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2008 Tremec TR6060 (MM6/MZ6) Corvette Transmission
Source: GM Powertrain
2008 Model Year Summary
FULL DESCRIPTION OF NEW AND UPDATED FEATURES
WIDER GEARS INCREASE TORQUE-HANDLING CAPABILITY
STRONGER ONE-PIECE COUNTERSHAFT NOW STANDARD ON ALL VERSIONS
HOUSING STRENGTHENED TO MINIMIZE FLEX AND IMPROVE SHIFTING
NEW SYNCHRONIZER SYSTEM IMPROVES SHIFT FEEL AND REDUCES EFFORTS
FLUID PUMP INTEGRATED INTO FRONT CASE ADAPTOR
DOUBLE-CONE REVERSE GEAR SYNCHRONIZER EASES REVERSE GEAR SELECTION
The 6-speed uses Texaco ATF Type III 1863 fluid and is certified "fill-for-life," requiring no fluid changes. The clutch is activated hydraulically, which automatically compensates for clutch disc wear, eliminating manual adjustments. The Tremec TR6060 six-speed has evolved from a design that aimed to require virtually no maintenance in all but the most severe conditions.
Both the standard Corvette and the high-performance Z06 use the TR6060 designated as MM6, which is validated to 500 lb-ft of torque, while the TR6060 with the Z51 option features higher ratios and is designated as MZ6. It is validated to 428 lb-ft of torque.
Design features include a combination of double-cone and triple-cone synchronizers on all gears. Synchronizers act like clutches to speed up or slow down a gear that is being shifted to. Double-cone synchronizers have two friction surfaces to effect this gear acceleration, and triple-cone synchronizers have three friction surfaces. The greater the friction surface, the easier the transmission is to shift. In addition, double-cone and triple-cone synchronizers are smaller in diameter than a single-cone synchronizer with the same friction area allowing the transmission to remain more compact. Bearings in place of bushings lower the friction of the shift rail movements for the Corvette, making the shifter feel naturally lighter and more direct.
Refinements common to the design of all six-speed Tremec TR6060 transmissions include needle bearings on all forward gearsets and 5th and 6th gear synchronizers located on a countershaft. The countershaft location of the 5th and 6th gear synchronizers allow those gears to be selected without affecting the 1st through 4th gearsets, contributing to ease of shifting.
The sixth-generation Corvette with the Z51 option uses the MZ6 version of the six-speed, with ratios developed for the M12 which was used in the Cadillac CTS-V. These ratios are higher in first, second, and third gears than the MM6, as well as a lower-ratio fifth gear to increase top speed for the Z51 option.
When the high-performance Z06 version of the Corvette was introduced for 2006, a stronger single-piece countershaft replaced the previous two-piece countershaft for the MM6. The output shaft was enlarged to a 32-spline unit, which is more durable than the 27-spline unit used in previous applications. Also in 2006 the 6L80 six-speed automatic transmission was introduced, and the bolt pattern for the rear of the case extension of the manual transmission was changed to match the same bolt pattern as the automatic.
Originally, the Tremec T56 evolved as a higher-torque capacity, six-speed version of the proven M49 five-speed manual transmission, and was introduced in the 1993 Chevrolet Camaro and Pontiac Firebird. It was also added to the 1997 fifth-generation Corvette. For the 2008 model year, it has evolved into the TR6060.
Further applications included high-performance models, such as in mid-2004 the Cadillac CTS-V, which used the LS6 engine mated to the M12 higher-ratio version of the transmission, as well as variants that were used in the Pontiac GTO and Chevrolet SSR models.