Awful scraping sound when reversing

[angled]

Hi,

In the last couple of weeks I've noticed my genII 3 has an awful screeching / scraping sound when reversing. I noticed for the first a few weeks ago when reversing at full lock with the windows down and the radio off, but now that I pay attention to it I can hear it every time when reversing. No such sound at all when going forwards.

Any suggestions as to what could be the cause?

- Edward.

[rogwick]

Check the brake pad indicator for one (should be ok being a newish car though)

But also get the brake disc aluminium guard. The guard was rubbing on the backside of my disc making a loud scraping noise, I found it had knocked out of place. Jack it up fiddle the guard back into its locking position (or you may need to manually bend it back as it may have been knocked)

Check it and see if that fixes the problem. If not, maybe provide more info and possibly more responses on here. Hope that helps anyway.

[240MPS]

Edward is it only on full lock that it does it, If so do yourself a favour don't full lock it on the steering wheel, 2 things it gets rid of the noise and it puts pressure on the power steering pump which isn't good for it.... Try that first

[angled]

Yeah, I thought it might have been a full-lock induced problem but the scraping is clearly audible when reversing straight.

I've had the car since last September, it's got a tad over 13 000km on it. If the brake guard was bent wouldn't it also scrape when going forwards?

Thanks for the suggestions!

[03blk]

Had a terrible scraping sound a few months back coming from my front drivers side wheel after backing out my driveway.

I took the front wheel off and shone a torch between the aluminium guard and brake disc. There was a tiny pebble jammed in there that was scratching on the disc.

I imagine if this was your problem it would happen when going forward too. But it may be worth a check if you can isolate the problem to one wheel.

[Nexus]

Word of caution:

I'm intensely familiar with this sound and having gravel in the brakes.

In my case it occurred repeatedly for approximately two months. Never while the vehicle was moving, always after it had been parked. Usually in the same location but gravel also found it's way into brakes while vehicle was parked in a number of other locations.

Gravel would come out obviously crushed when one flexed the shroud. All would be good until the next occurence. That occuring alongside two vehicle entries that seemingly bypassed entry security was too much for me and in paranoid investigator mode, looked into it, suspecting vehicular inteference.

Discussion with many service agents lead to perception that "once or twice in a vehicles lifetime" was a norm for something like this happenning "randomly". So the overwhelming statistical significance of repeated instances strongly suggest inteference - i.e. someone willfully placing gravel in the brake assembly.

Took to service and requested brakes be inspected in detail, particularly front, gravel shrouds, Gravel was found in the disc. The going theory is that gravel was placed so as to obstruct the calipers, was then crushed at which point to get's caught in the rotor, eventually it makes it's way out, at which point in fouls between the gravel shroud and disc. On one occaision it was so severe that when jacked up after stopping almost immediately, the gravel jammed in there was a very significant impediment to the rotation of the wheel and tyre.

There's more to the story, but suffice to say that after someone saw me seeing them loitering near the vehicle, all instances of gravel intrusion ceased.

I expect it would be near to impossible to place gravel as necessary to do this deliberately with the stock wheels. I have a much more open wheel face that would make it easier.

So I'd be (a) interested in hearing from anyone who has experienced anything similar in order to gauge norms, and (b) asking if you have aftermarket wheels with an open face?

I don't know exactly where the gravel was placed, so someone very familiar with the OEM brake assembly might be able to detail that?

[angled]

No, they're the stock GenII MPS3 luxury wheels (which may be the same as the normal GenII MPS3?).

The gravel-in-the-brakes theory could fit as I first heard the noise out at the Cotter Dam area in Canberra. We'd driven the back way through Uriarra and there was a *lot* of gravel on the road at one point on Brindabella Rd:

Urayarra Crossing, Mount Stromlo Australian Capital Territory 2611 - Google Maps

I recall it was enough for me to lose traction (but thankfully, not control).

I'll take it along to my Mazda place tomorrow to get them to check it out...

[Nexus]

Gen2 wheels are more open than Gen1. I don't think you could get your hand through the gen1. I imagine you could on the Gen2.
If cou're driving on gravel and splashing it about, the awnsers fairly obvious.
In my case I couldn't really audit the gravel against road etc, and it started immediately after a rotor replacement...
and persisted after a precautionary service during which brakes were cleaned out, so more than one incursion in my case.
Still have the same wheels and same make tyres. Hasn't happenned again.

Repeated occurrences could be due to a single incursion into the brakes if the gravel sits in the rotor until it finds it's way out, if there's bit's stuck that you don't get out first go.

[angled]

So of course when I took it into Mazda today for them to inspect, it didn't make a sound...

[angled]

Mazda identified the source of the problem today: gravel in the rear left disc brake. Rolfe Mazda in Canberra took it apart, tested it, cleaned it and put it all back together, all at no cost to me. Win!