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[chrisgixer]

Looks like we need the op to explain his ridge? Is it rust? Or wear?

If it is wear then it is very unlikely that the quality of the steel has changed enough to be significant - much more likely to be (as BIGtime said) due to the surface rust acting as grinding paste.

As you can see from the pic in the link, the rust comes in from the edge, UNDER the swept area. I fail to see how surface rust can make large chunks chip chunks chip off.

But whatever, as said, painting sorts it for long enough to wear the discs out before the rust kills them. (Heat resistant paint obviously)

[Andy H]

Looks like we need the op to explain his ridge? Is it rust? Or wear?

If it is wear then it is very unlikely that the quality of the steel has changed enough to be significant - much more likely to be (as BIGtime said) due to the surface rust acting as grinding paste.

As you can see from the pic in the link, the rust comes in from the edge, UNDER the swept area. I fail to see how surface rust can make large chunks chip chunks chip off.

But whatever, as said, painting sorts it for long enough to wear the discs out before the rust kills them. (Heat resistant paint obviously)

stage 1 - shiny new discs and pads - all good 
stage 2 - park overnight in the rain - first application of brakes next day and you can feel the surface rust grinding off 
stage 3 - park for a week (say) - rust gets more advanced and causes some pitting. First application of the brakes wipes the surface rust off but the pitting remains. The pitting allows some flakes of rust to develop and the pits and flakes chew away bits of the pad. The damage is now done. Rust can develop unhindered on this part of the disc because of the pits AND because the pad has a chunk missing. The area affected can start right at the edge but it grows as the edge of it progressively eats away more of the pad

My Omega is doing 18,000 miles a year at the moment & it hasn't ever reached stage 3 but my old Range Rover hasn't moved for a while & the discs are scrap

[chrisgixer]

So, paint them, then!

The rust doesn't come in on the surface to cause the damage described, it creaps in from the edge, although parking up doesn't help as the pads rust to the disc causing the radial "spoke" marks in the pic. There's no avoiding that.

But as said,  if you want to avoid that rust line that creeps in from the edge to meat those cracks, then paint the discs in areas that are not covered by the swept area.

In the vents, on the outer edge, and the centre hub area.


At the end of the day, that's all there is. Apart from buying pre painted/treated discs. There is no protection for the swept area. No matter what.

[tigers_gonads]

Sorry for the delay in getting back to you lot on this
Spend most of yesterday sat / laid on muddy grass verges / laid in puddles rebuilding the front suspension.
The only time it stopped raining was when I stopped for a sandwich / went for a dump 
I must be getting old because i'm aching like a bastard and sneezing my friggin head off now 
And to say I used to really enjoy this sort of thing 

Don't bother with the sympathy because I know your all laughing really 

Okay, back to the disc ...............  The ridge is on the outside of the drivers side disc only.
Only about 2mm into the face and about 1mm deep.
The inside is totally unmarked.
Pads on both sides are hardly worn and even across the friction face.
Passenger side disc looks like its fresh out of the box 

Other then a couple of hard runs, its been sat outside the house for the last month or so 
With the lads corsa there, its a no brainer really ........... 50 mpg plus vs 15 mpg 

Right, off to pop some pills now .............. 

[mickyboy123]

Hi chaps i had vx front disc on front 6 months ago, they do tend to look rusty if sat for a few days but they are as flat and smooth as the day they went on 4 k later.maybe you have a sticky caliper causing exssive wear

[terry paget]

Interesting how it has only occured on the outside of the right hand disc. Dodgy abrasive pad? Doubt it. More exposed to weather while parked? Maybe. I have long believed that daily use is the best way of minimising disc corrosion by rubbing off overnight layer of rust before it takes hold. Before asbestos was demonised disc wear ws much less.

[terry paget]

Interesting how it has only occured on the outside of the right hand disc. Dodgy abrasive pad? Doubt it. More exposed to weather while parked? Maybe. I have long believed that daily use is the best way of minimising disc corrosion by rubbing off overnight layer of rust before it takes hold. Before asbestos was demonised disc wear ws much less.

Sticky caliper theory I like. On the back I have had seized pads so only one pad and one disc side does any work. On the front we have a sliding caliper arrangement, but if the caliper sticks that reverts to braking one side of disc only too. Trouble with that theory is piston is on the inside nd TG's disc scored on the outside.

[Andy H]

Interesting how it has only occured on the outside of the right hand disc. Dodgy abrasive pad? Doubt it. More exposed to weather while parked? Maybe. I have long believed that daily use is the best way of minimising disc corrosion by rubbing off overnight layer of rust before it takes hold. Before asbestos was demonised disc wear ws much less.

Sticky caliper theory I like. On the back I have had seized pads so only one pad and one disc side does any work. On the front we have a sliding caliper arrangement, but if the caliper sticks that reverts to braking one side of disc only too. Trouble with that theory is piston is on the inside nd TG's disc scored on the outside.

That was probably caused by a stone getting trapped between the caliper and disc.

Might be worth pulling the pads out to check that there is nothing else trapped in there.

[EMD]

Sorry for the delay in getting back to you lot on this
Spend most of yesterday sat / laid on muddy grass verges / laid in puddles rebuilding the front suspension.
The only time it stopped raining was when I stopped for a sandwich / went for a dump 
I must be getting old because i'm aching like a bastard and sneezing my friggin head off now 
And to say I used to really enjoy this sort of thing

Don't bother with the sympathy because I know your all laughing really 

Okay, back to the disc ...............  The ridge is on the outside of the drivers side disc only.
Only about 2mm into the face and about 1mm deep.
The inside is totally unmarked.
Pads on both sides are hardly worn and even across the friction face.
Passenger side disc looks like its fresh out of the box 

Other then a couple of hard runs, its been sat outside the house for the last month or so 
With the lads corsa there, its a no brainer really ........... 50 mpg plus vs 15 mpg 

Right, off to pop some pills now .............. 

No pain no gain  Get on with it you lazy git 

[tigers_gonads]

Sorry for the delay in getting back to you lot on this
Spend most of yesterday sat / laid on muddy grass verges / laid in puddles rebuilding the front suspension.
The only time it stopped raining was when I stopped for a sandwich / went for a dump 
I must be getting old because i'm aching like a bastard and sneezing my friggin head off now 
And to say I used to really enjoy this sort of thing

Don't bother with the sympathy because I know your all laughing really 

Okay, back to the disc ...............  The ridge is on the outside of the drivers side disc only.
Only about 2mm into the face and about 1mm deep.
The inside is totally unmarked.
Pads on both sides are hardly worn and even across the friction face.
Passenger side disc looks like its fresh out of the box 

Other then a couple of hard runs, its been sat outside the house for the last month or so 
With the lads corsa there, its a no brainer really ........... 50 mpg plus vs 15 mpg 

Right, off to pop some pills now .............. 

No pain no gain  Get on with it you lazy git 

And you get ferked too