Z51 gear ratio
Thread Starter
Pro
Joined: Oct 2015
Posts: 524
Likes: 76
From: El Paso Texas
Z51 gear ratio
Hello Friends,
I have an 08 automatic with the Z51 option. I am curious why the gear ratio is higher with this option. I'm old school and always thought lower gearing (for example 4.11) would give you much quicker acceleration than a higher gear - like say a 3.23 ratio - which keeps rpm's lower. My tach only shows 2200 rpm at 100 mph in 6th.
What difference would I feel driving a car without the Z51 option? I don't track the car -- but I give it an old fashioned Italian tune-up a few times a month though.
Thanks to all!
I have an 08 automatic with the Z51 option. I am curious why the gear ratio is higher with this option. I'm old school and always thought lower gearing (for example 4.11) would give you much quicker acceleration than a higher gear - like say a 3.23 ratio - which keeps rpm's lower. My tach only shows 2200 rpm at 100 mph in 6th.
What difference would I feel driving a car without the Z51 option? I don't track the car -- but I give it an old fashioned Italian tune-up a few times a month though.
Thanks to all!
Race Director
Joined: Sep 2007
Posts: 16,557
Likes: 2,108
From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
Your rear axle gear is 2.73 and the non-Z51 ratio is 2.56. Compared to the "old days" that sounds awful. However, 1st gear in the trans is 4.03, so your overall is 11.00. When you compare that to a 4.11 rear with a 2.56 1st gear in a Muncie 4-speed, that overall is 10.52. It's just a matter of changing trans gears and rear axle gears to get good emissions and gas mileage, while still having ratios to provide good acceleration.
There is no 1 to 1 gear in the trans. 4th is 1.15, 5th is .85, and 6th is .67.
Enjoy the gas saving overdrives, and the old school overall for the fun.
There is no 1 to 1 gear in the trans. 4th is 1.15, 5th is .85, and 6th is .67.
Enjoy the gas saving overdrives, and the old school overall for the fun.
Safety Car
Joined: Nov 2007
Posts: 4,436
Likes: 875
From: Bay Area CA
Your rear axle gear is 2.73 and the non-Z51 ratio is 2.56. Compared to the "old days" that sounds awful. However, 1st gear in the trans is 4.03, so your overall is 11.00. When you compare that to a 4.11 rear with a 2.56 1st gear in a Muncie 4-speed, that overall is 10.52. It's just a matter of changing trans gears and rear axle gears to get good emissions and gas mileage, while still having ratios to provide good acceleration.
There is no 1 to 1 gear in the trans. 4th is 1.15, 5th is .85, and 6th is .67.
Enjoy the gas saving overdrives, and the old school overall for the fun.
There is no 1 to 1 gear in the trans. 4th is 1.15, 5th is .85, and 6th is .67.
Enjoy the gas saving overdrives, and the old school overall for the fun.
Back to the OP. The lower gears (higher numerical) will allow your car to come out of the corners quicker by keeping the rpms up little higher. So, for track or spirited driving it is a good thing!
Last edited by Mike's LS3; Sep 29, 2016 at 12:34 AM.
