Help! wierd auto trans shift

[Tntruckguy]

Well I have leaned on you guys before and it worked so here it goes again. I have recently replaced the trans module on the back of the transmission and that solved all my shifting issues except one. That being the transmission wants to shift into 3rd at a very low RPM.(it is more of a klunking sound) If I stay accelerated in 2nd it shifts fine. I am thinking that my mechanic used a pretty hefty conditioner when he changed the trans fluid recently. Any thoughts are appreciated and I think my Corvette actually makes me cooler than I really am. :cool

1980 Red t-top, L-48, auto trans with AC and only 46K miles on it. Does that help?

Thanks fellow Vette fanatics!!!

 

[gmjunkie]

Well I have leaned on you guys before and it worked so here it goes again. I have recently replaced the trans module on the back of the transmission and that solved all my shifting issues except one. That being the transmission wants to shift into 3rd at a very low RPM.(it is more of a klunking sound) If I stay accelerated in 2nd it shifts fine. I am thinking that my mechanic used a pretty hefty conditioner when he changed the trans fluid recently. Any thoughts are appreciated and I think my Corvette actually makes me cooler than I really am. :cool

1980 Red t-top, L-48, auto trans with AC and only 46K miles on it. Does that help?

Thanks fellow Vette fanatics!!!

Be my guess the detent cable needs adjustment or replaced!!

 

[Tntruckguy]

OK Dumb question!!!:WWhere is the best place to find this cable? Dont mean to be ignorate.

 

[gmjunkie]

OK Dumb question!!!:WWhere is the best place to find this cable? Dont mean to be ignorate.

It's also called a TV cable! It runs from the right side of the transmission to the throttle!! There should be some photos here somewhere in a post!!I'll see what I can find!!

 

[Tntruckguy]

Thanks!!

 

[Rodney Gold]

Short shifting is normally an indication of a governor problem , B&M make a governor weight and spring kit that can allow you to vary shift points at WOT and at lower RPM.
However I don't understand what the problem is , you *want* the tranny to change early unless your foot is buried in the floor. If you go WOT (wide open throttle) you would want the tranny to change at much higer RPM (which you can adjust using the weights and springs)
If you are in 3rd and you hoof the throttle , does the car change down to 2nd? If it changes down then your kickdown cable is fine , maybe just needs some adjustment as to where it kicks down , IE if you just touch the throttle in 3rd and it kicks down to 2nd , then it needs a bit more slack in the kickdown cable .
The best thing you can do for your tranny is fit a "shift" kit , this raises line pressures , gives a firmer shift and also prolongs the life of the tranny.

 

[KANE]

Short shifting is normally an indication of a governor problem , B&M make a governor weight and spring kit that can allow you to vary shift points at WOT and at lower RPM.
However I don't understand what the problem is , you *want* the tranny to change early unless your foot is buried in the floor. If you go WOT (wide open throttle) you would want the tranny to change at much higer RPM (which you can adjust using the weights and springs)
If you are in 3rd and you hoof the throttle , does the car change down to 2nd? If it changes down then your kickdown cable is fine , maybe just needs some adjustment as to where it kicks down , IE if you just touch the throttle in 3rd and it kicks down to 2nd , then it needs a bit more slack in the kickdown cable .
The best thing you can do for your tranny is fit a "shift" kit , this raises line pressures , gives a firmer shift and also prolongs the life of the tranny.

Rodney has a lot of good points.

Premature upshifts are indications of a transmission that may be on its way out if the modulator and detent cable is adjusted correctly.