Engine Throttle and Transmission Kickdown Cable Adjustment

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Tynan918

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Aug 2, 2021
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Late acceleration and shifting...TH350 transmission...

It's said if I replace this setup (which I completely did, I may have to readjust the throttle cable and then the kickdown cable after the throttle cable is adjusted correctly...

Well lets get it started...first things first...

How do I correctly adjust my throttle cable ?
 

PJNJ201

Not-quite-so-new-guy
Feb 9, 2021
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Late acceleration and shifting...TH350 transmission...

It's said if I replace this setup (which I completely did, I may have to readjust the throttle cable and then the kickdown cable after the throttle cable is adjusted correctly...

Well lets get it started...first things first...

How do I correctly adjust my throttle cable ?
You can do it by yourself, but if you have a friend help it will be easier and more accurate the first shot. Not sure how your set up is, but theres usually a bracket that the cable housing sits in with a clip. My car is carbureted, i had my buddy sit in the car and push the pedal to the floor as i loosened the bracket and and put the cable where it should be and then tightened it back up. I wasnt getting full throttle. Kickdown cable, there should be a clip lock behind the bracket, you pop it open and pull the throttle back, lock it back in place and then let the throttle go. Sorry if its a little confusing. Post a pic of what you have and how its set up, we might have something very similar
 

CopperNick

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Uh, some confusion arising here. First thing to confirm is that what you have is a 350, aka TH350. Reason for this question is that 350's only come with a kickdown cable for passing purposes. Otherwise all the shifting gets taken care of by a vacuum line to the modulator valve located by the tail shaft housing on the passenger side of the case. Even the "E" variant that has the lockup converter still is govermed by vacuum.

It is only when you get into dealing with the 700R4 and the 200R4 units that you start to find the shifts being governed by a TV Cable that connects to the carb at the engine and to t-mission down on the passenger side. This TV Cable is connected to a wire link internally in the t -m.

In order of appearance, the throttle cable is anchored in a bracket located beside the Timer. That bracket has two square holes in it and the upper is for the carb throttle cable and the lower is for the TV cable. Be aware that there are multiple versions of that bracket and that they land closer or farther from the carb according to what their OEM was.

The throttle cable housing just snaps into the bracket. Once it is set you pull the cable out and attach it to the pivot point on the carb thrrotle lever. Done. You may still have to set the idle stop but short of swapping in a different mounting bracket there is no way to "tension" the throttle cable and no reason to; it sets itself.

The TV cable is a whole NUTHER kettle of worms. It has to be tensioned correctly. Too little tension and you get late shifts; too tight and they come too soon. Either situation if left unremedied will result in the death of your slush box.

The steps for this are almost worth surfing U-tube and finding a video or scoring a service manual.

As briefly as possible. Slip the TV Cable housing into the bracket and snap it into position. At the end of the housing you will find/feel a plastic sleeve that feels like it has teeth or ridges on it. You will also see a "D" shaped button on the housing. Depress the button, and it might fight back, and with it depressed, push that sleeve all the way into the housing until it can go no further. BE Sure you have it bottomed out. Now pull the cable out of the housing and attach it to the correct pivot, the bottom one, on the carb throttle lever.

To set the tension, With the Engine Turned Off, Rotate the the Throttle lever to completely open the butterflies; You Want Wide Open Throttle, aka WOT. What will happen when you do this, is that the sleeve that you pushed into the housing should come sliding out and should also automatically stop at the correct position giving you the correct adjustment for the TV cable. Put the air cleaner on, do whatever else you need to do to go for a test drive, and go for a test drive.


If it is shifting okay and at the correct rpms or points, STOP. You're finished.

If it still isn't shifting correctly, still too early or late, you need to go back to the driveway and go through the whole setup all over again. (BEEN HERRE AND DONE THIS MORE THAN ONCE) If you still can't get the TV sleeve adjustment to cooperate, then you will have to go in and manually depress that D button and move that plastic sleeve yourself. Start with it fairly close to bottomed out and, using a flat bladed screw driver, GENTLY extend it out of the housing one click at a time. you will feel the click when you release the D button and tug on the sleeve. The button grabs the sleeve and locks it into position.

