Weird scrubbing/ low groaning noise from rear brakes?

[Michael O'Connor]

So my A3 has had this weird sound coming from the rear brakes since I bought it. I usually notice it under low speed braking but I'm going to assume it's there under high speed braking too. It's 2006 model but only 16K on the clock and has been very well kept and maintained by prev owner and myself, so I don't reckon an age thing.

On my recent service earlier this month I specifically asked the mechanic to look at this issue, and he came back saying that the brakes only have about 30% use of them and are 'like new'. He reckons it's me not braking hard enough. I took this into account and have tried doing this, but the sound is still there. Personally I find the brakes are pretty good and as a result it's pretty hard to brake more or 'harder' to an extent without jerking forward/ slowing down drastically and aggressively, unless it's when I'm at speed.

I've already searched this problem and someone had said something about lip corrosion or something, but it's just really weird that the mechanic found nothing with the brakes. He's a very trusted old friend of my old man who worked as a mechanic at Mercedes for a long time, so I trust that he knows what he's on about and also isn't trying to get money out of me by replacing stuff etc.

Any ideas?

 

[samuelh_888]

Replace the rear pads with some OEM quality pads. See if that improves things. Rear brakes don’t really get a great deal of use, balancing out the pitching when you brake.

 

[Michael O'Connor]

Replace the rear pads with some OEM quality pads. See if that improves things. Rear brakes don’t really get a great deal of use, balancing out the pitching when you brake.

Right yeah that's what he said, they only come into play when the nose of the car goes down too much or something. Not sure why they're groaning under low speed braking then, it feels like it's just the front brakes doing the work when I do that. I'll try that and see though, cheers!

 

[prt57]

I had something similar recently with the front brakes on my Mk 4 GTI in that I would get a grating sound under braking.
I had fitted new genuine discs and pads about 70,000 miles ago and they had been totally fine. The outside of the discs looked fairly OK and the pads looked about 50% worn.
Like you, nothing appeared out of order.
I am a person who does not rely on the brakes too much, making use of engine braking. This is probably where the problem originated along with not driving the car after washing it.
When I took the pads out which were not sticking in the calliper I could see the inner side of the disc had strange circular shapes of what looked like black rust into the metal. I could feel that they were not totally smooth.
So I replaced with Brembo discs and pads and now silent again.
So maybe your car has stood around with damp brakes allowing corrosion to the discs. The rear brakes do not exert much force and so the rust has not been scraped off giving a grating noise like mine.
Providing your noise only happens under braking then it has to be something similar.

 

[SootySport]

I would go further and change the pads and discs. Over the 12 years the pads & discs may have been contaminated by something or other.

 

[Michael O'Connor]

Thanks for the replies guys! Guess I'll look into getting some new rear discs and pads then!

I think I'm going to go with OEM ones as Brembos will have to be declared to my insurers I'm assuming, and I bet they'll try hike my premium up

What would be a good brand of OEM discs/ pads?

 

[prt57]

Brembo are oem equivalent.