Well I just took out my 4.10 rear and installed a 2.56 rear so I can drive it on the street like a normal car.
The transmission doesnt downshift to first and is making it hard to drive from a stop so I unhooked the vacuum modulator and then it would only stay in first and I had a hard time getting it to shift out of second. I had the vacuum line hooked up to the front of the carb teed into where the AC hooked was this too much vaccum?
Well then I hooked it to the side of the carb the ported vacuum where the distributor vacuum is and it still wont downshift to first from a dead stop. Now I can throw the shifter down and it will go to first but thats it.

CAn anyone help?
Thanks

I just drove it agian and I have it Teed into the ported vacuum port and its still doing it but I noticed that when I stopped I could push it down into first and then back up to third and it would shift right.
Any help on what I can do?

Fix the sticking valve in the valve body?

You don't want ported vacuum for the modulator. Excessive line pressure at idle, and I've seen it cause a false neutral on deceleration.

Ok I moved it back to the base of the carb but now I noticed that it is shifting back down to first but as soon as I take off just about half a second later it is shifting to second, you can feel it and here it trying harder to go.

HELP!
Changed the vacuum modulator back to the original one and its still doing the same thing. Could it be the govenor?

I am having similar issues with my th400. If it isn't going into 1st when coming to a stop with the shifter drive, then more than likely you have very fine debris affecting the governor.

Jack the car up from the rear/passenger side (minimize fluid lose).
Pull the gov cover (4 bolts/domed cover, pass side).
Pull gov, ispect for debris or damage (rarely will this be noticeable).
Holding the weights in, tip back and forth, observe the valve (spool) inside the gov (view through the port slots).
The valve should move freely inside the gov bore.
If not, try to move it with a pick or small screwdriver (don't scratch it).

Usually soaking it with carb spray, while shaking vigorously will free if up, otherwise, pull and inspect/clean valve (remove roll pin/gear).

I experienced brief normalcy before eventually returning to no downshift issues. I just purchased a remote filter to run inline (hosed off cooler lines). Hopefully I can clear this and the occasional delayed shift to 3rd in drive.

My ENTIRE system was brand new when assembled last Feb. Spent $2600 on COAN th400 & 10" converter. Got less than 50 miles before performance rapidly took a dump. Shipped back to Indiana, warranteed, returned. Operated perfectly for a week or so, then started the erratic shifts. I always have manually shifted, so it had little effect, but the old lady almost HAD to use it the other day and I'm afraid she'll leave it in drive and bake the tranny.

I'll post my results.

PS. I did flush between trannys. I've already gone though 2 1/2 cases of Amsoil synthetic fluid, at nearly $9 a quart. Hence, my decision to incorporate a filter, rather than change.

So your recommending a filter in the cooler line? Does the fluid go through the cooler then to through the system? But shouldnt the filter inside the tranny do the same? What type of filter do you recommend for tranny fluid?

Thanks for the responce I was thinking govenor and now youve gave me a reason to pull it out. Agian thanks