I've got a '97 A4 convertible. I've always thought that I had 2.73's. According to this calculator and some others I recently tried, I have either 3.73's or 3.42's. I know these werent available from the factory in an A4...and the woman I bought my car from who was the original owner didn't do anything to it, besides put 8,000 miles on it in two years, what gives? I just took my car to the muffler shop today to get the true duals put on, and at 60mph my rpm was right below 2000...I know the factory tachs are a little off,(I think the average is they run 200 rpm higher than actual), but I can't see it being off by that much. I know my torque converter is locking up, I could feel it and hear it.....is there any markings on the outside of the rear end housing that will tell me what's factory installed. I don't have the original drivers side door anymore because a deer ran into me, so I don't have the sticker listing my factory installed options. I was going to go with 3.73's but if I already have 3.42's I don't know if its worth the little bit of difference I would see.

I know most likely I should have a 2.73 in there. but the numbers in the calculator are WAY too far off for it to just be me looking at something wrong.

edit:
My friend has auto tap with obd2 cable. if he hooks it up to my car, will it tell him what gear the pcm is programmed for???

 

mark the driveshaft and rotate the tire once, see how many times the driveshaft rotates, that is your gear ratio

 

97 Z's came stock with the 2:73 but offered the 3:23 as an option. So you could easily have the 3:23. The 3:42 was only offered with the 6 speed.

 

when your at a stand still..and you step on it..what are your shift points?? Does it make the 1-2 shift at about 57 or so mph?? and the 2-3 shift at like 95?? If it does..than you have the 2.73's..thats what my car has, and those are roughly the shift points..

 

My guess is you've got the 3.23's. If you go to that calculator, select "1993 - 97 F-body A4" from the pull down chart in the top left and calculate it. At 2000 RPM in 4th gear, it shows a speed of 68 MPH, so if you said that 60 MPH is running the engine just below 2000 RPM, then it seems you've got 3.23 gears.

 

I guess they must be 3.23's then. The 1-2 shift happens at like 38-40 if I go Wide open throttle all the way......would it still be worth it to change to 3.73's?

 

If you can read the PCM (with LT1_Edit or Tunercat) you can see what rear end it's programmed for. Assuming no reprogramming (or a changed gearset) it's not likely that this is in error. Though of course, it could be. I sounds like you have 3.23's though. If you want to be absolutely sure and aren't confident using the method described by "Serene" you could always take the diff cover off and count the teeth on the ring and pinnion. Teeth on the ring gear/teeth on the pinion is truly your final drive ratio.

Is switching from 3.23 to 3.73's "worth it"? Depends what you are trying to accomplish. It's a pretty big jump, so you will notice a difference. That much I can say for sure. Will you like the change? hard to say. Depends how you use your car and on what mods you have. The stock motor is a fairly low revver and I think 3.23's are a good ratio for an A4 and a largely stock motor. The exception would be if it's used for drag racing. In that case, a higher stall converter is the first step in this area nad then gears if you have the traction to launch even harder. Choosing gears for drag racing also depends on your trap speeds though.

Rich Krause

 

Current Mods:
jet hot long tubes, 2.5" true duals w/bullets, k&n fipk, lotsa little stuff, stock internals, NX wet kit(haven't used it yet)35-175HP. BMR SFC's.

Eventually:
High stall or M6 conversion.
Moderate Cam.
Wolfe 4 or 6 point weld-in.

Everything you typed was entirely correct. I do eventually want a higher stall converter(2800-3200), but I was told on another thread that gears must be done first because a small gear(2.73-3.23) will be very hard on my trans with a stall. That is ofcourse unless I do an a4-m6 conversion(which is what I really want to do), then I won't have to worry about it.........

Bottom line: I don't care about e.t.'s.......I've been to the track once since I've had the car(it was a lot of fun), but my overall goal is to have a car that is extremely fun to drive and put me back in my seat. I don't put many miles at all on my car, and it will never see the highway for more than acouple miles here and there to open it up a bit. Does that mean that 3.73's would be the best? I don't however, want to do anything to the car that will slow it down in ANY way......I value the opinions I get on this message board, especially the ones that come from guys with thousands of posts.....so input you give me will be appreciated.

Jeremy

 

If your interest isn't the srti[p you will be happier with gears and the stock comnverter. Or. at most, something that raises the stall by a couple of hundred rpm. Maybe 2,000-2,200rpm.

Rich

 

If your interest isn't the srti[p you will be happier with gears and the stock comnverter. Or. at most, something that raises the stall by a couple of hundred rpm. Maybe 2,000-2,200rpm.

Rich