iquois

How can i find out what gears were stock in my 98 LS1 Z28? I'm sure that the gears in it now aren't stock and I'm not sure how to figure out what I do have now. My speedometer shows 74 mph at 2300 rpm, but when checking on radar I am running 65 mph. Any advise on how to begin...................?

StealthZ06

iTrader: (1)

The M6 came with 3.43's
The A4 came with 2.73's (I think)

Diolar Magnum

M6=3.42
A4=2.73 / 3.23

natronathon

First off, do you have an auto or a manual? if you have an auto, then I can help, otherwise you can completely disregard this!

well here is how i would figure it out. My car when in overdrive with 3.23's is doing about 2000 rpm at 65 mph. Assuming we have a similar tire size, I think a proportion could prolly help.

my gear set - your gear set

3.23 / 2000 = X / 2300

3.23 * 2300 = X * 2000
X= (3.23 * 2300) / 2000
X= 7429 / 2000
X= 3.7145 ~ 3.73's

Granted its hard to be incredibly accurate with rpm readings and mph so the 3.7145 is off a bit, but my educated estimate is that you are running 3.73's. Man, thats not a bad setup. Bet that helps the ol' acceleration quite a bit

nathan

spy2520

iTrader: (3)

you can use the same method with indicated speed and actual speed.
x= (3.23 * 74) / 65. Same thing and also yields something close to 3.73.

Hoss Ghoul

iTrader: (2)

Just call any GM/Chevy dealer, get the service dept. and give them the VIN, that's how I found mine out.

natronathon

if his speedo it 10 mph off, then the gears are more than likely not stock, because even a sizeable change in tires would not result in being more than a few mph off one way or the other. Sounds to me like he has higher than stock gears

Hoss Ghoul

iTrader: (2)

When I went from 2.73 to 3.73 in my third gen I was off 10-20+ as speed increased, generally 15-20. 50=35, 82=60(exactly)...check out www.thirdgen.org for calculators.

iquois

Thanks....looks like it's gonna be 3.73's

jaberwaki

not true even a little bit.....

go from a stocker to a 28" tire your mph will be way off...