Metallic scraping sound under hard left-hand cornering / removal of rear brake guard

I've noticed a couple of times recently that when taking a left-hander really hard, especially if it's a lowish speed bend taken flat-out and the body rolls to about the most a GTA's ever does, I can hear a metallic scraping sound. It's not that loud - I first heard it recently with the windows down - it sounds a bit like an exhaust gently rubbing the ground, and it's a constant noise, not like something is bouncing along the ground. Any ideas? If I look around the underside of the car on the RH side I can't see anything that looks like it's rubbed at all, the wheels/tyres all look fine, and I checked the wheel nut torques. I need to get it sorted as this could presumably become more serious and annoying at Donington in October...

Also, on that note, have the people that track their cars removed what looks like a dust shield from the rear brakes? Looks like it wouldn't help the cooling... I'm tempted to removed them when I upgrade the front pads, if its a simple job...

I had exactly the same thing in a non-GTA 147. Turned out to be something to do with one of the brake calipers being gunked up, and was sorted out at a service at my local indie.

Sorry I can't be more precise, but might be an idea to give them a clean.

What tyres are you using and are they pretty new?

Any chance it is the wheels rubbing? (either front or back)
The rears would rub the soft padding first and make sort of a low caaaawwhhhh noise.
I remember a good while back you mentioned some rear padding issues when your car was new.

I experienced this once once with heavily loaded car on an uneven surface, but my rear dampers were set to a very soft setting (zero in fact!).


The front wheel arch lips rubbing the tyre sidewalls makes a more
kkkkeeeeehhhhh like noise.

I had this problem recenty with a 225/40/18 8x18 alloy tyre (ET 38) combination and had to get the insides of the arches rolled which fixed the problem.

However while I can't swear to it, now that I know what front wheels rubbing defintely sounds like I can't rule out that the standard wheels rubbed slightly under extreme track use with new tyres and high pressures (plus much stiffer springs than normal, but same ride height).

Maybe check the paintwork under the arch, although it suprisingly doesn't actually get messed up too much from rubbing - the tyres get much the worse impact.

Perhaps put some bluetack or something there and see if it gets smeared?

One other idea, is your sump guard bedraggled and hanging down a little?

I haven't removed the rear dust guards (heat shield?) myself.

I would guess that the high speed nature of Donnington won't present too much a of a challange for the rear discs.

Also I suspect that the increased braking force of your car due to DS2500's would mean that the rear will become lighter due to increased weight transfer under max braking and the rears will actually be doing less total work than if the car had standard front brakes.
Just a theory, I can't swear that its fact

Cheers,
TB

Cheers. It's on standard 17" teledials and 225/45 P Zero Rossos, all fairly new. I can's see any rubbing damage on the tyres or wheels, inside or out.

The noise is a very high-pitched, and very metallic, sound. I think the engine undertray is in good nick, I'll have a better look around it. The rear wheels used to rub in the arches on my last 156 when driving hard with someone in the back, that was a very different sound.

More pressingly (and annoyingly ) I clipped the rear wheel arch on the entrance to the tunnel to my parking space today so will be making an appointment with Chips Away very shortly - while it's in my garage I might jack it up and have a look around the underside...

Originally Posted by jwyatt

More pressingly (and annoyingly ) I clipped the rear wheel arch on the entrance to the tunnel to my parking space today so will be making an appointment with Chips Away very shortly - while it's in my garage I might jack it up and have a look around the underside...

Bad luck, No doubt the fantastic turning circle of the GTA greatly assisted you in that manouvere !

Indeed!!! I have to turn off a narrow one-way lane into a very narrow entrance to the car park, close enough to the wall to use a swip card. I then have to take 3 goes at a corner into a very narrow tunnel that is just straight-in in my wife's Focus, before executing a 4 or 5 stage manouvre that is again one move in the Focus. Getting out is similar. It's not the highlight of my day (thought the noise bouncing back of the walls makes up for it).

I don't normally do this sort of thing, typical I do it to a car I actualy care about and that's in A1 condition Still, I may get Chips Away to sort a couple of chips while they're at it...

Hi there,
Realise this is a bit of an old post but found it doing a search for exactly this annoying bloody problem. Just wondered if you ever found out what it was? I have spent all morning checking and cleaning and fiddling but cant see any trace of rubbing or scraping and it's starting to drive me mad.
Thanks for any advice.
Nick

Hi Nick, if its a metallic noise that varies with wheel rotation sounding like like ka ka ka ka ka ka it could be a driveshaft on the way out..

Front disc heat shields could also be the culprit to these metallic noises...

Thanks for the advice I will look into both suggestions. But just to be clear the problem I have is exactly as described in the opening post-metalic scraping only in fairly tight left hand corners when pushing hard with max roll and nearly full lock. It is starting to worry me so a visit to the garage is required I think.

If it is the heatshield scraping on the disc, the sound it makes is quite "Catastrophic", but in reality it isn't anything major. At most will require removal of front caliper and disc, and either replacing the shield, or bending it back into place, so it does not catch on the disc....the only problem with removing and fitting a new one, is that the little bolts which hold the shield onto the hub/upright, usually tend to shear off when trying to come undone! So perhaps using a little heat could help this...its usually the bottom one where the shield curls beneath the hub/upright, beneath the lower wishbone balljoint. And this is the most important bolt, as it keeps the shield in place away from the disc!