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[henryd]

It's not just omega's, I see many different makes with the same issues 

[VXL V6]

Presumably its something to do with the caliper design, the inside pad is pressed against the disc with the piston, the outside is pressed against the disc by the force of the caliper movement.

I would expect the piston to press the inner pad against the disk first and then, after overcoming any stiction on the slider pins, the frame would move and press outer pad against the disk.

Yep, agree with that.

I did wonder if the inner pad could vibrate slightly more movement on the piston than the outer pad that has two pressure points of the caliper body against it.

[pirate]

modern disc,s are realy crap metal and rust between box and fitting to the car i always paint middle of disc,s with american rotor paint stops them furring up,also looks alot better,
one of the worse makes out there are bmw disc,s and calipers go rusty in 4 mths,wifes suzuki swift now 5 years old nothing.

[Andy H]

Presumably its something to do with the caliper design, the inside pad is pressed against the disc with the piston, the outside is pressed against the disc by the force of the caliper movement.

I would expect the piston to press the inner pad against the disk first and then, after overcoming any stiction on the slider pins, the frame would move and press outer pad against the disk.

On the Omega I don't think the design of the caliper is the issue. I think it is due to additional corrosion of the inner face (as described above) and intermittent use of the car. I haven't had the issue with my Omegas but I have used them as daily drivers. I expect that the cars that have shown the problem have been used for weekends and holidays.

One shown is used every week, on a 150 mile round trip. The 2.2 was the same, that was in very regular use too.

I wouldn't call that daily driving 

I can well believe that TB uses the brakes enough to sweep the surface rust off  but I think the damage is done when a car stands for 4 or 5 days at a time.

[tunnie]

Presumably its something to do with the caliper design, the inside pad is pressed against the disc with the piston, the outside is pressed against the disc by the force of the caliper movement.

I would expect the piston to press the inner pad against the disk first and then, after overcoming any stiction on the slider pins, the frame would move and press outer pad against the disk.

On the Omega I don't think the design of the caliper is the issue. I think it is due to additional corrosion of the inner face (as described above) and intermittent use of the car. I haven't had the issue with my Omegas but I have used them as daily drivers. I expect that the cars that have shown the problem have been used for weekends and holidays.

One shown is used every week, on a 150 mile round trip. The 2.2 was the same, that was in very regular use too.

I wouldn't call that daily driving 

I can well believe that TB uses the brakes enough to sweep the surface rust off  but I think the damage is done when a car stands for 4 or 5 days at a time.

Never that length of time, over weekend it could stand at most. Still don't think that can be enough to cause that level or poor wear 

Like I say, 2.2 also is the same, that was a daily driver.

[Andy H]

Maybe it is the new style roadsalt, it (allegedly) has something in (animal fat? mollasses?) that makes it stick to the road for longer. Unfortunately it also sticks to windscreens, motorcycle helmet visors and (probably) brake disks.

[TheBoy]

Presumably its something to do with the caliper design, the inside pad is pressed against the disc with the piston, the outside is pressed against the disc by the force of the caliper movement.

I would expect the piston to press the inner pad against the disk first and then, after overcoming any stiction on the slider pins, the frame would move and press outer pad against the disk.

On the Omega I don't think the design of the caliper is the issue. I think it is due to additional corrosion of the inner face (as described above) and intermittent use of the car. I haven't had the issue with my Omegas but I have used them as daily drivers. I expect that the cars that have shown the problem have been used for weekends and holidays.

One shown is used every week, on a 150 mile round trip. The 2.2 was the same, that was in very regular use too.

I wouldn't call that daily driving 

I can well believe that TB uses the brakes enough to sweep the surface rust off  but I think the damage is done when a car stands for 4 or 5 days at a time.

Rarely a day in the year when the Silver Bullet isn't used. Maybe occasionally a Sunday it doesn't go out. It suffers as much as all the others.

[TheBoy]

Maybe it is the new style roadsalt, it (allegedly) has something in (animal fat? mollasses?) that makes it stick to the road for longer. Unfortunately it also sticks to windscreens, motorcycle helmet visors and (probably) brake disks.

I think that has a lot to do with the general car corrosion, but I don't think explains this scenario 

[chrisgixer]

My old 3.2, and my old 99cdx discs went the same way, used daily. My current car is used on a shift system for work. The discs went the same way.

If it was metal quality, why wouldn't it affect the the whole disc...?

