Clonking brakes.2013 Beetle

[emver]

My 2012/3 Beetle 2.0Tdi makes a moderately loud clunking noise on braking. The noise is related to road speed, probably clunking with every revolution of the wheel, and only appears during braking. It seems to come from the nearside rear, but noises are often deceptive. The car has done 33000 miles from new and is on its original discs and pads.

I've dismantled the rear brakes, expecting to find a loose pad or broken retaining clip, but all seems ok. Both rear discs are moderately scored with some rust pitting on the outer edges for around 7mm from the outer edge. The offside disc is slightly more scored but the noise seems to come from the n/s. The pads are less than half worn.

I suppose the next step is to replace the discs and pads but I'm a little reluctant to do that because brake efficiency is fine and scored discs have very little effect (rear brakes do very little work anyway), and the car has only done 33k miles since new.. But if somebody can convince me that this is the cause of the clunking, I'll be happy to do it.

[emver]

Problem solved. There was a slightly corroded patch on the NSR disc. The noise came from the pad striking this patch on each rotation.
A couple of minutes' work with a sanding disc on my angle grinder cured it.