Official: Brake Pad Knock Back Thread

[Vegas69]

As some of you know I and a few others have fought brake pad knock back issues. With a fixed caliper like many of the large manufacturers use, any slack in the bearings under load cause the pads to recede the pistons into the caliper. This isn't so great the next time you hit the brake pedal since you experience more pedal travel than the previous stroke.

The first time I autocrossed my car I had to pump the brakes between the corners. I determined I had .020.021 play end play in each axle. I bought some different retainer plates and got it down to .005/.006. While that has improved it tremendously, I'm still not satisfied on the street or track. I know it's not the front because I have C6 bearing packs and they only net .001 play. At this point I called Wilwood and they don't offer a floating caliper so I would need to switch brakes if I go that route. My number two thought is to go to a tapered bearing. I called moser and they said most circle track and autocrossers run a tapered bearing but he couldn't guarantee that would fix my problem. He also said .005 was tight enough for a roller bearing.

I can't really get anybody to cough up a spec on how tight the axle end play should be. Wilwood is actually sending me some shims but how much tighter can I go and will .002-.003 really help that much. Has anyone changed from a roller to a tapered bearing and has it helped? I'm experiencing a change in brake pedal even on the street under normal drving conditions. While it's managable on the street and track. I want a consistant brake pedal. I had a brief conversation with Frank at Prodigy yesterday and it's happening with other brake manufacturers as well. He said he knows a guy that is running a 10psi residual valve in the front and back. While I'm sure that would fix my issue, I feel it will cause excess heat and pad wear on a cruise that could potentially cause brake failure.