A 14-bolt axle is a General Motors corporate rear axle housing found under 3/4- and 1-ton vans, 4x4 pickups and trucks. Easily identified by the 14 bolts that attach the rear cover to the axle housing's differential cover, the 14-bolt axle is a strong and durable unit. It is often used in the manufacture of rock-crawling buggies and 4x4 pickup trucks. This axle is a full floating design, which means the axle does not support any of the vehicle's weight, it merely delivers the power to the wheel from the differential. The vehicle is supported by a wheel-hub assembly that uses an inner and outer wheel bearing to mount the hub to the axle housing.
Produced from the 1970s until 2000, the 14-bolt axle is a very common and often easily located rear axle in salvage and junkyards around the world. This makes the ability of finding replacement axles and carriers a somewhat easy task in most areas. One of the best-loved traits of the 14-bolt axle is that the axle very rarely requires replacement parts because it rarely breaks. The design of the axle, along with the heavy construction of the components, results in a very strong axle package able to withstand high amounts of horsepower and torque without being damaged.
The number of axle splines used in the design of an axle commonly indicates the strength of the axle, with the higher number of splines relating to a stronger axle. The average truck axle is equipped with 28 splines, however, the 14-bolt axle uses a 30-spline axle shaft that indicates an even stronger axle. This, coupled with the strength of the carrier and differential unit, makes this type of axle a common choice in vehicle upgrades and in the construction of performance off-road vehicles.
If there is a drawback to using the 14-bolt axle, it is the lack of performance-locking differentials and gear sets designed for the heavy-duty axle package. General Motors produced the axles with 4:56 gears from the factory, making the axle very usable off-road. While locking differentials and spools are not produced for this axle, the original differential can be easily welded to create a locked-spool-type differential that will endure just about anything that it is put up against. The wheel bearings of the 14-bolt axle can also be easily changed along the side of the trail with little more than a hammer and screwdriver.