Help! TH350 Doesnt shift at WOT

[Wajulia]

My 1981 vette with a TH350 (all original) doest not shift from 1-2 or 2-3 at wide open throttle. If the throttle is lifted to about 3/4, it will shift. Going WOT will cause a downshift. If I am patient and let the RPMs come up a few hundred, I can go WOT to the 2-3 shift.

It shifts very nice during all other driving condition. Could the Detent cable being misadjusted cause this?? Is there a way to address this without a transmition rebuild.

 

[TimAT]

Back the detent cable off a couple of clicks. Make sure the hoses are good to the modulator too. If it shifts fine except at WOT, the cable is most likely the problem.

 

[Wajulia]

Thanks

I just replaced the modulator because it would not shift out of 1st.

Is there any problem running without the Detent cable attached just to see if this is the problem. I know that it wont downshift, but will it let me know if the detent cable is causing the lack of WOT upshift?

 

[TimAT]

On a 350/350C no problem at all. Unhook it and you can feel the valve in the trans move- the more you pull the cable, the harder it gets until you hit the stop- if it moves easily, or you don't feel any increase in force to pull the cable, then the valve in the trans may be sticking.