rear gear question

**speedracer25f** · 11-19-2007, 11:02 AM

I currently have the 2.73 rear in mine. I want to upgrade to the 3.23. Two questions, has anyone put the 3.43 rear in thier automatic car and if so how does it drive. And once I change the rear how do I recalibrate the speedometer.

**98formy** · 11-19-2007, 11:50 AM

To change to speedo, you need the pcm reprogrammed. I am having the same debate, I also have 2.73's and its also my DD. To me, 3.23's would be a logical choice for the way I drive, but then I drove a 3.73's it not be enough

**98BlackTA** · 11-19-2007, 12:47 PM

I put 3.42 gears in my daily driver A4 and love it. Though it did cut down a little on gas mileage. It pretty much depends on what you want. i had 2.73 in mine and wasn't fast enough on take off for me. When i put the new gears in i can roast the tires up into 2nd gear, third if the tires are cold.

**StuntmanMike** · 11-19-2007, 02:20 PM

Originally Posted by 98BlackTA

I put 3.42 gears in my daily driver A4 and love it. Though it did cut down a little on gas mileage. It pretty much depends on what you want. i had 2.73 in mine and wasn't fast enough on take off for me. When i put the new gears in i can roast the tires up into 2nd gear, third if the tires are cold.

How much mileage did you lose? I was thinking of going the 3.42 route with my A4, but it's a DD and I drive about 300 miles a week, so mileage is a big concern.

**2001NBMZ28** · 11-19-2007, 03:02 PM

There's not much difference between 3.23 and 3.42. I put a complete M6 rear in mine and a converter at the same time, mileage went down some but well worth it IMO (had GU2). If I was just doing gears I'd consider 3.73's even with today's gas prices. Remember you'll need 2 series gears if keeping the original 2.73 carrier. Another option is keep the 2.73's and get a torque converter - highway mileage will remain the same.

**firemedic0135** · 11-19-2007, 03:25 PM

I have 3.73 in my DD but I dont drive 300 miles a week either.
Your rpm's at 70 will be about 2400 and will increase 400 per 10mph in OD.
Other than that they are the chit.Absolutly a blast to drive around.
You will burn up some street tires.
As stated above you will need to get a 2series ring gear if you go bigger than 3.02 if memory serves me right.

**98BlackTA** · 11-20-2007, 10:02 AM

Gas mileage wasn't hurt too bad just a little haven't actually measured it to see. Don't really care with how it drive now it was more than worth it. As far as needed a two stage gear i don't know about when i changed mine i swapped the entire rear end out of a 2001 Camaro SS M6. So i didn't just change gears i changed entire rear ends

**StuntmanMike** · 11-20-2007, 02:11 PM

Great info!

I was wondering about the carrier, but IIRC I saw 3.xx ratio gears for 2 series carriers in Summit Racing, so that's one possibility.

Since I don't know how to set up gears though, maybe swapping out the rear for one out of a M6 might be the way to go.