I have a big foot 6x6 that when the brakes are applied the brake handle will jump back and forth. It doesn't matter if done lightly or hard. Although the harder you pull the harder it jumps. I replaced the pads and rebuilt the calipers and changed the brake fluid with dot 5 and same result. After just a couple hours it has already eaten one of the pads about half way.

Would this be bad disc? What is the best way to check? Thanks for any help with this!!