Trouble with RCA's

okay here is my problem, every time i tap on my brakes my speakers would pop (like a clicking noise) i figured it would be my ground, checked it and its not that....after some researching and testing stuff, i found out it was this really old pair of RCAs we have had for quite some time (7 years). and i disconnected them and it seems it stopped but now since its winter, the front 2 speakers will still pop even though they dont work....could it be just static electricity since its so dry and cold??? help me out!!!