Considering the 2.73 performance axle in combo with automatic, F55, and NPP for my soon to be allocated '08 C6 coupe.

What's your take on the performance axle? How would it affect the street driving and cruising experience?

Thanks,
Dan

 

The difference between 2.56 and 2.73 is very very minimal.

My understanding is that the option is very cheap (350 I think someone told me)...so for that much money I would go for it.

But by no means are you going to be significantly faster with it..probably not even noticeably faster...but yes, your car WILL accelerate a little faster and turn SLIGHTLY more rpms.

Nothing at all to be concerned with though about the rpms...if you do not plan on EVER changing gears to a lower ratio then I would go for it. If you want more performance in the future then just leave it stock.

 

I have this in my 08 and at 80 mph it's only turning 50 more rpms than my 07 did. It's a noticable difference as far as pep is concerned and a worthwhile option to get for a mere $300.

 

Yes, for 300 I would probably get it myself...but I'm very skeptical on that small of a gear change being much of a noticeable pep, lol.

Of course I can't speak from direct experience from corvettes as I have not ridden in one ith 2.73 gearing...but I couldnt see it giving you more than .1 in the 1/4, which is not noticeable by feel alone.

Did you test drive an 08 without and an 08 with? Or are you comparing it to your 07.

 

Go for it. My 08 (Z51) has it and is noticeably quicker than my 07. I realize there is also HP involved, but it just feels good.

 

Yes, I test drove both (on different days) but couldn't differentiate without going back to back.

I will say that your comments are giving me great comfort in choosing this option. Especially if it won't cost me much fuel efficiency or comfort during long excursions.

Thanks!

 

manual 342

 

I test drove an 08 at the C6 Bash with standard gearing but ordered mine with the 2:73 and yes, I'm also comparing it to my 07. You'd be surprised how much difference there is in small gear changes. I know I'm dating myself here but back in the day you could tell quite a bit of difference going from a 4:56 to a 4:88 gear. I actually ran a 6:10 gear for a while on the street when I was running at an 1/8 mile drag strip for a while. That was a bit much for the street but man would it haul the mail for a short distance.

 

well I'm just saying...the difference between 2.56 and 2.73 cannot be more than .1

And wtf did you run a 6:10 gear in that could still make it down the 1/8th? How tall were the tires you were running?

 

It was a 66 Mustang GT with a built 302 in it. 10" slicks but I honestly don't remember the size regarding the roll out on them. And that was back when we were running 4 speeds, didn't have 6 gears to row thru. I had a tire company put two grooves in them because I got busted for running slicks on the street. Officer said they had to have tread on them so the tire shop took care of that for me.

 

A mere $395.00 (MSRP) actually.

 

The rear end gear ratio is of course only part of the equation for final gearing..... you have to look at the transmission gear to know your gearing.... to receive your final gear ratio for each gear, simply multiply the transmission gear by the rear end gear. Here are what they are, and actually the difference between the 2.56 & 2.73 is fairly dramatic due to the very steep 1st gear within the A6 in the C6.....

Here are the 1st 4 gear ratio's of the A6:

4.02
2.36
1.53
1.15

Here are the final's with 2.56 gear

10.29 1st gear
6.04 2nd gear
3.91 3rd gear
2.94 4th gear

Here are the final's with the 2.73 gear

10.97 1st gear
6.44 2nd gear
4.17 3rd gear
3.13 4th gear

As you can see above, there is a big difference between the two gears.... 10.97 vs 10.29 is a big difference, and would be very noticabley more torquey, tighter and more explosive.

In comparison, here is what an oldfashioined th 350 with 4.11 gears are

1st gear = 2.52 x 4.11 = 10.35
2nd gear = 1.52 x 4.11 = 6.24
3rd gear = 1.00 x 4.11 = 4.11

As you can see above, there is a big difference between the two 1st gears.... 10.97 vs 10.29 is a big difference. If you're a racer, this is the most important gear and is where you find the most et improvements.

One other thing, while the manual 6 speed guys have a better final gear ratio, their 1st transmission gear is considerably duller, thus here is their result:

1st gear = 2.97 x 3.42 = 10.15
2nd gear = 2.07 x 3.42 = 7.14
3rd gear = 1.43 x 3.42 = 4.89
4th gear = 1.00 x 3.42 = 3.42

As you can see, the 1st gear of even a 2.56 auto has more gear than a 3.42 geared manual at 10.29 vs 10.15, and the 2.73 equipped auto has way more gear at 10.97 vs 10.15.... however, after that the manual has more gear, but they need it considering they do not have a torque converter to help flash their rpm up.

As a long time racer, I am very impressed with the auto transmission gear ranges of the C6 A6.... the ratio between each gear is spaced nicely, thus it does a better job after each shift of staying higher in the rpm band to keep inertia up.... (The 700R4 of the C4's is horrible for this....)

In my opinion, the 2.56 gear is just fine if you're going to keep your motor stock with the exception of bolt-ons.... but if it is in your plans to add an aftermarket cam eventually, it would probably help your motor to increase the gearing considering your cam will typically shift your rpm band up.... that added gearing, coupled with a good torque converter will help you get and stay in your working rpm band much quicker..... which of course helps produce happy timeslips.

 

Thanks, I didn't remember exactly what it was. Close enough, right?

 

Yes.

 

Great info, thanks!

 

Go with the 2.73's!!
I have 3.15 on My A6,and I love 'em!

 

I have a new C6 A6 and I would get the 2:73's if I ordered it again. Even if it's a small amount of 'grunt', it's also a small amount of money!