General Front disc brake marks

[Miffed]

Anyone else noticed black coloured marks on front discs ? I'm wondering if this has been caused by overheating ? I've noticed a 'deep drumming' noise when braking from high speed & fully-laden otherwise brakes okay

 

[Denzil]

hello, not sure about black marks on front disks, but my sedicci is 2007 reg has got 32k miles on the clock, and has just had to have both front disks replaced because they were deeply grooved and worn, not pleased, my old astra had 90k on the clock before the disks went.

 

[tinytim]

The marks are where the pads have sat on a hot disc; the "drumming" is a sign of a warped disc; both are caused by keeping the brake pedal pressed while stationary when the discs are hot (meanwhile dazzling the poor driver behind with the brake lights); uneven cooling then warps the disc.
non-asbestos pads require softer discs to achieve the same braking efficiency so they wear out quicker,,,,,

 

[Miffed]

TT, appreciate your reply but I don't think my driving style is the cause ;-) The front discs on my other cars show no signs of overheating and I drive them the same ?! If the discs were warped then I would expect to 'feel' that through the steering under braking, which I don't. I think the problem is due to defective parts during manufacture but the difficulty is proving that ?! regards

 

[tinytim]

Sorry, no criticism of driving style intended or implied.
Modern discs wear out quickly for reason stated; classical sign of warped disc is vibration/juddering when braking and steering is not usually affected; I once had a Saab 99 that had repeated warping of the discs, this was because the handbrake operated through the front pads, a system later abandoned for this reason.
Vented discs often make an odd whistling (flute-like) noise that alters when braking due to air passing over the holes (and acting like a flute) but the discs on my Sedici are solid.
The other possible explanation for the marks is electrolytic surface corrosion between dissimilar metals in the pad and disc; the pads always remain very close to the disc and if there is some salt water between them then this type of corrosion may occur....

 

[Miffed]

TT, cheers

 

[Dodsley]

I get noise from the front when braking, loud but no noticeable vibration through the steering wheel, but only after I've been driving for some while and then not every time. Still warped discs do you think TT?

Mine's a Sedici 1.9 Eleganza with appx 40k on the clock and the original discs.

 

[tinytim]

might be just worn pads but inspection required......