2015 mazda6. 70k miles. New rotors and pads 10k miles ago. Southern car (not crusty).
Rear brakes have new dragging noise. Only while braking. Only hear it at low speeds. Not a wheel bearing.
Pulled wheels to check pads today. The pads look nearly new. Turn the hubs and the RR hub is "dragging".
Pulled apart the calipers. Cleaned and greased the slide pins with brake lube. Re mounted the wheels and test drove.
Same noise. I'm an architect with some tools, not a skilled mechanic. What else should I be checking?
sounds like the piston is sticking in the bore not allowing the pad to retract away from the disc slightly. Usually caused by not changing the brake fluid. Brake fluid absorbs water over time, which causes thing to rust or corrode internally.
Usually means a new caliper
Every mazda 6 I have put pads on have had this issue.
The pads fit too tightly in the carrier and don't have any freedom of movement. They need ground down a bit so they have some room to float. The ears especially seem to not fit well.
Also, check for a collapsed hose.
wvumtnbkr said:
Every mazda 6 I have put pads on have had this issue.
The pads fit too tightly in the carrier and don't have any freedom of movement. They need ground down a bit so they have some room to float. The ears especially seem to not fit well.
Also, check for a collapsed hose.
Hoses seem fine. When you say "they need ground down" do you mean by normal wear.. or something else?
Now that I know for sure there is still plenty of pad present I'm inclined to tell my son just drive it.
MiniDave said:
sounds like the piston is sticking in the bore not allowing the pad to retract away from the disc slightly. Usually caused by not changing the brake fluid. Brake fluid absorbs water over time, which causes thing to rust or corrode internally.
Usually means a new caliper
This makes sense - quite likely the case. RA has calipers for fairly cheap.
OHSCrifle said:
wvumtnbkr said:
Every mazda 6 I have put pads on have had this issue.
The pads fit too tightly in the carrier and don't have any freedom of movement. They need ground down a bit so they have some room to float. The ears especially seem to not fit well.
Also, check for a collapsed hose.
Hoses seem fine. When you say "they need ground down" do you mean by normal wear.. or something else?
Now that I know for sure there is still plenty of pad present I'm inclined to tell my son just drive it.
Not the friction material. The actually backing plate firs too tightly in the carrier.
If you can't freely move the pad a little inside the carrier and it is a really tight fit, you need to grind the ears of the pad down a bbit.
If that is the issue, a new caliper won't fix it.
If you have an internally collapsed hose, a new caliper won't fix it either.
Basically, the hose will collapse internally when the brake pedal is pressed and released. When released, the hose will suck shut and not allow the fluid to return to the master cylinder. This will act like a stuck caliper.
Cleaning the rust out of the carriers is regular maintenance, at least here.
Check to make sure the backing plate is not hitting the rotor while you are in there.
Pete. (l33t FS) said:
Cleaning the rust out of the carriers is regular maintenance, at least here.
Check to make sure the backing plate is not hitting the rotor while you are in there.
Thank you Pete.
For this and for your response in every single "help" request I ever posted on GRM. Seriously.
Does the rear have the parking brake inside the hat of the disc? You might be surprised at what happens to the shape of brake components when they are applied.
My van got new rear rotors and pads a few months ago. I had a dragging noise without brakes applied and it went away when I applied brakes. I pulled the rotors and there were witness marks on the inside of the rotors and the parking brake shoes where they were rubbing. Quick adjustment and the noise was gone. I've also had the same issue with backing plates. They look like they're not touching, then they rub when you turn the wheel or apply brakes
In reply to Curtis73 (Forum Supporter) :
The parking brake is integrated. I did not pull the rotors but now have one more item to check. Thanks Curtis.
Update. Due to worse noise.. I pulled the wheel and checked again.. turns out the "back" side pad was gone and cutting into the rotor - so I'm off to buy parts.
This car has the brake cylinders that have to be twisted to push them back so I bought a little cube tool from Lisle. I mean Amazon.
I'm not certain how to tell if a stuck cylinder is the culprit. Any tips?
..the pads were definitely wedged pretty tightly in the caliper. I'm hoping new parts+ a cleanup and new grease will let it slide.
In reply to OHSCrifle :
If you cannot turn the caliper in, it's bad.
It pays to use a thin flat screwdriver to lift up the boot and take a look at the piston. If the piston is rusty, it's donezo.
IIRC these have weirdish calipers where the piston is not centered on the pad. This is only important because it means you do not line up the piston pin notch in the caliper "vertical" or the piston will foul on the pin. If it is that type then there will be a little arrow on the caliper to line the notch up with.
Pete. (l33t FS) said:
In reply to OHSCrifle :
If you cannot turn the caliper in, it's bad.
It pays to use a thin flat screwdriver to lift up the boot and take a look at the piston. If the piston is rusty, it's donezo.
IIRC these have weirdish calipers where the piston is not centered on the pad. This is only important because it means you do not line up the piston pin notch in the caliper "vertical" or the piston will foul on the pin. If it is that type then there will be a little arrow on the caliper to line the notch up with.
Thanks Pete. I was able to turn it.
OHSCrifle said:
Update. Due to worse noise.. I pulled the wheel and checked again.. turns out the "back" side pad was gone and cutting into the rotor - so I'm off to buy parts.
This car has the brake cylinders that have to be twisted to push them back so I bought a little cube tool from Lisle. I mean Amazon.
I'm not certain how to tell if a stuck cylinder is the culprit. Any tips?
..the pads were definitely wedged pretty tightly in the caliper. I'm hoping new parts+ a cleanup and new grease will let it slide.
I'm betting on the wedged pads... that was my issue more than once....
Victory. Thanks GRM assistants!
This stuff gets easier every time.
Yay! I have lots of E36 M3 experience with mazdas. Love them anyway!
Many aftermarket pads have looser tolerances and end up being tight in the carrier. I still buy them, but make sure they are not too tight or loose. Usually a little file work cleans up the edges and they are fine.
porschenut said:
Many aftermarket pads have looser tolerances and end up being tight in the carrier. I still buy them, but make sure they are not too tight or loose. Usually a little file work cleans up the edges and they are fine.
As the stamping tooling wears, the backing plates get longer, and the edges get rougher. This is what causes new aftermarket pads to not slide freely in a properly clean caliper bracket. I see this even with high-quality aftermarket pads. They almost always need a little cleanup on the ends to make them slide without binding.
I figured they made them oversize so that they don't click and rattle after some bozo uses a cookie to clean the rust out of the carrier, wrecking its tolerances. But that makes sense too!
The old (bad) pad was literally stuck/wedged in there. Not crusty at all because Georgia - just brake dust and grime.
When I cleaned it all up and lifted the caliper.. and the new pads slipped right out, I knew the new pads weren't too tight. LOL.
In reply to Pete. (l33t FS) :
A "cookie"?
In reply to OHSCrifle :
3M sanding pad type of device.
In my perfect shop, those and electric drill drivers will be banned. I see a lot of brake pulsations and loose pads after people use those damned cookies on the caliper carriers and the hubs. And I chuckled when the one soon-to-be-former-coworker was whining that he had to pay $500 for a MINI lower airbox after he stripped all the screws in it by using a drill driver instead of a ratcheting screwdriver like someone who wants to get work done fast AND not wreck things would do.
