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Locking Differentials Explained

Posted in How To on July 31, 2003
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If you've read any off-road magazine, you've heard the term locking differential. And, you've probably heard people endlessly praise the benefits of lockers off-road and bemoan their drawbacks on-road. The one thing you probably haven't heard is how these mysterious traction-aiding devices work. We poured over diagrams and studied all the internal pieces until we had a full understanding of how these things are put together. Now, we'll break the silence and reveal the inner workings of these technical marvels so you too can understand how lockers work.

In this article, we'll scrutinize the three most popular aftermarket lockers--the Detroit Locker, the ARB Air Locker, and the Lock-Right. 4 Wheel Parts Wholesalers in Burbank, California, was kind enough to let us raid their shelves and tear apart an example of the Detroit Locker and ARB Air Locker so we could photograph the insides of each. Both of these lockers are available through 4 Wheel Parts Wholesalers, or the lockers can be ordered directly from the manufacturers.

The Detroit Locker

Also called the NoSpin, the Detroit Locker is generally regarded as the granddaddy of all lockers currently available. The Detroit Locker is made by Tractech and is a positive-locking traction device that locks the two axleshafts together when engine power is applied. This unit is completely mechanical and requires no wires, plumbing, or other pieces. It has been on the market for many years, and its design borders on ingenious because of its simplicity. Time has proven this locker to be the strongest, most bulletproof mechanical locker on the market.

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The ARB Air Locker

The concept of air lockers is not a new one; they've been used in heavy industry for many years. But it wasn't until a few years ago that a reliable air locker was made available to the public for regular trucks. ARB, an Australian-based company, has made a significant impact on the locker industry by offering a locking device that combines the positive off-road benefits of a locker without the negative on-road handling characteristics. The ARB Air Locker acts and feels just like an open differential when it's disengaged. But when the unit is actuated by compressed air, which is provided by an external air compressor, it locks the side gears of the assembly, which locks both axleshafts, and forces them to turn at the same speed regardless of traction.

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The Lock-Right

While the previous lockers may be great for off-road performance gains and reliability, they have one major drawback--installing them is difficult. Both require removal and resetting of the ring gear, which takes several special tools to be performed properly. This generally means getting a professional involved, which can be expensive. This is why Powertrax developed the Lock-Right, a mechanical-locking differential that can be installed by anyone with a little mechanical aptitude. The Lock-Right uses the original open differential carrier and replaces the side and spider gears. It can't be used with a limited-slip carrier, and installation does require careful marking of all the original carrier settings in the axlehousing. Because it uses the original carrier, the Lock-Right isn't considered as strong as the other two, but the significant price difference attracts the budget-minded.

PhotosView Slideshow


4 Wheel Parts Wholesalers
ARB Air Locker
Seattle, WA 98134
Powertrax (Lock-Right)
Costa Mesa, CA 92626
Tractech (Detroit Locker)
Warren, MI

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