TC lockup switch?

Penni

Penni

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Oct 5, 2010
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Can anybody tell me how/when to use this? When i bought the truck it came with it and when i bought the truck i didnt know anything about diesels and now after some mods im considering getting into some pulls every now and again. This truck was a pulling truck before so i know it should be able to handle it. My question isnt how to use the TC switch in daily driving, but how to use when hooking to a sled and pre-spooling the turbo ext... Any opinions will be appreciated!
 
im pretty sure the tranny wont go into lock up in 1st or 2nd gear with a stock vb, you can put it lock up early in 1st or 2nd but it will just take you right to 3rd and lock up so i dont think you could really use it for any pre spooling
 
With a stock 47re or 47rh valvebody, which you have, the torque converter will lock in 2nd, 3rd, and 4th/OD if you have a lock-up switch installed and flipped to the on position. You can flip the switch on before the sled pull starts and transmission will operate normally in 1st gear. As soon as it makes the shift to 2nd, it will lock-up. If you don't rev out 1st gear enough, it could cause the motor to bog down.

For example, when my Drag truck was mostly stock, I made a few passes with a lock up switch. I would flip the switch on before the race started. I would stage, launch, and run through 1st gear normally, as soon as it shifted to second, there was a ton of RPM drop and it would bog the motor and actually cause me to run slower. The reason why is I put the gear selector in D so it let the valvebody decide when to shift. I would shift from 1st to 2nd around 2500 rpm. This put the motor below 2000 rpm in 2nd gear. Now if the torque converter is unlocked, then the engine is allowed to rev a little higher since it's not directly connected to the transmission, rather its in fluid coupling. When a lock-up switch is turned on, it directly connects the transmission to the engine just like a clutch.

Once my Drag truck had about 280 HP, it had enough power that it wouldn't bog if I used the lock-up switch and times dramatically improved with it's use since fluid coupling does not transfer all available HP to the wheels. Another solution if you're limited on power is to manually shift the transmission. Keep the gear selector in L till you have about 3000 rpm, then 2nd gear lock-up will be at a good torquey RPM 2200 or so and won't bog.

A third solution is to not hit the lock-up switch till you're halfway through second gear.


In short, your HP, turbo, gearing, tires, track conditions, etc, etc, weather conditions, etc, etc, will all determine when is the best time to lock-up and in which gear or gears.

Just know this, when you turn on the switch and you're in 2nd gear or higher, it will lock up just like a manual transmission with a clutch.
 
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sounds like something that you need to play with a little cause of all the variable involved. try different things. or just put a manual in it and say screw that automatic
 
Put a gsk kit on that truck and you can rev higher and it should help with locking earlier
 
When i drag race i leave my gear selector in 2. I will spool up and launch in first gear. once it hits second gear on its own i will lock it up in second between 2100 and 2300 rpms but you have to hit it just right or it wont work like it should. After its locked i move the gear selector into D and it wont shift right when you throw it into D, well at least in my truck it wont let it shift until 3500 rpms but after that i just let the tranny do its own thing.
 
Watch out and make sure you look for any orange/black wires. My 98 12 valve has 2 orange and black wires on the same plug. 1 was TC solenoid and the other was like pin 20 wait to start light.
 
so i have tried to lock mine up in manual second and it will only lock in "d", do you have to have the upgraded vb to lock it in the manual 1st and 2nd gears?
 
Yes the vb has to be set up to lock the converter in manual second.
 
I'm going to test this manual 2nd lock-up theory tonight at the track but I swear my 95' Junker will lock the converter in 2nd gear regardless of gear selector position (D vs 2).
 
D Twigg, you were right. I tested out my lock-up switch several times and it does not lock the converter with the gear selector is in (2). With the gear selector in (D) the torque converter will lock with a lock-up switch in 2nd, 3rd, and OD.
 
I remember talkin to someone and they said that you can have the valve body set up to lock the converter in manual 2. I had asked for my new valve body to be set up so when it is in manual 2 I can lock it in. When I finally get my truck back and my new trans working properly I'm going to experiment and see how it does when pulling and racing.
 
my 96 12v will lock the converter in 1st. With the ats race VB i can flip the switch and stall the truck while stopped or in 1st.
 
How do you run the jumper wire on a 95' 12 valve? Theirs no relay. I installed one on my 02 bit my buddy wanted a lockup as well and I couldn't figure out exactly what was doin wrong. The truck is runnin a suncoast tranny
 
their is a different program in the ECM for 47rh to the 47re & 48re
 
Gasoline Sucks said:
my 96 12v will lock the converter in 1st. With the ats race VB i can flip the switch and stall the truck while stopped or in 1st.
Click to expand...

be careful, saw a guy break a billet input and trash his converter because he forgot to unlock his.
 
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