In the next few months, I'm planning making some mods on my 98 Z28 A4. I'm trying to decide if I should got with a 3.42 or 3.73. Anyone know what type of mileage and what RPM's you turn at 60 mph with each of these.

Also, does the 98 come with a 7 1/2" or 7 5/8" rear end?

fyi...other future mods will include a Direct-Flo lid, SLP MAF, new exhaust, and torque converter around 3000 stall.

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1998 Z28
A4 w/2.73's

 

If you're getting a TC then I wouldn't go any higher than a 3.42.Also I "think" that the 2.73's come with a 2 series carrier,so you will have to get a new posi also.Good luck.
Kevin

PS
I'm going with a 3200 stall also and I am keeping my 3.23's.I didn't want to kill my top end too much by going with too steep of a gear.Some guys say that the 3.23's are the perfect balance for a stall converter on an A4.Just something you might want to check into.You may be making your car into a BEAST!

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1998 Black Z28 A4
-------1/8-------
8.584 @ 83.64 MPH
Pics
Camaro/Firebird Birthday Bash

 

2.73s do come with a 2 series carrier, but Summit sells 3.42s that will fit a 2 series carrier...... I have a set of richmond 3.42s in my to series carrier where i updated from 2.73s...


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Arctic White 1998 Z28 Camaro LS1 A4
3.42 Gears, Whisper Lid, Exhaust,
NOS Dry Kit.

 

I swapped my complete 2.73 rear with a 3.42 rear out of an M6 car. Bought it off a guy who got a new Strange, complete with T/A girdle and stud kit for $350. Neither car had traction control. Went from 80 MPH at 2K RPM in OD to 65 MPH after speedo correction.

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A4 (3.42)/Whisper Lid/Corsa Catback/FTRA/BMR STB, LCA's, APHR/160+Tstat/SLP Fan Switch/HPP3

 

If you could find a stock, complete rearend with 3.42's, then that would be the cheapest route. You can find them pretty easily out of M6 cars that have upgraded to a 9" or 12-bolt rearend, and they'll usually sell them for $300-$350. You'll pay that alone for a set of gears, install kit, etc. Throw in another $200-$250 in labor, and you could've had a spare rearend for cheaper!

I had 3.42's in my '98 T/A A4 for a while, and it tached 2,300 at 70 MPH. My SS has 3.73's, and it tachs 2,450 at 70 MPH. I lost 2.5 MPG by going to 3.73's from 3.23's. FWIW. 3.42's will be more friendly on the street after you swap torque converters. 3.73's paired up with a Vig 3200 stall will hit HARD! It did when I was running that converter in my SS. BTW, we do sell all of the P.I. Vigilante converters here at L.G. Motorsports, so feel free to give me a call if I can help you out.

Trevor - LGM

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'02 SS: 11.63 @ 114.06 MPH, 1.588 60'; 3,515# raceweight, 1,102' D.A.
naturally-aspirated with bolt-ons, a cam, and a fat converter!
L.G. Motorsports (972) 272-7753
Check out the SS!

 

Sounds like the 3.42 may be a better choise then as I want the car to be comfortable to drive. I believe I need to decide for sure on that TC first though.

One more question, does the factory 3.23 come with a series-2 or series-3 carrier?



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1998 Z28
A4 w/2.73's