turbo 400 kickdown switch

[dooguy]

anyone have some info on how to adjust this switch on a 72 gas pedal mount

[kwmech]

The mount has different holes in it for the switch. Finer adjustment in the past I have put a piece of hose around the tip that sticks out

[dooguy]

Originally Posted by kwmech

The mount has different holes in it for the switch. Finer adjustment in the past I have put a piece of hose around the tip that sticks out

i am not seeing any adjustment in the mount. switch can only fit in one position. I have seen different posts that say you need to reset switch and then depress accelerator to self position, but i have had no luck trying the suggested reset methods.

I'm thinking like you said putting something over tab that sticks out

[LockDoc]

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Here is the one I have. I see no adjustment in the bracket or switch. There are three holes in the bracket, two of them are for locator tabs on the switch and one is for the screw.

The instructions for adjustment you are reading are for the TH350 kickdown CABLE. I don't know if any of the 400's use that system or not. That adjustment will not work for the electric switch.

[71CHEVYSHORTBED402]

Originally Posted by kwmech

The mount has different holes in it for the switch. Finer adjustment in the past I have put a piece of hose around the tip that sticks out

Interesting, I found my original one like this. It's a plastic wrap of sorts. Next to that is a new one.

[LockDoc]

Originally Posted by dooguy

anyone have some info on how to adjust this switch on a 72 gas pedal mount

I will look at the one I have in the morning and take a couple of pictures of it to see if there is anything different on it.
.

[Accelo]

The switch is self-adjusting.

There is a locking tab on the switch which can be moved by finger pressure-- it's on the rectangular beige plastic part right against the steel. Just a silly little spring tab. Start with the pedal in the idle position. The switch won't be contacting the metal of the gas pedal assembly. Push in the tab on the switch, and "force" the movable part toward the pedal--you'll hear the ratchet/clicking noise. Then allow the switch to come back to it's normal position, so that spring tab pops out again. THEN move the throttle to wide ope, this sets the adjustment. There should be no need for rubber tubing on the gas pedal if the switch is adjusted properly.


I was designed so it could be installed at the factory and the first time the vehicle was floored it was set/adjusted.
Cheers

[LockDoc]

Originally Posted by Accelo

The switch is self-adjusting.

There is a locking tab on the switch which can be moved by finger pressure-- it's on the rectangular beige plastic part right against the steel. Just a silly little spring tab. Start with the pedal in the idle position. The switch won't be contacting the metal of the gas pedal assembly. Push in the tab on the switch, and "force" the movable part toward the pedal--you'll hear the ratchet/clicking noise. Then allow the switch to come back to it's normal position, so that spring tab pops out again. THEN move the throttle to wide ope, this sets the adjustment. There should be no need for rubber tubing on the gas pedal if the switch is adjusted properly.


I was designed so it could be installed at the factory and the first time the vehicle was floored it was set/adjusted.
Cheers

I will check mine and take a picture when I go back out. (after lunch)

I didn't know about that. Thanks.
.

[dooguy]

Originally Posted by Accelo

The switch is self-adjusting.

There is a locking tab on the switch which can be moved by finger pressure-- it's on the rectangular beige plastic part right against the steel. Just a silly little spring tab. Start with the pedal in the idle position. The switch won't be contacting the metal of the gas pedal assembly. Push in the tab on the switch, and "force" the movable part toward the pedal--you'll hear the ratchet/clicking noise. Then allow the switch to come back to it's normal position, so that spring tab pops out again. THEN move the throttle to wide ope, this sets the adjustment. There should be no need for rubber tubing on the gas pedal if the switch is adjusted properly.


I was designed so it could be installed at the factory and the first time the vehicle was floored it was set/adjusted.
Cheers

i will pull my off again and see if I can figure it out
Thanks

[LockDoc]

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The only thing I can see are these tabs. Is that what you are referring to?
.

[dooguy]

I have same switch as lockdoc. I'm having no luck pushing the tabs lockdoc is pointing and pushing moveable part of switch. I must be missing something or maybe switch bad?

