SS Z51

Someone explain this to me. I was working on calculating MPH vs. RPM in different gears. Why do they state on an 08 Z51 a final drive of 3.42 if the rear axle says its 2.73? Where am I missing the multiplier?

C6 4 AL

The manual trans is 3.42 the A6 is 2.56 or optional 2.73

Vette_DD

If the tranny is an A6 and the car has the Z51 option, I don't think there's a choice. It will have the 2.73 rear axle ratio (if it's a 2008 or later).

LarryMJones

The numbers you are posting are axle ratios from what I can determine. Some publications on the Vette indicate axle ratio of 2.56 on the auto others say final drive ratio 2.56.

But the transmission 5th & 6th gears are over drive gears. The auto 5th is 0.85, 6th 0.67. If the 2.56 is the axle ratio you have to use the following.

To get final Drive ratio you multiply transmission ratio x axle ratio.

Fot the Auto 6th gear 0.67 x 2.56 = 1.71 final drive ratio

For the 6 speed manual 0.5 x 3.42 = 1.71

I have always thought the 2.56 was axle ratio, and the Corvette Action Center 2007 Production data sheet list it as a 2.56 axle ratio. Maybe someone knows for sure.
LJ

Vette_DD

You know there are websites that will do this for you if you know the rear axle ratio, right?

http://mysite.verizon.net/foofoo2/c6/

haljensen

Don't forget the Manual Z51 different trans gears and the Auto Z51 different rear gear that give slightly better acceleration ratios (higher numerically final drive ratio) to the Z51 cars.

M6 3.42 X .57 6th = 1.95 final drive

A6 2.73 X .67 6th = 1.83 final drive

LarryMJones

I suspect you are correct on the manual 6 speed. My source had manual 6th at 0.5 not 0.57.
And I just confirmed the posted numbers are axle ratios not final drive ratios.
I just found a Motor Trend confirming the manual 3.42 final drive ratio is 1.95.

That confirms the standard auto is 1.72 final drive ratio.


Recap
Standard Auto Final drive ratio 1.72
Optional 2.73 Auto 1.83
Manual 1.95

If your headed to Bonneville you better take an auto with 2.56 axle.
LJ

Vette_DD

--GEAR------Mode--or--Option
------------ZR1---Std 6-spd---Z51 6-spd--6-spd Auto--4-spd Auto
------------------- & Z06 ----- & GS
--1st-------2.29----2.66--------2.97--------4.03--------3.06
--2nd-------1.61----1.78--------2.07--------2.36--------1.63
--3rd-------1.21----1.30--------1.43--------1.53--------1.00
--4th-------1.00----1.00--------1.00--------1.15--------0.70
--5th-------0.81----0.74--------0.71--------0.85
--6th-------0.67----0.50--------0.57--------0.67
Rev---------????----2.90--------3.28--------3.06--------2.29
-
Axle Ratio--3.42----3.42--------3.42---2.56(or 2.73)--2.73(or 3.15)


Gear Ratio times Rear Axle Ratio
--GEAR------Mode--or--Option
------------ZR1---Std 6-spd---Z51 6-spd----6-spd Auto------4-spd Auto
------------------- & Z06 ----- & GS
--1st-------7.83----9.10-------10.16-----10.32 or 11.00---8.35 or 9.64
--2nd-------5.51----6.09--------7.08------6.04 or 6.44----4.45 or 5.13
--3rd-------4.14----4.45--------4.89------3.92 or 4.18----2.73 or 3.15
--4th-------3.42----3.42--------3.42------2.94 or 3.14----1.91 or 2.21
--5th-------2.77----2.53--------2.43------2.18 or 2.32
--6th-------2.29----1.71--------1.95------1.72 or 1.83
Rev---------????----9.92-------11.22------7.83 or 8.35----6.25 or 7.21

haljensen

Read JimTN's post above, it shows the M6 Z51 6th gear at .57. the Manual Z51 trans used different gear ratios for every gear except 4th.

LarryMJones

Didn't realize the 6 speed manual had different gearing on the Z51.
That's where the 0.5 and 0.57 final transmission ratios cmae from.

In any event the ratios posted are for the rear axle are not final drive ratios. this requires the calculation.
LJ