In order to choose the best used axle, buy an axle that is mounted on a vehicle similar to the one it will be installed on. This ensures that the axle will fit your specific type of vehicle, and the actual mileage of the used axle can be verified on the donor vehicle's odometer. If you must purchase an axle that is already removed from the vehicle, examine the axle housing for signs of damage and refrain from buying any used axle that appears dented, bent or burned. You may want to remove an axle from the axle housing to examine the axle splines, verifying the axle will fit your application. You should also check the wheel bearing and ensure that the bearing has not seized and damaged the axle.
Occasionally, it becomes necessary to replace an axle on a vehicle. While the axle is a strong and durable component, you will always want to ensure that the used axle is of the best quality to replace your failed unit. Any axle that has been involved in any type of collision can be damaged in some way. While the damage is often insignificant, it can be enough to cause the replacement axle to fail soon after being installed. Bent axles are the most commonly purchased used axle complaint, so be sure to thoroughly inspect a used axle for straightness before making a purchase.
Heat is another primary cause of damage to a used axle. Burned bearing seats and damaged axle flanges are often associated with a failed axle bearing and the ensuing heat involved with the failure. You should check all bearings for wear, paying close attention to the bearing seats and checking for galling and heat-related discoloration of the steel. Commonly, signs of a dry bearing will indicate a used axle that you will not want to purchase. It is imperative that the axle splines be counted to ensure the axle will fit your differential.
On some types of axles, a C-clip is used to retain the axle in the axle housing. In order to get the best axle possible, you should examine the area of the axle that is held by the C-clip to ensure no damage has occurred to that area of the axle. Occasionally, a worn C-clip will cause wear of the axle itself, rendering its use questionable at best. Any sign of twisted or damaged axle splines is reason to avoid that particular used axle.