What you are trying to achieve is just enough tension on the cable that you get smooth shifts on time. To get there you have to sneak up on it meaning that you start with a slack cable and the sleeve completely in the housing and advance the sleeve a couple of clicks at a time, as many times as it takes to get the tension right. That correct amount of tension is totally subjective and it will be the transmission that tells you if you got it right. If you think you are close but.... looking for just that leetle bit more, then it is ONE click at a time. Too many clicks and you end up with brutally hard shifts that come too early and too quickly.


Me? I went through all this last spring and early summer with a 700R4, there may still be pictures somewhere. And yes it is a monumental PITA.

The plug in on the driver's side of the case?? That is for the converter lock up. There is a wiring diagram posted to my Transmission swap thread by another forum member that really helped. You can live without the lockup, you just don't get the rpm drop in fourth on the highway.
 
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CopperNick

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Okay, me again and a followup here.. In the event that I just discussed the wrong transmissions and did all that typing for nada, with respect to the TH350, that cable has no adjustment. You thread it through the bracket, snap the housing into position, and slip the cable end onto the pivot on the throttle lever on the carb. Usually there is a clip needed to secure it. Shifting, like I mentioned, is all about vacuum. So. just me here suggesting that a check of the vacuum line and the modulator might be in order. For the line, a lot of it is rubber so, splits, rot, and internal decay. A rubber hose can look just fine and as soon as you put vacuum on it the inner liner scrunches up like a wadded up paper bag. That line goes all the way to the nipple on the modulator which is exposed to road crap and salt and water and general abuse. Checking the modulator usually means removing it and heading for the bench and a source of vacuum to see if it is responding or not. AT the upstairs connection for the vacuum line, usually a fitting on the manifold behind the carb, again checking for damage.

Last thing to consider is your vacuum output in general. Throw a vacuum gauge on the motor to see if it is generating enough vacuum at idle to keep the transmission happy when being driven.


And a from left field notion, check the fluid level in the transmission, jic.



Nick
 
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PJNJ201

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Feb 9, 2021
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Okay, me again and a followup here.. In the event that I just discussed the wrong transmissions and did all typing for nada, with respect to the TH350, that cable has no adjustment. You thread it through the bracket, snap the housing into position, and slip the cable end onto the pivot on the throttle lever on the carb. Usually there is a clip needed to secure it. Shifting, like I mentioned, is all about vacuum. So. just me here suggesting that a check of the vacuum line and the modulator might be in order. For the line, a lot of it is rubber so, splits, rot, and internal decay. A rubber hose can look just fine and as soon as you put vacuum on it the inner liner scrunches up like a wadded up paper bag. That line goes all the way to the nipple on the modulator which is exposed to road crap and salt and water and general abuse. Checking the modulator usually means removing it and heading for the bench and a source of vacuum to see if it is responding or not. AT the upstairs connection for the vacuum line, usually a fitting on the manifold behind the carb, again checking for damage.

Last thing to consider is your vacuum output in general. Throw a vacuum gauge on the motor to see if it is generating enough vacuum at idle to keep the transmission happy when being driven.


And a from left field notion, check the fluid level in the transmission, jic.



Nick
Good information. Sounds like me and you kind of went through something very similar. Reminds me of the time not too long ago the vacuum line slipped off my modulator while i was driving and i thought i blew my trans 😂
 
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Tynan918

Royal Smart Person
Aug 2, 2021
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Okay, me again and a followup here.. In the event that I just discussed the wrong transmissions and did all typing for nada, with respect to the TH350, that cable has no adjustment. You thread it through the bracket, snap the housing into position, and slip the cable end onto the pivot on the throttle lever on the carb. Usually there is a clip needed to secure it. Shifting, like I mentioned, is all about vacuum. So. just me here suggesting that a check of the vacuum line and the modulator might be in order. For the line, a lot of it is rubber so, splits, rot, and internal decay. A rubber hose can look just fine and as soon as you put vacuum on it the inner liner scrunches up like a wadded up paper bag. That line goes all the way to the nipple on the modulator which is exposed to road crap and salt and water and general abuse. Checking the modulator usually means removing it and heading for the bench and a source of vacuum to see if it is responding or not. AT the upstairs connection for the vacuum line, usually a fitting on the manifold behind the carb, again checking for damage.

