Originally Posted by wmwhitey
Ok guys one more question why the 4.88 gears over the 5.13? wont the 5.13 just give me more low end power?
Neither will actually produce any more power. What gearing does is raise your RPMs more rapidly, so that the engine puts out more of its power at lower speeds. In other words, it has the effect
of putting more of the existing engine power at the wheels more rapidly, but it doesn't actually change the power curve of the engine.
For example, where you might have been at 1800 RPMs at 70 mph in 6th gear with 3.21s on 35s, you'd be at nearly 2800 RPMs with that same set up with 4.88s. Your engine puts out considerably more power at 2800 RPMs than it does at 1800 RPMs, and, therefore, the jeep will be much more "powerful" at 70 mph with 4.88s than with 3.21s.
The reason you don't want to go too high is because you "run out of gear." With 5.13s, you'd be spinning almost 2900 RPMs at 70 mph in 6th gear. If you ever pushed 80 mph, you'd be over 3000 RPMs with no "7th gear" to shift to. In general, that's too high for most folks to be comfortable with on the highway long term.
But if you never go on the highway, by all means head to 5.13s.