# New LS1 Owners - Newbie Tech - gear ratio

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draggz28
02-15-2011, 11:08 PM
just bought my 99 z28 and i would like to know what my gear ratio is how do i find that out

RPM WS6
02-15-2011, 11:39 PM
just bought my 99 z28 and i would like to know what my gear ratio is how do i find that out

If it's an M6, and has stock gears, it's 3.42. There was no other option.

If it's an A4, and has stock gears, it's either 2.73 or 3.23. You can determine which by checking the RPO code on the sticker found on the driver's door jamb. 2.73 = "GU2" and 3.23 = "GU5". If the sticker is not present you can check the driveshaft; an aluminum shaft = 3.23 and a steel shaft = 2.73 (this is of course assuming everything is still stock).

Camaropar
02-16-2011, 09:25 AM
Yep almost certainly is 3.42. If someone did a swap the easiest way is to run the car up in 4th @ some mph (say 70) and read your tach. Use an online calc and viola, instant gear ratio.

KSLAYR73
02-16-2011, 11:56 AM
What did the A4 SS's come with?

Z28/2002
02-16-2011, 02:13 PM
What did the A4 SS's come with?
Either 2.73s or 3.23s

RPM WS6
02-16-2011, 04:02 PM
Either 2.73s or 3.23s

All A4 SS and WS6 cars came with 3.23s. RPO GU5 (3.23) was a required option with either WU8 (SS) or WS6, when an auto trans (RPO MX0/M30) was selected.

GU5 was not included in the WU8 or WS6 package price though, so it was listed as a separate costed line item on the window stocker.

jim ravencraft
02-16-2011, 08:19 PM
:angel:hi,
if unsure with ratio. raise rear end and support.place in neutral mark tire with chalk and rotate one revolution. count number of turns on drive shaft. 2 3/4=2.73--3 1/4 =3.23-
3 1/2= 3.42- 3.3/4 =3.73-4 1/10=4.10-4 1/2= 4.56. this is the fool proof way if no tag or marks on housing...........old school...........have a blessed day..........jim

Camaropar
02-16-2011, 11:19 PM
hi,
if unsure with ratio. raise rear end and support.place in neutral mark tire with chalk and rotate one revolution. count number of turns on drive shaft. 2 3/4=2.73--3 1/4 =3.23-
3 1/2= 3.42- 3.3/4 =3.73-4 1/10=4.10-4 1/2= 4.56. this is the fool proof way if no tag or marks on housing...........old school...........have a blessed day..........jim

Tried and true method, I didn't mention it however because if you have a Torsen like many LS1 cars do it makes it quite difficult if not impossible to do.

TheZDeWolfe
02-24-2011, 03:34 AM
99 z28's with the a4 didnt come with 3.42's i swore the last time i checked into mine i thought i read that it had 3.42's. Now you say that im gonna check into that again,something dont sound right?

RPM WS6
02-24-2011, 12:28 PM
99 z28's with the a4 didnt come with 3.42's i swore the last time i checked into mine i thought i read that it had 3.42's. Now you say that im gonna check into that again,something dont sound right?

3.42s never came stock on any automatic LS1 Z28 of any year. There were only two options for the auto trans cars:

GU2 (standard): 2.73
GU5 (optional): 3.23

The only way you could get 3.42s from the factory in an LS1 Z28 was with an M6 trans.