To make a long story short my stock transmission gave out on last year Hot Rod Power tour and I ended up having to replace it on the road. A friend I met on the tour had a freshly rebuilt 700R4 with extra clutches and heavy duty internals. It was built by a local performance shop in Detroit, MI and was built to run behind a 502 in a truck. The guy who built the trans owns Thomson Automotive who builds motors and transmissions for GMs race cars and other projects so I know he knows his stuff.

It had been sitting for a couple of years and I bought it and the guy let me use his lift and shop to install it. I used a stock type convertor since I did not want to mess up the new trans by running my Vigilante. The problem I have with it is it will not shift into 3rd at full throttle. The trans shifts extremely hard on the 1-2 shift and shifts fine on the part throttle 2-3. I do not know if it has a vette servo or not and I put the tailsection from my stock trans on it. What are some things I can check to see why it will not shift. I have changed the fluid a few times and adjusted the cable to proper spec. I am going to be removing the trans to put my Vigilante back into it and I want to get this problem sorted out. I have never built a trans, but I have installed shift kits in some different models. I did not know if a check valve might be stuck or a ball got put into the wrong place. thanks for your help

 

Sounds like you need to adjust the kick down cable. When you adjust it you need to adjust it from the foot feed not at the engine. Try that hopefully it will help.

 

First, TV cable (this is not a downshift cable as on a TH350) must be tight at WOT, so the setting here is critical. Second, the fluid level must be correct. See what happens. If the transmission was built with the right internals, then I would call the guy who built it and see what he says he will do here. How many miles on the transmission since it was installed? Did it ever make a 2-3 WOT shift?

 

I have made sure the cable was tight at WOT and it still makes no difference. Is it possible the TV cable is stuck in side the trans because when I hooked up the cable to it when I swaped trannys it felt a little different than my old one. I am running a Lokar cable on it and have Lokars bracket. What about a check ball being in the wrong spot, is there any way this could be a cause? Fluid is full and at the right level. Thanks for your help so far.