Rear End Gear Suggestions
Burning Brakes
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From: North\East Wisconsin
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From: Reno is so close to Hell you can see Sparks , State Of Confusion
St. Jude Donor '12-'13-'14
If you have the 2.73 now I would go to 3.43 or 3.73, Not enough gear to go 3.15 for the cost involved, Here is a chart that shows the gearing and rpm for you.
Mr.Bill
Mr.Bill
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From: Cohoes New York 12047
Thanks Mr Bill This is great data.(exactly what I needed to know) Probably going with the 3- 73 while I have someone to do the change
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A 3.42 rear differential from a 6 speed car will make a big difference. Or go with a set of 3.73 gears - then you'll really feel a difference. Just be sure to have the computer programmed for any new gears.
Burning Brakes
Joined: Jul 2010
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From: Peters Colony Republic of Texas
Will gas mileage be a concern to you?
If the gas mileage your daily driver achieves will be important to you, then changing to a 3:73 ratio differential may be disappointing.
I agree with others that changing to the 3:15 ratio won't make enough difference for you to feel good about spending the money. Changing to a 3:73 will very noticeably reduce your mileage (compared to the 2:73). A 3:42 ratio may be a happy compromise.
Also, if you occasionally race (1/4 mile) your car and the engine is modified, a 3:73 may give you more rear tire spin than you might prefer, thus hurting e.t.'s.
All of the above are things to consider before you pull the trigger.
I went through the same decision process as you are going through when changing the 2:73 diff in my A4. Settled on the 3:42, and I'm happy with it. Now...with 600rwhp (and >500 lb. ft. of torque), I still get lots of tire spin at launch (unless I roll on the throttle), but at least it's manageable.
Just my $0.02 worth.
the Lizzard
I agree with others that changing to the 3:15 ratio won't make enough difference for you to feel good about spending the money. Changing to a 3:73 will very noticeably reduce your mileage (compared to the 2:73). A 3:42 ratio may be a happy compromise.
Also, if you occasionally race (1/4 mile) your car and the engine is modified, a 3:73 may give you more rear tire spin than you might prefer, thus hurting e.t.'s.
All of the above are things to consider before you pull the trigger.
I went through the same decision process as you are going through when changing the 2:73 diff in my A4. Settled on the 3:42, and I'm happy with it. Now...with 600rwhp (and >500 lb. ft. of torque), I still get lots of tire spin at launch (unless I roll on the throttle), but at least it's manageable.
Just my $0.02 worth.
the Lizzard
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From: Greensboro Nc
I would think a 3.42 would be the best balance of economy, performance, and cost. Just swapping in a 6 speed diff should be sufficient strength wise for a stockish powered auto, and you can find take off diffs pretty cheap
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St. Jude Donor '13-'14-'15-'16
I went from the 3:15 to the 3:73 gear and love it. Car is an automatic had it tuned at ECS . I have changed gearing in several Corvettes and to me this is best performance mod to start with. Instant snap from the jump and still have top end and cruise abilities. Never really checked MPG but have not noticed significant drop off. 
Drifting
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From: Outer banks North Carolina
Been there and done that! My old "97" coupe had the 2.73 gear and ran 13.40 on it's best day. I installed the 3.42's and a tune and it went 12.90 with ease. The gas milage drop was from 30 highway to 27-28 highway. You will not regret going with 3.42's!
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From: Cohoes New York 12047
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From: Reno is so close to Hell you can see Sparks , State Of Confusion
St. Jude Donor '12-'13-'14
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From: Cohoes New York 12047
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From: Reno is so close to Hell you can see Sparks , State Of Confusion
St. Jude Donor '12-'13-'14
All the rear ends have a plate that is visible with the gears on the tag, It should also be in the glove box on the rpo codes.
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I got a 97 6 speed car did all the rear ends come with the 3:43 gears? would like to go to the 4:10 gear since i have to pull it to change out a broken output shaft and i have it that far apart. Who makes a good gear set?
Instructor
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From: La Mesa California
How about changing my 2011 c6 coupe 6L80 a6 tranny, diff 2:56 to a 3:15 ......can you show me those and tell me what kind of tune I would need. I have no engine mods accept I added a z06 oil cooler, steering cooler and 2 bm tranny coolers, and a 3" dewitt radiator. I do good on the track but would like to stop using 2nd gear so much for drive off out of the corners.
Drifting
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From: Jasper Alabama
I have a 2002 coupe A4. Never understood why GM went with 2.73 gears on the vettes. 3.15's would have been a better stock gearing for them. Anyway's I swapped out my 2.73's for a Z06 3.42 differential and a 2800 stall. Sent my PCM to East Coast Superchargers and they did a.mail order tune to reprogram performance parameters and shift points. After putting it all back together total night and day difference. Is totally what you expect a Corvette to feel like when getting on the gas. Totally streetwise as well.
God bless him.