Kickdown Question

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scott_s

scott_s

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Kick down question:
I had to make some pretty big adjustments on my throttle pedal and kick down linkage when swapping carbs. The P.O. had the wrong carb hooked up and had it all out of whack. You can see the newly exposed threads in the pics.
Car runs great and goes through the gears nicely now, but doesn't kick down in passing gear.
I see HOW to adjust the kick down, but I can't access it in my garage.
Will I damage anything if I drive it like this until I get it to a shop with a lift?

To clarify: it shifts fine up and down through the gears. Shifts are soft and normal/not harsh or clunky.
Under light throttle, hits 2nd around 15mph, 3rd around 22-25mph.
Under harder acceleration, it holds the gears a little longer but still shifts great.
What it DOES NOT DO is drop from 3rd to 2nd if I punch it, like trying to pass a car.
lengthened kickdown.jpg
pedal lengthened.jpg
 
Your shift points are about right. I would try lengthening your TV rod another 2-3 turns and see if that helps. No damage here, just loss of kick-down.
 
The early cars wouldn't kick down unless you floored it. You have it adjusted so that the kd arm never goes completely back as it should.
 
Confirm that you are getting full extension of the TV rod at full throttle. Engine not running- have someone push the pedal to the floor. Is the carb butterfly open fully? At this point, is the TV rod fully extended or is there play in it? At full throttle, the carb butterfly and the TV rod should be maxed out.
 
At full throttle, the carb butterfly is 100% open. I disconnect the TV rod and can push it down. I gave it another turn out and took it for a test drive.

I also found this information:
In 1968, part-throttle downshift functionality was added to A-904 transmissions used with six-cylinder engines. This feature permitted the transmission to shift from third to second gear in response to moderate accelerator pressure. Previously, an automatic 3-2 downshift occurred only if the driver pushed the accelerator to the floor. This change was made to maintain acceptable in-town performance with taller final-drive ratios in the rear axle — 2.76:1 rear axle gears were being furnished in applications previously equipped with 2.93:1 or 3.23:1 gearsets. Part-throttle downshift functionality was extended to V8 A-904s in 1969, and to most A-727 transmissions in 1970 to 1971.

I wasn't aware that I had to completely mat it. Knowing that, it DOES kick down, but only holds 2nd gear for a couple of seconds before going back to 3rd. Does that mean I need to keep extending the TV rod?
 
What makes you think that new-found information is correct?? I don't believe ANYTHING; worse about fifty year old info..
 
Well, it pretty much echoes what you said.
CudaFactHackJob said:
The early cars wouldn't kick down unless you floored it. You have it adjusted so that the kd arm never goes completely back as it should.
Click to expand...

I'm not trying to argue or be combative/contrary.
I'm new and I'm learning and I'm trying to fix my own s**t myself.

So..... keep adjusting TV rod until it holds passing gear a little longer or ????
I still think I should do the lower adjustment, just because.
 
Oh, and if it wasn't for combative/contrary behavior on this website; it would be close to dead..so...not really an issue...for me...
 
CudaFactHackJob said:
Carb all the way open...arm on trans all the way back... simple.
Click to expand...

OK, so I held the throttle all the way open and I actually had to screw the TV rod back IN a couple of turns to make it snap on the throttle rod at that point. Maybe I had it TOO far out?
I'll do another test drive tomorrow and report back.

CudaFactHackJob said:
Oh, and if it wasn't for combative/contrary behavior on this website; it would be close to dead..so...not really an issue...for me...
Click to expand...

Me either. It's all good. I was referring to myself more than you anyway. :thumbsup:
 
Oh, I know; I'm always on my best behavior in here.... Sounds far out. But I don't know which way you mean. Do you mean that the arm adjustment wasn't allowing the carb to open all the way?
 
The carb was opening all the way.
I disconnected the TV rod and opened the throttle all the way and then pushed down on the TV rod all the way.
In that position, the TV rod would not snap on the ball. It was too long. I turned it in about two turns and it lined up, so I snapped it back on.
 
If I understand you correctly, then I don't think you will have a better kickdown when you test drive it.
 
Then I don't understand the instructions above.
I thought you were saying open throttle and adjust rod to fit....

Maybe you meant for me to make the TV rod longer so that when throttle is wide open it pushes the lower lever all the way back?
OK.....starting to click. Sorta.
 
@CudaFactHackJob I might be a little slow, but it's all starting to sink in now!

I extended the TV rod even more and took it for another test drive. Definitely kicks down and holds it on passing gear longer now.
At around 50 MPH, it holds it for maybe 3 seconds.
At around 35 MPH, it holds it for about 5 seconds.

I wound it out one more thread when I got home. How long should it hold passing gear before shifting back into 3rd?
 
"Maybe you meant for me to make the TV rod longer so that when throttle is wide open it pushes the lower lever all the way back?"...Yes, we want the arm all the way back at the exact same time the carb is all the way open.
 
scott_s said:
How long should it hold passing gear before shifting back to 3rd?
Click to expand...
Assuming the kickdown rod is extended to the max without interfering with the carb WOT; the max RPM automatic shift to 3rd gear would be controlled by the value of the installed governor valve.
 
But it should hold it for more than 3-5 seconds, right?

As bad as the P.O. had the linkage messed up, I'd really like to check the lower adjustment as well.
 
scott_s said:
But it should hold it for more than 3-5 seconds, right?

As bad as the P.O. had the linkage messed up, I'd really like to check the lower adjustment as well.
Click to expand...
As RPM's build up, the pressure also builds. When the pressure reaches the max the governor allows, it will automatically upshift to 3rd. This assumes, obviously, that you leave the gear selector in "D". If you manually put the gear selector in "2", the trans will shift from first to second and should stay in second until you manually upshift to "D".
 
"How long should it hold passing gear before shifting back to 3rd?" That depends on what speed you were at when it kicked down and how fast your car can speed up.
 
I was able to get underneath and check the lower adjustment using the FSM instructions.
Apparently, everything is adjusted per spec.
I guess it's all it's gonna be.
 
Do what? What else?
The adjustment at the trans is adjusted per the FSM.
I'm getting full throttle.
If anything, the TV rod is LONGER than the FSM calls for, but if I shorten it, the upshifts come too soon.
 
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