Nate;

The oe threads may have been stripped out, OR, someone may have just installed a longer bolt through existing threads, and added an additional nut as a locking "jamnut". That design of clamp is quite secure, but considering that if the bolt were to loosen, there is no sort of plan "B", back-up security (without any sort of shape distortion from circular or a pin through the shaft) the PBUS(1) would be allowed to slip through the clap resulting in the total loss of brakes (!), I would be tempted to add one of these myself....or at the very least, to certainly Loctite the bolt. I wonder if anyone has ever had one of these bolts loosen, and lived to tell about it?

Cheers