[Evilmoretea]

Hey all day 2 of owning the G42 M240I

Heard a horrible metallic screech from the right rear side today. The noise got worse and louder with acceleration. Happened about 20/30mph

It stopped within a few seconds and I got out and inspected, couldn’t see any visible damage, noise gone and car appears to be driving fine. A

It was just after I had gone over a speed bump and we are in the middle of a storm in the UK so heavy rain and lots of stones, dirt and other debris in the road.

My best guess is that this was possibly a stone or something trapped between the brake pad and disc?

Weirdly the noise got worse with speed and not with braking.

As the noise is gone I’m unsure if I should take it into to the service centre for a look or not, it’s literally only two days old.

Thoughts and similar experiences?

[wb8164]

I'd agree that a stone likely got trapped in-between the brake disc and either a dust shield or the caliper and pads. I've had this happen to me on two occasions. One time the rock worked its way out when I stopped and reversed for a few feet. The other time, I had to remove the wheel and pry the rock out.

You could look to see if there is any kind of score line in the disc on the right rear (check inner and outer).

I'd just keep your ears open for a bit. I'm thinking (and hoping) that it's a one and done for you.

Good luck,
Bill

[Pentland]

Yup. ^^^^^^ this. Quite common.

It’s loud! You either need to:
Disassemble the heat shield from the disc (least preferable option)
Rock the car forward and back to dislodge the object.
Drive around to wear down the stone and it will fall out.
However, often the stone will just fall out when the disc cools down.

[Evilmoretea]

Originally Posted by Pentland

Yup. ^^^^^^ this. Quite common.

It’s loud! You either need to:
Disassemble the heat shield from the disc (least preferable option)
Drive around to wear down the stone and it will fall out.
However, often the stone will just fall out when the disc cools down.

Yeah I’m now pretty certain it was a stone in the brake disc.

The noise stopped within a few seconds so I presume it fell out by itself.

Now just wondering if to take it in anyway to have them double check it is clear of debris or am I being over cautious?

Sound gone means don’t worry?

[Pentland]

Originally Posted by Evilmoretea

Yeah I’m now pretty certain it was a stone in the brake disc.

The noise stopped within a few seconds so I presume it fell out by itself.

Now just wondering if to take it in anyway to have them double check it is clear of debris or am I being over cautious?

Sound gone means don’t worry?

Ain’t broke don’t fix it.

[RockCrusher]

Similar experience with my Boxster. First time on a residential street littered with twigs from an ice storm making a slow full lock u-turn heard a horrible noise. Long story short with some backing up and full lock turns of the steering wheel whatever it was -- twig is my guess -- fell out.

Then some years later got in the Boxster at work and backed it out of the parking space. At some point heard a horrible noise. But I knew what to do. But no matter what I tried could not dislodge the object. Jacked up the right front corner of the car removed the wheel/tire then pried the splash shield out a bit from the rotor and a small < pea sized jagged little rock fell out.

No damage to the rotor.

[Wasp_Factory]

Had exactly this on my front right. Perfect sized and shape stone went down the gap between the the back of the disk and the metal shield behind. Makes a horrible noise. Had to take the wheel off and hook it with a long thin screwdriver.

[Evilmoretea]

Originally Posted by Wasp_Factory

Had exactly this on my front right. Perfect sized and shape stone went down the gap between the the back of the disk and the metal shield behind. Makes a horrible noise. Had to take the wheel off and hook it with a long thin screwdriver.

Yeah I guess that’s what I’m not sure about, the noise is gone so presumably so is the stone. Do I now need to take the wheel off and inspect it to make sure? Or is lack of noise good enough

[Antique-ace]

Originally Posted by Evilmoretea

Hey all day 2 of owning the G42 M240I

Heard a horrible metallic screech from the right rear side today. The noise got worse and louder with acceleration. Happened about 20/30mph

Thoughts and similar experiences?

