rear gear ratio
07-21-2018, 08:17 AM
#2
For your '86 if you raise the rear wheels and turn a rear wheel one complete revolution while counting the pinion (drive-shaft) rotations you can effectively calculate the ratio. Is your car an A4 (automatic) or perhaps a MT (4 + 3). If you knew that your speedometer was correct (confirm with GPS) and your tachometer thought to be correct you could do the math by entering in the tire diameter, MPH and RPM into the mathematical formula.
If you were interested in the 'as built' you could use the SPID LABEL on the console door and check the RPO codes. You need to be sure the VIN on the SPID matches the actual car.
If you were interested in the 'as built' you could use the SPID LABEL on the console door and check the RPO codes. You need to be sure the VIN on the SPID matches the actual car.
Last edited by WVZR-1; 07-21-2018 at 08:20 AM.
07-21-2018, 11:09 AM
#3
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An 86 coupe will have the RPO sticker behind the drivers seat under the compartment lid, a vert will be under the console door. Look for codes that start with "G" and post them here, then we'll tell you what it came with. G44 is the one you want to find, but being an L98 its not the end of the world if you have others.
You can figure it out, which is the only way if someone changed it without opening the diff, from the RPM in 4th gear at 70mph pretty easily.
You can figure it out, which is the only way if someone changed it without opening the diff, from the RPM in 4th gear at 70mph pretty easily.