Grinding noises emanating from the front end can indicate a couple of things. If it happens as you apply the brakes, it means the brake pads have worn through and the calipers are now clamping down on the bare metal of the rotors. If the grinding is heard steadily when the vehicle is in motion - especially if accompanied by a "ticking" noise when you turn the steering wheels - your Subaru Legacy Axle Assembly may be damaged.
The modern Subaru Legacy Axle Assembly is a complex system that is made up of an axle shaft, CV (constant velocity)joints and the U (universal) joint. Its job is to transmit the rotational motion of the engine and transmission to the drive wheels.
Especially important are those cv joints, which allow the front wheels to flex up and down over bumps and while being steered. For these to function properly, they must be packed in grease, then sealed and protected from the elements. The rubber concertina-like gaskets surrounding your cv joints are called the "boots." These must be durable enough to protect the joints from road grit, dirt and dust - no mean feat, given their location on the car! Because the cv joints are precision mechanisms, the briefest exposure to road contaminants can do major damage. If either boot has been cracked - even slightly - the damage is probably already done, even if there are no sounds. Replacement of a cracked or torn boot is a complex and expensive job. It's easier and cheaper to see us for a complete, remanufactured Subaru Legacy Axle Assembly that's as good as new.For right around $100, with a few hours and ordinary hand tools you can install an entire rebuilt front end assembly!