I have a rebuilt C4. When put in drive it starts out in 2nd then shifts to 3rd. BUT, if I give it more throttle when taking off, it will move the car in 2nd, then downshift to first. Under light acceleration, it starts in 2nd. Under harder acceleration it will start in first. I can manually shift 1,2,3 no problem. What are the things I should look for. Danford1 PS trans was rebuilt by a trans guy I've used before no problem. He isn't available right now for me to ask him (out of town)... so I'm coming here to get quick answers. Thanks!
Think we need a tutorial on how the C4 modulator, governor, and kick down rod interact to control upshifts and downshifts. Anyone know of one?
It is a 1981 trans with 1981 valve body. It has the green stripe modulator. If I start in 2nd, it stays in 2nd. I noticed more about it today. If I just come to a stop sign, stop, then go, it starts in 2nd. If I come to a red light and sit there, it will start off in 1st most of the time. Sometimes, if I stop then manually shift to 1st for a second then back to drive, it will start off in 1st some of the time. Kick down doesn't work. I need to rig my kick down cable better. It upshifts way to quick. If I leave it in drive say from a red light so it will start off in 1st, then hammer it and hold it at WOT, it will shift into 2nd no more than 3800 rpm. Most times it is around 3000 rpm. Shifts 2nd to 3rd at 3000 rpm too. This is on a 200 cu in 6 with Tri-Power and a Comp 260H cam with Clifford dual exhaust header. The engine revs to 5000 no problem. The trans shifts way to quick. I know I can adjust the modulator to correct that. I will be doing that Sunday. I'll also fix my kick down cable Sunday. I need to sort out the taking off in 2nd portion though... I'm wondering if I hook the vacuum line to my vacuum canister instead of manifold vacuum if that will help. Perhaps I'll try that Sunday also. Danford1
Nice engine! Don't connect your modulator to the vac can. It maintains 18 - 20 inches of mercury. The modulator will sense very light throttle all the time. I have no clue on your shifting problem, sorry! Maybe having some pressure tests done on it will show up something.
Ok, I won't connect to vacuum can. The trans is getting better and I think it is because I'm getting the engine to run better supplying more vacuum at idle. In gear it has about 10 inches vacuum now. Before it had 6-8 inches. The low vacuum is from the Comp cam in it. The best it has at idle in park is 15 inches. Can't get 18-20 ... I'm still tweaking the carb tune and timing. As I improve the engine, the trans problem improves I'll know more tomorrow as I'll have time to work on the car. Cheers. Danford1
OKay ..... What issue and how do I correct it? The trans and valve body were fine. I rebuilt the engine so since the trans was out I decided to get it rebuilt. I can ask the trans guy if he did anything to the valve body. If he did - all he did was clean the valves. It already had some sort of a shift kit in it. Danford1
I've played with valve bodies before in AOD's. I know the C4 is much simpler. Do you know of a web site with an exploded view of the valve body so I could check each valve and spring for correct positioning? Danford1 PS. Some people are fans of synthetic fluid, some people say stay away from it. I'm a fan of Amsoil. My trans has Amsoil universal ATF in it. Just thought I'd throw that out there...
This should help http://www.fordification.com/forum/viewtopic.php?f=39&t=38042 If you had a spare i would swap it in and see what happens
Thanks for posting the links. I looked through a lot of the trans links. Still couldn't find the valve body exploded view... Guess I'll have to keep looking. Danford1
