Z51 axle ratio
 

The Z51 package includes a performance rear axle ratio. What is that ratio and what is the basic ratio?
Thanks in advance
Al

3.62 vs 3.80

Pardon my ignorance but that’s not a big difference, right?

Depends on how you look at it. It is about 5% more torque multiplication.

Probably .2-.3 tenths in 0-60 time.

Changes effective gear ratio across the board. Car will accelerate harder in every gear due to torque multiplication. Also makes the ratios relatively closer with less rpm drop between shifts.

Hi Sub, I've been looking for this for a while. Where did you find this info? Any idea on the other gear ratios? Gotta put it in my spreadsheet for track use. Thanks!

Literally everywhere.

yes

Err, no.

Let us pretend 1st gear is 2.97 and that second gear is 2.17
With 3.62:1 rear gears the ratio between 1st and 2nd is 2.97/2.17 = 1.368
With 3.80:1 rear geats the ratio between 1st and 2nd is 2.97/2.17 = 1.368
Now if you shift the 3.62 geared car at 6250 RPMs you end up at 4566 RPMs in 2nd gear
....... if you shift the 3.80 geared car at 6250 RPMs you end up at 4566 RPMs in 2nd gear

No difference in the ratio of the ratios.

Almost no difference at all. You can barely feel any didifference going from 3.50 to 3.90, 3.62 to 3.80 for get about it.

if it were that sig. then there would be lower gas mileage with Z51.

Maybe I'm explaining it wrong... but if you plot speed vs. gear vs. rpm you'll find the high numerically rear end geared car the lines will be closer together.

Wrong, it is not "almost no difference at all." Tell me how much a 5% increase in torque multiplication comes out to.

Just going with simple math, the overall ratio ie rear diff X gear is what matters.
This works out to 10.7514 vs 11.286 for 1st gear, 7.8554 vs 8.246 for 2nd gear.

How much fuel mileage is the z51 going to cost me? .25 mpg?

Oh, OK. Tell you how much difference there is between 3.62 rear ratio and 3.80? Beyond the obvious minute numerical difference the answer is real simple. Nothing any of us are going to feel. As if a 0.18 gear ratio can be perceptible. Anyone familiar with this will tell you that a gear ratio change that small is so negligible that it is not worth doing and that is whether you believe it or not or know it or not. Thanks but no thank you for the lesson Pal.

No axe to grind here but, if it makes no difference, why do they do it?

So Sub driver thinks he is getting a "faster" car when he coughs up his additional 5 grand. HP is the same so they need some difference to claim what is supposed to be a slightly quicker 0-60. They need to justify the $5,000 charge. This package is really profitable for GM as it is essentially a substitution of a bunch of parts to ones that are more suited to track use. To put it another way 0-60, with or without Z51 in the real world is a drivers race as they call it.

Nothing!? ;)
 

That's why they have two overdrives!? But, ask Sub since it must be literally everywhere!:lol:

I once went from 2.73's to 4.11's -- THAT difference you could feel!

PUNKY whats with that picture ?