The GM Tremec TR6060 6-Speed Close Ratio (C6 Corvette ZR1 LS9, per GM) is a six-speed manual gearbox.
First gear is 2.29:1 and 6th is 0.68:1. Divide one by the other and the overall spread is 3.37:1. That is a middling spread for a six-speed: enough first gear to leave a junction without drama, and a top gear that is not only for motorways.
6th is an overdrive at 0.68:1: the output shaft turns faster than the input shaft. Two of the six gears are overdrives. 4th is direct drive at 1.00:1.
The biggest step is 1st to 2nd, where the ratio drops 30%. The smallest is 5th to 6th at 17%. On each upshift the revs drop by the same percentage as the ratio.
The final drive lives in a separate diff, so the speed table shows three common ratios: 3.42, 3.73 and 4.10. With a 3.73 final drive and 225/45R17 tyres, 6th at 6,000 rpm works out at 283 km/h (176 mph), and first runs out at 84 km/h (52 mph). That is how tall the gear is, not a top speed. Drag and power decide that. At 70 mph in 6th the engine turns about 2,390 rpm.
Nearly the same box as the GM Tremec TR6060 6-Speed (Camaro ZL1 1LE, per TREMEC): 2nd is 1.61 here and 1.63 there. That page is the one listed for search; this one stays for anyone after this exact version.
Ratios
| Gear | Ratio | Step |
|---|---|---|
| 1st | 2.29:1 | - |
| 2nd | 1.61:1 | 29.7% |
| 3rd | 1.21:1 | 24.8% |
| 4th | 1.00:1 | 17.4% |
| 5th | 0.82:1 | 18.0% |
| 6th | 0.68:1 | 17.1% |