My transmission isnt shifting the way its supposed to.. it pulls great from a stop but when i accelerate the car will get to high rpms and it just wont shift ( we're talking at like 45-50 mph estimate) when i release the gas and press it again it just picks up where it left off... i had a buddy ride up the street with me and he said he thinks its stuck in second... i really dont know, i checked the fluid and it was a little low so i added some, didnt fix the problem, its a th350 turbo trans... what can i do to try and fix it before i just give up and get it completly rebuilt? i dont want to because it pulls great but its gonna mess up my motor eventually im guessing... thanks

 

lol i am full of answers today

check the dipstick, see if it is bright red or burnt/dark red.

If its bright red, Thats good, your transmission isn't fried!
If its dark/burnt red, your transmission is gonna need a rebuild

Also if it smells like burnt toast that is an obvious sign that its time for rebuild.

Hope this helped

 

Check to be sure the vacuum modulator on the tranny is plumbed in to a vacuum line.

 

Edit: Beat me to the post 72 Cutlass 455. Too lazy to edit.

I'm no tranny guy but there are a couple of basics to check first. Fluid level is okay for sure?

Engine running on level surface, move lever through all ranges, place transmission in park, check oil level.

Check the modulator? (can-like thing attached on the right side of trans with vac line going to it), is the vacuum line connected? not pinched or leaking? Make sure any other vacuum lines aren't disconnected and that there is vacuum.
The few times I've had that happen is when a vac line was disconnected or it was a bad modulator, but it could also be internal for sure. Transmission filter ever been replaced? Clogged or restricted can affect things.
The chassis service manual has a transmission diagnosis section but it gets way too technical for me beyond this stuff.

I don't mess around with women, electronics or automatic transmissions.

 

I read this post and wondered... where does the vacuum modulator get vacuum? Ported or manifold vacuum?

 

I have been told to take it from the manifold.

 

Correct