Foretwoone

I feel like an idiot even for asking for help with brakes, just seems so basic but this ones got my head spinning.
I replaced my front pads and rotors a few weeks back and then had a local Mavis do the rear shoes, drums, wheel cylinders and hardware kit. Within a few days i started to get a scraping/grinding noise which i was convinced is from the rear. I took it back to Mavis and left it and they call me a few hours later and say they cant find a noise. So i go pick up the car and argue with them and the guy gets in and we go for a spin.....no noise. Fast forward 12 hours and on my way to work it starts up again. For kicks i test just braking with the emergency brake and get no noise but the new drums are definitely not round. So tonight i decide to pull the calipers, pads, and rotors and check for scoring or a pebble and nothing.....perfect wear on the pads, no damage to the rotors, nothing binding.

Any ideas?


BTW its an 01 if it makes any difference.

Gimmy

Is it a constant grinding? And is it under heavy braking, light braking. Does it make noise when you turn the wheels? And did you lube the caliper sliders? (Not the official name, but the pins that let the caliper slide together)

Foretwoone

Oh sorry, forgot to mention that the grinding is pulsating which would make sense if the rear drums are out of round. Its only noticeable as im coming to a stop....i'd say 35mph and under. Caliper pins were lubed, and new rotors, not my first time doing disc brakes so i kinda had an idea of what to look for there, plus new rotors wouldnt cause pulsating. If i really lay on the brakes its very quiet. I just dont get how if its the rears as i suspect why wouldnt i get any noise with just using the e-brake?

Gimmy

Depending on the quality of the disks it is possible they have runout. normally a rear drum won't look round from the casting but the contact surface will be round. If it sounds like a muffled or hollow noise that would be the drums. But if it is a sharp noise and very clear then I would say the disks. One thing to do would be jack the front take the tires off and rotate the hubs and see if there is grabbing.

Also there is a chemical they put on the disks so they don't rust. And if you don't spray it off with brake clean they will squeal until it burns off.

Radi

I got a scraping noise from my rear drums shortly after replacing all the hardware back there-
turned out the little cable for the auto adjuster had started to work out of the crimp on one end and was allowing the finger that adjusts the star wheel to scrape on the drum.

Foretwoone

Checked a few things this morning based on your suggestions Gimmy. No rubbing or binding on either front hub, i had sprayed the rotors decently when i installed them but redid it for good measure.
The noise is really more of a scraping, not so much grinding. By that i mean it doesnt sound like metal eating into metal, but i'll have to pull the drums later and see if anything is loose.......or go back to mavis and raise hell. Depends how lazy i want to be.

Turbo X_J

Wait until you hear the noise, go back to the place throw the manager in & go for a spin.

Gimmy

It's a lost cause to argue with a shop unless you can make the noise when they are with you. And even then they will say that's not from us. Just don't let them know that you looked at it yourself