Th400 orange wire

[benn95]

There is one orange wire connected to the side of my th400 transmission where does it go

 

[idahovette]

Should be for the kick down(passing gear). Goes to a switch either on the carb or inside on the firewall at the throttle linkage

 

[benn95]

Like what kind of switch ? I know it goes thru the firewall and is it absolutely necessary

 

[Ricko1966]

It makes it down shift when you stand on the gas. You need a switch that closes when you mash the throttle. If you don't mind manually shifting down to accelerate no you don't need it. I used a nitrous button on the shifter when I was 16 in one of my creations. I'd mash the gas hit the button it would down shift and take off I told people that didn't know me I had nitrous. Actually it was just the simplest way my 16 year old brain could rig a convienent switch. Now I'd use a vacuum switch that closes at a vacuum reading I'd determine using a vacuum gauge to see what vacuum zi had when I wanted a downshift.

 

[benn95]

Ok so there is a switch that is on the gas pedal mount where when you push the gas all the way down it hits that switch that must be the one your talking about it's kinda like the brake switch but for the throttle?

 

[Radiohead]

Yup

 

[DoubleDingo]

Ok so there is a switch that is on the gas pedal mount where when you push the gas all the way down it hits that switch that must be the one your talking about it's kinda like the brake switch but for the throttle?

Yep. And if you're already doing highway speeds it most likely won't kickdown. At least my truck doesn't. It'll kick down below 55mph, but it won't 55 and higher. That's fine by me, with 4.10s you're already getting higher in the rpm range at 55, so the secondaries are enough to get moving faster. It's fun getting around cars quickly at slower speeds though.

 

[Matt69olds]

The trans will tend to “short shift” at WOT without it. Meaning if you stand on it at low speeds, the trans will automatically upshift far earlier than you would want it to. Besides this inconvenience and the no kickdown, that’s the only disadvantage.

 

[DonL]

Like what kind of switch ? I know it goes thru the firewall and is it absolutely necessary

I’m using a Lokar cable-operated switch on mine

Expensive but very well designed and made.
Check out this page from Summit Racing https://www.summitracing.com/parts/lok-kd2400ht