Rear brake issue (pics attached)

[Jimbo10]

Need some help chaps.

Been hearing an annoying rotational noise coming from the rear offside wheel so took it into Audi and they sent me an AudiCam video.
Car was up on the ramp and the technician span the wheel with his hand and it stopped at the same point on every turn. The diagnosis from Audi saying "rear brake pads + discs have high spots / some corrosion, this is the cause of the friction noise”.

They recommended I change the discs and pads to stop the noise.

However the question is, Why is this happening? The car has done 18,000 miles. There are no lips on the disc. There is no excess wear on the discs. They told me there is 80% material left on the pads.

The video would suggest either a warped disc or the caliper not releasing far enough?
If I were to change the pads/discs as recommended, whilst it will stop the rubbing noise neither components are showing excess wear, so why change them?
If they’re being changed because the disc is warped, then why has this happened (considering the other three brakes are working perfectly)?

I went out today for 30 minutes of driving with moderate to hard braking to see if the disc would clean up but you can clearly see from the images that the rear offside disc is an indication that something is not right.
My biggest concern is that with this being a braking component, it is now a safety issue and there is an underlying issue here, which needs to be identified.

My initial thoughts are that the caliper is at fault and therefore a warranty issue? Any idea's?

Offside

Nearside

 

[desertstorm]

I would say there is an issue with the slides on the caliper sticking or the piston sticking. The pad is not contacting the disc properly and that has led to the very poor surface condition of the disc.

 

[Rob2k68]

Are you in the U.K. near the coast ? Some very bad corrosion on the hub face hence they’ve been painted black - looks like something has seized/rusted causing uneven wear.

 

[SJC]

To be honest that does not look that bad. I had to replace mine as the face of the disc started coming off in sections. Got pads and disks swapped and same is happening again. Unfortunately if you wash you car and don’t run it. Use some wheels cleaners that are aggressive and also don’t do enough braking this will happen over time.

 

[deanshaw24]

It’s not that bad no, but it shouldn’t be happening. There is clearly and issue, be it the slider in the caliper or mayby a build up of dirt that’s got stuck in the brakes. Have a word with th dealer and try and get it done under warranty

 

[Jimbo10]

Are you in the U.K. near the coast ? Some very bad corrosion on the hub face hence they’ve been painted black - looks like something has seized/rusted causing uneven wear.

I painted the hubs due to the classic rust issue the A3's seem to suffer from.
Don't live by the coast no, but as only one disc is affected...I'm not sure that would be the reason because surely the other three would be similar

It’s not that bad no, but it shouldn’t be happening. There is clearly and issue, be it the slider in the caliper or mayby a build up of dirt that’s got stuck in the brakes. Have a word with th dealer and try and get it done under warranty

They recommended I change the pads and disc for £245...

 

[deanshaw24]

I painted the hubs due to the classic rust issue the A3's seem to suffer from.
Don't live by the coast no, but as only one disc is affected...I'm not sure that would be the reason because surely the other three would be similar


They recommended I change the pads and disc for £245...

I would come back at them and ask why they think the discs and pads need renewing at such low mileage. See what their answer is. They can’t blame it on th elements or the other 3 would be in the same condition.

 

[Retroman]

The car was probably sat on a forecourt for several months. I bought an Aygo for my daughter a couple of years back and her front discs were similar with around 15,000 on the clock. The pads were around 50% worn so I changed them, cleaned and lubricated the calipers and after some heavy braking and bedding-in, they cleaned up the discs nicely. The combination of new, unglazed/uncontaminated pads and bedding-in, seems to clean up a disc face nicely.

 

[Jimbo10]

The car was probably sat on a forecourt for several months. I bought an Aygo for my daughter a couple of years back and her front discs were similar with around 15,000 on the clock. The pads were around 50% worn so I changed them, cleaned and lubricated the calipers and after some heavy braking and bedding-in, they cleaned up the discs nicely. The combination of new, unglazed/uncontaminated pads and bedding-in, seems to clean up a disc face nicely.

I am not mechanically savvy enough to service the brakes myself, nor would I want to for safety reasons.
My concern is that it is only on one disc. I was told the pads have 80% material remaining (so I don't see why I would replace them).

I just don't understand why Audi would recommend changing the pads and discs when both components have plenty of wear left in them. Surely when looking at the issue they would've realised the pad and disc aren't working in harmony?

It's kind of embarrassing for me because I feel like I'm telling the mechanics how to do their job but surely it's obvious that something is amiss here. I mean just looking at the ****** disc is enough evidence of that?

 

[msdmjb]

It suggests shows that the pads either aren't pushing on or pushing on hard enough to the disc.
As you say, if you left a car for a while you might see this but would then expect it to clean up once used again.

My advice would be to find a quiet straight road and use the handbrake as an emergency brake a few times to see if that cleans it up, if not then if you are comfy drop the pads out of the problem corner to see if any dirt/debris/stone etc is in there interfering. Audi seem to have jumped to replacing stuff rather than investigating, if you aren't comfy removing the pads might be worth a local mechanic spending 30mins doing it for you using liberal amounts of brake cleaner. You might just have a sticky piston or a seal has interfered with the piston.

 

[SJC]

Prior to removing rear disk pads. Also look up previous posts on replacing rear disks and pads. If you don’t, well... let’s say you could end up with a lot bigger problem than a rusty disk

 

[AJB]

My advice would be to find a quiet straight road and use the handbrake as an emergency brake a few times to see if that cleans it up

I'd do this on a car with a cable operated handbrake, but not on your A3. I've never tried it, but I believe that pulling the handbrake switch up whilst you're moving uses all 4 brakes and ABS to do an emergency stop; ie it's just the same as stamping on the brake pedal as hard as you possibly can, with no way of modulating it at all.

Given you say you've already tried some moderate to hard braking, then if it still looks like that I'd say there's something up with the caliper. Did it look the same before you tried the hard braking, or was it worse before (worse as in a bigger rusty area, and smaller shiny areas). If it'd been parked up for a year or so, and just brought back onto the road then I'd expect the disk to look like that, but if it's seen regular use I wouldn't...

Just replacing disks and/or pads without getting to the bottom of why one side has ended up like that whilst the other hasn't is just asking for a new set of disks to go the same way...