nitch

For anyone that comes across this thread, I got to the bottom of it. It was a failed bushing in the lower control arms (banana arms). They're fluid filled and both had cracked and leaked their fluid. I hadn't noticed the knocking to be honest as it had been a gradual issue and I'd convinced myself it was a brake problem. I also thought it would have been noticed by the garage during service and MOT time. Anyway, replaced the arms both side and the pulsing brake problem has gone. I did it myself so if anyone has any questions, let me know

Keep us updated Gustaf. Does anyone know if the brake calipers are the same on all models? I've got a 2015 BiTdi Allroad so trying to identify the correct parts for it. Thanks

Really interesting, thanks. It could be that mine have loosened so will have a look. Did a quick google and found guide in case it's useful - https://www.audiworld.com/forums/a6-c7-platform-discussion-194/2015-caliper-guide-pin-bushing-corroded-2974183/

To be honest, I didn't get around to doing this. I had new tyres fitted and it did seem a bit better afterwards so don't know if the old ones were out of balance. But the problem was still there. However, recently it seems to have improved. I've been on some long journeys and do, if it's safe, try and brake hard once in a while as I read somewhere that some deposits can build up so it can help clean up the surfaces. Might be worth giving that a go one evening or early bank holiday morning. I find it hard to believe that cleaning up that surface is going to make a difference, especially given how the symptoms for me aren't always consistent with speed/braking power.

It's a heavy, powerful car but it's pretty rare that the brakes get much abuse so I'm surprised it's happened. I will also check out the corrosion mentioned above but I can't get my head around why that would cause the symptoms. Anyway, I'll update once I get around to it. Cheers

I asked a simple question, got a fairly frosty response. But appreciate some more input, Tim. I'm taking the car to a local specialist to check the discs and if there's a problem to either have them skimmed or replaced. Cheers

I understand that but why would it cause the vibration under light braking? If the corrosion is moving the rotor out slightly, it's still out there when I brake harder and the vibration goes. Any ideas on the reason? Cheers

No not yet but when I have the time, I'll take a look at them. If I'm honest, I'm struggling to see what that corrosion is doing that would cause my symptoms but will give it a go as it's a free fix. Thanks

Hi Steve, did you just change the fronts in the end? I get the judder when lightly braking at 40+ speeds which goes the second I brake harder. Was that similar symptoms to you? Thanks

Caffrey, have you managed to get to the bottom of this? I still get the same problem just braking lightly at 40+ speeds. New tyres all round. Had the discs checked by the garage that services and mots my car and they reckoned they were fine but will ask them to check again. The judder does feel like something is loose but the second you brake a bit harder, it's fine.