DigitalWidgets

OK, I've searched and can't seem to find all the pieces to answer my question, so please excuse if this is a repeat (or if I'm asking the question wrong).

I've got a 2011 GS with A6 transmission. I'm trying to get some basic gear/rpm/speed numbers memorized so that I can better utilize (ok play with!) the paddle shifters. Specifically, the red line speeds for 1st, 2nd and 3rd gears. I'm pretty sure 3rd redlines over 105mph, and I won't ever be hitting those kind of speeds on city streets, but I'm really interested in some of the specifics.

I've found some links to charts, but I can't seem to find information on what ratio my car has so that I can look to the right column.

Any help or information would be greatly appreciated.

deecount

Here's a good site -

http://www.brianhouk.com/Corvette/C6Gearing/index.html

I think all GS A6's come with 2.73 rear axle.

FIVEPOINTSEVEN

From the NCM...2.73 for the 6spd AUTO and 3.42 for the 6spd MANUAL.

j_digi454

Maybe today they do but my 07 A6 F55 has the 2.56 rear. I believe that you could order the 2.73 as an option starting in 08 or 09. I also believe the GS A6 comes with the 2.73 standard.

Thanks for the link.

jimmie jam

i believe my 07 F55 A6 also has 2.56's. i don't think i had an option when i ordered the car to change the ratio. FWIW.

DigitalWidgets

Thank you all so much. I was using the wrong term, axel ratio not gear ratio. 2.73 was the magic number. It sounded familiar from all the research I did when I bought the car, but then again 3.15 and 3.42 also sounded familiar and I couldn't find confirmation from the Chevy web site since the redesign last year (at least that's where I think I originally saw that number).

Thanks again! I'll be printing that out and playing around with it!

Vette_DD

Everything you always wanted to know about rear axle ratios on auto tranny cars, but were afraid to ask.

speedlink

OK, so I'm challenged. Just so I understand the ratio's. The higher the number, the quicker the car will be with a lower top speed. But the more engine rev's you have, the lower the fuel mileage. Do I have that right?

06 C6 vert

In theory you should get better mileage around town with shorter gears.

I'm pretty sure with the 256 you are doing 86 mph at redline in second. Any higher and you can get into the limiter.

Vito.A

An easy way to remember it is to think of low gearing like low (1st) gear in a manual transmission. It has lots of torque with fast acceleration, but a low top speed. Higher gearing is the reverse.

These cars come with very high rear axle gearing because of CAFE, Corporate Average Fuel Economy. Corporate GM is forced to install very high gears just to increase the fuel mileage a very slight amount.

By contrast, the standard axle ratio for early Corvettes was a 3.42 or 3.70 with optional 4.10 for improved performance.

06 C6 vert

Easy way to wrap you mind around gearing.

A high ratio is shorter gearing.

A low ratio is taller gearing.

Best for me not to confuse ratios with high and low gears.

LarryMJones

5th and 6th are way too high. Improves fuel milage but performance would really improve if the entire transmission gearing could be set for a top speed of 150. Lower gearing all the way through.

We only put up with it because the LS 2 & 3 have enough power to pull the higher gears. But at slow speeds it takes a lot of throttle just to stay with traffic.

It would be good to have a lock out on 5th & 6th for in town driving.
LJ

DigitalWidgets

For anyone interested, I took the 2011 GS Gear Speeds and created a easier to read (or peek at while driving) printable PDF for printout/reference:

http://www.corvettenews.com/Assets/2011GSGearSpeeds.pdf

JoesC5

1955--3.55:1(powerglide trans)

1956, 1957--3.55:1(powerglide), 3.70:1 with optional 3.27:1(3 & 4-speed manual)

1958, 1959, 1960--3.55:1(powerglide), 3.70:1 with optional 4.11:1, 4.56:1(3 & 4 speed manual)

1961--3.55:1(powerglide), 3.36:1(3-speed manual), 3.70:1(4-speed manual) with 3.36:1,4.11:1. 4.56:1 optional

1962--250 HP & 300 HP with powerglide or 3-speed or 4-speed manuals had 3.36:1.
1962--340 Hp & 360 HP had 3:36 with a 3-speed and 3.70 with a 4-speed. 3:08, 3.36, 3.55, 3.70,4.11 & 4.56 optional.

1963,1964--250HP &300 HP with powerglide or 3-speed or 4-speed had 3.36:1 with 3.08:1 optional with the 4-speed.
1963-- with 340 HP with 3-speed had 3.35:1
1963 with 360 HP and 1964 with 365 HP or 375 HP with 4-speed had 3.70:1 with 3.08, 3.55, 4.11, 4.56 optional.

There never was a 3.42:1 ratio offered.

They offered just about any gear ratio one would want, depending on how one wished to use their car.



All those transmissions had 1:1 high gear, no overdrive as we have now.

Gearhead Jim

Actually, the A6 should achieve a slightly higher top speed with the 2.73 gears. That's because the tranny ratios result in 6th gear being way too tall for top speed, you'd need to be doing way over 200 mph to get max HP in 6th. Even 5th is slightly too tall in the A6, but the 2.73 axle allows the engine to rev a little higher and make a little more HP.

Most of us don't get much chance to use that information...