Tremec's New 6060 Six-Speed: Features And Applications.pdf

The T56 six-speed transmission has been refined since Tremec bought the BorgWarner manual-transmission business. The T56 is now the six-speed of choice for the Ford Mustang, Chevrolet C5 and C6 Corvettes, Pontiac GTO, Cadillac CTS-V, Dodge Viper and Sidewinder, and Aston Martin Vanquish. Tremec also manufactures aftermarket versions of the T56 for use in earlier cars to replace a T5, Muncie, T10, Saginaw or Toploader. The T56 is enjoying huge success because of its ability to handle high torque loads, its smooth shifting and its quiet gear train. With fifth and sixth being overdrives, there is the benefit of smooth highway cruising at low engine speed to conserve fuel. The T56 shift fork uses triple-cone synchronizer technology for the first and second gears, and dual-cone synchronizers for third, fourth, fifth, sixth and reverse. The previous Cobra T56 unit used dual-cone synchros for first, second, third and fourth, with single-cone synchros for fifth, sixth and reverse. The T56 synchronizer diameter has been increased, and the synchro hubs have been narrowed to shorten the amount of travel required to complete a shift. The speed gears are also redesigned with a two-piece assembly, where the plate bearing the clutch teeth is laser welded to the gear. The T56 design uses one-piece forged gears, which although durable do not allow the precise machining found on the 6060 gears. The gear-face width of the speed gears has been increased for higher torque capacity. The clutch teeth on the 6060 speed gears have positive stops to prevent over-shifting, and this eliminates the need for stops on the shifter assembly. The T56 countershaft was a two-piece design, which has been replaced by a one-piece counter-shaft on the 6060 for increased strength. A slight redesign of the main transmission case eliminates the previous T56 adapter plate with the bellhousing, increasing torsional rigidity for the case assembly.