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Discussion Starter · #1 ·
So my project is finally driveable. Runs great and rides great. Problem is I cannot get it do downshift when I mash the pedal. I have checked the linkage and verified that the linkage pulls the lever properly. It downshifts fine when slowing down but no kickdown. I rebuild the C4 myself with the help of the Bad Shoe video. Didn't have any trouble but obviously something ain't right. 66 C4 with 289.



Any suggestions?
 

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Perhaps your throttle pedal is not pulling the lever as far as you are expecting. I would remove as much slack as possible to see if the kick down engages. On my 68, I had to tie a knot in the kick down cable to shorten it because there was not enough adjustment in the threaded portion of the cable. After tying the knot, I was able to set the adjustment nut about half way.


This cable on my car is like this one:
 

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Did you check the location of the throttle lever in relation to the Kick Down Valve when you put the valve body back in? It's very easy to miss & the lever hangs up on the long bolt that secures the stiffener plate. When located correctly, the throttle lever should spring back from the kick down position. Check this picture.

 

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Discussion Starter · #4 ·
Did you check the location of the throttle lever in relation to the Kick Down Valve when you put the valve body back in? It's very easy to miss & the lever hangs up on the long bolt that secures the stiffener plate. When located correctly, the throttle lever should spring back from the kick down position. Check this picture.





Certainly possible. Something to check. Rebuilt the trans 3 years ago so memory not so good


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As was mentioned, easy check is to put the front of the car on jack stands and have someone step on the gas all the way down and see if the cable attached to pedal is pulling the downshift level forward on the side of C4 trans. When I added the Trans GO shift kit I did not put the kick down lever properly as shown Pony Gaz and had to open it up and make sure that lever was in the right spot, then my kick down was working great again. Should have a springy feel if you manually move the kick down level with your hand.
 

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Discussion Starter · #6 ·
Just a follow-up, the kickdown lever is fully engaged when I floor the accelerator. I'm pulling the valve body once my transgo kit arrives so I will doublecheck the lever engagement inside.
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Discussion Starter · #7 ·
So I tore into the valve body to make sure I installed the shift kit properly. Found out I forgot to drill a hole in the separator plate so I took care of that. Kickdown is fully engaging but no downshift. I even took apart the kickdown portion of the vavlebody to make sure nothing was wrong. Still perplexed.
 

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Discussion Starter · #8 ·
So I fixed the shifting problem for the 2-3 shift by a new modulator and the 1.625 pin. I did have a problem with the throttle blades not being completely open at WOT so I readjusted the linkage and again readjusted the kick down cable. The cable appears to fully engage the lever at the end of its travel. I can verify there is resistance then I manually push the lever and I was careful to make sure the lever was engaging properly when I put the valve body back on. The transmission shifts pretty close to perfectly under normal driving and WOT launches. But it WILL NOT downshift when I floor it. Any risk in further shortening the cable even though I am pretty darn sure it is fully pulling the lever? Any other thoughts?
 

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If you tighten the cable too much, it'll just limit your throttle travel at best, or pull the end off your kickdown cable. I can tell you from driving a car with a C4 for years, the kickdown on them doesn't mess around either. If it CAN grab a lower gear, it does. But that does bring up another point! What speed are you going when you test this, and what kind of rear gears do you have?


Is it possible that you're just spinning things too fast for it to grab 2nd? Your car will ignore the kickdown if you're at high speed. For my car, running 2.80 rear gears, it seems like about 75 mph is the end of where it'll consider downshifting. If you were using higher numeric gears like 3.50's, your cutoff might be low enough that it's just never going to downshift, when you're out on the freeway.
 

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Discussion Starter · #10 ·
If you tighten the cable too much, it'll just limit your throttle travel at best, or pull the end off your kickdown cable. I can tell you from driving a car with a C4 for years, the kickdown on them doesn't mess around either. If it CAN grab a lower gear, it does. But that does bring up another point! What speed are you going when you test this, and what kind of rear gears do you have?


Is it possible that you're just spinning things too fast for it to grab 2nd? Your car will ignore the kickdown if you're at high speed. For my car, running 2.80 rear gears, it seems like about 75 mph is the end of where it'll consider downshifting. If you were using higher numeric gears like 3.50's, your cutoff might be low enough that it's just never going to downshift, when you're out on the freeway.

Thanks. Might shorten the cable just to make absolutely sure it is fully engaging the lever. I have tested the kickdown at many speeds up to 50/ Won't go into first when I mash it going slow and won't go into second when I mash it above 35. It seems to shift into third around 30. Maybe I'll crank the modulator a little more and see if I can get it to shift a little higher and see if that makes any difference. I also drove a 68 Mustang with 289 and C4 in high school so I am reasonable familiar with how it should shift as I was constantly mashing the throttle as a teenager
 

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If you grab the downshift lever on the transmission and manually push it forward does it spring back, this is to confirm that it is right?
 

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Discussion Starter · #12 ·
Yes, with no external spring connected to the kickdown lever I can feel the spring in the valve body. I also took apart the valve body to inspect the Shiftdown piston and it moved freely in the valve body.


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Discussion Starter · #13 ·
Anybody have a pic of the kick down lever installed on the tranny? I'm sitting here wondering if I have it installed 180 degrees off. Does the lever install toward the top of the shaft or toward the bottom of the shaft?
 

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Discussion Starter · #15 ·
Thank you. Looks like mine is installed properly!


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Discussion Starter · #16 ·
SOLVED


So I had adjusted the lever about 5 different times with a driver in the seat pushing the pedal down all the way and I could verify it was pulling the lever completely. No matter how many times I tried it just would not kick down. So for its and giggles I decided to adjust is as short as it would go which added about 1/4" less travel. Low and behold it downshifts now!!!!!!
 
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