97rebuiltZ28

So recently my rebuilt Camaro took a dump on me and I might be trading for a 97 Trans Am stock just like my Camaro. My Camaro has 2:73 and this car has the 3:23 performance axle.

I haven’t found a thread that compares the acceleration feel of the 3:23 vs 2:73. So how does it feel all stock?

Shadyredeyes

You won't notice a whole lot of difference to be honest. The 3.23 might pull just a little harder off the line, and your RPM's will be just a bit higher at cruising speeds.

97rebuiltZ28

Okay thanks! I have a number sheet that says that in 2:73 cars 3rd take you to about 160 and in 3:23 it takes you to about 135. So does third at least feel more stout?

Injuneer

Off the line it will feel significantly different. The torque at the rear wheels is increased by 18.3% (3.23 / 2.73 = 1.183). But each gear will top out (redline) at 18.3% lower MPH.

Assuming a 26” tire (stock are either 25.7” or 26.1”), and 5,800 RPM redline, max speed in each gear (anything over ~155 MPH is theoretical, stock engine torque is not enough to overcome aerodynamic resistance):

2.73

1st - 54 MPH
2nd - 101 MPH
3rd - 164 MPH


3.23

1st - 45 MPH
2nd - 85 MPH
3rd - 139 MPH


And to be "correct", the ratio is expressed as a decimal, not with a colon where you typed it. 2.73 (or even more correctly 2.73:1) means the driveshaft has to rotate 2.73 times in order for the axle/wheels/tires to rotate one time.

97rebuiltZ28

Thanks Fred!

Midnight_Z

Injuneer, what would be my mph's in 1st though 4th gear with a m6 and 390 gears? Stock tire height. Currently have 342's. Redline at 6200.

Injuneer

There are two different "stock" tire diameters:

245/50-16 or 275/40-17 = 25.7"
235/55-16 = 26.1"

For a 26.0" diameter, 6,200 RPM redline, with a 94-02 T56 (not for a 93):

3.42

1st - 52 MPH
2nd - 78 MPH
3rd - 108 MPH
4th - 140 MPH


3.90

1st - 46 MPH
2nd - 69 MPH
3rd - 94 MPH
4th - 123 MPH

JakeRobb

Just in case anyone with a 93 reads this:

Your fourth gear is the same, but in ‘93 the T56 F-cars came with different (numerically higher) ratios for 1st, 2nd, and 3rd. Your max MPH for those gears will be lower, and acceleration in those gears correspondingly quicker. The first gear ratio is about 10% different (2.97 instead of 2.66); 2nd and 3rd are smaller differences than that, but I don’t remember the ratios off the top of my head.

Injuneer

There are two different versions of the 1993 T56 - M28 (3.36 1st gear) and M29 (2.97). With the significantly higher numerical 1st gear, they used of either 2.73 or 3.23 rear gears with the T56.

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