In Reply to: 3.64 or 3.91 Differential posted by SamK on December 21, 1999 at 14:33:09:
The 3.91 represents 3.91 rotations of the input shaft per 1 rotation of the wheel. This is lower than the 3.64:1 gear ratio most US '02s came with. In the same way it is easier to start from a stand-still on your bicycle when it is in its lowest gear (corresponding to the inner most cassette gear) it is easier for your '02 to get up and go from a stand-still with the lower 3.91 gearset. If you have a 4spd and you don't do much highway driving, I would reccomend the 3.91 as it makes the car noticeably quicker off the line. Since 80% of American driving is stop light to stop light, this is really what the ratio should have been from the factory. However, if you do much highway driving, I reccomend the 3.64 because the rpms will be slightly lower on the highway (about 3-400 rpm @ 80mph). The best of both worlds is 3.91 & 5spd OD (there are other more expensive options). Does that answer your question?
'72 BMW 2002tii
'94 LR Defender 90