This 89 LO3 Camaro I bought appears to be all stock. RPO codes say 2.73's. But when I was crusing at 70mph I was at 2400rpm. Thats what my other Camaro would do with 3.42's. Or is that just how the Lo3 is? My speedo might be off, I might actually be at 75mph. But still, I thought it would be like 2000rpm.

 

More likely, your tach is off.

If you want to know what your gears are, take off the cover and look. It's the only way to know for sure.

 

You don't really have to take the diff cover off...... Cant you lift the rear end off the ground and spin your tires by hand. if your driveshaft makes 2 and 3/4 turns for one revolution of your rear tire you've got a 2.73........ approx 3 1/2 turns of your drive shaft for 1 revolution of your tire youve got a 3.42??? I know it's really backyard engineering and you need a buddy with you but........ maybe easier and not as messy as pulling your diff cover. At least it kinda gives you an idea

 

You don't really have to take the diff cover off...... Cant you lift the rear end off the ground and spin your tires by hand. if your driveshaft makes 2 and 3/4 turns for one revolution of your rear tire you've got a 2.73........ approx 3 1/2 turns of your drive shaft for 1 revolution of your tire youve got a 3.42??? I know it's really backyard engineering and you need a buddy with you but........ maybe easier and not as messy as pulling your diff cover. At least it kinda gives you an idea

 

I marked a spot on the driveshaft and spun the tires one full turn. The driveshaft went all the way around 4 times and ended in the spot it began. Whats that mean?

 

it means you should not listen to the other guy. just pull the cover off and change your fluid.

 

if i pull the cover off what am i sposed to look at?

 

you need to count the ring gear teeth and pinion gear teeth.



now to make it easy for your self MOST will have the ring gear and pinion geat tooth count stamped on the edge of the ring gear



it will have a few other numbers but, should be pretty easy to figure out which ones you are after

you just ( / ) the ring gear tooth count by the pinion tooth count. this will give you your gear ratio