Differential Tech

Getting a grip with the wavetrac differential.

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A performance car with an open differential is nothing out of the ordinary. Lotus even refused to equip the twin-turbo V-8-powered Esprit with anything but an open diff. Why? Limited-slip and locking differentials, while good at putting power to the ground, often make a car more difficult to rotate. Luckily, technology and design have come a long way, and now it is possible to get the straight-line grip you want from a limited-slip differential along with the nimbleness achieved with an open diff.

We wanted to test out the latest and greatest in limited-slip technology so we contacted WaveTrac, part of Autotech Driveline in Aliso Viejo, California, to check out its latest unit in a BMW 335i. First, let’s talk a little bit about the different types of differentials out there and then we’ll look at what’s involved with the install.

DIFFERENTIAL (DIFF) 

Essentially, the differential is a set of gears powered by the engine and transmission (and in RWD and AWD vehicles, a driveshaft) that work together to turn the axles going out to the drive wheels. It allows the wheels to spin at different rates of speed, which is necessary if you want your car to turn without tire slip. For example, if you were to drive in a circle, the inside wheel drives less distance than the outside, so different wheel speeds are obviously necessary. There are three basic types of differentials: open, locked, and limited slip.

OPEN DIFF