Kickdown issue

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j_anderson

j_anderson

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1972 Dart with 727. Linkages have been adjusted per the factory spec. With the pedal to the floor, the KD lever is all the way back against the stop but kickdown will not engage. This transmission was rebuilt at a local shop just before I installed it.

If the linkage is pushing the KD lever all the way back when the pedal is on the floor, what could be wrong in the transmission that it isn't working?
 
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"Possibly," they have the lever on the wrong side of the valve inside / didn't assemble the valve body correctly. It wasn't rebuilt as a manual valve body, was it?
 
royslead said:
"Possibly," they have the lever on the wrong side of the valve inside / didn't assemble the valve body correctly. It wasn't rebuilt as a manual valve body, was it?
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I'm not sure if it was rebuilt as a manual valve body. In any case, I have done my due diligence with the KD linkage adjustments so it's going to the shop to have them figure out why it isn't working. I was just curious if anyone has experienced this before.

The transmission was from a big block but was rebuilt into my small block casing. Unsure of the year of the 727.
 
Did u verify the carb is all the way open by having someone inside pressing it to the floor and u checking the travel at the carb? Some years didn’t have the part throttle kick down. Kim
 
oldkimmer said:
Did u verify the carb is all the way open by having someone inside pressing it to the floor and u checking the travel at the carb? Some years didn’t have the part throttle kick down. Kim
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yes, we adjusted the throttle cable to have the carb fully open with the pedal to the floor then verified the KD linkage was pushing the lever all the way back in that condition.
 
The lever that needs to 'push back all the way' is the lever on the trans, not the linkage on the carb. Which one are you checking?
 
All the way against "WHAT" stop?
 
Bewy said:
The lever that needs to 'push back all the way' is the lever on the trans, not the linkage on the carb. Which one are you checking?
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When the carb is at WOT (and fully open) I’m referring to the lever on the trans being fully back
 
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oldkimmer said:
Did u verify the carb is all the way open by having someone inside pressing it to the floor and u checking the travel at the carb? Some years didn’t have the part throttle kick down. Kim
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The non existent part throttle kick down is what I was thinking as well.
 
j_anderson said:
I will report back after I get it to the shop just to close the loop for future people who may experience the same thing
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You might want to grab a pic of the part throttle kd assembly so you know what it looks like, if you don’t already.
 
The kickdown in my 67 Charger stopped working. Disassembled the valve body, cleaned it up, and put it back together. That fixed the problem.
 
TrailBeast said:
You might want to grab a pic of the part throttle kd assembly so you know what it looks like, if you don’t already.
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I am unsure of the year of my 727 but do you mean an assembly like this?

Screenshot 2024-06-10 at 10.38.09 AM.png



65 Cuda 340 said:
The kickdown in my 67 Charger stopped working. Disassembled the valve body, cleaned it up, and put it back together. That fixed the problem.
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this is a freshly rebuilt unit but anything is possible
 
j_anderson said:
I am unsure of the year of my 727 but do you mean an assembly like this?

View attachment 1716260830



this is a freshly rebuilt unit but anything is possible
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Haven’t seen that one specifically, but yes that is the idea.
It’s an add on to the valve bodies that don’t have it and is really easy to add.

I added one when I had the 904 in my Dart and it was night and day difference for kick down.
 
TrailBeast said:
Haven’t seen that one specifically, but yes that is the idea.
It’s an add on to the valve bodies that don’t have it and is really easy to add.

I added one when I had the 904 in my Dart and it was night and day difference for kick down.
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Hope it's something simple like this. As it sits now, mine doesn't have the function at all. I've tried flooring it from various speeds above 40mph.
 
The PT KD is NOT required for WOT kickdown. It is called a Part-Throttle kd so that you do not HAVE to floor it.

Some shift kits crank the line pressure up quite a bit, and eliminate the Governor pressure. Now, the kickdown linkage controls the Throttle pressure, to increase the pressures to the various clutches, when the engine sees a load increase. The governor pressure controls the rpm at which upshifts occur, and synchronizes the commands with the roadspeed; and it is in conflict with the throttle pressure.
In other words, if the throttle pressure system is calling for an increase of 15 psi, but the governor is calling for a shift at the same psi, no shift will occur.
The governor, has to be calibrated to the rear end ratio, then adjusted to work with new VB calibration.
There are AFAIK only three governor flyweights provided by Chrysler, to be matched to about 8 rear ratios, so you have quite a bit of matching to do. So most kits I have seen, provide details of how to eliminate the governor, making it a manual-shift VB.
Personally I love a well-calibrated governor working together with the PT KD valve. I think it it's worth at least 4 attempts to getting it right, lol.
Personally, I do not like a full-time manual-shift routine.
To make adjusting the line pressure easy, I drilled and tapped an access port in the trans case, right where the allen key needs to go. Unfortunately, on a Mopar trans, the rear extension has to come right off to service the governor.

Oh I should mention, that if you still have a full-auto VB, and the governor flies apart, then the trans will auto-shift gears extremely early and offer no KD.

I'm not an automatic guy, so not 100% sure if I got it all correct, but pretty sure, lol.
 
I have an appointment on the 19th. The trans guy still thinks it’s linkage related. He keeps saying the rod needs more length to activate the KD but the KD lever already goes the maximum distance rearward when the pedal is floored so, I guess he will find out.
 
j_anderson said:
I have an appointment on the 19th. The trans guy still thinks it’s linkage related. He keeps saying the rod needs more length to activate the KD but the KD lever already goes the maximum distance rearward when the pedal is floored so, I guess he will find out.
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Can post some pics how I have it set up at the carb and the bell crank? Without seeing thus all we can do is keep guessing. Ask the tranny guy what year the vb is and the case is. Kim
 
oldkimmer said:
Can post some pics how I have it set up at the carb and the bell crank? Without seeing thus all we can do is keep guessing. Ask the tranny guy what year the vb is and the case is. Kim
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I don’t have a lot of confidence in the trans guy if he thinks the only solution is lengthening the rod.

A&A trans makes different governor weights that they recommend when the car owner tells them what the trans is currently doing, but personally I think the PT kick down will handle it just fine.
 
oldkimmer said:
Can post some pics how I have it set up at the carb and the bell crank? Ask the tranny guy what year the vb is and the case is. Kim
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I will snap some photos when I am back to the car this weekend (it's stored in a shop an hour away from where I live). I will also ask the trans guy about the year of the VB and case. Actually, I might be able to get the numbers off the case this weekend.
TrailBeast said:
I don’t have a lot of confidence in the trans guy if he thinks the only solution is lengthening the rod.
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I agree
 
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