Hello all. I have recently installed a new TCI C4 Transmission (Street Rodder Pan Fill Style). New Street Rodder Torque Converter too. I am having some really strange issues out of it.

1. After the first couple of times through the gears, the truck shifts way early. The 1-2 shift is around 10 mph (normal), but the 2-3 shift is around 12 mph. In fact, sometimes it seems as if it skips 2nd altogether.
2. Once the truck warms up, it stops shifting down to first gear at redlights. If I punch the throttle good it will kick down into first.

If I manually run through the gears, I get clean crisp shifts.
If I really get on the throttle, shifts are very firm and I have 2nd gear.

What I have tried:
1. I've checked vacuum... 18-20 in. vacuum at 700 rpm. Measured at the intake and at the modulator valve.
2. I've tried 3 different vacuum modulators (green stripe). No matter how far I adjust, the shift points don't seem to change (I adjusted the second one all the way in just to see if anything changed so that's why I replaced it again).
3. I took the modulator pin out and measured it to be 1.66-1.67 inches.
4. I took the governor apart and rebuilt it. No debris or stuck pistons in it. I thought that helped at first, but after driving for a bit the same issues came back.
5. The kickdown is installed and adjusted properly (fully pressed down when the throttle is wide open).

I am at a loss for what could be causing these problems unless it is the valve body itself. Any thoughts or suggestions? I should point out that I have read every thread I could find on this and haven't found any good answers.

Thanks for all the help! This is my first post to the forum.

 

Wanted to post an update to this thread for anyone who runs into this issue in the future.

I ended up taking the truck to a transmission shop nearby as could find no one who could diagnose the condition.

The transmission shop took a look and believe it or not the kickdown cable was the issue the entire time...

Initially the kickdown was adjusted like this:
1) Hold the throttle wide open
2) Adjust the screw on the kickdown until the kickdown is fully depressed at wide open throttle.
This in essence meant that the kickdown rod was engaging at early acceleration and essentially throwing the shift points of the transmission off.

The shop adjusted it such that you didn't engage the kickdown until the throttle was about 3/4 of the way depressed. I think this took some trial and error work on their part until they got it right. So now when you look at the carburetor, the kickdown does not touch the throttle at all.

I will say this contradicts some of the information on the internet, but it is working very nicely now.

I hope this helps, if anyone needs more clarification let me know.

 

Thanks for posting back and closing the loop on this.

Are you saying TCI's instructions were incorrect as far as the kickdown's initial setting?

 

Sure thing...

TCI never actually provided instruction for adjusting the kickdown. When I was working with their tech support department I did tell them how I'd adjusted it and they never said it was incorrect. They too believed that the issue was internal to the transmission due to the strangeness of the symptoms.

I don't want to bash TCI either, as I don't know if any technician would have been able to diagnose over the phone. The shop I took it to said they just tried messing with it as a last resort before tearing into the engine.

Looking back, I wonder if I had purchased the lokar cable kit and scrapped the OEM kickdown if the problem would have ever existed.