904 Kickdown throttle pressure adjustment question

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C2ndLTpigeon

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I recently rebuild my 904 trans along with my engine. I sourced out a kickdown lever that looks to be the proper length. My car will shift through all 3 gears, 1-2 around 15-20 mph and into 3rd qround 30 mph which seems kind of fast and this is if I genitally accelerate.

I cant tell if the trans kicks down when I step on it, but im wondering if the original 2bbl throttle cable has anything to do with it. when I push the kickdown lever all the way back it moves freely, when I hold the throttle WOT with my hand at the carb the KD lever is maxed out as well as WOT. When I use the gas pedal it seems the cable does not open the throttle all the way, if I hold the throttle WOT and tighten the cable then when it returns close the plates are open a little.

So will the trans only kick down the gear if the lever is all the way at the max point? If so it will never get there due to the cable. And if the cable is the issue which should I get?

Am I missing anything as far as kickdown adjustment? Besides making sure the rod is all the way back when its WOT and spring tension pulls it forward.

I really do not want the possibility of smoking this transmission after all the work I put in. Like I said it shifts all 3 gears, and have driven it the past 3 days, when I get back from a good drive the car smells "hot" might just be all the new gaskets, painted surfaces, exhaust pipes giving off new smells. Just hope its not the trans.

The specs of my car are:
1973 Valiant
318, with hughes whiplash cam
904 stock converter, installed B&M shift improvement kit set for street performance.
7 1/4 rear (for now) unsure of gear ratio but obviously highway gears.

Pictures of the kickdown lever at idle
DSC02514.JPG


Kickdown with gas pedal presses as far as it will go.

DSC02517.JPG


Kickdown going all the way back when I manually WOT which seems to go back a little more than pressing the gas pedal down all the way.

DSC02515.JPG


I appreciate all the help, still learning these things.
-Rafael
 
looks to me like you have the 2 bbl bolt to the manifold throttle cable bracket on now. When switching over to a 4 bbl with the higher rise manifolds you need the 4 bbl bolt to the manifold throttle cable bracket as it sits higher and is about 1" more forward too.

So I would say you have the wrong throttle cable bracket on now sitting to low and too far back making it throw off the cable geometry to the 4 bbl carb and kickdown linkage, not giving it the proper stroke.
 
Did you adjust the linkage per the factory shop manual?
What I have done so far according to manual, I have held the lever on the trans forward (do not have the spring tool) While I had a 3/16 pin holding the bell crank in place. My dad adjusted the intermediate rod while I held the lever and attached the ball socket. I removed the pin and went to the lever at the carb. Manual says to adjust lever rod but mine is a fixed rod which looks to but up to the carb and go all the way back if I manually hold it WOT
 
looks to me like you have the 2 bbl bolt to the manifold throttle cable bracket on now. When switching over to a 4 bbl with the higher rise manifolds you need the 4 bbl bolt to the manifold throttle cable bracket as it sits higher and is about 1" more forward too.

So I would say you have the wrong throttle cable bracket on now sitting to low and too far back making it throw off the cable geometry to the 4 bbl carb and kickdown linkage, not giving it the proper stroke.

Oh, I thought I had the right one. I ordered this one from Mancini Racing, 340 4bbl bracket. Mancini Racing Throttle Cable Mounting Bracket
 
If you are getting full throttle and the car is shifting, then you are good. If you want the car to kick down quicker when you press the pedal, adjust the rod along the firewall counter clockwise (making it longer) 1 turn at a time until you are happy with it.

PS: You have the correct 4bbl bracket.
 
If you are getting full throttle and the car is shifting, then you are good. If you want the car to kick down quicker, adjust the rod along the firewall counter clockwise ( making it longer) 1 turn at a time until you are happy with it.

PS: You have the correct 4bbl bracket.

Thats what I thought, the bracket is for a 4 bbl, but it seems im not getting the max WOT position. If I hold it at WOT and set the nut on the bracket and let it go, when it returns to closed the plates are open a tad which is not right. Meaning there is a small amount of travel that the cable will not pull open.
 
