grunt1152

So I just picked up my 95 T/A and Im pretty sure it has a different rear gear than stock. The car runs about 5mph over what the spedo is reading and the tires are not whats causing it to read wrong. The car pulls harder than any other Camaro or T/A Ive rode in.

Is there any calc out there to see what size gear im running rather than pulling off the diff cover?

RamAir95TA

iTrader: (2)

An easy thing to do is to jack up the rear wheels, throw the car in neutral, accurately mark the driveshaft and wheels, and spin them by hand, counting the revolutions.

grunt1152

How many revolutions equal what?

rich5368

iTrader: (2)

A less accurate way that will get you in the ballpark is at 70mph auto drop out of overdrive and see what your rpms are. If it's a manual use 4th. That'll get you in the ballpark. The car going faster than the speedo reads suggests that you have a lower gear than stock. If you had a higher gear then the speedo would read higher than your actual speed.

grunt1152

Its a m6 car so it had 3:42s stock. Im wanting to say it has 3:73s. When I drive it in a few I'll post what the tach is showing at 70 in 4th.

1994Z28Lt1

iTrader: (1)

if it now has 3.73's and the computer wasn't tuned to correct it, when your speedo shows 70 you would actually be going 64

so it sounds like you got it backwards

jaycenk

iTrader: (1)

Mine is off in the other way. so when I am doing 60 on the spedo I know I'm at 55 lol. Damn F body

grunt1152

I misstated what I said in the first post but that is right. The speedo shows 70 and I'm actually doing about 64 or 65. I run the car to 70 (75mph on the speedo) and I was running about 3200rpm. So 3:73?

Z48LT-1

Driveshaft goes around 3.42 times for the wheels (both of them) to go around once - 3.42:1. Driveshaft goes around 3.73 times for the wheels to go around once - 3.73:1. You won't be able to get the last decimal with any accuracy, but the difference will be about a quarter revolution of the driveshaft, which ought to be evident.

Best -- Gary

I have yet to see any problem, however complicated, which, when you looked at it in the right way, did not become still more complicated. -- Paul Anderson