Question about C6 A4 rear end swap
Thread Starter
Drifting
Joined: Sep 2010
Posts: 1,311
Likes: 0
From: Chicago IL
Question about C6 A4 rear end swap
Hello guys, got a mostly stock 2005 A4. Couple of quick questions for the experts:
1.) Whats the stock gear? 2.56? 2.73?
2.) How do I determine what ratio is currently in my car? The previous owner added headers, CAI, and B&B exhaust....so I dont know if he stopped there or swapped the rear end too.
3.) Assuming the car has the stock ratio of 2.56 or 2.73, will a swap to a 3.42 be very noticeable when I get the car back?
4.) Does it really cost close to $2,500 for the swap (including installation labor and re-programming) ?
5.) As far as "bang for the buck" is this upgrade worthwhile? I enjoy hard launches for very short distances (under a city block). Could the $2,500 be spent in other ways to get more of a performance improvement?
Thanks in advance fellas.
Phil
1.) Whats the stock gear? 2.56? 2.73?
2.) How do I determine what ratio is currently in my car? The previous owner added headers, CAI, and B&B exhaust....so I dont know if he stopped there or swapped the rear end too.
3.) Assuming the car has the stock ratio of 2.56 or 2.73, will a swap to a 3.42 be very noticeable when I get the car back?
4.) Does it really cost close to $2,500 for the swap (including installation labor and re-programming) ?
5.) As far as "bang for the buck" is this upgrade worthwhile? I enjoy hard launches for very short distances (under a city block). Could the $2,500 be spent in other ways to get more of a performance improvement?
Thanks in advance fellas.
Phil
Safety Car
Joined: Jan 2008
Posts: 4,711
Likes: 3
From: Middle of No where AK
The stock gearing is 2.73. If it was swapped there should be a stamp on the rear end indicating the gear set. If you do swap to a 3.42 there will be a very noticeable difference in rpm and the way it drives. If you havent done a stall that is another way to get that out of the hole feeling as well. If your going to do an upgrade you also need to consider changing to the 06 and up rear (I didnt but many have) which will cost you a few hundred more. As far as costing 2500 Im not sure. I bought my diff from rpm and then installed it myself with the help of a friend. It took us 4 hours and saved a bunch of money. It will need to be retuned after install because the shift points will be way different.
Thread Starter
Drifting
Joined: Sep 2010
Posts: 1,311
Likes: 0
From: Chicago IL
Hey batmobile....thanks for the reply. RPM quoted me a price of $1795 for a straight swap plus $119 freight. That price was on a 2005 housing. Not sure how much more it would be for an '06+ housing instead. Since I can barely assemble my kid's tricycle, im gonna need a pro install/re-program. I was quoted at around $600 for that...bringing me up to around $2500 total. Seems a bit pricey for just a set of new gears! I always thought swapping rear end gears was an under $1,000 job.....welcome to the "cost" of the corvette owner's club I guess, huh? 
Thread Starter
Drifting
Joined: Sep 2010
Posts: 1,311
Likes: 0
From: Chicago IL
Team Owner
Joined: Sep 2005
Posts: 20,352
Likes: 568
From: Ventura County, Calif
There is an equipment and option code label on the left side, inside of the glove box lid. They're listed alphabetically. Just look for Z51 and I think the 3.15 rear end code is G90.
Last edited by RicK T; Sep 14, 2010 at 04:55 PM. Reason: typo change A90 to G90
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
Thread Starter
Drifting
Joined: Sep 2010
Posts: 1,311
Likes: 0
From: Chicago IL
Team Owner
Joined: Sep 2005
Posts: 20,352
Likes: 568
From: Ventura County, Calif
Race Director
Joined: Mar 2005
Posts: 11,549
Likes: 27
From: Southampton NJ
yes they could but after market looks different check the sway bar if its fat but that could have been added , does it still have the stock runflats if they say 200 treadwear thats the z51 tire
