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Traction Does Matter

The Latest On The Locking-Differential Horizon

Jimmy NylundPhotographer, Writer

Back in January 1990, Four Wheeler magazine introduced the All-Trac locking diff, which later evolved into the Lock-Right, both the brainchild of John Zentmyer. Many trail miles have passed since, but that doesn’t mean the gears in Zentmyer’s head have stopped turning. On the contrary, his company, Traction Matters, now has three new inventions to share with Four Wheeler readers.

First is the Right-Trac, which Zentmyer describes as an improved Lock-Right. Next is the Silentek, a retrofit kit for Lock-Right diffs that’s meant to eliminate the clicking sound that results when cornering. Last but certainly not least, the All-Lock is a completely different approach to locker mechanisms, largely aimed at minimizing the sometimes annoying traits of a locker.

Primarily, as Zentmyer explains, it’s the square teeth on the Right-Trac that gives it strength. Without any forces trying to spread the diff case, the case effectively becomes stronger than stock, only having to deal with rotational forces. To make the square-tooth design work, a different disengagement design was needed. Drive gears pull together when overriding (going around a corner), which offers the benefit of not needing a relief cut in the teeth for C-clip installations.

From what we saw, assembly appears to be easier since the small parts now go toward the outside, rather than in the center.

Using a two-way sprag clutch, the All-Lock is a new approach to the locker world. Sprag clutches are usually found in automatic trannies and helicopter rotors, and they act much like a ratchet but without teeth. No teeth should mean faster reactions, and getting as little backlash as possible should minimize the handling quirks on the street typically associated with lockers going around corners. Since the axle gears effectively multiply the backlash, having only a little to start with should be helpful. There’s about three degrees’ worth in the All-Lock, we’re told, and the unit indeed reacts extremely quickly and operates smoothly, as we observed on an All-Lock–equipped vehicle on a lift. Like the Right-Trac, the All-Lock puts the forces perpendicularly to the axleshafts, so stress on the diff case is reduced.

Not a locking differential but an upgrade kit, the Silentek is made to eliminate the clicking sound of Lock-Rights. Neither the Right-Trac nor the All-Lock clicks in the turns (the All-Lock can’t since there are no gears), but those who dislike the sound of the Lock-Right, new or used, can install the Silentek, which prevents the locking teeth from trying to engage during a turn.

Four Wheeler was the first magazine to lay eyes on these new products from Traction Matters, and at the time (November 1999), they were not in production. We’re told the All-Lock should be available for GM 12-bolts and Toyota FJ40 Land Cruisers by the time you read this, with the Right-Trac following shortly thereafter. (The popular Dana 44 will be the next target axle.) The Silentek will likely be the last to appear in production form.

Additionally, at this writing, the only scheduled way to purchase any of these products was from Traction Matters directly on the Internet (guess the computer age really is here). For more info, contact Traction Matters at its Web site or ask a friend who’s more in tune with keyboards than wrenches to download the free stuff for you. We suspect that once production is in full swing, you’ll be able to find these Traction Matters pieces at your favorite four-by store.