Crimecrusher

As I was going over options yesterday I noticed that the stock gearing shows to be 3.42 and the Z51 option shows to be 2.73. Am I missing something here? I thought the Z51 had the higher gearing for better throttle response?

Can someone please clear this up or explain it to me....thanks.

BradJ

The 2.73 is only for the automatic Z51, which is lower than the standard 2.56.
All manuals get the 3.42.

Duck916

Those are rear axle ratios. Bradj is right about their application. (I think automatic buyers can opt for a lower 3.15 ratio, instead of the 2.73.)

The Z51 gear differences are in the transmission gear ratios. I'm pretty sure that the lower gears have lower ratios (higher numbers) for better acceleration and auto-cross performance. The result is sometimes referred to as a wide-ratio transmission.

talon90

The 2.73 you are seeing is for automatic (A6) cars only. All manual (MN6) cars which includes Z51 and Z06 have the 3.42. All non-Z51 automatic cars have a 2.56 with the option to order a 2.73. All A6 Z51 cars have a 2.73 standard.

eboggs_jkvl

On a side note:

The Z51 gearing in the tranny makes the 3.42 in the rear act like a 3.91 gear as compared to the stock tranny gearing. A little spunkier off the line.


Elmer

Crimecrusher

Thanks everyone, that explains it.

Vette_DD

No, that was only an option for the 2005 models with auto tranny.

ilkhan

A6 gets 2.56
A6 Z51 (or the perf gear option) gets 2.73

all M6s get 3.43

The A6 Z51 gets a gear change at the differential. The M6 Z51 gets the gear change at the transmission. That help?

HawaiiC6

I know that the Z51 package on the M6 is 3.42 with larger trans gearing to give it more punch then the base or non Z51 cars. Now on the A6 cars with the Z51 the rearend ratio is 2.73 does anyone know if the automatic trans gears are different from the base A6 non Z51 cars?

XCELER8

What about an 05 A4 w/ Z51??

Jon

Vette_DD

Yes, the A6 cars without Z51 get the 2.56 rear axle ratio. However, you can order the 2.73 rear axle ratio as an extra cost option. The gears themselves are the same ratio.

..GEAR......Mode..or..Option
............Z06...Std.6-spd...Z51.6-spd...6-spd.Auto...4-spd.Auto
..1st.......2.66....2.66........2.97.... .....4.03........3.06
..2nd.......1.78....1.78........2.07.... .....2.36........1.63
..3rd.......1.30....1.30........1.43.... .....1.53........1.00
..4th.......1.00....1.00........1.00.... .....1.15........0.70
..5th.......0.74....0.74........0.71.... .....0.85
..6th.......0.50....0.50........0.57.... .....0.67
Reverse.....2.90....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)

talon90

For 2008 all A6 non Z51 cars have a standard of 2.56 as was mentioned above and can be ordered with a 2.73. All 2008 A6 Z51 optioned cars have a 2.73. 2006 and 2007 A6 cars Z51 or not have a 2.56, period. No difference in the rear end on a Z51 vs. a non Z51 for those years. No option of a performance axle.

talon90

The 2005 A4 had a 2.73 standard whether it was Z51 or not. There was an optional performance axle of 3.15 that was available. Check your RPO codes in the glove box for code G90 for the performance axle. If it has GU2 it is the 2.73.

CH-Z51

Thanks for that info, I've been wondering which gear was in my 05 Z51 and you confirmed that I have the 3.15.

m_LeDez

So I have a '05 M6. To get the gearing close to a Z51 I would need to change the rear diff. gears to a 3:90's, correct?

I wonder if anyone has changed out their std. C6 gearbox to a Z51 gearbox. $$$$ !

HawaiiC6

Now you have me confused you are saying that the Z51 package for Automatics in the production years 2006 and 2007 have a 2.56 rearend gearing PERIOD WITH NO OPTION FOR A 2.73??? Why was I told that the Z51 package was with a performance rear axle ratio meaning 2.73, along with the crossed drilled rotors and the performance suspension?

XCELER8

Sweet. I have a G90=3.15 Learn something new everyday..

Thanks
Jon

GaussianMist

I hear a lot of people in the C6 Tech talking about 4.10 gear upgrade. How does this compare with the Z51 gears? With all the info. posted, I'm not quite sure if they are talking about the same gears.
I don't mean to hijack the thread.

Ron H

Interesting.

Back in the day (late 60's and early 70's), the auto-cross manual transmission of choice was the M22, which was a close ratio transmission. This was developed road racing with coarse cut gears, aluminum case and close ratio gears. I believe the thinking was that when down shifting you were higher in the RPM range so you could be back on the power curve sooner.

This thinking makes sense to me, so I am quite interested to hear what the reasoning is that a wide ratio tranny would be better.

talon90

There was no performance axle option offered in 2006 or 2007. All 2006 and 2007 automatic transmission cars (Z51 or not) have a 2.56 rear period. You will find many, many underinformed sales folks out there, sad but true. The 2008 Z51 has a standard 2.73, the non Z51 2008 automatic has a 2.56 standard with an option for a 2.73 performance axle. I suspect that the dealer was simply confusing what is currently available with what has been available in previous years.