Question on gears

**01A4Z28** · 02-16-2011, 04:34 AM

Ok i'd like to put a set of 3.73's or a set of 4.10's in my 01 but do i have to tune for them to make sure the speed o will read right?

**TA98** · 02-16-2011, 05:08 AM

you dont have to. but if you dont your speedometer will be off and that messes up your odometer and you will be racking up more miles than youre actually driving

**importhater81** · 02-16-2011, 07:06 AM

Are you an a4 or m6?. a4's require tuning after a gear change to shift properly.

**02sunsetorangeZ** · 02-16-2011, 08:56 AM

i think he is an a4, his name is 01a4z28 lol

**oldmanZ28** · 02-16-2011, 04:46 PM

Assuming you're an A4,which gears do you currently have,2.73s' (GU2) or 3.23s' (GU5) ?
what part of Ohio are you in ?

**98maro** · 02-16-2011, 04:53 PM

If it's an auto. 3"42 or 3'73s

**TLS_Addict** · 02-17-2011, 10:24 AM

Originally Posted by importhater81

Are you an a4 or m6?. a4's require tuning after a gear change to shift properly.

I was told you dont need to have a tune to get it to shift properly, only the speedo will be off. That is from a tuning "expert".

Can I ask where you got that information from? I am not calling you out or anything just curious.

Originally Posted by 98maro

If it's an auto. 3"42 or 3'73s

Good call. I just got a set of 3.73s.

**35th-ANV-SS** · 02-17-2011, 10:27 AM

A4 cars have MPH based shift points I believe. A large enough gear change could affect this.

Probably affects the TC lockup also?

**TLS_Addict** · 02-17-2011, 10:39 AM

Good info 35th.

**shady milkman** · 02-17-2011, 11:27 AM

what are you looking for your car ? people get so scared with autos and gears...if you are doing drag strip ..dont be afraid of 4.xx ..my lord we have a order drive gear ...if you are on the street look into 3.73 to 4.10

**Deezl SS** · 02-17-2011, 11:34 AM

I have 4.10's in my auto street car. I can daily drive it without issue....I run about 2600 rpm at 70 on the highway.

**TLS_Addict** · 02-17-2011, 11:44 AM

Only thing that scares me of the gear change is that some people break the rears out. I dont think I am pushing any huge amount of power I just wanted a little extra for the street and the 2 or 3 times a year I plan to go to the drag strip.

**shady milkman** · 02-17-2011, 12:08 PM

Originally Posted by TLS_Addict

Only thing that scares me of the gear change is that some people break the rears out. I dont think I am pushing any huge amount of power I just wanted a little extra for the street and the 2 or 3 times a year I plan to go to the drag strip.

true but remember autos preload the drivetrain so the shock is so much less than a m6

**shady milkman** · 02-17-2011, 12:11 PM

from a 3.73 to a 4.10 is only about 10% more torque "increase"

**importhater81** · 02-19-2011, 02:30 PM

Originally Posted by TLS_Addict

I was told you dont need to have a tune to get it to shift properly, only the speedo will be off. That is from a tuning "expert".

Can I ask where you got that information from? I am not calling you out or anything just curious.

I went from a 3.23 to a 4.10 in my own a4 car. Due to the different speed to rpm ratio a gear change will bring,a tune is a must in a a4. I'm no "expert tuner" by anymeans. I speak from my own experience.

**TLS_Addict** · 02-22-2011, 05:24 PM

Originally Posted by shady milkman

true but remember autos preload the drivetrain so the shock is so much less than a m6

Very true, less "shock" at launch. I have a stock converter so I will try to just leave around 1600-1700 like last time.........unless my car breaks loose earlier which it might do...lol

Where do you start to get that chawing when you are braking it and hitting the gas?

Originally Posted by importhater81

I went from a 3.23 to a 4.10 in my own a4 car. Due to the different speed to rpm ratio a gear change will bring,a tune is a must in a a4. I'm no "expert tuner" by anymeans. I speak from my own experience.

No doubt. I am going from 2.73 to 3.73 and YES I am getting a re-tuned pcm to compensate for it. I feel it necessary.....I want a correct speedo and no issues what so ever.

**01A4Z28** · 02-22-2011, 06:02 PM

Originally Posted by oldmanZ28

Assuming you're an A4,which gears do you currently have,2.73s' (GU2) or 3.23s' (GU5) ?
what part of Ohio are you in ?

i do currently have 2.73's, i was leaning more towards 4.10's i road in my buddies car and was sold on them and his is also an a4.

i am from marietta

**shady milkman** · 02-22-2011, 08:45 PM

Originally Posted by TLS_Addict

Very true, less "shock" at launch. I have a stock converter so I will try to just leave around 1600-1700 like last time.........unless my car breaks loose earlier which it might do...lol

Where do you start to get that chawing when you are braking it and hitting the gas?

No doubt. I am going from 2.73 to 3.73 and YES I am getting a re-tuned pcm to compensate for it. I feel it necessary.....I want a correct speedo and no issues what so ever.

chawing ?

**oldmanZ28** · 02-23-2011, 04:35 AM

since you're 2.73s' which has a 2 series carrier,you'll need a 'thick' set of gears,unless you get a 3 series carrier (from a 3.23 or 3.42 rearend).
I'm 4.56s' in an A4 and spinning 2500rpm at 60mph,changing your ratio from 2.73s' will give you
-1775 rpm @ 60mph with 3.23s'
-1875 rpm @ 60mph with 3.42s'
-2000 rpm @ 60mph with 3.73s'
-2250 rpm @ 60mph with 4.10s'

you will need a 'tune' to correct speedometer and shift points,but not the type of 'tune' that is associated with a dyno tune,just find someone that has a laptop tuner with 'open' license.
changing from 2.73s' to 3.23s'/3.42s' would be much cheaper/simpler by just swapping in a complete 'take-out' rearend. If that were the case you would need to make sure you got a 'channel compatable' rearend. You didn't state if you're 3 channel ABS or 4 channel ABS & Traction Control.
Most will upgrade their convertor first(before gears) for perfomance.