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C6 kickdown
#1
Ok, I've been doing some reading but need a schooling on the kickdown cable.  When I bought my car it did not have one.  Now the transmission does downshift if I step on it and it seems to have a vacuum line going to the transmission.  So I figured that was the kickdown all along.  But reading some of the threads on here getting ready to install the 1406 carb I see most people needed an extension.  It was through these pictures that I now know what a kickdown looks like.  

So my question is, how much more aggressive does it make it downshift? And why does my transmission downshift when I punch it? Is there anything bad with running without one?

Thank you in advance.

1971 Mustang Grandé, 351 Cleveland 2v, C6, 9"
-Fitech EFI
-Comp Cams 284hr
-Aussie Heads
-Weiand Xcelerator intake
-Long Tube Headers
-Boss Hogg "Street Bandit"


My Build
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#2
The vacuum modulator on the transmission basically sets the shift points. Your kickdown lever, on the transmission, may be tied in the wide-open throttle position, which will give you kickdown, but not operate normally. The C6 won't be damaged by running it without a kickdown (like an AOD will).



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#3
I have been running without the kickdown for years. I use the shifter to kick down. Without the kick down you will notice that at about 65 or 70mph if you step on it, it will not drop into second gear. Mine doesn't but again, I use the floor shifter. I actually prefer the control.

'Mike'
73 Convertible - 351C/4V CC heads/4bolt/forged flat tops/comp 270/rhodes/mallory unilite/tri-power/hookers/glasspacks/c6/3.50 limited slip/Gear Vendors/Global West sub frames, strut rods and shelby style traction bars/ Rear sway bar/tilt steering (not original)

Pics of modifications included in:
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#4
Edelbrock sells a kickdown extension specifically for using a 1406 on top of a 351C. It's not expensive. I have it (also on a C6) but because I installed a thick spacer the kickdown rod doesn't reach and I've been driving without it.
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#5
Good to know, thanks for the response guys. will e you are spot on, it will downshift but once I am up to highway speed it will not kick down to second when I hit it. Was never sure if it was a rpm thing or the lack of the cable. I may track one down just to try it out and see how it feels, not that my car sees the highway much. lol.

I've always been around modern vehicles so before this car I've never owned anything carbureted, or with less than 5 gears. So I'm never quite sure how it should operator normally. Again thanks!

1971 Mustang Grandé, 351 Cleveland 2v, C6, 9"
-Fitech EFI
-Comp Cams 284hr
-Aussie Heads
-Weiand Xcelerator intake
-Long Tube Headers
-Boss Hogg "Street Bandit"


My Build
  Reply
#6
I don't mean to steal your thread, but I am wondering:
Does your C6 go from 1st to 3rd as quickly as possible?
Mine does (unless I am driving aggressively) and I was told it was because I have no kick-down.
I have changed and adjusted the vacuum modulator ad even swapped out the valve body for a different one with a different shift kit. No difference.
Has anyone else experienced this?

Bob

Tachs, Voltmeters, Headlight kits, Wiper delays and more at
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Rocketman's Classic Cougar (and Mustang) Innovations, LLC
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#7
Hmm. I never had an original transmission in my car so I can only say the trans does what the valvebody tells it to. If you'd like it to shift with a more performance feel, they try an old fashioned shift kit.

When I bought my car it too was missing the kickdown rod. Never hurt anything. Back in the mid 90's it was tough to find one. Think I got one from a mustang junkyard in Oklahoma. Still needed bushings. After I installed it, it wasn't as big of a deal as I thought. But I guess it was the right thing to do.

Mike
__________________________________
Black 1985 GT
Yellow 1973 Mustang Mach 1
Black 2012 5.0 GT, 6-speed, Brembo brakes, 3.73's
Wimbledon White 1966 F-100 Shortbed Styleside, 390ci, Tremec 3550, FiTech EFI
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#8
(02-10-2017, 07:28 PM)TheRktmn Wrote: I don't mean to steal your thread, but I am wondering:
Does your C6 go from 1st to 3rd as quickly as possible?
Mine does (unless I am driving aggressively) and I was told it was because I have no kick-down.
I have changed and adjusted the vacuum modulator ad even swapped out the valve body for a different one with a different shift kit. No difference.
Has anyone else experienced this?

Mine does not.  Again no kick down.  I believe the vacuum modulator can be adjusted with an allen screw.  Check this on the web.

I forget how it operates but if there is NO vacuum (line is disconnected) to the vacuum modulator it acts really strange so that is not your issue.

'Mike'
73 Convertible - 351C/4V CC heads/4bolt/forged flat tops/comp 270/rhodes/mallory unilite/tri-power/hookers/glasspacks/c6/3.50 limited slip/Gear Vendors/Global West sub frames, strut rods and shelby style traction bars/ Rear sway bar/tilt steering (not original)

Pics of modifications included in:
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#9
I do find mine likes to be in 3rd by about 25mph. But it will downshift at that low of a speed. I'm very curious. Going to look online for a lockdown and try one out this year. When I bought the car they didn't have the air line hooked up, it was so bad I had to shift it manually around town. You almost had to come to a stop before it would downshift from 3rd. And it would take off from a stop in 2nd.

1971 Mustang Grandé, 351 Cleveland 2v, C6, 9"
-Fitech EFI
-Comp Cams 284hr
-Aussie Heads
-Weiand Xcelerator intake
-Long Tube Headers
-Boss Hogg "Street Bandit"


My Build
  Reply
#10
Adjusting the tiny little screw in the vacuum modulator will modify the upshift...to a point. I've often found a new modulator usually needs a bit of adjustment after a transmission rebuild since it often will upshift to 3rd at 25 mph. I prefer a shift to 3rd around 35 mph with nice easy acceleration. Pedal to the metal upshifts are a different animal since the pressure is much higher.

As memory serves, turning the adjusting screw inward raises the shift point.
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