Tow mode

[Chevy1925]

Torque Converter slip is still slip. If I'm over 1000rpm difference it will not engage the TCC until either I back out of the throttle or tranny catches up..

How else you explain TCC not locking up until 40mph under a load and 15mph empty with nothing changed both in T/H.

My LB7 wouldn't lock TCC until 50mph at WOT but would empty @15mph and around 40mph with a trailer behind it. All while in T/H

your pulling my comment way out of context of where its originated from. i also never argued the point of the TCC slip but since it keeps coming up, it doesnt matter if you are in tow mode or normal. if you exceed the slip limit before the clutch locks, it wont lock in either mode.

so to bring it all together. if your in normal mode at a stop, mash the throttle to the floor, TCC slip is under the allowed amount, converter lock up will occur in 2nd gear as it should and shift from there. If you are in tow mode at a stop, mash the throttle to the floor, TCC slip is under the allowed amount, converter lock up will occur in 2nd gear as it should and shift up from there. if either mode has TCC slip above the allowed amount, no lock up will occur until its below it.

T/H mode has the TC clutch lock up a lot sooner.. Equals truck runs faster

that means this above comment is false in a drag racing situation which is where the OP is talking.

OP asked why guys used tow mode at the drags. thats where my comments stem from and where they apply to. we arent talking about you towing big loads

 

[Mike L.]

The lb7 is small difference.

The LMM is 2 tenths. (Stock trans)

I've seen it both ways. I consider it a wash like Rob said.

 

[malibu795]

1st to 2nd is a 42% drop
2nd to 3rd is a 28% drop
3rd to 4th is a 23% drop
4th to 5th is a 30% drop in input shaft rpm.
And you WOT shift rpm is 3000rpm..the TCM will see a 1000rpm and greater difference between engine and transmission input rpm. And not allow the TCC to engage until that difference/slip is back within specs.
I have to deal with it all the time towing hence I have stated else where I want a 1500-1700rpm stall in my truck.. OEM it too loose..
Most don't until they are at the track

 

[Mike L.]

Torque Converter slip is still slip. If I'm over 1000rpm difference it will not engage the TCC until either I back out of the throttle or tranny catches up..

How else you explain TCC not locking up until 40mph under a load and 15mph empty with nothing changed both in T/H.

My LB7 wouldn't lock TCC until 50mph at WOT but would empty @15mph and around 40mph with a trailer behind it. All while in T/H

Converter slip has nothing to do with it when it comes to pulling a load. You cannot compare this to drag racing. When towing a load;
a certain turbine speed compared to output speed at a certain rpm ( all programmed into TCM )is when the converter clutch will lock. Same basic principle as if your fuel filter is plugged. With a plugged fuel filter you will never attain the proper rpm at the right time to satisfy the TCM and you will have delayed shifts, or have to let off the throttle to get it to shift or apply the converter clutch.

 

[Chevy1925]

1st to 2nd is a 42% drop
2nd to 3rd is a 28% drop
3rd to 4th is a 23% drop
4th to 5th is a 30% drop in input shaft rpm.
And you WOT shift rpm is 3000rpm..the TCM will see a 1000rpm and greater difference between engine and transmission input rpm. And not allow the TCC to engage until that difference/slip is back within specs.
I have to deal with it all the time towing hence I have stated else where I want a 1500-1700rpm stall in my truck.. OEM it too loose..
Most don't until they are at the track

no you dont... stall wont fix the TCC slip issue

 

[WolfLMM]

He wants a converter that couples better.

 

[Chevy1925]

He wants a converter that couples better.

Good man :thumb:

 

[WolfLMM]

Good man :thumb:

cant tell if trolling me or I'm the troll

 

[Chevy1925]

cant tell if trolling me or I'm the troll

neither. coupling would be what hes after. just because you put a lower stall in, doesnt mean you get better coupling. only time you see stall is holding the brakes and giving it the throttle.

 

[ikeG]

neither. coupling would be what hes after. just because you put a lower stall in, doesnt mean you get better coupling. only time you see stall is holding the brakes and giving it the throttle.

There are a lot of threads on here where people apparently have this train of thought, though.

 

[rg3whitelbz]

My experience is the only thing that made my times better was a lockup box. Tow haul or not with my built trans at the track I wouldnt feel lockup until top of 3rd.(without the box)

 

[WVRigrat05]

Doesn't matter though, same limiters will kick in inhibiting lockup regardless of tow/haul.

My 1057 wouldn't lock til over 65 at wot, but it'd lock in tow haul no matter what. This stock one doesn't lock for shit in or out of tow haul, and when its locked a quick tap of the throttle it unlocks. Really annoying esp when towing.

 

[Mike L.]

My 1057 wouldn't lock til over 65 at wot, but it'd lock in tow haul no matter what. This stock one doesn't lock for shit in or out of tow haul, and when its locked a quick tap of the throttle it unlocks. Really annoying esp when towing.

If the converter does lock, no matter what speed, your issue is control. Converters don't lock when they want to; they lock when they are told to.

 

[Tyler_LBZ]

Mike is correct.

To the OP, If I understand correctly you want to know the benefit of running T/H at the track.

With a built trans and custom tuning you can program the T/H mode to shift much more aggressively and at different shift points when at the track. My truck used to have a trans tune loaded where T/H mode was set to shift around 4Krpm at WOT and the converter was locked 2-6 gears when shifting so there was no converter slip at all even under normal driving conditions, not WOT (almost shifted like a manual). It shifted firm and very quick, not ideal for daily driving but thats why it was set for T/H mode pretty much only used at the track and for occasional pulls on the street, made it very fun to drive

Granted at the track your running WOT anyway so there isn't going to be much difference unless your raising the shift points to get more RPM out of it.

 

[malibu795]

Explain this?
35,600lbs gross staring facing up hill 50% throttle 400rwhp. Lock with no weight at 15mph

https://youtu.be/thdUZDh0bgo