I've just finished off installing a SBC with a TH350 into my vehicle. Every thing is hooked up and running well except that the tranny won't kickdown into Ist. The kickdown cable is set up so that kickdowns from Drive to 2nd occur almost too easily. No matter what I do, I can't get the tranny to downshift into 1st from any speed.

Starting off from a stop I do have 1st gear working...

I don't know if I should pull the kickdown adjuster any farther back. I fear breaking the end off of it in the tranny...

I appreciate any ideas.

I should have mentioned that I have just rebuilt this TH350. This isn't my first rebuild of a a tranny but perhaps the first mess up. :-(

Thanks, Jim

 

A freind just told me that I have a vacuum leak... How could kickdown work from 3rd to second, but not 2nd to 1st with a vacuum leak? I figure it would be more prone to kickdown early with less vacuum...

 

It's not a vacuum leak. That's just somebody's monkey-spank, that has diarrhea of the mouth.

Sounds to me like the kickdown cable isn't pulling out far enough at WOT.... needs adjustment. Try it. Have somebody operate the throttle, and watch it while they floor it and see how far it moves, make sure it doesn't destroy anything. Which is highly unlikely regardless.

 

Thanks, I'll pull back on the slider adjustment a tad more tonight.

 

you want the cable to just be a little tight at full throttle. basically go WOT and the slack should be gone. don't make the cable too tight.

 

The kickdown assembly inside the tranny required a fair bit of cable loading to actuate. Is it possible to set the stock wire cable too short causing it to break or will it just limit the throttle pedal stroke?

 

OK. I've tensioned the kickdown cable to the point where the gas pedal throw becomes limited and WOT can't be reached- still no 1st gear kickdown. Lots of 2nd gear kickdown...
I can't believe I've f&&*d up somehow.

 

Does anyone know where I should look in the tranny to repair no kickdown to 1st?
Thanks, Jim