There are many aspects of an axle that you must check when attempting to choose the best heavy-duty axle. Gear strength, axle strength and overall weight-carrying potential should all be verified in a heavy-duty axle choice. Other aspects that you should focus your attention on are the availability of replacement parts, the difficulty in making the axle fit the vehicle it is intended for and wheel and tire choices that will fit the axle. Along with gear strength, gear ratio selection is also a limiting factor in some heavy-duty axle applications and should be considered prior to making a decision for your vehicle.
When choosing a heavy-duty axle for your vehicle, you will need to decide whether you want the axle to match your vehicle's manufacturer or whether you want the best possible axle for your vehicle. Nearly all automotive manufacturers make what they describe as a heavy-duty axle package for their vehicle lineup. Most of these optional axle packages consist of enhanced gearing and differential choices. In general, these axles are only minimally superior to the standard axles offered from the manufacturer. They have two common features: they are more expensive and offer reduced fuel mileage.
If you are attempting to build a vehicle for a specific task, such as a heavy hauling truck or a high-horsepower racing vehicle, you may choose to venture away from the original equipment axle options that were offered for your vehicle. Nearly all automotive enthusiasts and builders agree that the Ford rear-end is the absolute strongest and most heavy-duty axle available for any vehicle. This axle is used in every type of vehicle from heavy-duty pickup trucks to Nascar® race cars and Top Fuel Dragsters®.
You may choose to add options to your heavy-duty axle, such as full-floating axles and Timken® axle bearings to further strengthen your axle. The full-floating design removes the weight of the vehicle from being carried and supported by your axles and places it on two bearings on the inner and outer sides of the wheel hub. This results in the axle providing only the power to propel your vehicle and creates a stronger version of the heavy-duty axle.
An aspect of a heavy-duty axle that is often overlooked is the size of the wheel studs. The larger the diameter of the wheel stud, the stronger the axle. The larger diameter enables the wheel stud to support a greater amount of weight, torque and horsepower.