accelerator pedal and kickdown switch; 69 THM400

[Don W.]

I have the 69 THM400 option on my car. At the top of the accelerator pedal arm is what I think is the kickdown switch. My pedal barely makes contact at the full throttle position. Does the switch require a lot movement to properly activate? Is there a way to adjust the contact and what is the correct original position and set-up for this configuration? I may have a bent pedal arm. thank you...Don

[Terry M.]

Re: accelerator pedal and kickdown switch; 69 THM400

I have the 69 THM400 option on my car. At the top of the accelerator pedal arm is what I think is the kickdown switch. My pedal barely makes contact at the full throttle position. Does the switch require a lot movement to properly activate? Is there a way to adjust the contact and what is the correct original position and set-up for this configuration? I may have a bent pedal arm. thank you...Don

Don,

THis switch is self adjusting. See your copy of the Chassis Service Manual for instructions.

I know the switch has to be moved one direction (I just don't know which), and the the accelerator is pressed all the way to the floor, and the switch adjusts.

[Edward J.]

Re: accelerator pedal and kickdown switch; 69 THM400

Don, The THM400 transmission kick down is not like a the THM350 which uses a cable to control throttle pressure and has a wider range for transmission down shift. the THM400 works on internal pressure and has a smaller kick down area, generally after about 35/40 MPH they will not kick down into second. I believe for the adjustment the black plunger on switch is pulled forward and then push the accelerator pedal to floor once. and this sets plunger to correct setting.

[Jeffrey S.]

Re: accelerator pedal and kickdown switch; 69 THM400

Don,
The entire switch assembly is adjustable. The "driver", as it is called in the service manual, is not self adjusting. The switch fastens to the steel bracket by one bolt. Loosen the bolt and the switch can be moved closer or farther away from the accelerator lever. I just went through this since my '69 TH400 lever did not move the switch at all at full throttle. I think mine has a wear problem at the connecting points of the lever/accelerator since it is adjusted as far as it can go and it still is too far away- but that's my problem. I found it necessary to put a small piece of 3/8" ID hose over the driver to "fatten" it up and now it works perfectly. The permanent fix for this is to remove the lever and bend it so it is close to the driver/switch or replace the whole assembly. Attached is a photo of a switch -not from a '69 Corvette- but you can see what is under there. The bracket is different from yours and the switch may also be somewhat different but you get the idea. I would first try loosening the fastening bolt and moving the switch. Hope this helps.
Jeff

[Joe L.]

Re: accelerator pedal and kickdown switch; 69 THM400

Don,
The entire switch assembly is adjustable. The "driver", as it is called in the service manual, is not self adjusting. The switch fastens to the steel bracket by one bolt. Loosen the bolt and the switch can be moved closer or farther away from the accelerator lever. I just went through this since my '69 TH400 lever did not move the switch at all at full throttle. I think mine has a wear problem at the connecting points of the lever/accelerator since it is adjusted as far as it can go and it still is too far away- but that's my problem. I found it necessary to put a small piece of 3/8" ID hose over the driver to "fatten" it up and now it works perfectly. The permanent fix for this is to remove the lever and bend it so it is close to the driver/switch or replace the whole assembly. Attached is a photo of a switch -not from a '69 Corvette- but you can see what is under there. The bracket is different from yours and the switch may also be somewhat different but you get the idea. I would first try loosening the fastening bolt and moving the switch. Hope this helps.
Jeff

Jeff------


The switch pictured does look like it could be a Corvette switch----the 1970-77 variety, GM #1242101.

By the way, you don't want to need one of these switches, especially the 1968-69 variety. The 1968-69 switch, GM #1993424, was discontinued without supercession in December, 1988. I don't know of a replacement. The 1970-77 switch, GM #1242101, was discontinued recently but there should still be some around for awhile.

[Jeffrey S.]

Re: accelerator pedal and kickdown switch; 69 THM400

Joe,
I Googled that part number yesterday and got many available priced from $19.99 up to over $200. The cheap one claims to be a reproduction.
Jeff

[Gary R.]

Re: accelerator pedal and kickdown switch; 69 THM400

That looks like the 75 cowl door switch too, it was mounted in the same position if I recall.

[Joe L.]

Re: accelerator pedal and kickdown switch; 69 THM400

Joe,
I Googled that part number yesterday and got many available priced from $19.99 up to over $200. The cheap one claims to be a reproduction.
Jeff

Jeff------


Which part number are you talking about, the 68-69 or the 70-77?

[Joe L.]

Re: accelerator pedal and kickdown switch; 69 THM400

That looks like the 75 cowl door switch too, it was mounted in the same position if I recall.

Gary------


Yes, the switches were the same-----GM #1242101 for both THM kick-down as well as cowl door.

[Steve L.]

Re: accelerator pedal and kickdown switch; 69 THM400

I'd love to take one of these "adjustable" switches apart to see how they work.

[Jeffrey S.]

Re: accelerator pedal and kickdown switch; 69 THM400

Jeff------


Which part number are you talking about, the 68-69 or the 70-77?

\
I just Googled "Turbo 400 kickdown switch". All responses that came up were for the '70-'77 switch
Jeff

[Joe L.]

Re: accelerator pedal and kickdown switch; 69 THM400

\
I just Googled "Turbo 400 kickdown switch". All responses that came up were for the '70-'77 switch
Jeff

Jeff------


OK, as I mentioned previously, the 70-77 switch, although GM-discontinued, should still be around.

[Jim T.]

Re: accelerator pedal and kickdown switch; 69 THM400

Don my 1970's kick down switch has always worked but it is very rare for me to use it. It will kick down to first and second gear depending on my 70's speed. Reason I don't use the kick down is that I can control what I want to do by just selecting second gear or first gear without going to the floor with the pedal. I am using a Holley double pumper on my 70 and control what I want the engine to do with my full and complete control of the Holley. Most use of going to second does not require flooring the gas pedal.