Calipers are designed to apply even pressure to both sides of the disc. Anything else would be unacceptable. Opposing piston calipers and single piston calipers like the omega seem to suffer the same.

I have seen the same issue on punto, golf, polo, BMWe39, focus, mondeo, since posting the same type of question a few years ago on here. I don't remember the calliper or splash guard design on those cars, but accepted that its not a problem specific to the omega.


...it seems to me that the splash/dust guard design on omega coincides with the rust line, at least to start with, in that the very bottom of the guard does not cover the bottom 10mm of the disc, and also leans away giving a bigger gap at he bottom.

Pinched this pic from Terry Pagets thread, so please ignore the stand, we've had that discussion, and focus the bottom of the disc and the guard.
https://www.dropbox.com/sh/f6kx9dg8ujqxp7t/jjxhb6lONv

[chrisgixer]

Maybe it is the new style roadsalt, it (allegedly) has something in (animal fat? mollasses?) that makes it stick to the road for longer. Unfortunately it also sticks to windscreens, motorcycle helmet visors and (probably) brake disks.

I think that has a lot to do with the general car corrosion, but I don't think explains this scenario 

Again, why not the whole disc? And just the inboard outer edge.


Also, as mentioned earlier, this affects the pads as well, which wear away in the adjacent area. IMO its the rust that swells the metal and takes more pad material away than the non rusty area.

[chrisgixer]

Rear omega disc iirc. Shoes in shot for Andy P. 

Notice that the chipped away part, on its left edge, lines up with a line across the face of the disc. Like the rust has eaten inward to the centre from the outside edge.

Although... The jagged lines that run across the face are very similar to the broken off leading and trailing edges of the pad. NOT the outer area, square with angled corners, but the area that actually touched the disc (its not uniform, like the leading and trailing edges of the pad have been chipped away).... its printed on the disc face in rust as caused when parked up from hot in damp conditions.

So two factors at play perhaps. The pad outline printed on the disc face in rust from parking up in the damp, and the outer band of corrosion.

[dbdb]

I'm not sure why only the edge is affected but on mine the n/s front inner disc has much wider rust band than the o/s so I don't think it can be the shield design. 

Why the surface goes I now understand, once rusts starts if you don't brake hard only the surface will be removed, the rust continues to eat away at the steel and soon the actual steel (excluding the rust) becomes below the surface level of the unrusted surface.  From then on the pad will only touch the unrusted part and the rusted parts will just corrode more and more, with the pads occasionally scraping off some surface rust under heavy braking.

I plan to treat the rust with some rust convertor, at least that should slow down the corrosion and maybe the unrusted level will catch up with it.

My original discs lasted 190K miles.  The replacements fitted by VX started to rust after only a year.

[tunnie]

I'm not sure why only the edge is affected but on mine the n/s front inner disc has much wider rust band than the o/s so I don't think it can be the shield design. 

Why the surface goes I now understand, once rusts starts if you don't brake hard only the surface will be removed, the rust continues to eat away at the steel and soon the actual steel (excluding the rust) becomes below the surface level of the unrusted surface.  From then on the pad will only touch the unrusted part and the rusted parts will just corrode more and more, with the pads occasionally scraping off some surface rust under heavy braking.

I plan to treat the rust with some rust convertor, at least that should slow down the corrosion and maybe the unrusted level will catch up with it.

My original discs lasted 190K miles.  The replacements fitted by VX started to rust after only a year.

 

Must have done mega miles in a short space of time, I thought 6 years and 70k odd at best was impressive   

[dbug]

I'm not sure why only the edge is affected but on mine the n/s front inner disc has much wider rust band than the o/s so I don't think it can be the shield design. 

Why the surface goes I now understand, once rusts starts if you don't brake hard only the surface will be removed, the rust continues to eat away at the steel and soon the actual steel (excluding the rust) becomes below the surface level of the unrusted surface.  From then on the pad will only touch the unrusted part and the rusted parts will just corrode more and more, with the pads occasionally scraping off some surface rust under heavy braking.

I plan to treat the rust with some rust convertor, at least that should slow down the corrosion and maybe the unrusted level will catch up with it.

My original discs lasted 190K miles.  The replacements fitted by VX started to rust after only a year.

 

Must have done mega miles in a short space of time, I thought 6 years and 70k odd at best was impressive   

Thought your car only had 68K on it? http://www.omegaowners.com/forum/index.php?topic=115730.msg1463126#msg1463126

[tunnie]

Errrr one up the road is not mine