KJ Jones
Brand Manager, 5.0 Mustang & Super Fords
December 1, 2009

While our normal practice here in Tech Inspection is to focus on products that are primarily geared toward street-driven Mustangs, this month's main attraction-UPR Products' rearend locator (known by racers as a "wishbone") for '79-'04 Mustangs-is a bit more track-specific than our usual subject matter, but we're making light of it here nonetheless, because for many of us the quarter-mile is like a second home for our Ponies.

Those of you with 'Stangs running in the 10-second-and-quicker/120-mph-and-faster range at the dragstrip are probably all-too familiar with the unnerving swish-swash, tail-wagging sensation that you sometimes feel in the seat of your pants when the car is barreling down on the big end on 8-, 9-, or 10.5-inch slicks or drag radials. The dancing-rearend phenomenon is usually caused by a differential housing that is actually moving from side to side as the car accelerates (despite a rollcage, subframe connectors and antiroll bar to help stabilize the chassis).

Yes, boys, horsepower really will do that to a Mustang, and driving through it, which sometimes seems more like simply holding on and praying that disaster doesn't strike, has long been the only way to deal with the situation. That's because a fix used to require the serious expense of stepping up to additional suspension upgrades, such as torque arm/Panhard bar setups, which actually are better-suited to road-race applications.

A rearend-centering wishbone is another alternative for stabilizing drag 'Stangs. The triangular-shaped, tubular device, which attaches to a vehicle's rear framerails and then comes together in a common point below the center of the differential, basically locks a rearend housing in place and prevents sideways movement. The brace actually helps improve a Pony's consistency on the 1,320 as well.

UPR developed a chrome-moly locator for Fox-through-New Edge Mustangs (PN 2013; $299.99), and the part apparently is just what Rich Bach's '90 'Stang needed to cure it of top-end uncertainty when Rich is clicking off mid-8s on 275/60-15 drag radials. Rich had Don Helsel of Crazy Don's Chassis Works in Island Park, New York, handle installation duties-leveling the brace is a critical part of the install.

If you're a welder, installing this piece can be a DIY effort. However, if you're not confident with a MIG or TIG machine, we strongly recommend you seek the assistance of a chassis expert. That's what Rich did, and we recorded the event for you in the accompanying photos.

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