These adjustments can take a little time to dial in.
I would take the kickdown out of the equation, and just concentrate on getting full throttle.
You might be on to something with the 2bbl throttle cable. I can't remember if I had to go to a 4bbl cable. Then revisit the kickdown adjustment.
 
These adjustments can take a little time to dial in.
I would take the kickdown out of the equation, and just concentrate on getting full throttle. Then revisit the kickdown adjustment.

I figured this would be more of a throttle issue than a KD. Is there another cable I should be using or is the stock 2bbl cable sufficient for the 4bbl set up?
 
I figured this would be more of a throttle issue than a KD. Is there another cable I should be using or is the stock 2bbl cable sufficient for the 4bbl set up?

I can't remember if I used the original 2bbl cable, or had to find a 4bbl cable.

What happens if you move the cable forward a little bit in the bracket ?
If the cable won't let the carb close all the way, then it is definitely to short.
Get the throttle cable figured out first, then go to the kickdown.
 
Think you are ok with the 2 bbl throttle cable, I have used them on the the 4bbl conversions before. As long as they are not pinching or bent too tight.
 
I can't remember if I used the original 2bbl cable, or had to find a 4bbl cable.

What happens if you move the cable forward a little bit in the bracket ?
If the cable won't let the carb close all the way, then it is definitely to short.
Get the throttle cable figured out first, thenit go to the kickdown.

Will mess with it in the morning, thanks for the help as always John :thankyou:
 
Did you change the lever on the trans to a 4bb; lever they are shorter . 727 and 904 4bbl are also clocked different. The cable bracket looks correct.

Notice the 4bbl kever has a larger hole so they are not interchangeable . But if you drill your own hole inward in the correct clocked lever it works

DSCF2913.jpg


DSCN2763.JPG
 
I personally never had to change the 2bbl lever on a 904, for a 4bbl conversion. The 2bbl linkage from the firewall to the trans all bolted right up.
 
You can raise that cable by adding one inch to the kickdown lever..
 
Did you change the lever on the trans to a 4bb; lever they are shorter . 727 and 904 4bbl are also clocked different. The cable bracket looks correct.

Notice the 4bbl kever has a larger hole so they are not interchangeable . But if you drill your own hole inward in the correct clocked lever it works

View attachment 1715604988

View attachment 1715604989

Never knew that .... thanks ! Good to learn new stuff .
 
After testing it today, It seems to kick down from 3rd to 2nd at lower speed, but if your at 45-55 and floor it, it will not kick down it will stay in third and continue to accelerate at a decent speed, not sure what the max speed in 3rd is that it will not kick down to second.
 
After testing it today, It seems to kick down from 3rd to 2nd at lower speed, but if your at 45-55 and floor it, it will not kick down it will stay in third and continue to accelerate at a decent speed, not sure what the max speed in 3rd is that it will not kick down to second.

Need to make sure your carb butterfly's are full open when you floor it to make the most power. The more power you have available the easier it will kick down.

Like if it is only opening the carb butterflies half way, it is not going to kick down.

Sounds like you need to lengthen out that kickdown rod 2 more turns too.
 
I agree with JohnnyDart here. Forget about the kickdown and get the throttle opening up correctly. Then add the KD linkage and adjust that.

I'm using the 2 bbl throttle cable and KD trans lever on my 4 bbl stock cast iron intake 273, with the correct Commando/Charger 4 bbl throttle bracket, and it shifts up and down properly.

273KickdownCorrect.JPG
 
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After testing it today, It seems to kick down from 3rd to 2nd at lower speed, but if your at 45-55 and floor it, it will not kick down it will stay in third and continue to accelerate at a decent speed, not sure what the max speed in 3rd is that it will not kick down to second.

As mentioned. If you have the room, lengthen the firewall rod another turn or two. Or until it kicks down. You are looking for a happy medium in the adjustment, if that makes sense.
Eventually you will know when its right.
 
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