I had a very similar experience to this back in November. I had just left the parking garage at work and driven only 2 blocks when I heard a horrendous metallic screeching sound that was like the worst, loudest brake squeal that I've ever heard. At first I thought the sound was coming from a large dump truck next to me in traffic, but then I realized the sound was coming from my car. I could not determine which wheel the sound was coming from.

The sound was so alarming that I decided to drive the car straight to the dealership, but before I got there the screeching sound stopped rather suddenly after I made a right turn.

Once I got to the dealership I told the SA about what had happened. They did a very thorough inspection of the brakes the next morning including removing each caliper and inspecting the pads and rotors. They found nothing abnormal and attributed the screeching sound to a stone or some other piece of debris getting caught between the brake disc and the dust shield since there is a rather narrow space between them. I've never experienced anything like this before or since this happened.

[Wasp_Factory]

I guess it has to be the perfect sized and shaped stone, thrown into exactly the right spot for it to be a problem. Too big, it doesn't drop down the gap, too small, it drops straight through and a millimetre either side and the stone will bounce off. Chances of it happening are slim.

OP - if you can't hear it, it has gone. It sounds like the end of the world - a sound even worse than kerbing your alloy!

[Evilmoretea]

Originally Posted by Wasp_Factory

I guess it has to be the perfect sized and shaped stone, thrown into exactly the right spot for it to be a problem. Too big, it doesn't drop down the gap, too small, it drops straight through and a millimetre either side and the stone will bounce off. Chances of it happening are slim.

OP - if you can't hear it, it has gone. It sounds like the end of the world - a sound even worse than kerbing your alloy!

Don’t even get me started on kerbing, I take forever to park just to avoid this. Noticed the turning circle isn’t as good as the 230i.

Drive throughs are a nightmare

[Pentland]

Originally Posted by Evilmoretea

Don’t even get me started on kerbing, I take forever to park just to avoid this. Noticed the turning circle isn’t as good as the 230i.

Drive throughs are a nightmare

Alloy wheel insurance through car2cover - worth every penny. Covers diamond cut too.

[Evilmoretea]

Originally Posted by Pentland

Alloy wheel insurance through car2cover - worth every penny. Covers diamond cut too.

Yeah I heard Mrs P had a run in with a kerb right?

Is it just me or is this thing extremely awkward on tight corners like at the drive through or tight car parks?

Keep feeling like the rear doesn’t rotate in those situations and I’m gonna scrape the side of the body or allow if that makes sense.

[Pentland]

Originally Posted by Evilmoretea

Yeah I heard Mrs P had a run in with a kerb right?

Is it just me or is this thing extremely awkward on tight corners like at the drive through or tight car parks?

Keep feeling like the rear doesn’t rotate in those situations and I’m gonna scrape the side of the body or allow if that makes sense.

No. My wheels are perfect but I have used them before.

[Evilmoretea]

Originally Posted by Pentland

No. My wheels are perfect but I have used them before.

But you get what I mean about turning circle right?


You ever wincing when trying to go through a drive through or right parking? Or am I just a bad driver lol.

Seems like a poor turning circle given the length of the car. Just have to be a bit more careful

[RockCrusher]

Originally Posted by Evilmoretea

Yeah I guess that’s what I’m not sure about, the noise is gone so presumably so is the stone. Do I now need to take the wheel off and inspect it to make sure? Or is lack of noise good enough

In my case while the passenger front corner was jacked up and the wheel off I did look over the side of the rotor which the rock was in contact with and there was no signs of any damage.

While in my experience the rotor suffered no damage, not even from the rock, I can't say your car's rotor escaped unscathed.

If you are knowledgeable in the proper way to raise the car and remove the wheel tire and feel you can visually recognize the presence of rotor damage then inspect the brake hardware.

If not then arrange to get the car to the dealer and have a tech do this.

I'll add if when you drive the car and use the brakes there is no signs of any noise or other issues then you are probably (probably) ok to drive the car to the dealer.

If there is any noise that's not a good sign and flat bedding the car to the dealer is probably called for.