spooldup
Super Member
I was sent this email from someone i bumped into along the way. It is a very good article and it taught me allot. Hope it helps you guys as much as it has helped me.
Here part 1,
Sure.. The TC (torque converter) lockup switch is just what is says. Its a switch you install to manually lock the clutch in the torque converter. I dunno how familiar you are with automatic transmissions/torque converters so I'll keep this simple.
The torque converter transmits the engine power to the drive line via fluid coupling. This is what allows an automatic transmission to operate but not require the engaging/dissengaging of a clutch by the driver as you would in a stick shift. Unfortunately some of the engines power is wasted in the "slippage" or inefficiency of this fluid coupling. Its the price you pay for the ease of operation of an automatic transmission.
A sy/ty transmission (as well as all factory 700R4's) are equipped with a torque converter that actually has a clutch built into it just like a stick shift would have. Once the vehicle is moving at a predetermined speed the computer commands this clutch to engage. This physically couples the eng and drive line togeather and you no longer have any "slippage" in the fluid coupling to soak up eng power. You get 100% of the engines power transmitted to the driveline.
Thats fine for someone who just enjoys driving but for someone like me (along with a LOT of other ppl) I want to go faster in a drag race. I installed a switch (any single pole single throw switch will do) to lock the clutch in the TC when I want to. In a sy/ty its very simple to do. All you need to do is connect a wire on one side of this single pole single throw (abbreviated SPST) switch to the Tan/Black wire (labelled "F" on the ALDL connector) on the ALDL connector under the dash. The other terminal on the switch needs to be connected to chassis ground.
This switch when activated over rides the computer (doesnt harm the computer BTW) and locks the TC when the you WANT it to not when the computer wants to.
Here's part 2,
on to TC clutch (TCC) stuff.
Once the TCC switch is activated the TCC will only engage once the transmission has shifted out of 1st gear. It will not lock in 1st gear but it is now "armed" and will lock the instant the transmission shifts into 2nd gear. If it did lock in 1st gear then when you came to a stop the eng would die just like you came to a stop in a stick shift but didnt/forgot to disengage the clutch. I think everyone that has driven a stick shift has done that by accident before at one time or another.
Anyway, with the TCC switch "armed" once the trans has shifted into second the TCC locks immediately and never releases until you disarm the switch or you apply the brakes. The TCC signal is interuped through the brake light switch on a syty BTW. That is a factory installed safety feature..
So, basically what a TCC switch does is eliminate the "slippage" of the TC once the vehicle is moving and it no longer needs the torque multiplication of the TC. The TC actually becomes a performance hinderance once the vehicle speed has climbed and the eng is now operating in its peak RPM range. You have 100% of the engines power being transferred to the drive train since the fluid coupling is not "wasting" any of it.
On the pros and cons...
Pros.
1. Most often will make an auto trans equipped vehicle a little faster/quicker in a drag race.
2. Lowers the trans fluid temp slightly during a run vs not having the TCC locked.
3. Produces BIG smiles when you outrun the fellow in the next lane....
Cons.
1. prematurely wears out the internal clutch in the torque converter (if you manually lock it a lot at full throttle as you would when racing).
2. The clutches in the transmission will wear quicker also due to the TC not "absorbing" any of the engines power. Similar to "power shifting" a manual trans.
3. The gear changes are more violent thus transmitting this mechanical "shock" to the rest of the drive train.
4. If there is a worn/weak component if the drive train somewhere it will fail eventually and probably sooner than if you didnt lock the TCC.
Thats about all I can think of right now. I use one due to having a aftermarket higher stall converter (more slippage) and it actually dropped 3 tenths of a second off my times and I gained 2mph just by locking the TCC.
Here part 1,
Sure.. The TC (torque converter) lockup switch is just what is says. Its a switch you install to manually lock the clutch in the torque converter. I dunno how familiar you are with automatic transmissions/torque converters so I'll keep this simple.
The torque converter transmits the engine power to the drive line via fluid coupling. This is what allows an automatic transmission to operate but not require the engaging/dissengaging of a clutch by the driver as you would in a stick shift. Unfortunately some of the engines power is wasted in the "slippage" or inefficiency of this fluid coupling. Its the price you pay for the ease of operation of an automatic transmission.
A sy/ty transmission (as well as all factory 700R4's) are equipped with a torque converter that actually has a clutch built into it just like a stick shift would have. Once the vehicle is moving at a predetermined speed the computer commands this clutch to engage. This physically couples the eng and drive line togeather and you no longer have any "slippage" in the fluid coupling to soak up eng power. You get 100% of the engines power transmitted to the driveline.
Thats fine for someone who just enjoys driving but for someone like me (along with a LOT of other ppl) I want to go faster in a drag race. I installed a switch (any single pole single throw switch will do) to lock the clutch in the TC when I want to. In a sy/ty its very simple to do. All you need to do is connect a wire on one side of this single pole single throw (abbreviated SPST) switch to the Tan/Black wire (labelled "F" on the ALDL connector) on the ALDL connector under the dash. The other terminal on the switch needs to be connected to chassis ground.
This switch when activated over rides the computer (doesnt harm the computer BTW) and locks the TC when the you WANT it to not when the computer wants to.
Here's part 2,
on to TC clutch (TCC) stuff.
Once the TCC switch is activated the TCC will only engage once the transmission has shifted out of 1st gear. It will not lock in 1st gear but it is now "armed" and will lock the instant the transmission shifts into 2nd gear. If it did lock in 1st gear then when you came to a stop the eng would die just like you came to a stop in a stick shift but didnt/forgot to disengage the clutch. I think everyone that has driven a stick shift has done that by accident before at one time or another.
Anyway, with the TCC switch "armed" once the trans has shifted into second the TCC locks immediately and never releases until you disarm the switch or you apply the brakes. The TCC signal is interuped through the brake light switch on a syty BTW. That is a factory installed safety feature..
So, basically what a TCC switch does is eliminate the "slippage" of the TC once the vehicle is moving and it no longer needs the torque multiplication of the TC. The TC actually becomes a performance hinderance once the vehicle speed has climbed and the eng is now operating in its peak RPM range. You have 100% of the engines power being transferred to the drive train since the fluid coupling is not "wasting" any of it.
On the pros and cons...
Pros.
1. Most often will make an auto trans equipped vehicle a little faster/quicker in a drag race.
2. Lowers the trans fluid temp slightly during a run vs not having the TCC locked.
3. Produces BIG smiles when you outrun the fellow in the next lane....
Cons.
1. prematurely wears out the internal clutch in the torque converter (if you manually lock it a lot at full throttle as you would when racing).
2. The clutches in the transmission will wear quicker also due to the TC not "absorbing" any of the engines power. Similar to "power shifting" a manual trans.
3. The gear changes are more violent thus transmitting this mechanical "shock" to the rest of the drive train.
4. If there is a worn/weak component if the drive train somewhere it will fail eventually and probably sooner than if you didnt lock the TCC.
Thats about all I can think of right now. I use one due to having a aftermarket higher stall converter (more slippage) and it actually dropped 3 tenths of a second off my times and I gained 2mph just by locking the TCC.