[Joe Schmoe]

I replaced all four corners with OEM pads and rotors, greased the shims (each side of each shim) and flushed Toyota Dot 3 fluid. The hum is not a faint hum - it's VERY VERY loud. The corner with the hum did give me trouble - using the cube, the piston seemed to stop short of turning all the way down...at least it looked like it didn't crank down as far as the left rear. Nonetheless, I proceeded and was able to get the pads over the rotor....though just barely. The hum showed up and I took a look...one of the caliper mounting bolts had backed out a bit. I tightened it down and hoped that solved it....nope. Today I loosened up both caliper mount bolts and used the lug nuts to hold the rotor flush to the hub then re-tightened the caliper mount bolts.....a little better, but the hum is still not solved. Maybe the caliper wasn't mounted properly and the pads aren't/weren't parallel to the rotor?

I'm not sure what's left to do. I can try to bed the pads in again...maybe flush some more fluid through the line? Any ideas?

 

[plebian]

Sounds like a stuck piston in the caliper. A write up to unstick 'em is here. It's usually easier and not that expensive after core fees to get a new caliper.

 

[Joe Schmoe]

Sorry, I didn't describe the piston issue well - it turned and turned freely, and continued to turn, and turn and turn....it just seemed to reach a point where the piston was no longer receding into the caliper and that point wasn't as as deep as the other side - it protruded more. Should it bottom out and stop turning at some point?

 

[GuySmily]

I got a loud hum from the rear brakes with RPF1's installed. My SSR Comps don't do it. Sounds like a SUPER loud resonance, right? I should have recorded the sound when I had the RPF1's on...

 

[Joe Schmoe]

I got a loud hum from the rear brakes with RPF1's installed. My SSR Comps don't do it. Sounds like a SUPER loud resonance, right? I should have recorded the sound when I had the RPF1's on...

Yeah, that describes it. I didn't have anything to clean the face of the wheel mounting surface or hub, but it's torqued down properly. But then the car came with Gorilla plastic hub centering rings....they seem especially cheap/low quality. Maybe I'll pick up and try a wire wheel.

 

[carlbecker]

You might try switching rear rotors and see if the noise follows the rotor, if so get the rotor replaced. You have checked for a dragging pad as you can easily spin the affected assembly. New rotors so the surface should be the same across the pad area. Piston needs to recess enough so that the caliper can slide over mounted pads without any forcing. I would double check all your mounting bolts if you had a loose bolt. Braking is the most important function.

 

[OKSpyder]

I had the same issue with cup on the right side when replacing the pads and rotors. Very stiff to turn in and would not seat all of then way down. Found that the cup was stuck and not moving when applying the brakes. Ended up installing a new caliper.

Left side acted like it should when turned in and no problems from it.

 

[butch_mr2]

I'm sort of doing the same thing this weekend. I've replaced the pads and now doing the SS brake lines replacement. Hopefully finished it over the weekend. Let me know what you find out if any. I might have the same results after (cross finger).

 

[carlbecker]

BGB instructions mention turning the piston in until it turns freely. It will not stop. Not recessing the same as left side doesn't sound good but I would look everything else over before replacing caliper. If you do remove the caliper you might want to check P brake operation manually by hand. If the rotor did not keep the noise look at all the clips and pads for proper fitment.

I would be interested in the solution.

 

[Joe Schmoe]

I redid the corner with the problem - reseated the pads in the caliper making sure they were in the clips properly and cranked the piston down a little more. Problem solved.