Epitome

In the options section of my car's original window sticker, for $22 is an optional "Performance Axel Ratio". What is the performance ratio in the car now and what was it without this option? Just curious. Also, I am changing the rear differential fluid and I assume it has posi-traction. In my old Camaro with posi traction, GM required that you add an anti foaming additive. Do I need to do the samething for this car and is there some special fluid I should use? Thanks

WVZR-1

For a '90 there could have been a few - The RPO codes will signify which. That is on the back side of the console door. What are the three digit codes that start with G?

The performance axle option was the same for a coupe and A4, a 'vert with A4 and there were also 2 M6 axle ratios codes. The base axle ratio for the A4 coupe and A4 'vert would be different.

You do have limited-slip and you do need the additive. There should be a tag on the differential plug.

Let's assume it's an A4 - A coupe would be a 3.07 (G44) and with out the performance axle (G92) would have been a 2.59 (GM1). A 'vert would be also 3.07 (G44) but with out performance axle (G92) would have been 2.73 (GU2).

Epitome

Ok thanks....I know that G80 means a posi traction rear on Buick Grand National, but they were all 3.42. Seems funny to me that a "performance ratio" is only 3.07 lol....but that first gear gear is a little lower in a 700r4 trans compared to the 2.74 in a 200r4 in the Buick.....I am just referring to things I know best...thanks, I will check.

Epitome

I just checked the codes...as you stated, it is G44. There is also a G92...whatever that means. Thanks for the help.

WVZR-1

G92 only signifies that it's an axle ratio other than "base". Different packages with different car lines would change the available ratios, that's the reason for the 2nd RPO code signifying the actual ratio.