I'm going to be upgrading my gears maybe to 3:43. However, I have no Idea how to tell what size I have in there. I know you should be able to tell by the sticker on the door but my sticker is gone. Anyway other way I can tell? RPM's at certain speed maybe. MY car is an A4 BTW.

 

2.73 or 3.23 I believe..

 

yeah, i just wasnt sure what one it is

 

ask in GEARS and AXLES..

 

how many rotations does your driveshaft make for your tires to make one? I think that is a quick easy way to tell (not 100% accurate) but if it takes under 3 then you are rolling on most likley a 2.73... if its over 3 then most likley a 3.23 or higher.

(correct me if i'm wrong)

 

Easiest way to know
If you can select first gear: 3.23
If yoy cant select first gear: 2.73

 

That's not completely accurate. Only some of the cars with 2.73s were limited to no first gear selection. I know because I had one that was not.

Best way to tell is to look at your GUx RPO code. If it says GU5, you have 3.23, if you have GU2 then it's 2.73.

 

the RPO codes should be listed inside the glove compartment, not door. look for the codes infinitebird posted.

..or do the driveshaft rotation to wheel/tire rotation ratio.

 

I got nothin in the glove box. I know I dont have a no. 1 gear either.

 

You probably have 2.73s then

 

best of 9.20's at 80mph in the 1/8th with K&n cai & muffler is what I got before all my mods, does that sound like 2:73 territory?

 

Whats your 60 foot

 

if you dont have a first gear selector then yeah youve prolly got 2.73's and try the driveshaft thing, it usually works.

 

You can also drive at 70 mph in your 1:1 gear (3rd in an auto). Keep a load on the engine and check your RPM. If you're at 2730 RPM, you have 2.73s. If you're at 3230 RPM, you have 3.23s.

 

You can call somebody at the GM dealer and run the VIN, they will tell you in a flash...... Or you could calculate the angular velocity of the wheel and compare the speed to the engine speed, that will also give you ratio.

 

that looks like it would take too much effort lol, crunching them numbers, ehhh

 

hahha yep it would. I had to do that on my 65 Impala. Actually it didnt take to long. I did it while I was sitting in my Art history class. That was one of the few times I didnt fall asleep.

 

Just do it the most accurate way and pull the cover off and divide the numbers of
teeth on the ring gear by the pinion gear . (Driven gear divided by the drive gear.)

 

Exactly. Take the cover off, you will see a part number, then a set of nunbers after that. Mine said 13 42. Take 42/13, and that is 3.23. which is the ratio. I pulled some gears out of an S-10, I was looking for 11 41, which is 3.73's

 

60 foot somewhere around 2 seconds maybe more? I dont have the slip anymore