Stephen68

Hey guys, i just recently picked up a 97 Z28/LT1 and have a question. According to my RPO codes, my car has 2.73's in the rear (GU2). Can anyone tell me if these gears should be slow shifting or long legged? Basically i need to know from someone how these gears feel under acceleration so i can figure out if i have a problem or not. My old 94 Z had 3.73's in her and when you got on the gas you knew it. When you get on the gas in this 97 it seems like its starting out in 2nd gear. Also, my car came from factory with no 1st gear selector on the shifter cover if that makes a difference.

Injuneer

When the car was ordered new, someone neglected to check the GU5 "Performance Rear Axle" option. That would have resulted in 3.23 gears.

Yes, a lower numerical gear ratio results in less torque multiplication at the rear wheels. With the 2.73:1 gears instead of the 3.73's that you are used to, your current ride has about 27% less torque at the rear wheels, on the launch.

If you look at the combination of the transmission gear ratio and the rear axle gear ratio, you get:

1st Gear w/3.73 = 11.41:1

1st Gear w/2.73 = 8.35:1

2nd Gear w/3,73 = 6.07:1

(this ignores any torque multiplication of the toreque converter)

So you can see that the 2.73's in 1st gear are not quite as weak as the 3.73's in 2nd gear, but they are give up a lot compared to them.

Stephen68

Thanks Injuneer, i was hoping it wasnt my actual tranny. The previous owner said it had a shift kit in it but had no idea what kind....im kind of wondering lol. Anyways, i am planning on either 3.43's or 3.73's....found a complete rear end here local with 3.43's for $250.....

FirstYrLS1Z

no 1st gear selector on the shifter cover just prevents you from manually engaging 1st gear,1st gear auto function still exists(as from starting from a stop).
Most just remove the plastic tab to allow manual engagement of 1st,although I see no reason for wanting to manually engage 1st or hold 1st gear.
Need some posters to chime in to give some reasons to be able to manually engage or hold 1st gear.

Stephen68

Thanks FirstYrLS1Z, appreciate the info. On a separate note, can anyone recommend a good but cheap OBD2 code scanner? I just want to be able to pull the codes so nothing fancy.

97WS6SCharged

Actron makes a good OBD2 scanner that runs around $140 give or take. Gives you the code and a description and can clear it.