christopherjmartin

I'm getting ready to pull the trigger on installing 4.10s in my A6 but I saw a post yesterday that got me questioning that idea.

I couldn't find the post but basically what someone said was that "4.10s in an A6 are not recommended".

Is this true? If it is, why wouldn't they be recommended? Is there an "acceptable" limit as to what higher gear ratio does work well with an A6?

I don't want to spend all that money on the wrong mod so if someone has some insight into this I'd really appreciate it.

Thanks,
Christopher

BLK06VETT

Hello Christopher,

I Talked With Chuck At Cow Yesterday And He Told Me That 3.15 Or 3.42 Would Be The Most To Put In An A6 Car. I Am Going To Do A Gear Swap In My 06 A6 Also. Maybe One Of The Other Members Have Already Done This To An A6, And Could Shed Some Light On Which Gear Set Works Best Between 3.15 And 3.42. Hope This Helps.

Mark

Miaugi

...the A6 already has a very low 1st & 2nd gear, 4.10's would be good for shredding tires...but probably useless for regular street driving.

Follow the advice given above from Chuck Cow, he loves 4.10's (in a stick car), if he says it's too much for an A6...then it's true!

christopherjmartin

Did he happen to say why that was the highest you could go with?

Where are you getting yours done? I'm not all that far from you so if your experience ends up being a good one I might want to give the shop some extra business.

If you don't mind, could you PM me as to how much you're paying for the job? I'm still toying with the idea of doing it myself but may just end up having a shop do it instead.

Thanks for the response,
Christopher

BLK06VETT

I Am Trying To Find A Good Shop Around Here, A Lot Of Vett Guys I Have Talked To Are Going To A Guy In Sacramento I Think. I Will Give My Friend A Call And Find Out The Name Of The Shop. The A6 Cars Have A 4-1 First Gear And The M6 Have A 2-1 First Gear. Thats Why I Think 4.10s Work For Them And Not For Us A6 Guys.

Mark

DOUG @ ECS

4.10's are definately too much for an A6, personally I would recomend 3:15's.

christopherjmartin

I heard back from DTE and they said that 3.15s are the only gear ratio even available for my car so I guess that's the way I'm gonna go.

greentank

I did 315's two weeks ago. Love them.

Be advised - LS2Edit CANNOT adjust your shift points and speedometer, which WILL have to be adjusted. HP Tuners and EFI Live can. I'm stuck with LS2Edit for a short while, and I'm putting on 25% more mileage than I actually drive until I can get it retuned.

christopherjmartin

Is there really that much of a noticeable difference?

What did it end up costing you in the end? You can PM me if you'd rather not post it.

Thanks,
Christopher

johnodrake

Good choice! Even if 3.42 were available, that would be like having 4.56 gears in a MZ6 (for 1st gear)

mikegritch

If you could even put a set of 4.10s in the rearend of an A6 you would probably get to about 30mph. Here are the calculations based upon the transmission and model etc
A4 A6 M6 M6 - Z51
Rear Gear2.73 2.56 3.42 3.42
TRANSMISSION GEAR RATIO
1 3.06 4.02 2.66 2.97
2 1.63 2.36 1.78 2.07
3 1.00 1.53 1.30 1.43
4 0.70 1.15 1.00 1.00
5 0.85 0.74 0.71
6 0.67 0.50 0.57
EFFECTIVE REAR END RATIO
1 8.35 10.29 9.10 10.16
2 4.45 6.04 6.09 7.08
3 2.73 3.92 4.45 4.89
4 1.91 2.94 3.42 3.42
5 0.00 2.18 2.53 2.43
6 0.00 1.72 1.71 1.95

A4 A6 M6 M6 - Z51
Rear Gear4.10 4.10 4.10 4.10
TRANSMISSION GEAR RATIO
1 3.06 4.02 2.66 2.97
2 1.63 2.36 1.78 2.07
3 1.00 1.53 1.30 1.43
4 0.70 1.15 1.00 1.00
5 0.85 0.74 0.71
6 0.67 0.50 0.57
EFFECTIVE REAR END RATIO
1 12.55 16.48 10.91 12.18
2 6.68 9.68 7.30 8.49
3 4.10 6.27 5.33 5.86
4 2.87 4.72 4.10 4.10
5 0.00 3.49 3.03 2.91
6 0.00 2.75 2.05 2.34

As you can see you would have a 16.48 to 1 effective ratio in 1st gear. With my standard A6 if I'm not pushing the button the moment I hammer it I'm hitting the rev limiter.

