Unusual thud sound when braking

[kikkoman]

A weird problem developed this morning I need help figuring out. There's some kind of thud/pop sound coming from what appears to be near front right wheel only when the brake is applied. This issue just started this morning and weird thing is it doesn't happen all the time, isn't speed dependent and only happens once just after the brake is applied. Not only does it make a sound, I can kind of feel it from the steering wheel like something is binding. I've replaced a bad driveshaft on this car before so I know how that is and this is something different.

After driving the car gently home (everything feels normal when driving but kind of freaked me out) I've took both right-side wheels off to check if anything is loose (like the caliper, strut/shock, sways, control arm, etc.) around the wheels but I can't find anything unusual. Anyone with any ideas?

[jlevie]

A thud from a wheel when the brakes are applied means there is motion associated with that wheel. It could be from wear in the suspension or movement of the caliper. But something is moving.

[m_dudey]

Worn guide pins? That's what i think is happening to me. When I switch from braking while moving forward and then in reverse and vice verse, I hear a clunking sound, as if the calipers are shifting. And last time i checked the guide pins, they are very loose with lots of play inside the caliper bracket holes. I'm getting ready to replace the guide pins and rebuild them so we'll see if it's really that!