I recently purchased a `72 El Camino that was originally an L48/TH350 car but now has a 402 and TH400. Tranny works great but does not kick down at WOT. I don't know diddly about autos and need some help. As I undertand it, the TH400 uses a kick-down switch at the gas pedal and I guess I need that switch. Where can I get one and how do I hook it up?

I have the same problem. Have not done anything about it yet. BUT, the stock switch connects to a special bracket at the gas pedal area. And had wires going to the trans and to 12 volt. There are a few companies that make an after market type that will connect at the carb linkage. B&M is one that has it I think for about $50 with instructions how to connect. If you look in the Summit racing cat. or Jegs you'll see it. The stock one you'll never find the bracket that goes to the pedal unless you get lucky in a Junk Yard, I think other models of GM with 400 t had them too, like Olds, Pontiac

Pick up a copy of Haynes Techbook-Automatic transmission overhaul. You will find the answer to the "kickdown switch" and also where the unit fits.

Thanks Rich! I appreciate the reply. I saw the B&M item but it looks like it connects from the TH350 throttle linkage kickdown. My car doesn't seem to have that. Knowing that the TH400 has been used in a lot of non-stock applications (like replacing 4spds and other apps) I was hoping to find something that worked without scrounging the wrecking yards. So far, the best advice I've gotten has been the wrecking yard thing though.

Thanks Rich! I appreciate the reply. I saw the B&M item but it looks like it connects from the TH350 throttle linkage kickdown. My car doesn't seem to have that.

Exactly, same with me. I did buy a switch from OPG which is simular to stock but no bracket. Some guys have said you can make one to fit on the gas pedal bracket. The factory assy. manual shows what it looks like. Have not got there yet, as far as making a bracket. Just been doing some fancy down shifting with the shifter.
But still I think the B&M switch can be made to work. When you figure it out let me know.

Lokar makes a kickdown switch assembley that hooks up to to the carb linkage. I replaced my throttle cable and throttle bracket with the Lokar setup and it works and looks sweet. You should be able to get the kickdown to work with the stock throttle braket. It was simple to hookup and works just as well.
Steve

Like Steve said Lokar is another one, its simular to the working of B&M, connects at the carb linkage. Held it in my hand a few times but never bought it. Has a billet look to it. About $50

You can get the switch and bracket from Ground Up. TH400 kickdown switch part# ATE-2101. Throttle switch bracket part# ACC-8555

place an ad in parts wanted for pedal assembly and you will be surprised how many responses you can get,i did and bought one complete in vgc for 35.00 shipped from texas!

You can get the switch and bracket from Ground Up. TH400 kickdown switch part# ATE-2101. Throttle switch bracket part# ACC-8555

That's what I did. However, I haven't had a need to "kickdown". Makes plenty of power in third. ;)

I always manually drop it into 2nd on my 70 for passing gear :D.

TH400's usually can kick into 2nd gear without a kickdown switch..something to do with the modulator.
Mines been that way for 4 years :D