Tech thread: TCC Toggle Switch

[andym]

.......which means that a 1:1 ratio can't be achieved and thus allowing for higher RPMs at higher speeds - right?

Yes.

......

 

[Skandocious]

It's like a manual transmission in that the drivetrain is locked together and there is no slipping as you'd find in a conventional torque converter.

With the switch in the off position, the circuit is broken and cannot be completed. The computer cannot ground the wire because it's open.

With the switch in the up position, the computer will control the lockup just as if the switch wasn't there. All the switch does is close the circuit that you opened by cutting the purple/yellow wire.

Down, the circuit is grounded. The torque converter locks up and the computer is powerless to unlock it. Even when the computer tries to open the circuit to send the unlock signal, the circuit is still grounded and the converter stays locked.

Andy nailed it, thats how it works.

And eco, correction: It doesn't lock a 1:1 ratio from crank to rear driveshaft. It locks a 1:1 ratio from the crank to the input on the transmission. The gear reduction in the transmission still works the same and outputs different ratios at the tailshaft.

 

[Skandocious]

The torque converter likes to lock too early, robbing power. I think that's the biggest benefit.

It will also help me when driving through the mountains to be able to unlock it when going up a hill. It has trouble keeping up long grades at high elevations (5000 - 8000 ft) - so much so that I usually turn overdrive off to prevent gear hunting. Hopefully this mod will give me more options rather than downshifting to 3000 RPMs at 70 mph. It sucks enough gas as it is.

Absolutely.

Also -- slipping tc = hotter fluid. If you're towing at lower speeds and the TC is slipping a lot (not locked), then you can lock it to keep your fluid temp down.

 

[F 150Cobra]

but does it change gears? or when its locked its only got 1 gear and 1;1 ratio?

 

[Skandocious]

but does it change gears? or when its locked its only got 1 gear and 1;1 ratio?

Yes it can still change gears. Although when I locked mine in during 3rd gear and it changed to overdrive, the shift was not very nice. Like it had to slam into gear since the TC was allowed to slip to make the gear shift smoother.

 

[F 150Cobra]

im gonna go to radio shak and get the swith right now i wanna test this

 

[F 150Cobra]

wooohooo i did it.. its a neat mod its like running a manual when its on.. but the middle position and auto position i cant feel no difference

btw i cant downshift with it when its on and in 3rd press the accelarator more it shudders doesnt downshift.. and havvent tried it at WOT yet im scared lol.. did you do it chris?

 

[Skandocious]

I haven't played too much with it in the lock position, scares me too

At speeds under 35-45mph other two positions will not show any difference. You'll only see a difference with the middle position after 35-45mph, you'll be running higher rpms at a given speed. Try having it in the middle position at 50mph, then switch it to the bottom (lock it) and you'll see your RPMs drop.

 

[str8racing]

Will this help pulling a heavy trailer? Could you explain so this dummy can understand?

 

[F 150Cobra]

ohh and mine doesnt shut off when lock and at a stop. it wants to but barely keeps running ...

 

[Skandocious]

Will this help pulling a heavy trailer? Could you explain so this dummy can understand?

Yes sir it will. When the torque converter is allowed to slip it allows the engine to rev to a higher RPM for a given speed. Higher RPM = higher torque at the crank (for the most part).

For example (and I'm going to make up these numbers)... Normally at 65mph my TC would be locked and the engine would be running around 2050-2100rpms. If I unlock the torque converter clutch it will allow the torque converter to slip which brings the RPMs up to, say, 2300-2400rpms. Higher rpm = more torque = better pulling power.

 

[andym]

It also means higher heat because the fluid gets hot in the converter when it's slipping.

And I wouldn't leave it locked while you're stopped. It's bad for the lockup clutches.

 

[Skandocious]

It also means higher heat because the fluid gets hot in the converter when it's slipping.

And I wouldn't leave it locked while you're stopped. It's bad for the lockup clutches.

OOOoooo look who's suddenly and expert!! Mr. PleaseMakeaWriteupSoICanCopyYouChris

 

[TheRoadVirus]

Bahahahah, don't blow up your E4OD.

 

[Bob Ayers]

It also means higher heat because the fluid gets hot in the converter when it's slipping.

And I wouldn't leave it locked while you're stopped. It's bad for the lockup clutches.

Bad for the entire drivetrain!!!

It's actually dangerous in an emergency stop situation since there are no provisions to take it out of lockup in a stop!!!

 

[Skandocious]

Bad for the entire drivetrain!!!

