Just got finished rebuilding my th400 with a new cheetah turbo action valve body, reinstalled in car and i have all of the foward gears fine. My problem is that when i shift it into reverse i can feel the trans hit reverse, and then it seems as if there is no hydraulic pressure to hold it and pull the car in reverse (won't even spin the tires when on a jackstand!) I have only been through a TH400 a few times and i thought that the band was what was used to hold the drum to make reverse possible. According to the installation instructions it tells me to remove the band? Anyone have any ideas? I called Turbo Action and their "tech guy" had no idea what was wrong other than i was losing hydraulic pressure (yeah, no sh*t!) Anyone got any ideas? Stephen I know from reading that you are running a TA valve body, any suggestions?

Thanks!!!

 

If you find out what's wrong, let me know. My valve body was a transbrake version. My old TH400 is still sitting out in the garage. The transbrake uses the reverse circuit and mine also doesn't hold in reverse. I took the tranny apart many times trying to find the problem. I went through the TH400 book many times tracing possible problems but never found the fault.

I finally built a powerglide with a TCI transbrake valve body and never had a problem since.

I thought my TH400 problem was in the center support. Since I now have no way of testing the tranny, it just sits collecting dust. I'll probably sell off the internal goodies eventually.

 

Thanks for the response, I thought I was losing my mind, I have also had the trans apart to try to find the problem. Everyone that I talk to that works with tranny's on a regular basis says that there is no way to have reverse without the band, luckily the car only sees strip duty, so, I'm not that concerned about reverse. If I find anything else out I'll let you know. BTW what kind of internal goodies do you have for the trans, I might be inteerested.

 

i have heard that with the tci valve bodies set up for a transbrake, they have no reverse for that very reason. you aren't the only one to wonder about that. the tci transmissions with this valve body also have no band.

 

The Turbo Action valve body I had operated normally in D. Provided manual shifting through the gears and had a transbrake.

The TCI transbrake valve body and most other powerglide valve bodies with a transbrake, you need to engage the transbrake while in reverse to back up. I have a toggle switch mounted on my shifter cover with a safety latch over it. Since it's hard to hold the transbrake button and steer while backing up, I just shift to reverse, flip the switch and back up. When I'm ready to go forward again, I turn off the switch and pull the shifter down into first gear.

The TH350/TH400 transbrake valve bodies don't always need this done because of how the hydraulic circuits work in them.