Turbo63

I have a C6 with a 3:15 rear -- looks like GM offers others as an option? Can someone explain how the rear selected impacts performance? How does the 3:15 compare to the 3:42 or others that are available? I am ordering a C6 Vert w/z51 -- if I want maximum speed performance what rear do I choose? Does the Z51 already come with a specific rear? Thanks for the insight forum!

vettnutt

With Z51 you get the 3:15.

boogieman

Z51 Package comes with 3.42 gears

With the higher the gears you get more bite from your rear when launching the car. I had a C5 last year and put a 3.90 rear in the car. It was awesome on the line at Raceway Park. Of course what it really comes down to is what is it that you want the car to do. The higher the gear ratio the higher you RPMs will be when cruising. If you will use your car to do long cruising stick with a gear ratio that not too high. I personally will be changing mines to a 3.90

Juvatpilot

I think that the Z51 package comes with a variety of rear-end gear ratios. If you get the A4 tranny, then you have the option of selecting the 1:3.15 performance rear end, and your Z51 option will come with that gear ratio. If you elect the MN6 tranny, then you get the 1:3.42 rear-end, whether you select the Z51 option or not. The only other rear-end ratio option is the 1:2.73 which is the standard ratio with the A4 transmission.
The only variation on this theme is that the Z51 option with the MN6 transmission comes with a different set of transmission gear ratios unique to the Z51 package.

vettnutt

Vette_DD

Don't think this is entirely accurate. If you get the Z51 handling package with the auto tranny, you get the 3.15 rear axle ratio automatically, no choice. However, if you get the manual tranny, you get the 3.42 rear axle ratio, whether you get Z51 or not, as you indicated.

Only if you get the auto tranny without the Z51 do you get a choice of 2.73 rear axle ratio or 3.15 axle ratio. Then, the 3.15 axle ratio is an extra charge.

LS1LT1

HalM

Back to the original question...a numerically higher number in the ratio provides additional torque multiplication to the rear tires...

Vette_DD

Which tranny are you getting, manual or auto?

Zig

true, lower gears provide a taller top end.


what are your numbers ? i've got the 3.42, i idle @ 550, 90 is < 2k.

Zig

80 = 1400