Hey All,

I recently bought a 2000 coupe A4. Is there any easy way to tell what gearing it has?

Thanks for your help

 

A4 came with 2 gearing, 1 is 2.73 and the upgraded was 3.15, You can look at the tag on the rear end and it should say, Also it should be in the glove box, I can't remember the code for the gears myself, I know it will start with a G..

 

Place your A4 into third gear and get on the highway. At a constant 75mph (making sure the TC has locked) read the rpm value; then divide it by 1000.(This also works with the six speed manual transmission using 4th gear):

examples:
2730 RPM........ you have a 2.73
3150 RPM........ you have a 3.15
3420 RPM........ you have a 3.42 (not a factory available ratio with the A4)
3730 RPM........ you have a 3.73 (not a factory available ratio)
3900 RPM........ you have a 3.90 (not a factory available ratio)
4100 RPM........ you have a 4.10 (not a factory available ratio)
(assuming rear tire height has not been altered from the factory height)

The key is third gear, driving at a constant 75mph. AND, you must be using the same rear tire height as the factory installed tires. It may be up to 100rpm off depending on the amount of slip your TC has when locked.
With this method, you don't need a chart to compare your rpm/mph to. Just divide the RPM by 1000. This also works with the six speed manual transmission using 4th gear (again with identical tire height as from the factory).

FYI: individual overall ratio of an automatic A4 C5 in each gear:
2.73 - 3.15 - 3.42 - 3.73
8.35 - 9.63 -10.4 -11.4 (1st gear A4)
4.42 - 5.10 - 5.54 - 6.04 (2nd gear A4)
2.73 - 3.15 - 3.42 - 3.73 (3rd gear A4)
1.91 - 2.20 - 2.39 - 2.61 (4th gear A4

 

In your Glove Box there will be a spec sheet sticker and look for the G92 this will indicate that you have the performance axle with the 3.15 gear ratio.

If you do not then you will have the 2.73 gear ratio!

I would suggest, as many of us have already done, to get a used MN6 rear end with the 3.42 gear ratio in it and really enjoy your Vette!

With this set-up and a hand held tuner to set the computer for the 3.42's you will have a much much faster Vette and will not sacrafice much if any fuel mileage!

Let us know what you find!

Thanks,Matt

 

Here is a sheet on the difference in RPM's with different gear ratios: You'll find this helpful



Thanks,Matt

 

According to the chart my RPMs at 80MPH (yeah, save the flames, I know I'm a tool for runnig 80-85 on the hiway ) are going to go up by 475rpm, I'd think that would dramatically decrease my milage. What am I missing?

What does the tuner set to compensate for the lower gearing other then the ratio used to calculate speed for the speedometer?

 

the speedomoter on the C5 is not affected by rear axle ratio changes.

 

On a similar note: Does anybody know what axle GM was putting in 2000 FRC's with M8 option? Car is in storage, so looking in the glove compartment or at the rear end is not an option right now.

 

All FRC's came with the 6 speed so you have the 3.42 rear axle.

 

Thanks for the info everybody. Bummer that I now know I have a 2.73, tho.

 

No you are not missing anything at all!

It does appear to be a 2.73 gear ratio he has, so "YES" it would more of a jump then what my 3.15 gears were going up to the 3.42's that I now have in the Vette!

I will get cruising @ 70 MPH 29+ MPG and travaling at 80+ I get 24.8 MPG so for the performance gain the MPG isn't that bad!

I appologize because I was thinking he might have the 3.15's

I wont be a "DRAMATIC" change in the fuel mileage!

Plus as for the handheld tuner it will recalibrate the PCM for the new gears whereas the MN6 tranny does not need a tuner to change the gear ratio due to the sensor the MN6's have


Thanks,Matt

 

actually, they both (A4 and 6 speed) have the same sensor.

For the A4, one needs to alter the shift points due to the MPH's falling into different ranges during WOT; and the TCC Slip table so you don't set a false P1470 error code.

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