JKearney30

iTrader: (2)

98 z28
LTS, ORY, Borla Cat-Back, Lid and bought a LS6 intake that is going on this weekend.

I am doing the rear the following weekend as my rear is humming like crazy right now. Its A4 with a BEEFED tranny just did it a month ago. I currently have 2.73's and wanna go to 3.42's or 3.73's? Is there a huge difference? I want to go with 3.42's cuz it does see the highway quite a bit but I don't wanna put 3.42's in and regret it and want 3.73's. Is there a huge difference in feel and performance?

NC98Z

iTrader: (1)

Get you a set of Yukon thick gears and you'll want the 3.73s. The last set I had installed were quiet and didn't roar a bit. Go to this site and punch in your variables and you'll see there isn't that much difference between the 3.42s and 3.73s when the ODs locked up on the highway. http://www.pszweb.com/car/gears.htm

nemss1

agree, 3.73s in my opinion on a stock stalled auto

FirstYrLS1Z

iTrader: (4)

2.73 to 3.42= 25% increase in torque to rear wheels
2.73 to 3.73= 37% increase in torque to rear wheels

armyboyatc

iTrader: (29)

3.73 is a good street gear. I just put gears in my A4 Z28 and I put 4.10 in it. Go big or go home..... Im really gonna regret that when im stopping at the gas station every other day......

FirstYrLS1Z

iTrader: (4)

the 4.10s' aren't gonna be as bad as you think for gas mpg.
my 3.23s' gave me 24.5 mpg,the 4.56s' give me 21.5.
mpg is right foot dependent.

QwkTrip

iTrader: (23)

I just went from 2.73 to 3.42 and it's a real tire burner now. The A4 has a pretty steep first gear and you get torque multiplication through the torque converter as well. The RPM's are as high as I want on the freeway.

TXZ28LS1

iTrader: (5)

i had 2.73 when i bought my car. im running 3.73 right now, it woke up my car. but ive been wondering about stepping up to 4.10. im curious what to expect with a 3200 stall, 4.10.

Bob@BruteSpeed

iTrader: (16)

Back in 1978 I had a Trans-Am with a turbo 400, 3500 stall and a 12 bolt (from a '70 T/A) with 4.10 gears. 60 mph was about 3500 rpm... 4.10 gears with a 4L60E is very tolerable. If most of your driving is on the highway, then I'd go with 3.73 gears. Otherwise I'd go with 4.10 gears. Bob

Tobias05

iTrader: (1)

3.42s here. in both cars, unfortunately.

QwkTrip

iTrader: (23)

You can't make a suggestion for what rear gear ratio to choose for a 4L60E based on experience with a TH400. The transmissions have totally different gear ratios. The TH400 has a 2.48 first gear ratio. The 4L60E has a 3.06 first gear ratio. Mating 3.42 rear gears to a 4L60E gives you the same total first gear ratio as a TH400 with 4.22 gears. The whole point of the A4 transmission is to give you low gear response like an aggressively geared old muscle car without needing the old muscle car gears that blow away highway mileage and drivability. In any event, I would completely steer away from 4.10 gears in a stock 10 bolt because those gears aren't very strong and tend to break. No aftermarket gear is as strong and quiet as the original GM gears.

Bob@BruteSpeed

iTrader: (16)

I would agree with you if we are just talking about launching in 1st gear. However, a lot of people play around in 2nd and 3rd gear too. Bob

QwkTrip

iTrader: (23)

Very true.

JustAnotherLS2

1st gear? Whats that?

Kirby

I think this thread has me sold on 3.73s now when I tear down my rear end for a rebuild this week. Thanks for the input everyone.

dlk1950

I think you will be happy with the 3.73s.