TC lock up (mystery) switch ?'s

[MxerChris]

Almost time to pull the camper to Bristol again for the races, and was thinking of installing a lock up switch, but I have some questions on how to use it. First say I'm happily towing along and I come to a long hill and towards the top my RPM's start getting to low (below 1700) do I (A) flip the switch that unlocks the TC but leave it in OD (B)flip the OD off and the TC switch to unlock. I guess what I'm trying to figure out is how the TC switch is utilized so if I install one I will be properly using it. From south of Birmingham where I live, to Bristol there alot of hills just dont want to toast what seems to be a good transmission. Thanks, Chris... ... .

 

[Dennis Garrett]

Myself, I've used a 3 position (center off) switch mounted an inch below the turn signal lever, since right after I got the truck. I drive by the switch 99% of the time. I start moving in "Off". When I'm ready for lockup, and conditions are right, I move the switch forward, and it locks up, usually somewhere above 45-50mph in OD. It stays locked up, even when coasting, or when I tap the brake to turn off the cruise. When decelerating, I keep it locked down to about 1000 rpm, to take advantage of the engine braking. When moving around slowly in traffic, I use it the same way, only turn off OD if speeds are in the 40's or lower. It works the same way in "D". . When the wife wants to use the truck, I tell her to put the switch to the rear most position, which is the same as stock, lockup occurs automatically. I can baby my transmission with this setup, and have 150k on it now with no problems so far. Just remember to unlock at 1000 rpm when stopping, or it will want to kill the engine, just like forgetting to push in the clutch with a manual trans. I use an "On-off-On" switch, one with a long black handle from Radio Shack. Run the TC wire through the center & one end, and ground the other end. If the switch positions seem backwards, don't rewire it, just rotate the switch 180 deg. in the hole & retighten.

 

[MxerChris]

so basically with a 3 position switch I can leave it basically as stock when I want too, then when I'm towing I can prevent lock up too early, then when I get to a long hill when the RPM's get to low I can unlock the TC continue pulling the hill then relock after cresting the hill, does this sound correct or does turning off the OD come in to play? Thanks... ... ... .

 

[Joe G.]

I have a similar switch set up to the one Dennis has. My switch is mounted in a switch panel I made to replace the stock cup spiller.



I use a floor mounted push button to make unlocking and relocking more convenient. This button is wired in series in the ground wire to the switch. If the TCC is unlocked let the OD take care of itself unless it starts to "hunt". That is, shift in and out of OD. In that case turn off OD.



If you put the switch in the lock position it may NOT lock. The reason for this is that you have to have pressure to cause a lock even if the solenoid is in the locked condition. This is important because it WILL NOT lock when coasting. You have to pulling a little to cause the lockup. So lock up BEFORE starting down a hill or you will have to excellerate a bit going down to cause the lock to happen. This can get exciting if the hill is steep and crooked.