Rear axle ratio = Confused??
Thread Starter
Melting Slicks
Joined: Jul 2006
Posts: 2,090
Likes: 51
From: Georgetown TX
Rear axle ratio = Confused??
I have a '09 on order w/ F55 suspension. I opted for the 2.73 performance rear axle ratio because I felt it would make the car a little quicker off the line (equal to Z51?). Now I'm reading about the guys who go w/ the 4:11 gears w/ great results. Is the 2.73 option a waste of money ($395)?? Opinions and thoughts appreciated!!
Instructor
Joined: Jul 2008
Posts: 100
Likes: 0
From: Long Jetty NSW
I have a '09 on order w/ F55 suspension. I opted for the 2.73 performance rear axle ratio because I felt it would make the car a little quicker off the line (equal to Z51?). Now I'm reading about the guys who go w/ the 4:11 gears w/ great results. Is the 2.73 option a waste of money ($395)?? Opinions and thoughts appreciated!!
Race Director
Joined: Mar 2005
Posts: 10,399
Likes: 26
From: Austin Texas
This seems to come up everyday. The A6 w/optional 2:73 is a LOWER first gear than the M6 Z51 w/ a 3:42. Look at the overall ratio, not just rear gears. ie; first gear X final drive, not just final drive.
Instructor
Joined: Aug 2007
Posts: 218
Likes: 0
From: St. Peters Mo
You made a good choice, at least take delivery and try it, I luv my 08.2:73,a6...Pete
Pro
Joined: Jul 2004
Posts: 505
Likes: 1
From: peoria AZ
[QUOTE Is the 2.73 option a waste of money ($395)?? Opinions and thoughts appreciated!![/QUOTE]
Look at the big picture?????best bang for $395,
read just what you get W/Z51"its not just 2.73"
there's a list of options.
[/QUOTE]Look at the big picture?????best bang for $395,
read just what you get W/Z51"its not just 2.73"
there's a list of options.
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Racer
Joined: Jun 2005
Posts: 307
Likes: 1
From: Mine Hill New Jersey
Safety Car
Joined: Nov 2007
Posts: 4,537
Likes: 1,404
From: Bethesda MD
If you plan to leave the car alone, getting the 2.73s was a good choice. If you plan to modify the car, going to aftermarket 3.15 or 3.42 will provide more performance than the 2.73s. If you are going to switch, paying for the 2.73s is a waste of money so see if you can cancel it.
Team Owner
Joined: Feb 2001
Posts: 27,254
Likes: 136
From: Short Hills, NJ
I think when the original poster made the statement below
VERY FEW people would ever put 4.11s (aka: 4.10s) in an A6 car.
3.15s or 3.42s are the more preferable aftermarket choices for the A6 transmissioned cars...those factory optional 2.73s, though still not nearly as exciting as the aftermarket choices, are at least a decent step in the right direction over the standard 2.56s.
Race Director
Joined: Mar 2005
Posts: 10,399
Likes: 26
From: Austin Texas
Rough aproximate numbers;
140,000 'Vettes 05, 06, 07, 08 combined
60% Auto's = 98,000 Auto 'Vettes
MAYBE 2,000 autos w/aftermarket gears in 4 years production.
MAYBE 50 of those with 3:42 gears.
Not an overwhelming number.
140,000 'Vettes 05, 06, 07, 08 combined
60% Auto's = 98,000 Auto 'Vettes
MAYBE 2,000 autos w/aftermarket gears in 4 years production.
MAYBE 50 of those with 3:42 gears.
Not an overwhelming number.
Le Mans Master
Joined: Apr 2006
Posts: 5,933
Likes: 13
From: The Beautiful Inland Empire WA.
Do NOT go deeper than the 3.42's with the A6.......you won't have any traction anyway with those gears, and your highway RPM's will be up 500 or 600 RPM......that kind of RPM's on the freeway completely changes the character of the car -- from nice and relaxed to kind of frenetic sounding --- especially if you go with an aftermarket exhuast..
I had 3.73's with my A4 C5, and after driving it around for awhile, I just hated how it changed the car........kinda fun off the line (the torque with those gears would even completely overcome the traction control programming), but for anything else? I'd never do it again............I also lost about 5 or 6 MPG on the freeway --- from 29-30 to 23 to 25.....not worth it with today's gas prices!!!!
