Rotor cracks

[itsamitsi]

I serviced the old girl today and noticed these perfectly straight what appear to be cracks in the front rotors. They don,t go all the way through but are on the surface and can be felt. Each of the front rotors has 2 of them. Has anyone else noticed these on their Challenger?

[old Jack]

Most radial cracks are not perfectly straight, they tend to be a little wiggly.
You said there are 2 of these marks on each rotor, by chance would they be the length of the brake pad apart?

OJ.

[NTBenny]

OJ is onto it.

I can assure you these are not cracks. Cracks from over heating are usually small hairline wiggly lines in a radial pattern around the face of the rotor or can form around cross drilled holes.

Benny.

[itsamitsi]

No they are perfectly straight and about 1/3 of the rotors diameter apart. It's really weird. The rears don't have it only the front. I have a pic of the full rotor but it won't let me load it says file fail to load.

[itsamitsi]

Actually they are almost half the rotor diameter apart, just under.

[Boo Boo]

Is it possible that the mould is split here when they cast the rotors
This may cause the steel to cool differently to the rest of the rotor causing a soft or hard spot.

[itsamitsi]

Dunno... It's puzzling as it is only on the surface from what I can see. Both rotors are identical, small not deep straight what appear to be cracks with small pieces flaking away from the meeting edges. Like they were glued together....

[old Jack]

On closer inspection I can see what you are talking about, it could be bits of friction material that have deposited on the rotor and then these bits have been dragged backwards.
Is the photo of the right or left rotor?
Have you had any heavy braking episodes recently!
What is the condition of the pads, have they been removed and inspected?

OJ.

[littleriver]

I have similar on L/H Rear rotor
.



Brakes grab make a bit of noise in reverse. . Been measured and calipers checked .. all within specs ..
..

[NTBenny]

I'm fairly sure it's pad material being deposited on the rotor face after the pad has been stationary against the rotor. This line being the centre groove on the face of the pad.The material then continues to collect more material until it is essentially burnt off. I've seen it plenty of times. Not sure if anyone else is able to confirm this though?

Benny.

[green troll]

I'm fairly sure it's pad material being deposited on the rotor face after the pad has been stationary against the rotor. This line being the centre grove on the face of the pad.The material then continues to collect more material until it is essentially burnt off. I've seen it plenty of times. Not sure if anyone else is able to confirm this though?

Benny.

I’d second that. If your worried take some emery cloth to it and see if it removes it. Doesn’t look like a crack though

[wasarangie]

x3 I go with this as well. It's the rubbish pad material that does it. A few hard stops and high brake temps and the material sticks, if you notice a shudder or vibrations after some harder city or long down hill driving this will be the cause. I have seen it many times. Those disks look like they have had a hard time though, how many klms have they done?

[itsamitsi]

x3 I go with this as well. It's the rubbish pad material that does it. A few hard stops and high brake temps and the material sticks, if you notice a shudder or vibrations after some harder city or long down hill driving this will be the cause. I have seen it many times. Those disks look like they have had a hard time though, how many klms have they done?

It's the bosses shopping trolley. Done 63K. Braking is perfect, no shudder or squealing. Pads are spot on too....

[itsamitsi]

On closer inspection I can see what you are talking about, it could be bits of friction material that have deposited on the rotor and then these bits have been dragged backwards.
Is the photo of the right or left rotor?
Have you had any heavy braking episodes recently!
What is the condition of the pads, have they been removed and inspected?

OJ.

RHF. The left has identical marks in it too.

[old Jack]

RHF. The left has identical marks in it too.

Do you have a photo of the left, I suspect the trailing marks are going in the opposite direction.

OJ.