Strange noise on front wheel when braking at low speed . My mechanic found it .

[oldgrayman]

2012 Mazda CX-9 . About a year ago I had a full brake job . I took it to a different shop and had them investigate the noise . My guy said that there were some retaining screws missing on the rotor . He said a lot of mechanics do not put them back when they take the wheel apart , so he's not sure what their purpose is . Anyway , he got some screws from Mazda and replaced them on both front wheels . Noise is gone . He was kind of baffled for a while but stuck with it until he found it .

 

[ripcord]

Glad you got your issue resolved.

My brother once got a screaming deal on a used car because "the brakes were shot." We inspected the brakes and found a pebble between the rotor and the dust shield... And nearly new rotor and pads.

 

[eljefino]

That's weird. I can't argue with success, but the lug nuts should be holding everything together, solid, in a sandwich when the wheels are on.

 

[oldgrayman]

That's weird. I can't argue with success, but the lug nuts should be holding everything together, solid, in a sandwich when the wheels are on.

He said the exact same thing . I don't know . You only heard the noise at 20 mph or less and only going forward . That was the only thing he could find .

 

[Jimmy_Russells]

The retaining screws are there just to hold the rotor in place when the wheel is not on and/or if the caliper is removed. In service there is usually some corrosion between the hub and rotor that will hold it in place anyway, I think it’s mainly for the factory so the rotors don’t fall off.

I wonder if the screws were actually the problem or if disturbing the original install fixed the problem. Either way, glad it is fixed .

 

[oldgrayman]

The retaining screws are there just to hold the rotor in place when the wheel is not on and/or if the caliper is removed. In service there is usually some corrosion between the hub and rotor that will hold it in place anyway, I think it’s mainly for the factory so the rotors don’t fall off.

I wonder if the screws were actually the problem or if disturbing the original install fixed the problem. Either way, glad it is fixed .

You said a lot of the same things he said . Factory install thing , etc. He said there was a little bit of rust behind the rotor that he cleaned off just because . He charged me $85 bucks to do both front wheels and rotate the tires . Well worth it not to have to listen to the wife complain ...

 

[Hall]

I suspect there was debris or something and it got removed either just from disassembling things or the mechanic cleaned it up. Those retaining screws are absolutely not necessary once the wheels are on.

Noise is gone though and you (or your wife) are happy so that's all that matters.

 

[kschachn]

I suspect there was debris or something and it got removed either just from disassembling things or the mechanic cleaned it up. Those retaining screws are absolutely not necessary once the wheels are on.

Noise is gone though and you (or your wife) are happy so that's all that matters.

Correct, and in fact if those retaining screws were the cause of noise then there was a much bigger problem than just the screws.

 

[D60]

Yeah if we're relying on something like an M8 screw to locate a rotor in use, we're all dead.

 

[ZX11Rebel]

I owned a 1987 Mazda B2000 that had TWO "alignment" screws on the rear brake drums. This one shop I took it to for new tires did a "FREE" brake inspection and didn't reinstall those screws. My rear brakes started "clanking" making all sorts of noises. Only reinstalling those screws made the "clanking" go away. Those screws are there for a purpose!

 

[Hall]

Those screws are there for a purpose!

On that vehicle, with drum brakes - maybe. On Japanese-heritage disc brake rotors ? Nope

 

[ls1mike]

I never put them back in on my cars that have them.

 

[D60]

I never put them back in on my cars that have them.

I just found 'em helpful on KL Cherokees with lug bolts. The rotor has a very shallow hat and floats around pretty easily with the wheel removed.

But there's no noise when assembled if they're not present-- it's just convenience with the wheel removed and for running the bolts thru the wheel and the rotor

 

[Pablo]

Well finished the job and had a few loose parts sitting there usually is an indicator. Just saying.

 

[Nick1994]

How were your lug nuts squeezing your wheel, to the rotor, to the hub, not enough?

 

[Barkleymut]

. He charged me $85 bucks to do both front wheels and rotate the tires . Well worth it not to have to listen to the wife complain ...

Thats worth at least $250, you got a screaming deal

 

[RAR]

The answer is in your follow up: he cleaned out the rust behind the rotor where it meets the hub.

If that’s not cleaned out the rotor will ever so slightly wobble. It may turn into the noise you describe. The missing screw just allowed it to wobble even more.

The rotor retention screws are not absolutely necessary, but I either reuse or replace on cars because it looks hacked when they’re left off and the owner notices. I keep a bulk pack of each size if I need them. Usually they’re a problem and fail when someone put them back on with an impact set at “mega-gorilla” setting.

 

[notharry]

If some are put back in but not tightened they could hold the wheel away and cause the wheel not to seat. I install them if they are in good shape but normally toss them As said the wheel and lug nuts hold it in place. Also it is possible that on your vehicle. those screws hold the alignment on the rotor straight to the hub. I have a hard time believing this however, success is proof to me. That said the rotor would be seriously off balance and you would have all sorts of vibration at greater speeds. My feeling. those screws are there for ease off assembly on the line only

In conclusion, anyone's guess is a good as yours. Thanks for the post and ill pay more attention in the future.

 

[JeffKeryk]

I like to clean and re-lube brake components every couple of years. It allows for a through inspection and makes the brakes feel better. Placebo effect for the win!