SoldSyclone

The A6 has a 4.02 1st gear thats why.

That would be the same as putting 6.20's in a M6 would you do that?

Not to mention you would need to use 5th gear in the qtr mile LOL
You would lower your top speed to 142mph in 5th but you may be able to pull 160 in 6th.

M6 with 4.10's
2.66x4.10=10.9 so the same with the A6 would be
4.02x2.71=10.9

So 2.71 rear end if you like the 4.10's in a M6

But 2nd has a bigger split so 3.15's are better for 2nd, 3rd and 4th

Larry R. Quinn

Trust me , you will love the 3.15 differential in the A6 . It made a world of difference in mine . As mentioned before , get the right tune to take full advantage of the gear change .

greentank

Difference? Absolutely. Think about it...you're basically concentrating the work your engine does through the range of a gear by 25%. I couldn't see going higher than 315.....it feels just about perfect. The only downside I see is having to shift into 4th in the quarter mile....but I'm not a big racer, so I don't care much about that.

Gears cost around $2500 for mine (I got stage II. there are many stages, and options within the stages. DTE posts prices on their site). Shipping is around $200. Install around 4 hours. Haven't tuned it yet..but it needs it.

Took a friend and fellow C6 A6 owner for a ride on Monday....he was blown away. He said it was a totally different car than his. When I did the cam and heads, he noticed a difference, but not nearly as much as with the gears. He's now considering them himself instead of doing a cam.

glass slipper

And then you have the 2-2.5:1 torque multiplication of the torque converter (something overlooked by many people) at stall speed to multiply the effective ratio by creating an enormous amount of torque at the rear wheels ...I can hear the axle shafts snapping already (if it ever hooks).

TRJ

Doug,
I was also thinking of 3.15's for my 2007 A6 Z51, but I was concerned with the power I was putting down. I have 472.1 RWHP and 484.8 RWTQ on 345/30/19's. I wonder if I could get your opinion on getting the 3.15's, or staying with the stock 2.56's. TIA...

0Chuck CoW

Tell ya what..... 3.15's will be the best all around gear fror most A6 guys.....

BUT, we've got a 3.42 that you can't break for the real HIGH TRACTION GUYS!

VERY SOON I'll be able to ship you either rear AND the tuning for it to make it work...

We have a HUGE inventory of BRAN NEW GM cores we're preparing.... It will be sold as a package along with the correct computer calibration to make the whole jammy work just like stock.....

Most guys doing this right now don't have the programming worked out right.....

As soon as the remote tuning is working perfectly, we'll be able to ship you a complete turn key system for the A6 and there will even be an option for the AMAZING PRO-TORQUE A6 Converter.

Watch out MN6 CARS! HERE COMES THE A6!

STAY TUNED!
Chuck CoW

vetracer

I canceled my order for a set of 3:15's today because of this. My car was tuned with LS2Edit and to put the 3:15's in I would have to have a local shop re-tune my car with HP tuner to the "tune" of around $1000 in addition to the cost of the diff swap. No thanks, not right now I just got the car tuned with LS2Edit

Sure you may be able to re-program shift points but I would be interested to see if the software can be changed so that you cannot accidentaly engage a lower gear when you are going too fast as it does with the stock gears. That's a great feature to have when you are battling it out with another car on a road course.

greentank

The rev limit software functionality is pretty basic - I'd be VERY suprised if it was not included...but I'll let you know. $1000 for a tune!?!?!? You're being robbed. I hope they kiss you while they're at it. Even DTE, who takes 3 days to tune a car, only charges $500.

My current plan is to have Chuck re-tune my car sometime near bloomington gold. Some logistics need to be worked out, but one way or another, I have to get retuned soon.

TRJ

Thanks for the info Chuck, sounds great, I'll be all ears...