rear axle question
Thread Starter
Burning Brakes
Joined: Jun 2004
Posts: 1,211
Likes: 0
From: Nesconset NY
St. Jude Donor '04 & '05
rear axle question
Hi All
Not only is this a newbie question but also it will show that I really shoudn't do and mechanical mods by myself
I have been reading some threads about rear axles and I saw a lot of refernces to a standard 3.15 axle ratio. So I checked a speck sheet that one of the forum members sent me about my Vette and it says that I have a 2.73 axle ratio. I would like to know what the difference is and how it would relate to performance
Thanks
Tom
Not only is this a newbie question but also it will show that I really shoudn't do and mechanical mods by myself
I have been reading some threads about rear axles and I saw a lot of refernces to a standard 3.15 axle ratio. So I checked a speck sheet that one of the forum members sent me about my Vette and it says that I have a 2.73 axle ratio. I would like to know what the difference is and how it would relate to performance
Thanks
Tom
Race Director
Joined: Nov 2003
Posts: 12,346
Likes: 5
From: Mustang OK
Originally Posted by tmcclaff
Hi All
Not only is this a newbie question but also it will show that I really shoudn't do and mechanical mods by myself
I have been reading some threads about rear axles and I saw a lot of refernces to a standard 3.15 axle ratio. So I checked a speck sheet that one of the forum members sent me about my Vette and it says that I have a 2.73 axle ratio. I would like to know what the difference is and how it would relate to performance
Thanks
Tom
Not only is this a newbie question but also it will show that I really shoudn't do and mechanical mods by myself
I have been reading some threads about rear axles and I saw a lot of refernces to a standard 3.15 axle ratio. So I checked a speck sheet that one of the forum members sent me about my Vette and it says that I have a 2.73 axle ratio. I would like to know what the difference is and how it would relate to performance
Thanks
Tom
Last edited by GrayC5; Aug 4, 2004 at 09:37 PM. Reason: Spelling/Typing
Pro
Joined: Nov 2003
Posts: 665
Likes: 0
From: Hendersonville NC
Axle ratio will affect the rate at which engine RPMs are achieved and the distance traveled. The higher the numerical number of the axle the lower the gear ratio. A 4:10 axle ratio will allow the engine to get to redline quicker than a 3:42, but the trade off is higher engine RPMs at cruising speeds, and less highway mileage per gallon. If you are racing the car in the quarter mile a high numeric is desireable, as you can max out the RPM's and access all the available horsepower and torque. For the street, a lower numeric yields better gas mileage but less rapid access to the available power. The trick is to find the right ratio for the kind of driving you do as well as optimizing the power band of the engine. I have the MN6 and can't speak for the autos gearing, but I am considering a change to a higher numeric axle ratio as a performance mod to be done down the road. I believe there is a great deal of info here in the search function on this topic.
Le Mans Master
Joined: May 2003
Posts: 6,454
Likes: 3
From: Hells Sister City Phoenix AZ
St. Jude Donor '03
In layman's terms it's as follows:
If you're a typical "cruiser" 2.73's are probably fine, especially for gas mileage.
If you like the SOTP fun 3.15's would be better but gas mileage will suffer. Not worth the $$ to upgrade from 2.73 to 3.15 in MHO.
If you like to drag race then 3.42's or higher would be desireable and probably worth the $$.
Hope that helps!
If you're a typical "cruiser" 2.73's are probably fine, especially for gas mileage.
If you like the SOTP fun 3.15's would be better but gas mileage will suffer. Not worth the $$ to upgrade from 2.73 to 3.15 in MHO.
If you like to drag race then 3.42's or higher would be desireable and probably worth the $$.
Hope that helps!
Team Owner
Joined: Aug 2004
Posts: 24,129
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From: The Beautiful Pacific Northwest
St. Jude Donor '05-'06-'07-'08-'09, '14-'15-'16-'17-'18
How do you find out?
OK...where is the indication of which axle ratio is on my '02 A4 coupe? Not sure where to look.
Le Mans Master
Joined: May 2003
Posts: 6,454
Likes: 3
From: Hells Sister City Phoenix AZ
St. Jude Donor '03
Originally Posted by Red_Racer
OK...where is the indication of which axle ratio is on my '02 A4 coupe? Not sure where to look.
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
OK...where is the indication of which axle ratio is on my '02 A4 coupe? Not sure where to look.
look here:
http://mikemercury.home.att.net/ratio.htm
look here:
http://mikemercury.home.att.net/ratio.htm
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Originally Posted by eddie44
In layman's terms it's as follows:
If you're a typical "cruiser" 2.73's are probably fine, especially for gas mileage.
If you like the SOTP fun 3.15's would be better but gas mileage will suffer. Not worth the $$ to upgrade from 2.73 to 3.15 in MHO.
If you like to drag race then 3.42's or higher would be desireable and probably worth the $$.
If you're a typical "cruiser" 2.73's are probably fine, especially for gas mileage.
If you like the SOTP fun 3.15's would be better but gas mileage will suffer. Not worth the $$ to upgrade from 2.73 to 3.15 in MHO.
If you like to drag race then 3.42's or higher would be desireable and probably worth the $$.
Good, simple explanation.
Burning Brakes
Joined: May 2004
Posts: 996
Likes: 13
From: Dallas TX
According to the corvette museum stats, an A4 w/ 2.73 does a 4.9 sec 0-60, w/ 3.15 it does it in 4.75 sec (using the 01's 345 HP stats).
In my '04 A4 w/ 3.15 rear-end, I get 19.5 MPG with aggressive, town only driving. Gas mileage I think is only marginally effected between 2.73's and 3.15's. I think you'd be lucky if it saved you 1MPG.
If you are going to change out your rear-end and decide on going higher than 3.15, then you may need to consider another torque converter and tires other than the stock run-flats. (I think the A4's first gear has a higher ratio than any other vette transmission)
In my '04 A4 w/ 3.15 rear-end, I get 19.5 MPG with aggressive, town only driving. Gas mileage I think is only marginally effected between 2.73's and 3.15's. I think you'd be lucky if it saved you 1MPG.
If you are going to change out your rear-end and decide on going higher than 3.15, then you may need to consider another torque converter and tires other than the stock run-flats. (I think the A4's first gear has a higher ratio than any other vette transmission)
