At what speed does the torque converter lock in a 4l80e trans

I just got my humvee with a 6.5 turbo and a 4L80e trans--Shifts 2-4 are smooth but I cannot feel the torque converter lock up--Around what speed does it lock--Thanks George

gem1410 said:

I just got my humvee with a 6.5 turbo and a 4L80e trans--Shifts 2-4 are smooth but I cannot feel the torque converter lock up--Around what speed does it lock--Thanks George

Click to expand...

I don't understand... What about shift 1?

Are you only shifting b/t 2 and 4? Are you in limp mode?

What speeds do you feel your shifts? What is your top speed?

well see you are already in first gear starting off so the trans shifts to 2nd to 3rd then 4th--I do not feel the torque converter lock up which would feel like another shift--only took it up to 45mph as a 1/2 shaft is bad--At what speed does the torque converter lock up?--2nd gear comes in around 8 mph--3rd comes in at 15 and 4th comes in around 25mph--- The 4L80E is new to me so any info is helpful--Thanks

4th is overdrive, so when the trans shifts into "4th" that's when the convertor should lock up.
Try doing a foot to the floor test and see what speeds the things shifts at then.

JoeJrTheBarber said:

4th is overdrive, so when the trans shifts into "4th" that's when the convertor should lock up.
Try doing a foot to the floor test and see what speeds the things shifts at then.

Click to expand...

Agree with The Barber.

Also, you mention not driving over 45MPH due to half shaft issue. Perhaps you need to fix the half shaft and drive faster?

Thanks--I will replace the half shaft and see what it does

gem1410, I get the question - I run a 4L80e. My locking torque converter engages at the speed/RPM I want it to, using the Quick4 controller. It does NOT engage when it moves into 4th gear. In fact, it's almost like a 5th gear on the highway. Yours is probably set to engage at a speed that exceeds your comfort level, and you may not have a way to program those shift points. Any progress since your original post?

Glad you got it--fourth gear comes in around 35 mph--the torque converter locks-up around 43 mph and the rpm drops considerably --In one humvee I have you can feel the lock up like a 5th gear--the other humvee it kind of softly slides into the lock-up at 44 mph and the rpm drops--originally the lock-up was not happening due to the brake pedal switch being out of adjustment on one of my trucks-- thanks for the good info Jon0249

I’ve been wondering if my truck isn’t locking up as well. When I’m doing 65 MPH via GPS I’m at 2500 RPM on the nose. The trans shifts wonderfully but I’d sure like to have the RPM a bit lower. :/

hummer4x4guy said:

I’ve been wondering if my truck isn’t locking up as well. When I’m doing 65 MPH via GPS I’m at 2500 RPM on the nose. The trans shifts wonderfully but I’d sure like to have the RPM a bit lower. :/

Click to expand...

With a working tach, Hummer4x4guy, you should be able to see a noticeable drop when your locking T/C engages. And, depending on the shift controller you use, you might even have an indicator that comes on with the T/C engagement. 2500 is a bit high at 65 mph. My tach is inop, but the controller registers RPMs, and I'm right at 2000 when I hit 65. It's sweet. Are you sure you have a locking T/C? Stock units were non-locking.

Gem1410, my shift points are markedly higher than yours - I shift from 3 to 4 at approx. 40 mph, but I've set my T/C engagement at 56 mph. For the T/C to stay engaged, there has to be a fairly high amount of pressure, and I've found that at relatively low speeds (and consequently low trans pressure), the T/C goes in and out too much for my liking. I still need to tweak it a bit, but I can run up an long incline without the T/C disengaging with regularity. These beasts are just so heavy, and the pressure sensors in a 4L80e are actually very sensitive. I don't want to put an unnecessarily heavy load on the T/C at low rpm/pressure. Make sense?

I like the feel of the extra weight of the 12k humvees --the ride in my turbo 6.5 4l80e trucks is much smoother then an m998-----My trans is not adjustable and at the lower t/c engagement speed the t/c just slops in --on my other humvee the t/c locks up firm---same trucks but the transmissions have different shift points and t/c lock up points--close but different

I am also having a TCC problem. I have replaced the TCC solenoid when I change the fluid, swapped the speed sensors, and still no lock up. I had the brake switch disconnected as I was driving at 55 turning 3000rpm’s and engaged the brake switch and no change. I am thinking of replacing the switch but the ohms check good on it. Any input?

Ant929 said:

I am also having a TCC problem. I have replaced the TCC solenoid when I change the fluid, swapped the speed sensors, and still no lock up. I had the brake switch disconnected as I was driving at 55 turning 3000rpm’s and engaged the brake switch and no change. I am thinking of replacing the switch but the ohms check good on it. Any input?

Click to expand...

short The wires together....the switch is just opening and closeing to allow or deny voltage.

Retiredwarhorses said:

short The wires together....the switch is just opening and closeing to allow or deny voltage.

Click to expand...

So brake switch is working properly and still no torque converter lock up. Now I am leaning to the conclusion that the torque converter itself maybe cracked or damaged.