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Gear compatability ??


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I have never dealt with 4x4 until now, so sorry about what might be a silly question. The Silver 88 front diff says 3:55 but has a D35 in the rear. I want to put my D44 3:54 from the Black 88. Does the gearing have to be exact or is this considered "the same" ratio?

I probably will not use 4x4 mode very often but when I do, I don't want to cause damage if the gears don't match.

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Most of the gearing "differences" comes from people rounding differently.


Dana 35 "3.55" gear tooth count is 39 on the ring, 11 on the pinion. 39/11 = 3.545454545454.....

Some round up to 3.55, some round down to 3.54. AFAIK, the Dana 30(HP & LP), D35, and 8.25 all have the same tooth counts for 3.55.


Most 4.10 and 4.11 difference I don't understand, since most of our Jeep axles are 41 ring / 10 pinion. 41/10 = 4.10 exactly, so no rounding. The D44 however is actually different, at 45/11 = 4.090909 and 46/13 = 3.53846.


http://www.drivetrain.com/parts_catalog ... inion.html

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The difference between 3.54 and 3.55 is smaller than the difference between some of your tires due to air pressure fluctuations and tread wear. We are talking about a difference less than 1/5 of a percent (0.01976).


Assuming all your tires are exactly the same, on a straight road in 4wd, for every mile the front wheels travel, the rears will try to travel travel about 10 feet less. That's 10 feet difference over a MILE.


For all practical purposes they are the same, and are what came from the factory with a 4.0 4wd automatic and D44 rear axle (heavy duty rear axle, towing package, big ton/metric tonne package...).

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