just had this issue, i did not read every post in this but mine was bad wheel bearing causing rotor to push back pads making the pedal drop

this happens randomly, i assume when the wheel is side loaded it allows the rotor to push the pads back

i changed my right front wheel bearing and good brakes again

also check the caliper pins when you check your wheel bearings

hope this helps

steve

 

Thanks - when using your brakes, didn't your brake pedal wobble up and down in proportion to your driving speed? Or more random?

I just changed pads and didn't notice anything obvious during the process, other than that I had about a fingernail thickness left on one or two of them.

--Dave

 

randomly and more so when turning into a driveway or after turning and applying the brakes or applying the brakes while turning into a driveway the pedal would push back against my foot
not like warped rotors where the pedal rapidly pulses but more like a thump under my foot

 

Skipping a lot of detail, it was the ever-murkier-looking fluid in my MC - even though that MC was only a couple of years old - and even more so, the sudden loss of what must have been one brake circuit - that made me replace the damned MC again, a couple of months ago now. Of course, that made a huge and immediate difference in braking consistency, and I'd hoped had cured all. But no, my ABS and brake lights are like eternal flames.

Yesterday, some moron two cars ahead jumped out of backed-up freeway traffic in the center lane into my 55mph-flow fast lane, forcing me to kit the brakes HARD. RWAL? Pffft....My dually squealed like some nightmare pig, and I almost got sideways before I was able to let up and get it to straighten out. I don't think there was anything that wasn't locked up (or clenched!)

So what's the next diagnostic item...am I back to that (untouched) RWAL control valve?