A few weeks ago I hit a fairly deep pothole on the side of the rode and noticed a popping/grinding noise when I stop and go around corners. Went to a tire service center and they took the tire off and pointed out that the half shaft boot had a small puncture in it and was sending out grease on the underside of my truck. I then took it to the dealer since it should be covered under warranty and they kept if for two days and didn't "see" anything wrong. Of course the noise still goes on and they say it is my tires rubbing since I have mud tires. If it was my mud tires then why wouldn't both sides do it as well? What is the half shaft and how important is it to stay greased?