My 02 Sentra makes a popping noise in the right front end when going over bumps and when the motor shifts when coasting and acclerating again. When going over bigger bumps, the popping is accentuated with what feels like a slight vibration coming from the hub area. I've replaced struts with monroe quick struts which replaces all the hardware, but this didn't help. I'm thinking either ball joints or axles. Any ideas?