727 Kickdown Arm

[chtampa]

Tackling the kick-down linkage of my Gen 3 5.7 and SB 727 combination. I am using the factory style bell-crank system to begin my modifications with. I have the pivot at the intake and then the one on the side of the trans and then the linkage goes to the kick-down arm. I have found 3 different lengths of kick-down arms for the transmission and am curious as to why I would use one versus another. Are there reasons or applications that make these different?

 

[oldbee]

NOT an expert, but it's all about body style,motor,trans as far as I know. I got lucky with a factory 383 setup that adapted easily to a 440 engine; sorry.

 

[wagonman]

Like OldBee said but and this is a big but. It all depends on the combo, BB,SB,Slant 6. The year 1 piece 2 or 3 piece. Wish I could be more help. We sure could use a guide as to what fits what. Any one want to tackle this mystery?

 

[chtampa]

The guy that did my transmission for me sent it without the lever and told me that there had been no rhyme or reason to the lengths of shifter or kick-down levers between years, vehicles or anything and it didn't matter. I trust him but it seems like that sentence doesn't fit with Mopar and the **** side of me feels there is more to it.

 

[wyrmrider]

Think about it
the shorter lever will move - rotate quicker than the longer one- use the lengths to tune where you want the KD

 

[miller]

Think about it again.
From year to year, and the different models, various engines and carb types, all point to one thing. The trans lever length needs to mate with the carb throttle arm, that it gets hooked to.
It's the 'pivot distance' for both the carb, and trans levers, that need to be the same. Rod(s) only transfer that movement, whether one rod, or twenty!

 

[wyrmrider]

good thought
no spring on the KD rod to take up pushing past the KD point?

 

[oldbee]

good thought
no spring on the KD rod to take up pushing past the KD point?

Not sure what you mean ‘wyrm’ ; spring is for return & to keep linkage against throttle travel.

 

[lemondana]

The 3 rod 2 bellcrank setups use the shorter levers. All the long one piece kickdown rods use the same long levers. All A Bodies after roughly 66 use the 2 bellcrank and 3 rod setups. The 66 up to 70 B Bodies use the 2 bellcrank 3 rod setups also, although probably not the same part numbers. 318 might be the same in the A and up to 70 B bodies. I think all E Bodies all C Bodies and 71 up B Bodies use the long 1 piece rod. So I would use one of the shorter arms. The short arm on my 69 Coronet R/T has a shorter arm than one I took out of a 69 Charger with a 383 Magnum.

 

[dvw]

It all has to do with geometry. The lever is more than kick down. It alters the amount of pressure applied to internal components. The throttle pressure lever attachment must travel the same distance as the throttle cable attachment point at the carb. The further from the pivot the attachment is, the longer the travel distance. If the carb travel is longer than the throttle pressure arm travel, no adjustment will put the throttle pressure arm into full travel. Of course this ratio can be multiplied or decreased by changing any lever in the linkage. Not enough travel at the trans will result in low line pressure under heavy throttle killing the the clutches and 2nd gear band in short order. This problem is what led me to start repairing my own transmissions over 35 years ago.
Doug