Last thing to consider is your vacuum output in general. Throw a vacuum gauge on the motor to see if it is generating enough vacuum at idle to keep the transmission happy when being driven.


And a from left field notion, check the fluid level in the transmission, jic.



Nick
Great information.


with respect to the TH350, that cable has no adjustment. You thread it through the bracket, snap the housing into position, and slip the cable end onto the pivot on the throttle lever on the carb. Usually there is a clip needed to secure it.
 

Tynan918

Royal Smart Person
Aug 2, 2021
1,136
249
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Shifting, like I mentioned, is all about vacuum. So. just me here suggesting that a check of the vacuum line and the modulator might be in order. For the line, a lot of it is rubber so, splits, rot, and internal decay. A rubber hose can look just fine and as soon as you put vacuum on it the inner liner scrunches up like a wadded up paper bag. That line goes all the way to the nipple on the modulator which is exposed to road crap and salt and water and general abuse.
Ok I'll remove the line and check it for any damage.
Checking the modulator usually means removing it and heading for the bench and a source of vacuum to see if it is responding or not.
Yea I replaced the modulator a few months ago because there was transmission fluid dripping from the line at the modulator... I bought an adjustable modulator and turned it all the way clockwise until the screw stopped and been driving it like that... This modulator isn't dripping but like you said, I'll remove it and bench test it...
Last thing to consider is your vacuum output in general. Throw a vacuum gauge on the motor to see if it is generating enough vacuum at idle to keep the transmission happy when being driven.


And a from left field notion, check the fluid level in the transmission, jic
Pan bolts were really loose and leaked out all my fluid over time. I tightened down all the bolts and added 4 quarts of transmission fluid and a bottle of Lucas transmission fix...

As i was finishing up adding the fluid, I heard a gurgle sound and seen transmission fluid leaking from the top of the transmission...the leak is coming from the "vent tube"...only thing is, I don't have an actual tube there, it's just an open hole...

Screenshot_20220402-071518_Photos.jpg
 

Tynan918

Royal Smart Person
Aug 2, 2021
1,136
249
63
Okay, me again and a followup here.. In the event that I just discussed the wrong transmissions and did all typing for nada, with respect to the TH350, that cable has no adjustment. You thread it through the bracket, snap the housing into position, and slip the cable end onto the pivot on the throttle lever on the carb. Usually there is a clip needed to secure it. Shifting, like I mentioned, is all about vacuum. So. just me here suggesting that a check of the vacuum line and the modulator might be in order. For the line, a lot of it is rubber so, splits, rot, and internal decay. A rubber hose can look just fine and as soon as you put vacuum on it the inner liner scrunches up like a wadded up paper bag. That line goes all the way to the nipple on the modulator which is exposed to road crap and salt and water and general abuse. Checking the modulator usually means removing it and heading for the bench and a source of vacuum to see if it is responding or not. AT the upstairs connection for the vacuum line, usually a fitting on the manifold behind the carb, again checking for damage.

Last thing to consider is your vacuum output in general. Throw a vacuum gauge on the motor to see if it is generating enough vacuum at idle to keep the transmission happy when being driven.


And a from left field notion, check the fluid level in the transmission, jic.



Nick

 

CopperNick

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Feb 20, 2018
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You may also want to give some thought to the current setting on that adjustable module. All the way down on the adjusting screw usually translates to either totally closed or totally open in terms of effect on the system. Unless the instructions specifically stated to screw the adjuster in until it bottomed, you might want to revisit that setting and see if backing the screw out a turn or two from bottom gives you a better shift reaction. Just a thought.



Nick
 
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Tynan918

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Aug 2, 2021
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You may also want to give some thought to the current setting on that adjustable module. All the way down on the adjusting screw usually translates to either totally closed or totally open in terms of effect on the system. Unless the instructions specifically stated to screw the adjuster in until it bottomed, you might want to revisit that setting and see if backing the screw out a turn or two from bottom gives you a better shift reaction. Just a thought.



Nick
For sure, the only reason I turned it all the way was because I started from all the way from the left and kept testing as I adjusted it more right...couldn't really see any change, so I kept adjusting it to the right until I couldn't anymore.
 
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