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Discussion Starter #1 (Edited)
Thanks for taking the time to read. I am unsure what my next step should be and was wondering if anyone has run into this problem.

I have a th400 professionally built for my '98 LS1 Trans Am street car. Stock rev limiter was set at 6200 before. I had the problem last year that the car would get stuck in 2nd and redline at 85 mph. The place I had build it re-did the governor to shift at 6000, but it would never go to 3rd unless I let off the gas quick, then it would. So I pulled a stock governor from another th400 and put it in and then the car would shift into all gears, but at 5000 rpm. So I figured the problem was solved, just needed to mess with the springs and weights and get it dialed in. Fast forward to this year.

I finally decided to spend some $$ and upgrade heads and cam and get some more power. Got it all dyno tuned and it layed down 370 rwhp 365 rwtq on a mustang dyno w/ a th400, 3600 stall converter and 9" rear. It could be a lot better since I have outgrown the intake and throttle body and exhaust, but $$ won't allow those upgrades till next year. Had the rev limiter bumped up to 6500 since I also upgraded rod bolts, etc. Peak power is around 6100 rpm, so it was time to go over the governor and get it to shift up where the power was. Changed springs and weights and it would still not shift out of 2nd. Went over the governor again and now it will go through all gears and shift at 6000. I do have a kickdown switch hooked up. Thought I had everything pretty close. From a stop when I floor it, it will shift at 6000 and go through all gears which was very nice to finally be able to do.

Problem arises when I am already in 3rd and floor it. Kickdown switch is activated, putting it into 2nd, but it will stay there and redline and not go to 3rd no matter what. It will shift through all gears from a dig which is great for the strip, but when rolling and already in 3rd and kickdown is activated, no way. Works fine when the kickdown switch is disconnected, but it's not fun when I gun it from a roll with it disconnected. Feels like school bus. Should I keep tweaking the governor, or is there something else I should be looking at?

Thank you for any advice

mark jr.
 

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Discussion Starter #3
I can have the kickdown switch connected and run it from a stop and it will shift through all gears, I can also have it disconnected and start from a complete stop and it will shift through them all. The problem occurs when I am already rolling in 3rd gear and floor it, with the kickdown switch connected, it will kick down to 2nd, but never shift out of it. Just stay there and redline at around 80 mph.
 

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Very odd. Sounds like you may have a plugged governor filter, a worn out governor bore or a badly leaking governor tube. Don't forget there may be a governor filter inside the Valve body as well in the case by the governor tube.

Thats all I can think of that can be causing you so much grief.


Hutch
 

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Discussion Starter #5
Thanks for the info. I have to admit, it's been at least 8 years since I have torn a th400 apart and rebuilt it, and that was in class. I will look it up in the morning and find a diagram and procede from there. I looked on many forums and haven't been able to find someone with a similar problem. I appriciate the help ;) Probably get fixed next season because I put the car away very soon and time just doesn't exist for me. owning your own business takes too much time. Hopefully a non-rainy day shows up (no garage except for winter storage) and I can tear into it and see what I can find.

Thanks for pointing me in the right direction :cool:

mark jr.
 
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