Quote:
Originally Posted by Lakepilot
I agree with Malibu. The 4 speed used in Silverado's was a 4L60 and had the following forward gear ratio's
1=3.06
2=1.63
3=1.0
4=.7
The 6 speed that replaced this is the 6L80 and is geared as follows:
1=4.027
2=2.364
3=1.532
4=1.152
5=.852
6=.667
The gears in the axles then determine the final gear ratio i.e. 4.10 or 3.73 etc. Look at the 4L60 ratio of highest gear to lowest gear versus the 6L80. Much wider.
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Thanks for the info. That's a nice spread of gears and is different than I imagined. I can now see that the overall gearing could be numerically lower and still offer perfectly adequate towing performance.
You typically stay out of overdrive when towing, so the 6 speed is limited to 4 speeds and the 4 speed is limited to 3 speeds. With 3.42 gears, in fourth gear, the 6 speed would have roughly the same drive ratio as the 4 speed in 3rd gear with 3.92 gears.
I'd avoid 3.08 gears, even with the 6 speed. There's no good gear for towing. 3rd is too low (4.71) and 4th is too high (3.54).