Axle general maintenance:
Some Subaru inner CV joint boots include a series of rubber O-rings that ride in the bottom of the CV boot creases. These O-rings keep the CV boot from rubbing against itself during sharp turning maneuvers and extend the life of the boot. If the original CV boot is torn or otherwise damaged, make sure its replacement includes this feature.
When replacing the rear wheel bearings on AWD Subaru Legacy, Impreza, SVX and Forester vehicles, do not overtorque the lateral link bolt that secures the two transverse suspension arms to the wheel bearing housing. Do not use an impact wrench to remove or install the bolt. The proper torque is probably lower than you might think.
The torque values are different for different models and years, so refer to the appropriate service manual for the proper specs for the vehicle you are working on. If this bolt is overtorqued, it can deform the housing and may lead to a repeat failure of the wheel bearing. If you encounter a repeat wheel bearing failure in an unreasonably short period of time, the housing may have been deformed during the first repair. Replacement of the bearing and housing may be required.
There are some other points to keep in mind when working on the front and rear wheel bearings. Never loosen or tighten the axle nut with the weight of the vehicle on the wheel. The vehicle should be in the air with the wheel removed prior to loosening or tightening the axle nut. If this precaution is not taken, damage to the wheel bearing may occur.
The axle nuts are not reusable. A new nut should be used with the new bearing. Always insure that the new bearing is properly packed with suitable wheel bearing grease. The grease the bearing is shipped with is not sufficient. Always use the proper special tools to install the bearing and torque the axle nut to the correct specifications. To avoid wheel bearing damage, never use air tools to tighten or loosen a wheel bearing nut.