Front brake pads rattling against the rotors

[ElFenix]

2008 mazda3. Installed new pads/rotors last May, about 6000 miles ago or so. Car had previously had the original brakes (went 150,000 miles). Last month or so the front pads have been rattling against the rotors when just barely moving (or, with very judicious application of the pedal, not moving perceptibly). Pads/rotors are brembo.

Any ideas?


edit: why are threads i post from tapatalk labelled "announcement"

 

[kt]

Could be a lot of things with the amount of information given. Did you apply brake grease when on the pads? How about checking and re-applying grease on the caliper pins when you install new rotors/pads? Did you re-use hardware kit with the pads or new kit? Maybe air bubble in your brake system?

 

[mindless1]

What vehicle? Is it just one wheel or both (or all 4) ?

Pull the wheel(s) and inspect everything, though my first guess would be loose caliper bracket bolts.

 

[ElFenix]

Could be a lot of things with the amount of information given. Did you apply brake grease when on the pads? How about checking and re-applying grease on the caliper pins when you install new rotors/pads? Did you re-use hardware kit with the pads or new kit? Maybe air bubble in your brake system?

just front wheels. applied grease to edge of pads where they sit in the caliper, not on the back as these are supposed to be the quiet kind. inspected but did not grease slide pins. iirc we reused the anti rattle springs (unless pads came with new, then we used those). i'm thinking first order of business is to lube the caliper pins.

it's rainy today and they're dead silent.

@C1 @mindless1

 

[C1]

You are supposed to put a swirl surface on new rotors to effect non-direction of the break pads. This helps prevent pad rattle, drift and/or vibration.

Presumably new hardware (eg, anti-rattle clips were installed along with the new pads).

Ensure the caliper slide pins are suitably greased and that the caliper retaining bolts are tightened to specification.

Oh ya, dont know how old your vehicle is, but with that many miles also ensure that the calipers are not binding (due to accumulated dirt that has deposited in the caliper behind the piston over time).

As such, check for caliper/pad heating due to break drag. Driving at high speed and not using breaks should result in only a warm feeling wheel hub. If not, it may be necessary to clean and rebuild the calipers.

Finally, there is anti-rattle applications (applied to back of pads) which are available from auto stores. I dont like to use such stuff because it makes such a mess if/when you ever have to re-do the breaks.

 

[EXCellR8]

Did you use shims behind the pads in the front? the pads should be just barely riding the surface of the rotor when the pedal is not applied. if there is a little play there that shouldn't be it could rattle a little bit. And, since you're stating it's rainy today, a bit of water might be preventing the rattling.

 

[ElFenix]

Did you use shims behind the pads in the front? the pads should be just barely riding the surface of the rotor when the pedal is not applied. if there is a little play there that shouldn't be it could rattle a little bit. And, since you're stating it's rainy today, a bit of water might be preventing the rattling.

are these not pre-shimmed?

 

[herm0016]

have not seen separate shims on any modern pads.

 

[mindless1]

Shims usually don't determine play for a low frequency rattle condition. They buffer higher frequency movements that cause more of a squealing sound. I suppose it's possible to have a lower frequency sound from a (truly) warped rotor or air in the cylinder, but the typical noise from shim factors isn't a rattle.

Call them shims, or call them backing plates, etc... either way is a separate piece of material behind the thick one that the pad material is bonded to.

Sometimes that alone is not enough, particularly if the caliper piston is steel and the contact edge has a lot of rust. A lazier shop might just slap some grease on then instead of cleaning the edge off.

Backing up a bit, how was it determined that it is the pad(s) themselves rattling against the rotors? Might it be the shield behind the rotor rubbing, or even something simpler like lug nuts need retorqued?

 

[ElFenix]

Backing up a bit, how was it determined that it is the pad(s) themselves rattling against the rotors? Might it be the shield behind the rotor rubbing, or even something simpler like lug nuts need retorqued?

i crouched next to the wheel and observed them while having a helper on brake. it was visible (though i couldn't pick it up on video)

 

[kt]

If the rotor is not warped and is seated correctly, then it sounds like the pads may be stuck in the depressed position. If the edge of the pads are sufficiently greased, then it could be the metal spring part of the hardware kit. The metal spring is supposed to push the pads apart when the brake piston is not applied.

 

[mindless1]

Any progress made? Ultimately you have to pull the wheels and inspect it, going through the motions of a brake job if nothing is immediately apparent... so many things it could be, if we ignore odds and consider any possible source, even a defective pad that has separated from the backing plate.

 

[NutBucket]

have not seen separate shims on any modern pads.

They're usually integrated. I noticed for our 2012 Accord, the OEM parts diagram show them as separate and indeed there's a part number just for the shims. Aftermarket pads (I typically use Hawk) have them integrated.

 

[ElFenix]

Any progress made? Ultimately you have to pull the wheels and inspect it, going through the motions of a brake job if nothing is immediately apparent... so many things it could be, if we ignore odds and consider any possible source, even a defective pad that has separated from the backing plate.

been nothing but rain and no daylight the last few days, so haven't had the time to pull the wheels off and look.

 

[ElFenix]

cleaned and lubed the slides on all 4 corners, not sure it helped.