jodenesvette

What rear end gear ratio is the best for the highway, with a 6 speed manual transmission, on an 09 Corvette coupe?

catpat8000

The stock one.

Pat

AORoads

Best in what sense? If you mean cruising with the most economy, you can possibly get a lower numerical gear ratio for more mpg, but then it might really bog in 6th. As it is, the 3.42 is about as low as I'd go. As you go higher numerically, you get more oomph, but mileage will suffer some and related rpms go up, which could be a noise factor.

Others will chime in and say that 3.70 is fine, or so is 3.90. That will be your choice.

On a sidenote, I see you're getting a new '09, most likely a take back replacement for the '08 that stalled on your hill?

LJD51

Depending on what I am carrying in the back, I average 29.5 - 30 mpg at 75 mph in my '05 MN6 with 4.10s, Vararam SC CAI, tune and ported TB/intake. I will be adding a complete Z06 exhaust soon and having the tune re-calibrated.

You have an extra 30 horses to feed but I would think you should be able to maintain upwards of 28 mpg with 4.10s or even 29 mpg with 3.90.

I love my 4.10s...

jodenesvette

What are the choices that you can order? Which one would you pick for best highway mileage? Yes, we are ordering a replacement 09 with a stick. The 08, (auto) at 75 miles per hour, was 1600 rpm. Thanks for your help.

phileaglesfan

I don't think you have a choice with the manual although the Z51 changes the actual gear sizes in the manual tranny.

AORoads

I agree with philies. Unfortunately, in years past you could order different rear axle ratios with the man trans. No more. Only with the auto trans.

The stock and only rear gear with the man trans is 3.42. It's fine for me, but others (above and below) may like other gears. I doubt you will want to go to anything numerically lower than the 3.42. 1600 rpm on the highway is truly loafing.

LJD51

Either stay with the stock 3.42s or you might as well get an Aveo. If the stock gears suit you for highway driving, that's great but if you haven't done so already, take a ride with someone that has taller gears and see the difference.

Vette_DD

Here's a chart that shows the difference in gear ratios.

--GEAR------Mode--or--Option
------------Z06---Std 6-spd---Z51 6-spd--6-spd Auto---4-spd Auto
--1st-------2.66----2.66--------2.97-------4.03---------3.06
--2nd-------1.78----1.78--------2.07-------2.36---------1.63
--3rd-------1.30----1.30--------1.43-------1.53---------1.00
--4th-------1.00----1.00--------1.00-------1.15---------0.70
--5th-------0.74----0.74--------0.71-------0.85
--6th-------0.50----0.50--------0.57-------0.67
Rev---------2.90----2.90--------3.28-------3.06---------2.29

Axle Ratio--3.42----3.42--------3.42----2.56(or 2.73)--2.73(or 3.15)

Mike's LS3

Especially with the Z51 tranny gearing! Manuel transmissions allow for only 3.42 ratio. The auto's have a performance ratio option of 2.73 .

johnodrake

I still get north of 25mpg with all my mods!

jodenesvette

Thanks for all the help.