I was doing some electrical testing the other day with the switch and I forgot to switch it out of lock before starting the truck. In park there was no difference. When I put it in reverse the RPMs dropped to about 300 or 400 then revved back up and acted normal. I wondered what was wrong until I realized the switch was in lock. It didn't appear to have ANY adverse effect on the truck. It also did not stall or even feel like it wanted to. If you're speculating, then don't pass it off as fact.

It's actually dangerous in an emergency stop situation since there are no provisions to take it out of lockup in a stop!!!

Why is that dangerous? Even if the lockup would cause the engine to stall (which I don't believe it would -- see my above text or see Jurgen's in an earlier post in this thread), the brakes still work... I don't believe a locked TCC would hinder the brakes from stopping the vehicle the same way a manual transmission left in gear will not hinder the truck from coming to a screeching halt.

 

[Bob Ayers]

I was doing some electrical testing the other day with the switch and I forgot to switch it out of lock before starting the truck. In park there was no difference. When I put it in reverse the RPMs dropped to about 300 or 400 then revved back up and acted normal. I wondered what was wrong until I realized the switch was in lock. It didn't appear to have ANY adverse effect on the truck. It also did not stall or even feel like it wanted to. If you're speculating, then don't pass it off as fact.

Why is that dangerous? Even if the lockup would cause the engine to stall (which I don't believe it would -- see my above text or see Jurgen's in an earlier post in this thread), the brakes still work... I don't believe a locked TCC would hinder the breaks from stopping the vehicle the same way a manual transmission left in gear will not hinder the truck from coming to a screeching halt.

Tell us what happens when you come to a stop in DRIVE with the TC in lock up!! And the ABS system will try and keep the rear wheels from locking up! The automatic will downshift to a lower gear giving additional torque, with the manual, it will stay in the highest gear.

First, try a normal gradual stop, and then try an "emergency" stop.


Again, putting the TC into lockup without the provision for removing it in a stop is not a good idea!

 

[Bob Ayers]

Here is a real quick writeup for installing a toggle switch for the torque converter clutch on E4OD-equipped trucks.

DISCLAIMER: Use of a manual control TCC lockup switch, as described in the following writeup, can cause your transmission to entire limp mode if used excessively. Transmission damage should not result, and the condition can be remedied by simply resetting the computer. Generally problem will occur if one keeps the TCC unlocked for an extended period of time when the computer is expecting it to be locked (eg, extended drives at freeway speeds). Again -- this mod should not harm your transmission in any way, but be aware that the computer will sometimes have a temper tantrum for not having control of the TCC

Chris, how long does it take to throw the code, and the tranny start shifting hard? Don't you think the hard shifting will add additional stress to the tranny, and rest of the drivetrain?

Are you saying that you, or FTF will not be responsible for damages that may result from the suggestion of adding this switch to the TC circuit?

 

[Skandocious]

Chris, how long does it take to throw the code, and the tranny start shifting hard? Don't you think the hard shifting will add additional stress to the tranny, and rest of the drivetrain?

Are you saying that you, or FTF will not be responsible for damages that may result from the suggestion of adding this switch to the TC circuit?

I'm not sure how long it takes to throw the code. And no, hard shifting will not cause damage to the drivetrain -- that is the idea behind limp mode. Increases line pressure to firm up the shifts in the case of transmission slippage. The transmission does this to protect itself, not to hurt itself.

And of course neither I nor FTF are responsible for this mod... This is a discussion board... This isn't a certified Ford TSB or some crazy thing... It just a mod, like all other mods that people do. YOU'RE RESPONSIBLE FOR YOUR OWN MODIFICATIONS. If you don't understand why you're doing a mod, and thus don't know what it may entail, then you shouldn't be doing the mod in the first place.

 

[Bob Ayers]

I'm not sure how long it takes to throw the code. And no, hard shifting will not cause damage to the drivetrain -- that is the idea behind limp mode. Increases line pressure to firm up the shifts in the case of transmission slippage. The transmission does this to protect itself, not to hurt itself.

And of course neither I nor FTF are responsible for this mod... This is a discussion board... This isn't a certified Ford TSB or some crazy thing... It just a mod, like all other mods that people do. YOU'RE RESPONSIBLE FOR YOUR OWN MODIFICATIONS. If you don't understand why you're doing a mod, and thus don't know what it may entail, then you shouldn't be doing the mod in the first place.

Chris, how can you ignore the fact that the additional torque from the hard shifts won't add addition stress to the tranny and drivetrain (bearings, u-joints, ring & pinion gears, etc.)? Limp mode is a temporary thing, and is
not intended for extended use! So, you CANNOT say that this TC switch mod will not cause damage! The rich mixture with the engine in "Limp mode" will ruin CATs too if left go long enough!!!


Why would you think they would add the function for the PCM to monitor when the TC locks up, and unlocks? And when it doesn't, it throws a code?