texas99Z28

I own a 1999 Z28/A4 with the stock 7.5". What performance gain should I expect going form 2.73 to3.73? Also, is it even worth it to put ring and pinion into my stock rearend? My car is currently at 330 rwhp. What else should be replaced other than the ring and pinion. My car has about 56000 miles on it. Thank you for any insight.

jetlag

iTrader: (32)

Most people on here will say that spending any bit of money on the stock rear is a waste... and I would love to just go out and spend $2500 on a Moser 9"...but... I'm just going to put the 3.73s in and see what happens..haha

chevrolet02z28

i got 373s in mine did an auburn posi unit with slp's aam ring and pinion... dont seem to have a problem... in my opinion u really shouldnt unless yer beating the **** out of it 24/7.... have had mine in for a few thousand miles and no problems... running down the track on a 93 degre day i ran a 13.6 stock.... i did the posi unit and 373s a week later... and it was about 89 degrees... and it ran 13.1.... im hoping to run it in cooler weather once the track opens..., i definitely should do a hell of alot better running on a 50-60 degree day as compared to 90 with high humidity....

BOLO

iTrader: (40)

What do you want out of the car? is it a DD? street/strip?
You will definitely feel the difference in acceleration going from a tall 2.73 to a 3.73 gear. And ofcourse you will use up more gas doing so. Add a high stall converter in the 3600 rpm range or higher and cut your 1/4 mile time 1/2 second or more. Then you'll need some drag radials to hook up. As you can see it adds up to more mods in order to attain ones goal.
As far as the stock 10 bolt's longevity, it all depends on how much abuse its taking. I'm still on the stock 10 bolt w/ a 4.10 gear and knock on wood...it still holding up even on 150 shot of juice. Hope this help.

MattIROC

iTrader: (19)

I went the route where it costed me $355 total to swap from 2.73's to 3.73's. I went with the 2 series Motive 3.73's, new gear oil, posi additive (some say not needed, I got it anyways), and install from my dads buddy. I picked up 7 tenths from the change, the only change was a 20 degree temp drop. 60fts were the same. Since you have much lower miles on your rear than I do, I would go for it. My gas mileage hasn't changed much. I still average 19-22 with a mix of city/hwy, and I get on it just about everyday.

99w69kitt

iTrader: (6)

i am in the same boat they say to put bigger axles. that is whats usually breaks on the 10 bolts when you go to 2.73 to 3.73 but then again thats what i heard. I am going with a eaton posi lock 3.73 aam

99DROPTOPZ

iTrader: (5)

I have 2.73's too and I looked into the 12 bolt Moser 33 spline 3.73 and its $2400 on a discount so, I can't afford that right now, but that's the way I'm gonna go. I wanna be able to ride out to the track and not have to worry about my stock rear-end breaking on me. My car is street/strip car.

00BlueTA

iTrader: (8)

I went from 2.73 to 3.73 and it droped me from a consistant 13.3 to a consistant 13.0. I think it was worth the time, everyone has bad things to say about the ten bolt but from what I've seen its just luck of the draw. I have seen a stock 10 bolt down the the control arms phb t/a only 4.10 in it go 10.98's on more than a dozen occasions in a auto, or a M6 with contorl arms phb 3.73 go 11.35 on spray with 10 bolts. I would rec gears to anyone, even in the 10 bolt.

snake charmer

iTrader: (118)

+1 some on here are running 400+ na with 4.10s in a m6 with the stock 10 bolt . it is really in all you drive it as well as avoiding wheel slip .

dragracer44life

i got one tenths of a second...13.1-13.0