic.
Is the TCC the Torque Converter?? Also what and where are the aircon vac operated controls and also the vacuum modulator on the box. What is the box?
In the mean time I will drive it and try hitting the brake thing, and then I will check all of the vacuum lines and change the fuel filter even though it was changed about 1000 miles ago. The timing has been recently checked.
Thanks for the help!

 

[Rodney Gold]

Erm... not being nasty or anything , but I would take it to a good vette tuner rather than fiddling , if you arent familiar with the terms used and so forth...someimes its better to take it to the experts - let me loose with a soldering iron and a Pc board and it's a guaranteed disaster...

 

[Evolution1980]

'80 (I think) had a TH350C. My guess is you're feeling the TCC locking up and releasing.

Dont think the 80 has a lock up TQ , at least mine didnt have one.

The '80 did have a lock up TC. However, if it was engaging/disengaging, he'd see the tach jump and not his speedo. He's having the opposite problem, so it's probably not the solenoid (located by dropping the pan and filter, if I recall correctly).

Could be a timing problem as previously suggested or fuel delivery.

 

[401KVet]

Not a problem. You are right. I have done everything I can think of to do with my limited mechanical knowledge. I've always changed all my oil, and just about any part that needed to be replaced, but that's about it.
I am taking it to somebody who Knows Something tomorrow.
Thanks,

 

[damoroso]

In your first post, you said this was taking place at 60-65 MPH right? Have you tried it in the same RPM ranges in 1st and 2nd gears? It sounds like the engine is surging a bit to me. Trying it in different gears should eliminate the trans and the problem might even be more noticable at the slower (though same rpm) speeds making it a bit easier to identify. If the engine still surges I think that would indicate a carb or ingnition problem. I'd suspect the carb or fuel first though.