[LockDoc]

Originally Posted by dooguy

I have same switch as lockdoc. I'm having no luck pushing the tabs lockdoc is pointing and pushing moveable part of switch. I must be missing something or maybe switch bad?

I didn't try pushing on mine. I can do that in the morning. Maybe it has something to do with the 2 black slots on the side, I don't know.
.

[71CHEVYSHORTBED402]

Curious too. My 402 has the electric switch like above or close, with plastic lever. I'd be happy to see it more sensitive. Its due the 500 mile check up the rebuilt 400th, and I'll ask

[pjmoreland]

The photos above show the post that the pedal arm hits sitting approximately in the middle of the slot. What happens if you forcibly push on the post in the direction of the pedal arm? Will it scoot and stay?

[kwmech]

nope, just pushes back and forth--- spring loaded. I think somebody is pranking us. Been working on these trucks for 50 years along with automatic transmissions and never heard anything about this

[pjmoreland]

I knew I had one of these switches, but it took me forever to find it. It was in the first box I checked, but it was hiding under something so I missed it the first time.

If you push it forcibly in the direction opposite the spring, it pops out. Then, if you push the gas pedal to the floor, the pedal rod will set the switch to the correct position. I can hear and feel something ratcheting inside the switch when I reset it by hand.

[pjmoreland]

I created a video that shows the adjustment procedure:

TH400 Kickdown Switch Adjustment Video

[71CHEVYSHORTBED402]

Originally Posted by pjmoreland

I created a video that shows the adjustment procedure:

TH400 Kickdown Switch Adjustment Video

How cool is that? Thanks for the demo. Unless I'm missing something, seems that's how it's set; adjustment is perhaps a misleading term. That is, I don't know, unless a guy can force the spot a pinch, I'd have to look unless someone already has that answer. It's not in front of me, access to my truck a PIA, but at least it's shielded well.

I can say mine can use a boost, and why some tape or something is an easy fix, described above. I'm going to pull my old switch, grab the vintage plastic piece adding depth to trigger faster.


If memory serves me right, the switch installs one way. Edit, perhaps not, after looking at some notes, "The switch bracket’s tabs insert into the accelerator bracket’s RH holes." That may be for simple positioning, now I really should look.

Edit 2, my notes were off kilter. Should read, "The switch’s tabs insert into its bracket’s holes from the RH side.".................... More importantly, my switch, bracket and accelerator assm. say they install one way.

Edit 3 I put one sleeve of quality electrical tape around the lever, followed by a sleeve of shrink wrap. No I didn't shrink it. I won't swear to a difference, but can say it kicked down as I expected it to, satisfied. Darn it, I threw the plastic spring wrap from my old switch away. Why, why, why? I suspect that's OE, but I know it's vintage. Not the first I chucked a part that's at or near impossible to replace.

I believe the switch part numbers are #1242101 and #7506100. The former leads to all kinds of passenger vehicles; but as trucks go, only 71-72 with 400TH.

Here's one installed.

Great education on a 71-72 400TH switch, thank you. Once again I see another reason to LOVE vintage. Vacuum and simple mechanical. I remain blown away by the cold start system, very cool stuff. I need to learn how to check/adjust a divorce choke though, that's becoming a lost "art", though it's probably so easy once done, like the rest on these trucks. Lost my buddy who set it for me. He set me up with the parts, and rebuilt the carb too. I learned of his passing the day I had to put my shepherd down, "can't wait to see Dana for my 500 mile check", "no you won't". He really liked my truck, and I loved him, we go WAY back to when I was a boy. I was looking forward to he seeing what we finished. Chalk that up near the top for least favorite days.

[dooguy]

thanks for the video. My existing switch would not adjust like that. I have another on order, hope it behaves like your post
Thanks

[dooguy]

Received new switch today. Still doesn’t adjust as shown in video

[pjmoreland]

Originally Posted by dooguy

Received new switch today. Still doesn’t adjust as shown in video

Send me a PM with your address, and I'll send you mine. I don't need it.