How can I find out which differential my 1995 Z28 has in it? I'm not the
original owner and I've recently learned that there was a factory
performance option for the final gearing. The car has the 4 speed automatic.
There's a couple ways...
The easiest would be to look up the RPO code in the glove box and find out
which axle it came with stock. Although the rear gear still could have been
changed later on, so that's only going to tell you what it came with stock.
The only sure way to know what's in it now is to jack up the rear, put a
chalk mark on the axle, then count how many rotations of your tire it takes
to make the driveshaft go around one complete revolution. For example, if
you have to spin the tire 2 and 3/4 times, then you have 2.73 gears, etc.
Thanks very much. I'll look in the glove box and perhaps check the physical
rotation. I doubt the grears have been changed just by the fact that the
rest of the car seems to be box stock.
You have it backwards.. Turn the tire one time and see how many times the
driveshaft spins. That is if you have a limited slip differential.
If you have an open differential, it's a little harder to do. You need to
either turn both tires at once or hold one still while you turn the other.
In that case, the driveshaft will turn twice as fast so if you turn the tire
one revolution and the driveshaft turns 5.46 times, you have 2.73's.
The absolute way to get the gear ratio is to pull the cover and count teeth.
I can only speak for '98+, but auto's could have 2.75's or 3.21's (if I
remember correctly, could be anywhere in the 2.7X or 3.2X range,
respectively) depending on options. I'd have to check my RPO reference to
be sure, but it's not in a convenient location at the moment... heh heh
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