Tranny kick Down?

[gonzalo medina]

I added and edelbrock 4barell carb to my 390. My truck never came with a passing gear or "kickdown" like some call it. I hear driving my truck with out one will fry my tranny??? Can anyone explain the function of this kick down rod I am missing and how to obtain one? I don't want to ruin my fresh C6 transmision.Thanks in advance.

[Jake11]

Your ok. It's just for passing gear. It won't hurt anything.
It's probly gonna be a look used one deal. You could make one out
of elect. conduit pretty easy.

[68F250]

No kickdown won't fry it like an AOD but the C6 kickdown does serve a purpose besides downshifting. It boosts the line pressure to keep it from slipping under high load/demand. If it wasn't needed I think Ford wouldn't have put one on.

No kickdown allows the govenor to move the shift valve easier, making it shift too early, When the kickdown valve is hooked up and adjusted properly, the govenor has to build enough pressure to override the kickdown valve pressure and move the shift valve to make the upshift.

[Jake11]

That ain't so. Pressure rise is controlled by load/vac.-modulator.
All the kickdown does is trip a dump valve. It works with govenor so
it's reasonable. As in no 3rd to 1st at 100mph.

If your talkin Mopar, well yes your correct.

[68F250]

Ok, I'm gonna have to take a look at those hydraulic diagrams again.

[Jake11]

Heres a quick dirty map

C4 Press control-Mod.
C6"""
TH 350"""
TH400""'
727&904 Press control-Kickdown linkage
700/AOD(both early) Press control-Throttle cable.
That covers most popular models.

The later ones use a solenoid. Works off of MAP/TPS, to regulate pressure rise.And also PRND32L switch. AOD's don't have 2'nd.

[BobbyFord]

But the kick down valve boosts line pressure.

[Jake11]

Yeah. But it no control pressure regulation.