Control Trac - Off Road Testing

Off Road Testing

Early in the development, BorgWarner had employed a sintered bronze clutch material that exhibited an operating condition commonly known as "stick slip." The slippage had inspired engineers to replace it with a paper-based material mounted atop metal. The paper offered a better coefficient of friction and solved the slippage problem. BorgWarner's automatic transmission components division is credited for the solution.

However, heat proved to be a persistent issue. Excessive heat buildup would burn out the new clutch material. To solve the problem, engineers studied the clutch's torque capacity. It was determined that excessive heat buildup was caused by inadequate clutch torque capacity. Engineers increased the system's capacity and equipped a fleet of test vehicles, which they took to the Anza-Borrego desert in southern California. They made a total of 11 trips, subjecting the prototypes to heat, mountain driving, and deep sand with the intelligent multi-disc clutches being called upon for almost continuous delivery of torque. At first, the environment quickly burned out the clutches. But as engineers gained knowledge, the clutches improved. Eventually, the engineers were able to improve the clutch packs enough that the test vehicles could be virtually destroyed from hard off road use, but the clutch packs would still look good.