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Open Differential Vs Spool - Differential Differences

Posted in Features on April 1, 2004
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Bigger tires and a lift kit are the first two modifications most people make to their 4x4s. But after they've gotten the look they want, they find out that even with aggressive tires their truck still gets stuck in the fun stuff because only one tire on the front and one tire on the rear axle seem to be turning. Nothing's broken-it's just that even with four-wheel drive all you can count on is spinning those two tires if your 4x4 has open differentials.

To truly appreciate the capabilities of four-wheel drive, you're going to want some form of limited slip, or better yet, a locking differential in the front and rear axles. That way you can be sure all four tires will transmit their torque to the ground to get you over and through the tough stuff. So how do you know which one to get when there are more options now than ever? Follow along and see which combo makes sense for you.

What's New Open Differential AdvantagesIt's hard to imagine but there are some advantages to the open differentials that come in most of the 4x4s on the market. Of course, after you've driven a 4x4 with a locker you might as well throw this list away because traction is extremely addictive!

*An open differential is rarely going to break an axleshaft, nor is it likely to ever fail or wear out, except from abuse.

*They are smooth and predictable in all terrains. When one tires spins, the stationary tire acts like an anchor to keep the 4x4 from fishtailing.

*Tires won't wear out as fast because there is very little scrub when the vehicle goes around tight corners.

*An open differential is a lightweight piece, so reciprocating weight is low, and that means quicker acceleration.

*Use as a front differential when 4x4 has a rear locker and no power steering.

*They're free.

*They can be welded up solid for a poor man's spool, or upgraded with a Tractech EZ Locker or a Powertrax Lock-Right.

Is a Spool for You?With everyone jumping on the extreme off-road bandwagon, spools have become far more popular over the last five years. Their low cost, unmatched strength, and full-race mystique have driven their popularity. But they're not perfect-and they come with some serious drawbacks. A spool is basically a steel collar that splines both axleshafts together with a flange to bolt the ring gear onto. Very simple to be sure, but this differential replacement is too hard-core for 99 percent of street-driven 4x4s. Spools are suitable for competition vehicles, and some trail-only rigs where strength, consistency, and low weight are key. On pavement, a spool will chirp the tires around every corner, punish axleshafts, tear up tires, and make you wish you had saved up for a selectable locker. Plus a spool will have you fishtailing in your driveway when the pavement gets icy or wet. We know some of you didn't want to hear that, so if you still can't decide whether a spool is right for you, consider this: Over the last three years we've put spools in a Jeep, a Bronco, and two fullsize Dodges. We've been happy with the spool in each application when driving off-road, but it's no coincidence that we pretty much stopped driving any of those four 4x4s on the street. That's a pretty strong argument that spools are no good for a daily driver.

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