TH700 tcc on 1st

[4x4_76]

So, I was going to go with manual, but now that I want NV4500 and can't afford it right now, I keep the automatic.

There was an article on Petersens mag, where they installed custom built 700 behind the 6.2 diesel. If I remember correctly, 700 had ability to lock torque convertor clutch on first gear. I do have that magazine, but can't find it, I tried their web site too, but didn't find it from there, either.

Is that lockup feature useable, and does it kill the juicebox in a long run?

 

[dyeager535]

Bad idea. Torque converter clutch is not designed to hold under power, that's why they unlock so easily. The actual gears in a transmission use multiple clutch disks, the converter clutch is one.

Not to mention how much a PITA it would be to have to figure out a way to unlock it when coming to a stop.

 

[JPMSK5]

Hey hoss go to tciauto.com and look up the directions for lockup torque converter wiring. To unlock during braking a Bosch relay is used on the power side, brake lights and no power to lock up, simple, the ground side is controlled by a pressure on the OD and a vac switch which is adjustable, and then a third wire another ground to manual lock the converter, for like 1st-3rd gear, mine is wired up that way and works really good, I need more gears to make the OD work correctly. But thats my fault not the wiring or torque converter. I pulled 12000lbs last Saturday and used the converter as more gears, like a 6 speed, manual shift and lock, unlock and shift then lock again, worked great and never got the trans over 190degs.

 

[4x4_76]

Yeah, lockup control is a piece of cake with relay.

 

[bigblock72]

The TCC will only lock in second, third and fourth. You have to do internal modifications to get the hydraulics to work in first and reverse. The other problem is there isn't much line pressure at idle and the converter clutch will likely slip and self destruct in short order. With a constant pressure valve body it could be made to work but it's a bit of a can of worms. The clutch will hold the power if there is sufficient line pressure, I run mine in lock-up at WOT quite often with zero issues.