Gear Change

khopper · April 12, 2005

How much difference in gas mileage should one expect to see from going from 4.11 to 3.73 with all else being equal.

redvett · April 13, 2005

How much difference in gas mileage should one expect to see from going from 4.11 to 3.73 with all else being equal.

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If you are looking at changing gear ratios its not worth it. Unless you have a 2x4 and drive a zilion miles a year. Figure that a say 04 4x4 with 3:73's will get average 15.5 city and 18 HWY the cost of changing the gear & reprograming will be more than the recoupe on mileage.

snoman · April 13, 2005

How much difference in gas mileage should one expect to see from going from 4.11 to 3.73 with all else being equal.

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In a heavy truck, most likely zero and possibly even less around town. People are hung up on the 3.73 ratio as best for economy but what might work with OD in a 3500lb or 4000 pound vehical, does not work for a 5 to 6000lb one with oversized or aggressive tires that eat extra power. Through in a lift and add more drag it is gets worse. If you really want to save some gas, keep truck stock as possible with stock size smooth tread tires or put it on a seriuos diet and have it lose about 1000lbs. 3 things determine MPG, weight, drag and rolling resistance and gear ratios will not erase any of those. A truck need to be gear like a truck for best MPG and while a 3.73 was a good compromise 20 years ago before OD it is not today because even with a 4.10 the over all ratio is OD is about 2.9 to one which is pretty tall for a big SUV with a gas engine. There is no magic fix here though some would lead you to believe that there is one.