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Wavetrac Limited Slip Differential

Getting power to the ground in a BMW 335i

Wavetrac Limited Slip Differential BMW 335i

Our 2007 BMW 335i, with its 6-speed manual transmission and 75,000 hard miles was in dire need of a traction overhaul. How were we ever to give e9x M3’s a run for their money with an open diff? All that torque people rave about from the stout N54 twin-turbo six was just about useless from a stop light, and even more so on corner exit, unless unpredictable, one wheel squeal drifts are your thing… So, we got in touch with Wavetrac, Autotech Driveline’s differential branch, and got ourselves a bookshelf-worthy piece of equipment: the Wavetrac Torque Biasing Limited Slip Differential.

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Zero axle-load is a condition that occurs during normal driving, but it shows its ugly head most when driving in extreme conditions.  Zero or near-zero axle-load is when no load is applied through the drivetrain, where a drive wheel is nearly or completely lifted, something that happens in aggressive cornering, whether on track or autocross. Zero or near-zero also occurs during the transition from acceleration to deceleration, and back, even with both drive wheels on the ground. And for you guys who’ve got low, rigid vehicles and stiff sway bars, you may be familiar with lifting a back wheel when entering a driveway.

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Every other gear diff on the market, except the Wavetrac, will not power the gripping wheel, and during the transition from accel to decel, all other gear diffs, except Wavetrac, do nothing. Why is this? Other torque biasing diffs divide the torque between the two axles up to the available grip of each tire.


There is an innovative, patented device at the center of the Wavetrac diff that responds during these specific conditions where there is zero or near-zero axle-load. At or near zero axle-load, the axles, and therefore each side-gear in the differential, start to turn at different speeds. This speed difference causes the Wavetrac device to step into action. Wave profiles are precisely engineered and placed on one side gear and it’s mating preload hub. As the two side gears rotate relative to each other, each wave surface climbs the other, causing them to move apart. This creates enough internal load with the Wavetrac to stop the zero axle-load condition. With that, the drive torque is then applied to the wheel on the ground, the one that has grip and traction, and the differential will keep the power down.


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The Wavetrac unit uses 9310 steel gears run in case-hardened billet or forged steel bodies and ARP fasteners are used throughout. You NEVER have to maintain the diff. Yes, never! It will perform a lifetime of service without maintenance or rebuilds. If the standard setup isn’t quite right for you, you can alter the bias ratio and the diffs behavior to suit your needs with optional components. And to top it off, it’s got a limited lifetime warranty. A killer product, indeed.


So, how does it feel? Awesome. If you’re a driver, this is a no-brainer modification. And now, the trusty 335i is ready to be taken to the next level.



LSD - $1295

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