Brake disc rust circle

[junglie]

I have just has new discs and pads fitted on the front.

The image shows what the disc looks like and the same is true of the opposite side.

I have been braking reasonably gently, bar a couple of more deliberate applications(!), and have driven about 400 miles since new discs and pads fitted.

The ring of rust has not gone away whilst any surface rust from short periods of no use disappear immediately as you would imagine.

It seems that the pad is not touching the centre of the disc area. I thought it may be bedding in but it is identical on both sides.

The car is a BMW F11 if it makes any difference.

Any thoughts?

[GreenV8S]

Does that circle of rust correspond to a groove in the disc, or a groove in the pad? Presumably it must be one or the other.

[trickywoo]

I’d say your disc is fked and you ideally need a new set of discs and pads.

[junglie]

GreenV8S said:

Does that circle of rust correspond to a groove in the disc, or a groove in the pad? Presumably it must be one or the other.

That would be the logical answer but I can’t see anything and it would make more sense if it was only on one disc.

Identical issue on both sides leads me to believe it is something different.

[junglie]

trickywoo said:

I’d say your disc is fked and you ideally need a new set of discs and pads.

[Kawasicki]

Something is wrong. Get it checked. The pad not contacting that part of the disc is odd.

[junglie]

Kawasicki said:

Something is wrong. Get it checked. The pad not contacting that part of the disc is odd.

I agree, particularly as it is identical on both sides.

[Chris32345]

Take it back to the garage that fitted them either bad fitting or defective parts

[thebraketester]

BMW OE stuff or cheap crap parts?

[junglie]

Chris32345 said:

Take it back to the garage that fitted them either bad fitting or defective parts

I will.

I have used them many times for different cars and always very good so I’m sure they will sort it.

[junglie]

thebraketester said:

BMW OE stuff or cheap crap parts?

Not BMW OE but similar quality (Brembo) so should be fine.

[junglie]

Identical price to my local BMW garage doing other bit did not have time to take it to them.

[thebraketester]

junglie said:

thebraketester said:

BMW OE stuff or cheap crap parts?

Not BMW OE but similar quality (Brembo) so should be fine.

Ahh ok should be ok then.

[anonymous-user]

Dunno about anyone else but I would be finding a clear road and performing a series of very hard brake tests to bed it all, although there seems to be conflicting advice about whether to bed pads in gently or not.

I bedded in a set of ceramic pads on my old MX5 at Knockhill and after the inital run all four corners were pouring smoke, once cooled down they performed flawlessly and were very powerful.

[junglie]

JimSuperSix said:

Dunno about anyone else but I would be finding a clear road and performing a series of very hard brake tests to bed it all, although there seems to be conflicting advice about whether to bed pads in gently or not.

I bedded in a set of ceramic pads on my old MX5 at Knockhill and after the inital run all four corners were pouring smoke, once cooled down they performed flawlessly and were very powerful.

^ this

I am tempted to do just this but I have done a few reasonably hard stops to do just this.

I must say that the brakes need a firmer ‘shove’ than I would expect but it seems a modulation thing rather than overall stopping power.

[Dave.]

junglie said:

^ this

I am tempted to do just this but I have done a few reasonably hard stops to do just this.

I must say that the brakes need a firmer ‘shove’ than I would expect but it seems a modulation thing rather than overall stopping power.

If the pads are only contacting 2/3rds of the discs, it will need more pedal effort.

Any noises?

[RobXjcoupe]

Pads might not be sitting in the caliper properly. Doesn’t take much. Eventually they will touch all the disc as they are.

[junglie]

No untoward noises.

It has cured a slight vibration under braking which I put down to a warped rotor - the pads were at the end of their useful life and the discs had quite a lip on them.

[GreenV8S]

JimSuperSix said:

there seems to be conflicting advice about whether to bed pads in gently or not.

The answer is to follow the instructions that come with the pads. Some types need to be driven gently, others need to be put through specific heat cycles.

[Dave Brand]

Dave. said:

If the pads are only contacting 2/3rds of the discs, it will need more pedal effort.

No it won't.