WTHIRTY1

Is the cable from the pedal, that runs through the frame, the same size for the TH350 and TH400? I have a '70 Supreme that I know has the wrong kit installed and hoping that initial cable from the pedal is the same because I don't want to have to reroute a new one.

joe_padavano

The front and intermediate cables are both different. Moving the crossmember for the different transmission length changes both.

WTHIRTY1

Damn, I was hoping at least the front cable would be the same with maybe a different hook and intermediate cable.

joe_padavano

The threaded part of the front cable has to extend a given distance behind the crossmember. If the crossmember moves rearward, it requires a longer front cable to achieve the same extended distance. Front cable is 49.5" for TH400 and 44.5" for all other transmissions. Center cable for a 68-72 2dr is 82.5" for TH400, 95.75" for all other transmissions.

WTHIRTY1

The threaded part of the reproduction cables appears to be longer than the factory cable.

matt69olds

Many years ago when I was a poor broke teenager (other than age, not much has changed!!) I put a TH400 in my car to replace the junk 350. I was able to use an extra cable guide to add an additional pivot point and take up the extra 2 inches of slack.

While technically not correct, it did work for years.

joe_padavano

The TH350 front cable is 5" too short for a TH400. Where's the extra slack? The intermediate cable is easy to change. And let's be honest here. GM never spends a dime it doesn't need to - they'll make one design work in as many situations as possible to cut inventory.

matt69olds

I have slept ALOT since I put the 400 in. I might be fuzzy on the details. I do remember spending lots of time on each cable trying to free them up. For all I remember, I might have used an intermediate cable from another car to replace a damage cable on mine.

Now that I’m thinking about it, I’m wondering if I used a cable from a 4 door car, or a El Camino? Something with a slightly longer wheelbase than 2 door 68-72 A body. At the time, I did have anccess to a couple 4 door A body’s.

All I am certain about is how impressed I was with getting the cables freed up and the parking brake working, and my ingenuity with the extra cable guide. I’m betting the last time the parking brake was functional was during the Carter administration.

As I mentioned, it wasn’t correct or the best way to do it, but it did work.

joe_padavano

Just be aware that "worked" doesn't mean that it will work under all stressing conditions (like the primary brakes go out and you need the e-brake to stop the car). Normally the e-brake doesn't get a lot of use with an automatic. Automakers ensure that stuff like this works under worst-case conditions, with brake shoes worn and drums and the max ID tolerance. People frequently loose sight of the need to verify operations under all worst-case conditions.