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New Owner of 2016 JKURHR. What is the difference between the 4:1 Rock Trac system vs the 4.1 axle ratio? Looking at some of the posts here I see the two used interchangeably. Anyone feel like educating a newb?
 

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I am sure there are those who can explain it more eloquently than I. But the 4:1 is a ratio related to the transfer case. The 4:1 comes with the rubicon and hard rock models etc. The 4.1 which I believe more appropriately is a 4.10 is a gearing ratio in your axle differentials. Definitely not two interchangeable items.
 

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So they both are referring to a gear reduction ratio. One is complete 4:1 which refers to 4 revolutions of an input shaft equals 1 revolution of the output shaft. The second ratio 4.1 is not complete and and should be written at 4.1:1 which refers to 4.1 revolutions of the input shaft equals 1 revolution of the output shaft. The ratio reduction can refer to any mechanical assembly but the 2 that you have referred to here are common to a rubicon transfer case low range (4:1) and rubicon front and rear differential gearing (4.1:1).

Hope this helps
 

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With a 4.10 axle gear ratio your driveshaft will turn 4.10 times as your tire turns one full revolution. With a 3.73 axle ratio the driveshaft turns 3.73 times to one full tire revolution. The same formula applies with any gears that a JK has installed. The higher gear ratio number gives you greater torque. A down side to a higher numerical axle ratio is top end speed, and to an extent, gas mileage. 4:1 refers to the transfer case. A Rubicon has a 4:1 low range reduction, which means that for every revolution of the transmission output shaft the front and rear transfer case outputs reduce road speed, in low range, by 1/4. Torque is then increased by the same factor.
 
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