I already dremel'ed the slotted hole in the bracket a mm or two so I have room to align it, but the bracket (and chain) is straight. The noise still seems to be from it leaning/straightening with every link that rolls over. I've got a spare 105 rd that I may steal the tension pulley off of so there isn't any lateral play like the current idler has.
Originally Posted by
Onegun
The idler bracket is probably bent, or even more common, welded crooked from the start. Taking your time and a big crescent wrench, bend it back until it is dead vertical and under the center of the chain. A good plan is to drop the chain off it, then raise it back up to where it usually is when the chain is correctly tensioned, (VERY IMPORTANT. Does no good to get the idler true and plumb at the bottom when it's normally slid up to the top). Then tie a string with a weight on it onto the center of one of the chain rollers just ahead or behind the idler. Now bend the arm until the idler is right.
Next, get rid of the cracker-jack-quality idler wheel itself and get a quality one.