Air Lockers vs. No Air Lockers

geoffff · **Posted:** Fri May 11, 2007 1:48 pm **Post subject:** driving with the brake

When you have one wheel in the air (with an open differential), by applying a little brake and gas at the same time, you're increasing the amount of torque that can be applied to that wheel in the air. With the brake applied, it takes more torque to turn a wheel in the air. (It otherwise takes essentially zero torque to spin that wheel.)

Because an open differential always sends equal torque to both wheels, when you apply the brake with the gas, the wheel on the ground now also gets some torque, too -- the amount depends on just how much you press the brake.

-- Geoff

Jeffrey · **Posted:** Fri May 11, 2007 3:45 pm **Post subject:**

Having just returned from the SMB factory, I discussed this issue with them and got the opinion that in most cases, with the SMB 4x4, the ARB front locker working with the stock limited slip rear is sufficient. Most of the rigs they sell are equipped like that, and most of the off-road-ready finished vans I saw were the same. So I went with that configuration myself.

Buji · **Posted:** Mon May 14, 2007 10:28 am **Post subject:**

Jeffrey wrote:

Buji,

Unless I misunderstood, you are referring to lockers, but talking about manual locking front hubs. Two different things.

No you're right, I was spacing. I don't think anyone wants to crawl under a vehicle to engadge a manual differential!

Eaton is also manufacturing electronic locking differentials, but I'm not sure if they have an fitment for the this type of application.

jage · **Posted:** Mon May 14, 2007 11:00 am **Post subject:**

There are electric lockers available for the Dana44 and Dana 60, and there are also OX lockers, which are cable activated. Both are alternatives to ARB if you don't want to run air but still want selectable.

There is also the option of putting in a regular full-time locker, and the Jeep guys swear that you can't tell there is a Detroit in a front axle when you're in 2wd, but I'm still leery of doing this.

Also with a locker engaged in an axle, when the tires break traction, there is nothing preventing sideways motion and the axle whichever direction it wants. Whereas with an open diff, limited slip (usually), or an deselected locker, the wheel not under complete power will provide tracking, so while you may not go forward or back, you also won't be as likely to just go sideways.

Having had experience I'd rather drive on snow and ice open than with lockers.

oldfart3 · **Posted:** Sun May 20, 2007 8:10 pm **Post subject:** Lockers vs limited slip

We got a limited slip on the rear and ARB locker on the front of our van. I once had a Bronco with limited slips on both ends, and the front end had a nasty tendency to refuse to turn on slippery surfaces. Being able to totally unlock the front diff allows equal torque distribution to each wheel for most situations, while having the option of locking them together if you're really stuck.

The locker saved me an expen$ive tow when I had my van less than 2 weeks and got the right side wheels into the snow berm at the side of the road during a whiteout. With the axle unlocked, the right front wheel just dug itself deeper, while the left didn't pull. Locking the front axle allowed driving out.

John Tarr

BroncoHauler · **Posted:** Fri May 25, 2007 8:40 pm **Post subject:**

kzemach wrote:

Hey, can you explain more about this? Is this what the miltary refers to as "brake-throttle modulation"?

I was totally blown away by what we could do in a HMMWV: driving up out of right angle stream bed with a height of at least 3'... we'd literally be balancing on the RF and LR wheel with the other two wheels totally, way off the ground, and could move forward and backwards just fine. To do it, you'd start with the brake engaged while in drive. Then give it some gas, then slowly let off the brake until you were moving, and drive with both the accelerator and the brake pedels depressed. Worked like a charm. The guy who was showing me how to do it said something about there being a danger in quickly releasing the brake during this operation, as it could do some sort of damage, but all that explanation was lost on me; I'm not much of a gear head.

So, is this the same thing, or is there something in the HMMWV that's different?

It's a type of limited slip differential that has a clutch-pack in it, that with the brakes applied at least partially, tightens up more and more until it's almost fully locked. Cheaper and easier than an ARB locker but not as versitile IMO.

BroncoHauler · **Posted:** Fri May 25, 2007 8:42 pm **Post subject:**

Sorry for responding to myself, but I didn't qualify my answer. I'm familiar with a civilian-market differential like I described, and I ASSUME the military system is similar, but I don't know that for a fact.

kzemach · **Posted:** Tue May 29, 2007 9:24 am **Post subject:**

Bronco_hauler wrote:

Sorry for responding to myself, but I didn't qualify my answer. I'm familiar with a civilian-market differential like I described, and I ASSUME the military system is similar, but I don't know that for a fact.

You're probably correct: my understanding was that the H1 was essentially the same, at least for the functionality of the drive components. Thanks for the clarification on the question; I really don't know jack about drive systems so this is all very new to me.

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Air Lockers vs. No Air Lockers

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