I need help in selecting some rear end gears for my daily driven seldom raced 93 Z28 that has a LT4 Head and cam package, SLP 1 3/4" shorties, corsa cat back, random tech cats, 2800 rpm vigilante torque converter and a possible 75-100 shot of Nitrous. I have it narrowed down to 3.23, 3.42, and 3.73 the car currently has 2.73 in the rear any input would be appreciated.

Thanks a lot
Mike

 

3.73's are the popular choice for A4's. But seeing as how you rarely race, I would suggest 3.42's

 

2.73 to 3.42 here. I like it. Wouldn't want it reving any higher for the freeway driving I do. Don't forget to get a new reluctor ring if you go with a 3 series carrier. They are different and the ABS won't work if you leave the 2 series ring in. Ask me how I know. Man, your car is going to run soooo much better after the gear change if you have all those mods installed already. How is you low end now??

Jeff D.

 

I second the 3.42 selection, it will put you at
~5800rpm @ 100 mph in third (through the traps)
~3150rpm @ 70 mph & ~4500 rpm @ 100 MPH in drive and
~2300rpm @ 70 mph in OD

3.73 it will put you at
~6350rpm @ 100 mph in third (through the traps)
~3400rpm @ 70 mph & ~4900 rpm @ 100 MPH in drive and
~2500rpm @ 70 mph in OD

 

Could someone explain to me the difference between a 2 and 3 series carrier? I have a 2.73 car and understand mine is a 2 series, if I use the gears off a 3.42 car will they work? Are all of our cars 2 series?

 

I would go 3.42's with the nitrous. 3.73's if staying NA. I have 3.42's and they work well with the NX 150-175 shot.

 

I just got some 3.73's that i am gonig to put in my car within a few days here. So you all are telling me that I will be doing the quartermile while at the redline . I seemed to think that I would be able to still hit over 100 in 3rd gear.

The Calculator here says that you are WRONG

http://www.fbody.com/calc.htm

 

da wha!!?!?!


my third gear DOESN'T KICK IN until 96 mph.... at WOT....

 

I HAVE A SET OF 3.42 GEAR ILL SELL YOU FOR $100 LET ME KNOW IM TRYING TO SELL THEM AS FAST AS I CAN IF YOU WANT THEM ILL WILL TAKE PAYPAL AS PAYMENT

 

Go here for a great calculator to compare gear ratios.

 

I have 3.73s in an A4 and I don,t come near 6350 in third through the traps. I love my 3.73s but I had to buy some traction aids.
I have my rev limiter set at 6250 and I don,t ever hit it in third goin through the traps.

 

With a 25.9" radial, the typical diameter for street 4th gen's (no tire growth) in 3rd gear (1:1).

3.42: 6,000rpm = 135mph
3.73: 6,000rpm = 123mph

To give you a good answer to your question, it would help to know how high your combo revs.

Rich Krause

 

I would go with a 3.42 if I were you.

 

3:73 is the best all around street strip gear. were not talking about that big of a difference between the 2 but imo id use the 3:73.

as for the carriers,most a4 came with 2:73 gears and a 3:08 and lower carrier.
most of the 6spd cars acme with 3:42 gears and the 3:08 and higher carrier.

you can buy gears for either one as long as its a match. im saying you can buy 3:42 or 3:73 gears but you HAVE to buy them made for a 3:08 and lower carrier to be installed in your car.