There are no hacks. "Vibrating" a tank in game is impossible. You and your alleged 'PC Tech' clanmate need to educate yourselves about server side games. An important part of sportsmanship is not being a poor loser by blaming cheaters or imaginary hacks when things don't go your way.
I suspect OPs buddy has "Easier autoaim locking (time snapping)" enabled. He right clicks to autoaim on a tank but it doesn't lock so he tries again by right clicking a second later. However, the time snapping meant autoaim locked .5 seconds after his first right click when he moused over the sweet spot, and his second right click actually unlocked his autoaim. He did it himself. It can be hard to get used to, I've done it myself. One solution is to disable or drastically shorten the time snapping part.
http://forum.worldoftanks.eu/index.php?/topic/441413-0917-autoaim-indicationaddins-no-proximity-snapping-for-autoaim-but/