I had 3.73's with my A4 C5, and after driving it around for awhile, I just hated how it changed the car........kinda fun off the line (the torque with those gears would even completely overcome the traction control programming), but for anything else? I'd never do it again............I also lost about 5 or 6 MPG on the freeway --- from 29-30 to 23 to 25.....not worth it with today's gas prices!!!!
Team Owner
Joined: Feb 2001
Posts: 27,254
Likes: 136
From: Short Hills, NJ
I do agree that anything higher than a 3.42 gear in the A6 trans might be bordering on unstreetable for most owners.
Safety Car
Joined: Oct 2003
Posts: 3,597
Likes: 101
From: TN PA
CI 5-6-7-8-9-10-11 Vet
At 2000 rpm in 4th gear (1.15 to 1) on the A6 the MPH difference is less than 3 mph.....53.94 / 51.17 mph using 27 inches as the tire height.
At 2000 rpm in 6th gear (.67 to 1) the mph difference is 4.75 mph 92.58/87.83 mph (higher mph on the 2.59 gear car)
You should have a very slight acceleration increase with the 2.73 gears(ie 0-60mph)
You could also see a very slight drop in mpg's with the 2.73's
At 2000 rpm in 6th gear (.67 to 1) the mph difference is 4.75 mph 92.58/87.83 mph (higher mph on the 2.59 gear car)
You should have a very slight acceleration increase with the 2.73 gears(ie 0-60mph)
You could also see a very slight drop in mpg's with the 2.73's
Drifting
Joined: May 2007
Posts: 1,557
Likes: 1,275
From: EV is like bad sex with no moaning
I have an o8 a6 with the 2.73. It is easily worth the $395 since it costs a lot more if you have it done later on, of course you can go a little bigger then. But if you plan to track the car and mod it then do not do the upgrade and do 3.15s later. If you do not plan on drag racing or anything then just get the GU2 option, definitely worth it. Fuel mileage from stock 2.56 axle is 16/26 and with the 2.73 my sticker says 15/25. I plan on a cam, headers, cai, exhaust & tune with my 2.73. No rear upgrade for me as my car will never be tracked.
Team Owner
Joined: May 2004
Posts: 82,175
Likes: 1,319
From: McKinney TX
St. Jude Donor '21-'22-'23-'24
Look especially at the second chart below, which enters rear axle ratio into the equation.
--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)
Gear Ratio times Rear Axle Ratio
--GEAR------Mode--or--Option
------------Z06---Std 6-spd---Z51 6-spd----6-spd Auto-------4-spd Auto
--1st-------9.10----9.10-------10.16-----10.32 or 11.00----8.35 or 9.64
--2nd-------6.09----6.09--------7.08------6.04 or 6.44-----4.45 or 5.13
--3rd-------4.45----4.45--------4.89------3.92 or 4.18-----2.73 or 3.15
--4th-------3.42----3.42--------3.42------2.94 or 3.14-----1.91 or 2.21
--5th-------2.53----2.53--------2.43------2.18 or 2.32
--6th-------1.71----1.71--------1.95------1.72 or 1.83
Rev---------9.92----9.92-------11.22------7.83 or 8.35-----6.25 or 7.21
--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)
Gear Ratio times Rear Axle Ratio
--GEAR------Mode--or--Option
------------Z06---Std 6-spd---Z51 6-spd----6-spd Auto-------4-spd Auto
--1st-------9.10----9.10-------10.16-----10.32 or 11.00----8.35 or 9.64
--2nd-------6.09----6.09--------7.08------6.04 or 6.44-----4.45 or 5.13
--3rd-------4.45----4.45--------4.89------3.92 or 4.18-----2.73 or 3.15
--4th-------3.42----3.42--------3.42------2.94 or 3.14-----1.91 or 2.21
--5th-------2.53----2.53--------2.43------2.18 or 2.32
--6th-------1.71----1.71--------1.95------1.72 or 1.83
Rev---------9.92----9.92-------11.22------7.83 or 8.35-----6.25 or 7.21