c4 kick down

[71broncrollsport]

i have a 71 with a swaped in c4 i just got it running and was driving it and it doesnt seem to down shift. is the kick down the vaccum hose that goes from the intake to trans? is that the only part or is there also a linkage it also doesnt shift quick to 3rd it starts to shift and as it shifts it revs up and then shifts

 

[Bronc76]

There should be a kick down rod, i think its on driver side

 

[Broncobill78]

The vacuum hose running from the intake to the tranny is for the modulator valve (the round external valve at the back of the transmission). The kickdown is actuated by a rod that connects to the kickdown lever on the tranny and the kickdown linkage on the carb. The carb linkage is located right behind the throttle linkage. It sounds like the kickdown rod itself is missing from the swap, you'll need to pick one up & connect it before you'll get a 3-2 kickdown.

Might be a stupid question but hows your fluid level ? If the fluid level is good then you're probably looking at a rebuild because it sounds like it's slipping on the 2-3 shift. Make sure the modulator valve is good and that it's connected to a good vacuum supply. I don't know if C4 bands can be tightened to firm up a slipping shift. I'd make sure everything is setup the way it should be (kickdown rod, vacuum, modulator, fluid level, etc) and see what it does. If it still slips between gears I'd suggest have a tranny shop look at it.

 

[Bully Bob]

YEP..., and.,

Auto & stick have dif. carbs...you may need a carb. swap to get the req. linkage to hook up.

 

[71broncrollsport]

YEP..., and.,Auto & stick have dif. carbs...you may need a carb. swap to get the req. linkage to hook up.

thanks for the info. the fluid level is good. it has a 4 barrel holley on it so the kick down could have been taken off a long time ago so i need to inspect that area. so the linkage hooks up to the throttle. but does it hook to the arm that changes the gears on the trans(maybe its all missing)

 

[71broncrollsport]

The vacuum hose running from the intake to the tranny is for the modulator valve (the round external valve at the back of the transmission). The kickdown is actuated by a rod that connects to the kickdown lever on the tranny and the kickdown linkage on the carb. The carb linkage is located right behind the throttle linkage. It sounds like the kickdown rod itself is missing from the swap, you'll need to pick one up & connect it before you'll get a 3-2 kickdown.
Might be a stupid question but hows your fluid level ? If the fluid level is good then you're probably looking at a rebuild because it sounds like it's slipping on the 2-3 shift. Make sure the modulator valve is good and that it's connected to a good vacuum supply. I don't know if C4 bands can be tightened to firm up a slipping shift. I'd make sure everything is setup the way it should be (kickdown rod, vacuum, modulator, fluid level, etc) and see what it does. If it still slips between gears I'd suggest have a tranny shop look at it.

whats the purpose of the modulator valve and how can i tell its bad