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what difference does the rear axle ratio make??

trying to choose size for new truck


rear gear ratio is very important. A low gear (high numerically) pulls heavier loads easier because of TORQUE MULTIPLICATION .lets say you and your friend got identical trucks except for the gear .and lets assume the engines produce 300 lbs of torque at a given rpm ,and your truck has a 4:1 axle and his is 3.5:1 .that means your truck will be putting 1200 lbs of torque where his will be putting 1050 to the ground the flip side is your engine will be spining more rpm at any given speed because of the LOWER gear (i know its weird higher numbers are refered to as LOWER or SHORTER gears/low numbered gears like 2.73:1 are called Higher,Bigger or TALLER) LOWER GEARS less MPG but more fun! Go for the low gears and LIMITED SLIP DIFF (POSI/TRACTION LOK.etc) both rear wheels spin in the same direction when the tires are off the ground
May 28, 2018
hi Sparky. Here is the Magic question. How will you be using the vehicle most. A high axle ratio is a low number like 3.08:1 to 3.23:1 and is a all around gear for street driving the lower the number the less you are asking from your drive train and in turn the better the fuel mileage. The higher the number (low axle ratio) like 4.11:1 to 4.55:1 you are looking to do heavy duty pull or hauling. Now the higher the number known as low axle ratio your top speed will be lower, RPM'S higher, and less MPG this gear is for off the line torque. Now what did I say was the magic question? How will you be using the vehicle most, cruising 3.08:1, quick performance 3.23:1, light towing 3.55:1, moderate towing 4.11:1, heavy duty towing 4.55:1 One more thing with some of the new trucks with 6 speed transmission you can have a standard gear of 4.10:1 with good fuel mileage due to the new overdrive in the transmission. In all don't just ask a sales-man what he thinks. Talk to the service mechanic. I am telling you some thing blind here as you did not say what type of truck you are shopping for and is it a automatic or standard transmission.
May 28, 2018

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