C4 shifting problems F&*&$#@ C4

[RTG_RACING]

OK so here is the deal. This truck of mine will not down shift. I stop and it tries to take off in second then drops to first. If I am out on the highway it won't kick down when I floor it. The kick down is not hooked up. NOw I have heard that if I wire the kickdown lever back it will kick down. Other than that does anyone know how or what to adjust to get it to start out in 1st gear?

[Banjo]

not familiar w/C-4, does it have vacuum controlled modulator valve like C-6, if so that "could" be a problem? My C-6 was acting bizarre and I changed it (about $12 part) and it fixed my problems. The C-6 in my truck hasn't have a kickdown hooked up for at least 6 years that I know of and probably longer. However, I know this is different trans and might not work same. Banjo.

[fordman]

no if you wire it back it will be in second all the time.

[Randy Beck]

I had the same problem with my C6 a few years ago. I changed the tranny fluid and filter (drained the tq conv. too). I added a qt of the Lucas transmission additive to the new fluid and it down shifts fine now. I think the valves in the valvebody get sticky sometimes and don't work right causing it not to down shift like it should.

RB

[RTG_RACING]

I have rebuilt a few C4s but never had one do this. I am not sure who rebuilt this one. I may need to figure out how to hook up the kickdown.

[BobbyFord]

Hooking up the kickdown will fix the no kickdown when you mash it, (obviously).
There are several different modulator rods available to correct your "starts in 2nd problem" you want a slightly longer modulator valve rod to increase the line pressure. You may be able to screw the modulator screw "in" a half of a turn at a time to correct this.

[basketcase0302]

RTG,

I've had C-4's do the same. I'd start with fluid and filter, then the modulator valve. If I'm not mistaken it is adjustable, (with an allen or slotted driver, where you pull the vacum line off). Oh yeah, make sure you have plenty of available vacum measured at the vacum line at the tranny at idle.

Hope this helps.

Basketcase