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[chrisgixer]

I don't care what that eejit admin says. Paint them.


Vastly reduces the amount of rust, which kills them long before the wear depth and the minimum thickness of the disk is reached.

What sort of paint would you use Chris?

Good to see you around mate

De grease, then Heat resistant. There are rattle cans suitable. It won't last forever obviously, but delays the start of the rust process long enough to get the best out of them.

Obviously if the discs are already treated/painted with a rust deterant, like my 360mm phaeton discs for example  , then there's no need to bother. ....hopefully. Time will tell.

Gm discs are not treated. Others may well be, I haven't looked into omega ones.

[TheBoy]

That is quite normal (though not to that extent!) on Omegas.  The inside face seems to corrode in from the outer edge. Not sure if that is time related, or mileage related - suspect the former. What age are they?

I know chrisgixer painted the edge of his with caliper paint to stop the corrosion setting in, and recall he said it helped. Might be worth double checking with him?  But this needs to be done before the rust sets in.  Not tried it myself, but probably will for the next set I have to fit.


//Edit - should read entire thread first

[Field Marshal Dr. Opti]

I don't care what that eejit admin says. Paint them.


Vastly reduces the amount of rust, which kills them long before the wear depth and the minimum thickness of the disk is reached.

What sort of paint would you use Chris?

Good to see you around mate

De grease, then Heat resistant. There are rattle cans suitable. It won't last forever obviously, but delays the start of the rust process long enough to get the best out of them.

Obviously if the discs are already treated/painted with a rust deterant, like my 360mm phaeton discs for example  , then there's no need to bother. ....hopefully. Time will tell.

Gm discs are not treated. Others may well be, I haven't looked into omega ones.

New discs are Pagid. Are they 'treated'?

[Nick W]

New discs are Pagid. Are they 'treated'?

Usually, yes. The rears that have been on my  car for the last 3 years are just starting to look a little 'dirty.'
I can't imagine how painting the unswept areas would prevent the sort of wear shown, as that's down to the pad and caliper. Mostly the caliper in my experience.

[chrisgixer]

New discs are Pagid. Are they 'treated'?

Usually, yes. The rears that have been on my  car for the last 3 years are just starting to look a little 'dirty.'
I can't imagine how painting the unswept areas would prevent the sort of wear shown, as that's down to the pad and caliper. Mostly the caliper in my experience.

It's rust eating in from the edges. Add in heat, and expansion and contraction and the surface cracks off towards the middle as in the pic. Esp when the pad rusts to the swept area after a lay up in the cold. Nothing to do about that obviously but cracks and lines apear where the pad leaves a rust mark. Then chunks start falling off and the brakes vibrate and loose power.

The obvious pointer is the 10mm line that creaps in from the inboard face.

[Andy H]

The rust is very abrasive, it wears away the pad instead of the pad  sweeping the rust off as you might expect. That is why the rust band grows because the edge of it eats away at the remaining good brake pad.

Zinc coatings (including hot dip galvanising) work by sacrificial galvanic action.  The swept area will be protected from corrosion by zinc deposited elsewhere on the disc not by a protective coating isolating the swept area from the atmosphere.