What type of differentials do I have

[erasedhammer]

I was doing some testing with the low lock on the transfer case and noticed something interesting.

I was driving at low speeds with the t/c in high lock position, which means the front and rear axle are locked together, but when I went around a corner (for testing) the vehicle acted like the differentials on the axles were locked as well. The vehicle slowed and stopped and would not go forward around the corner even when I applied power.

But this made no sense, as when I put the t/c in either of the lock positions it should only lock the axles together, which in theory, should not make this much of a difference when turning, as each wheel in each axle should be able to turn freely of eachother.

Are all hmmwvs installed with limited slip differentials? And simply the act of locking the two axles together makes the effect of turning much more exaggerated?

Also, if the vehicle is off, and I go to shift from either high lock or low lock into high, then start the vehicle again, the t/c remains locked. It's only until I shift from those locked positions to high with the vehicle on does the t/c actually unlock. Is this normal?

 

[snowtrac nome]

the hmmwv has a gleason torsion torque sensing differential. It requires a little friction to put helical gears into lock up but a little brake pressure will do it the bucking and friction in a turn will happen with all 4wd vehicles even with open differentials because of the speed difference between the front and rear driveshaft speeds in a turn.

 

[NDT]

All 4x4s will bind up when you go around a curve on pavement with the front and rear axles locked together. Even my grocery getter Ford Escape will bind up in 4x4 lock.

 

[Action]

Do not drive a 4x4 on pavement with the t/c locked.
Sometimes you have to move it slowly for it to unlock after restarting.

 

[gimpyrobb]

https://m.youtube.com/watch?v=JEiSTzK-A2A


Some info on how they work.

 

[erasedhammer]

https://m.youtube.com/watch?v=JEiSTzK-A2A


Some info on how they work.

Yep, just saw that one. The Torsen is a pretty **** cool differential design

 

[seca954]

That's a great video. Thanks for the post.

 

[NormB]

I was doing some testing with the low lock on the transfer case and noticed something interesting.

I was driving at low speeds with the t/c in high lock position, which means the front and rear axle are locked together, but when I went around a corner (for testing) the vehicle acted like the differentials on the axles were locked as well. The vehicle slowed and stopped and would not go forward around the corner even when I applied power.

But this made no sense, as when I put the t/c in either of the lock positions it should only lock the axles together, which in theory, should not make this much of a difference when turning, as each wheel in each axle should be able to turn freely of eachother.

Are all hmmwvs installed with limited slip differentials? And simply the act of locking the two axles together makes the effect of turning much more exaggerated?

Also, if the vehicle is off, and I go to shift from either high lock or low lock into high, then start the vehicle again, the t/c remains locked. It's only until I shift from those locked positions to high with the vehicle on does the t/c actually unlock. Is this normal?

I recently had this exact thing happen - accidentally. I think I'd pushed the TC shifter forward while working under the gauge panel or something. Ran fine for about 3 miles until I pulled into a parking lot and IMMEDIATELY recognized what the locking and bucking was all about just not sure it happened. Then I saw the lever pushed all the way forward. The plate with H/L H N L on it was so badly worn I couldn't make out the top two settings anyway so a casual glance wasn't enough. Dropped it into "H" and drove around some more, no harm done.

I drove AWD Subarus for a couple years (nightmare, don't ask), Saturn, Toyota cars for commuting, then bought a Tacoma 4x4 about 7 years ago and discovered right away I didn't know the difference between AWD and FWD. I'm still learning.

I DID buy the little plate though from Equipment Parts Sales: "M998 HUMVEE TRANSFER CASE POSITION DESIGNATION PLATE 12338433 NOS (1)

SKU	129912007631"

I need every bit of detail I can get, it seems.

 

[NormB]

Do not drive a 4x4 on pavement with the t/c locked.
Sometimes you have to move it slowly for it to unlock after restarting.

Exactly what it says in the operator's manual - which I need to re-re-read apparently.

NB

 

[Hummermark]

Hi watched the torsion video but in the video he says nothing about applying a brake to make it lock up?
How come on the humvee you have to apply the brakes to lock up? I know this works as l have had my humvee in low lock and had two wheels spinning one on the frount corner and one on the opposite side rear corner.
l was stuck till I applied brake softly then all locked and could drive on.

 

[dk8019]

Hi watched the torsion video but in the video he says nothing about applying a brake to make it lock up?
How come on the humvee you have to apply the brakes to lock up? I know this works as l have had my humvee in low lock and had two wheels spinning one on the frount corner and one on the opposite side rear corner.
l was stuck till I applied brake softly then all locked and could drive on.

It's not specific to the HMMWV, but basically any Torsen differential. When you have spinning wheels there's very little applied torque, and the differential basically sees it as driving as usual. When the brake is applied, it transfers some torque to the other side locking the differential up.

 

[Action]

The power goes to the path of least resistance. When you apply brake, you just stop that wheel from spinning and the power will moves the other wheels too. The brake doesnt do anything onside the diff directly.

 

[snowtrac nome]

dk 809 is more correct a torson diff with enough friction will bind and hold until the load is released it does take some friction to initiate this,, I have seen soldiers bind them up hard enough to blow up the carriers. other wise under normal conditions with total loss of traction or one wheel high it will act like an open differential and spin out on the side of least resistance.