Mick Jagger lips on my rear brake discs (RS4)

[TopBear]

I've had a close look at my old discs that I took of last week, and am a bit concerned at what I think looks like an excessive inside and outside lip on those discs. The 2nd pic is even worse!!!

For those whom have changed discs\pads on a B5 RS4, does this look normal , or are the pads knacked?

One side


Other side

[DavidT]

What sort of use does the car get ? and did you put new pads on with the new discs?

[MarkB]

I'd say the disc's look in a very poor state and I wouldn't use the pads that were bedded into this disc's on any new disc's.

Depending on the thickness of the lowest part of the disc you could get them refaced and used again with new pads, but as I say they must still be thick enough to be able to do that.

[TopBear]

What sort of use does the car get ? and did you put new pads on with the new discs?

The car gets used daily for 'brisk' commuting. I've never tracked it in the 14K miles I've used it. New pads were fitted around 10K miles ago when it had a major service, with advisory that new discs would be required soon.

I put the old pads back on, as they've still got what looks like 50%+ life left on all of them.

[TopBear]

I'd say the disc's look in a very poor state and I wouldn't use the pads that were bedded into this disc's on any new disc's.

Depending on the thickness of the lowest part of the disc you could get them refaced and used again with new pads, but as I say they must still be thick enough to be able to do that.

I'd agree
I have put the old pads back in, as I my thinking was that the pads would adapt to the new disc face.

The discs were skimmed and they are apparently down at the minimum thickness already, thats why I replaced them, but I did hang on to the hardly used pads.

I guess my concern was, is this sort of thick banding on the disc a normal characteristic of wear on rear discs on the RS4? Or if not, what is likely to cause?

[MarkB]

With age the rust will creep in from both edges of the pad contact area.

I would recommend that you get new pads in ASAP as the old ones will have raised area's because of the rust on the old disks. This will mean the pads won't be fully in contact with the new disk and rust will start prematurely.

[TopBear]

So in normal use the net effect should be that the pad covers the entire surface area and I shouldnt be seeing anything like these circles of rust?

[MarkB]

Not straight away. You will see a look like that quite quickly if you leave the old pads in though. It's the pad that cleans the light rust off. Rust will eat the pads once it takes hold so the pads don't stand a chance

[DavidT]

New discs and old pads = bad idea, especially with the state of those discs, as Mark says.

The B5 RS4 discs are expensive from memory but the pads are cheap ?

I asked what type of use they had had because it looks like an easy life, kept outside with short journeys ? this is the enemy of discs in terms of rust vs wear.

Old pads on new discs can be dangerous because of the way they heat up small parts of the disc surface - you do not have proper braking effort and it can take months (1000's of miles) for them to wear down.

Have you checked the calipers are working OK?

[TopBear]

OK chaps, I shall get some new pads in there ASAP! Is there any recommendations other than the OEM ones?

[s4woody]

id say them discs are foooked ther topbear...the outside edge like markB said will eat the pads and make a terrible squeaking noise...

[PhilT]

I had a set that looked like that once. Obviously you should check the min thickness as your point of if they have any life left. In my case I got the grinder out and took off the lip, which was mainly rust.

[yorkie]

I would say time for new disks and pads mate.

[TopBear]

I would say time for new disks and pads mate.

The discs were replaced already, those are the old ones which came off the car.

[MarkB]

Just get some new pads on the new disc's so the new ones don't end up looking the same!