Torque Converter

[Spindrift]

I understand the torque converter in the 4L80E won't lock until you reach 50-53 MPH. Does the operation of the TC depend on speed or gearing, meaning, if I drop down into third gear in a towing situation and reach 50-53 MPH, should the TC lock?

Thanks.

[rjwest]

Yes, But if to much throttle, it will not lock.
I try to anticipate need for down shift, get into 3rd and feather throttle umtill lock up,
Than try to hold throttle just below TCC unlock.

Speedo does not control shift speeds, It's sensed by
tran speed sensor.

50-53 is with 3.73 gears, 4.10 will lock up
at 45 ( I think ) I swapped from 4.10 to 3.73
without reprogram of PCM. nad that was my lock up speeds. What I gained with taller gears on
high speed, I lost at hill climbs at 50-55....

[tanker]

I'm using a "BD" Torq-Loc on mine. I can lockup at 34mph, so I actually pull some good grades in 2nd. gear locked up. Gives me about 6 speeds forward. Less heat build up in the transmission, by no slippage. I'm also using an exhaust brake, which will not work without the converter being locked. Seems this only works well with 94-95 4l80E's, a change in the computer in 96 affects the operation in the later models. Member "Howie E." has one on his 97 burb, but has had some issues with it, but still uses it with care. smile.gif

[rjwest]

Tanker, Your lucky to have an older truck for the
Torque Loc, Will set codes in 96, got one in the garage that did not work, costly 250 doller error.

Installed the " poor mans TCC lock up sw "
for next trip through PA, Sure need 2nd TCC lock up
in PA, Can't get a run at the hills .

See how it works in a few weeks....

[Spindrift]

rjwest...while in 3rd, is your torque converter locking up at a speed lower than the 50-53 MPH that the TC would lock in 4th?

[rjwest]

Spindrift, No, Lock up speed is same in 3rd or 4th gear 50ish , Also when 4.10 gears were
installed, TCC lock up speed for 3 & 4 Gears was
45-47 MPH. I believe TCC lock up speed is determined by Rear transmission speed sensor...

[rjschoolcraft]

My Suburban has 4.10 gears and I too have the BD TorqLoc. Without the TorqLoc engaged, my converter will lock at about 53 mph with the go pedal matted...towing or not. It stays locked for the 3-4 shift. The PCM will lock the converter at lower speeds with part throttle application. With the TorqLoc engaged, it will lock at 36 mph in 2nd, 3rd or 4th. The lockup is controlled by sensing the VSS buffer signal so that the speed of the vehicle is known.

The factory lock-up considers vehicle speed, throttle application and other engine load related parameters to determine the appropriate lock-up point. With the TorqLoc on, vehicle speed is the only criteria. It will lock at 36 mph and unlock at 31 mph...no matter what.

I've learned to like the TorqLoc when towing for the same reasons that Tanker stated. I especially like the down grade control that it gives me. I do not have an exhaust brake at present. I also like being able to lock up the converter on long climbs in second gear.

[whatnot]

Is the converter supposed to stay locked when letting up on the throttle?

[Spindrift]

These questions are somewhat related so I'll post on this thread since I'm not having any luck on the other.

Does anyone want to venture a guess at the temperature differential you can expect if you were to install the sending unit between the tranny and the cooler vs. in the tranny pan?

Thanks.

[RLAM]

A "Gear Vendor" would make you awfully happy. By feathering the throttle and allowing the TC to lock up, I can run 3d and under(2nd over) locked up. Sure gives me alot of options.

[patrick m.]

my TCC will not lock before 45, under any conditions.
its been that way since i've had it, (thats with 3 different chips)

[rjschoolcraft]

Without outside intervention, the converter will unlock when the accelerator pedal is returned to idle position.

[patrick m.]

Originally posted by ronniejoe:
Without outside intervention, the converter will unlock when the accelerator pedal is returned to idle position. quite, mine will return very near to idle speeds on decel.