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Old 07-04-2007, 04:59 AM
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Default Re: Can Somebody Explain Gearing

Quote:
Originally Posted by Wisha Haddan H3
Now for the rest of the story ...

The transfer case basically has 2 gear sets: 4hi and 4lo (ignoring the locked/unlocked modes). 4hi provides a 1:1 gear ratio. It passes all engine power through from the transmission directly to the axles, without multiplication.

4lo provides a 2.64:1 ratio in the Base model or 4.03:1 in the Adventure model. So in 4lo, all the torque coming from the transmission is multiplied by either 2.64 or by 4.03 before it heads to the axles.

The axles each have a ratio of 4.56:1. This can't be changed without a complete axle rebuild. So whatever gear you select in the transmission and transfer case, it will be multiplied by 4.56 at the axle.

To put it all together, let's say you're wheeling and want to go up a steep hill. You put the transfer case in 4lo. Then you select 1st gear. Since we know the axle ratio, we can calculate your final "crawl ratio"

Crawl ratio = transfer case ratio x transmission gear ratio x axle ratio

Base model (auto) - 2.64 x 3.06 x 4.56 = 36.8:1
Adventure model (auto) - 4.03 x 3.06 x 4.56 = 56.2:1

Base model (manual) - 2.64 x 3.75 x 4.56 = 45.1:1
Adventure model (manual) - 4.03 x 3.75 x 4.56 = 68.9:1

Now you have an incredibly low drive ratio. You can't go fast, because you've traded distance (at a given RPM) for some incredible torque. But that torque will get you right up the hill.

Tire size is also a factor in all this, but that's another story.

very well said dude..
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