Has anyone else had this?

Sounds horrible when you're driving down the road but it's really nothing, just a pebble bouncing around between the rotor and the shield.

I've already had it happen twice in 2 months with my new 991.

Today it happened on a busy street and everyone was looking from the sidewalks as if my muffler had fell off and was dragging. It's really crazy how much rattling, squealling noise it can make.

I actually got out and checked around me car thinking a heat shield had falled off or something.

Then as I started driving again the noise abruptly stopped and it's been fine ever since. I know it was just another pebble in the heat shield.

 

No, but It sounds like a gong when a pebble hits the shield. Surprised me the first time.

 

Those shields are like like cymbals.

 

I had the problem and got rid of the rock by backing up a little faster than normal backup (this was Service Manager's solution).

 

Yes, but not for a loooong time (73 Triumph). If it's really jammed in there I suspect you can slide a blade screwdriver between the two surfaces. It only takes an infinitesimal spread to allow it to drop out.

 

Good solutions if it happens again. Thanks guys.

 

I removed the heat shields to help with cooling when on the track, but would not do that as a solution to an occasional rock hitting them.

 

What's that shield there for anyway? I assumed it was to keep brake dust off all the components in the wheel well area.

 

If you had ceramic composite brakes, the disc with the pebble would be scratched and thus ruined. Porsche makes you buy two new discs, the damaged on and the one on the other side. A small fortune. That's why I no longer order PCCBs.

 

I also had the problem several times and had my factory rep get involved. Dealer/factory rep found "witness" marks on the rotor. This was the second time they had to clean rocks out. First time they replaced a rear strut but then found a burnished pebble way up in the suspension. Mechanic showed me how the 991 is built. Porsche left a spot open in fender wells (no apparent reason) and rocks get picked up by the wide tires and which go through these gaps into brakes/suspension. It is a PITA and causes problems. PCNA has no remedy planned but my factory representative had a look and is aware of the issue. He has seen it before. This is also why we get more noise when you drive over road surface with rocks/pebbles. Avoid road surfaces like this if you can.

 

They replaced a strut for me the first time that was OK (a burnished stone was found). When it recurred, I asked for my factory rep to have a look.

This second time around they found a "witness mark" and needed to take the stones out that were caught in the rotor.

Stones usually work there way out but sometimes you need service and they have seen this before.

I love my 991 and avoid gravel roads when possible. Happy Holidays!

 

Happened to me this morning. Was just pulling up to a stop sign and it sounded like I was dragging a beer can. Backed up about 6 feet and the rock came out. Fortunately, I had read about the rock in the brake shield on another forum, and I knew instantly what it was. Otherwise, it would have totally freaked me out.

 

Not on the 991, but it's also a problem on the F8X M3/M4, most horrible sound when it happens. My BMW updated the shields, with an "escape slot" that allows the pebble to be ejected. Maybe Porsche can do the same.

 

Happened to me, sounds like a wheel is falling off. I was almost home when it happened so I was going to fix it but after a few miles it actually worked its way out.

 

Not there for brake dust control but there to keep road spray from getting on the rotors.