Hi. My rear brake disc (Tektro IO Mechanical Disc Brakes btw, 160mm if it matters) keeps coming loose and I don't have the right type of driver for the bolts. Closest I have is this hex wrench that kinda sorta gets the job done for like a day or two until the disc comes loose. Apparently it's been like this for a while because I remember dealing with this at least a month ago. Was rotating tread on my bike (I'm too poor to buy new tread right now) and I noted this. Anywho, what the hell is the driver needed for this bolt? Looks like a Torx head but I've already tried the two Torx bits I have to no avail (they were too small). OR Recommend me a good front/back hydraulic brake system for $100-150 that has 160mm rotors or converters to run larger rotors. I've had so many problems with the Tektro IO system that I don't want to get them replaced under warranty, and I can save up about $150 to get new brakes in a reasonable timeframe. Hydraulic because, well, if I'm going to spend money I may as well upgrade. =/ Thanks.