I just bought a 94 Z A4. My speedo is off quite a bit at mid speed. Example: I checked the speed the other day with a buddy of mine. He got his car up to 70 mph. I was right beside him and my speedo read 55 mph. I was told that the rear end may be geared down, so I had it checked. I have 2.73 gears and my gear code in the glove box reads GU2 = 2.73. If the gears are correct, and I just put in a speed sensor that is new, what else could be the problem? Thanks in advance for any help I can get.

 

What was your RPM at his 70 MPH? I'd try it again and bounce it off a gear/RPM calculator like www.f-body.org/gears/

 

You have aftermarket gears. I dont see why you ruled it out so fast.

 

Gu2 is coded in glove box. As I understand it, that means that it came stock with 2.73 gears. Am I wrong or what?

 

GU2 means 2.73 gears were stock. Someone can still switch the gears though, the RPO codes do not automatically mean that gear is still there.

 

No,no. I pulled the cover off today and the stamp on the gears read 42-15. Doing the math, that's 2.73 ratio. So, by my reasoning, I've got the stock gears back there, I pretty sure. So what else could cause the speedo to be off that much? At 70 MPH, my tach read a steady 2000. I'm wondering if the instrument cluster is bad or something. Anybody heard of this problem?

 

Tire size, computer tuning, tranny change?

 

mine reads around 1900 at 70 mph, and i have 2.73 gears.

 

Mine sits at 2000 at 70, so I know that's right. I'll have to get the computer checked and make sure it's set for 2.73 gears.