hi every one
i am new to this site and i am from dubai. i just bought my first camaro z28 1995 with gu5 gear. and friend is having camaro z28 1998 with gu2 gear. i just wanted to know the difference between gu2 and gu5 performance wise, how is the pick and the mileage. i came to this site because here in dubai there very less known about the technical details about camaro cars. and those who knows they charge to much. please help me.
thank you

 

Welcome to the site.. Here is a reference site for GM RPO codes they will be listed on the inside of your glove box General Motors GM RPO Codes: Letters E, F & G . Now your GU5 code is for 3.23:1 rear end, they came as a 'power option' on an automatic (A4) transmissions and most 6 speed manual (M6) transmissions had them installed. The GU2 in your friends car is a 2.73:1 rear end and was stock on the A4's . The difference between is (3.23 - 2.73) = 0.5 then 0.5/3.23 = 0.154 or 15.4% . So your engine (RPM) is turning 15.4% faster at the same road speed at your friends 2.73. You have more power and torque at the wheels (at the same speed) as your friends car due to your RPM's being higher (you are in a higher HP point on the engine performance curve), so your setup would be quicker taking off. On the other hand you will have higher fuel consumption as a trade off. I will say the difference between GU2 and GU5 is not very much, I added a 3.42 rear to my A4 and many people go to a 3.73 and even higher.

 

The GU5 option on the A4 cars was the "Performance Axle Ratio" option.

All M6's except the 93's came with GU6 3.42:1 rear axle. In 93, they used both the GU2 and GU5 ratios with the M6's.

As far as the ratio of engine speeds for any given road speed, you would calculate the increased RPM going from a 2.73 to a 3.23 using 0.5 / 2.73 = 18.3% RPM increase.

Good sources of "free" 4th Gen F-Body information:

4th Generation (1993 - Present)

4th Gen LT1 F-Body Tech Aids