Locking the Torque Converter

I have made the change of hooking up a switch to the wire that controls the transmission computer's ability to shift. So that I can lock the transmission in first gear when descending hills, etc. I think(?) the same can be done to control the lockup of the torque converter.

This would allow me to directly lock the transmission to the engine and descend even slower.

First of all, is this even a good idea? Will doing this screw up the transmission or torque converter or would my engine not run with the torque converter locked up at such low speeds/rpms? Will this cause the torque converter to build up excessive heat?

If this isn't such a bad idea, does anyone know which wire(s) to hook the switch to?

The descents in Moab left me wanting lower transfer case gears and I was wondering if this would get me part of the way there until that actually becomes a reality. Locking the transmission into first gear helps a lot, but it would still be nice to be a little more controlled coming down steep hills. My brakes would probably appreciate it too.

Thanks,
William Crawley

I'm looking closely at this mod too as I would like it on the Rubicon/Fordyce etc around Northern California. So you are asking this question after you already did the mod? I know if has done many times before. I think you should be fine, especially if you put in a diode to control unwanted electric spikes going in the wrong direction.
Troy

sounds interesting how do you do it

I have hooked up a switch to lock the transmission in gear, not the torque converter. I am wondering if forcing the torque converter to lock is a good idea and if it will accomplish what I want.

Thanks,
William Crawley

reson46 said:

I have hooked up a switch to lock the transmission in gear, not the torque converter. I am wondering if forcing the torque converter to lock is a good idea and if it will accomplish what I want.

Thanks,
William Crawley

Click to expand...

Yes

i have my AW4 fully manually shifted, with manual lock on the TC. I do not use it on the trail, only on the highway. I'm not totally sure if it would hurt anything, but I know that the factory design only locks the torque convertor in 3rd or 4th gear with light/medium pedal pressure. This leads me to believe that it is not good to put large amounts of torque through it locked.

i don't know this for sure, but with 35s, 4.88s, AW-4 and 1/2 ton brakes it's plenty of braking on even the steepest of the steep. you do realize that you need the shifter in the 1-2 position to get good compression braking right?

Yes, it is in the 1-2 position. With 32s, 4.10 gears, and the AW4, it still feels like I am racing down hills.

William Crawley

the lock up works well for decending down hills. IMO it will not hurt the torque converter. If it was hurting it you would be burning the friction matrial in it and you would get a burned smelling transmission fluid.

Which transmission computer wire controls the torque converter lockup?

Thanks,
William Crawley

I have done both the 1-2 gear manual shift control and the converter lock up mod. Both work very well after about 25k miles. I was able to use the info from http://www.go.jeep-xj.info/ to wire it all up. I put my illuminated switches on the console panel next to the shifter.

The 1-2 mod to control which gear you are in is by far the best option I have done. It is very helpful when off-roading to help get the rpm's correct for the conditions. The lock up mod to control the torque converter clutch is really helpful when going downhill and helps prevent "riding" the brakes. Works just like a manual transmission.

I have noticed my converter is not locking at freeway speed in od. And the water temp does increase while on the freeway. RPM's are about 300 more. 3.55 gear, 31 tire. I can use my manual switch however to lock the converter. Temp goes back down and RPM's go back top normal. I will be checking the switch on the brake pedal today to see if it needs attention.

Scott

you wont heat up the trans fluid actually, itll get cooler. the heat is generated from the friction of the impellers of the torque converter moving thru the fluid. that being said, i would be very cautious about locking the torque converter in first, and second, even for just descents. the friction material is only a very then strip in the converter designs for very light torque loads (cruising in 3rd or 4th) and i think just descents even would have a significant reduction in its life span.

Talk about dredging up an old thread. I've been locking the torque converter for years and locking it in first gear on decents. No problems so far.