The outer 25mm or so at the circumference of the rear brake discs on our 3 year old 24000mile Yeti are rusting, and appear not to be swept by the brake pads. Is this a problem? My garage says they are all like that but their own MOT tester says that new discs and pads would cost £189 although not suggesting that they be replaced. My concern is that next MOT might require replacements. If the disc should be completely swept by the pad, then surely there is a design fault? The reason I ask this is that the car is just coming out of warranty and if there is a problem here, then now is the time to get it addressed.

I think your problem sounds similar to this:

http://www.briskoda.net/forums/topic/290365-should-these-rear-brakes-pass-an-mot/

You beat me to posting my own thread!

Thanks for your replies. I did phone Skoda Technical in the end and they confirmed that this is normal. Begs the question as to why the disc instaed smaller then so the pads make contact with the full diameter of the disc. Also begs the question as to why my garage noted the rust and offered a quote for replacing discs and pads. And further the garage today said 'I wouldn't bother changing the discs until early next year as there will be further corrosion due to salt on the road during the winter'!

You beat me to posting my own thread!

  

It had made quite an impression on me as I've never come across this on any of my cars, so it was easy to remember where to locate the post!

Thanks for your replies. I did phone Skoda Technical in the end and they confirmed that this is normal. Begs the question as to why the disc instaed smaller then so the pads make contact with the full diameter of the disc. Also begs the question as to why my garage noted the rust and offered a quote for replacing discs and pads. And further the garage today said 'I wouldn't bother changing the discs until early next year as there will be further corrosion due to salt on the road during the winter'!

I will be taking the wheels off sometime next week and am now really curious to see what state my rear disks are in. Could be a good excuse to start moving on that brake upgrade I've been craving... :-)

I think your problem sounds similar to this:

http://www.briskoda.net/forums/topic/290365-should-these-rear-brakes-pass-an-mot/

 

For more information, see this thread: http://www.briskoda.net/forums/topic/281280-brake-rumble/  That thread includes a link to TP's guide to how to replace the discs and pads yourself.  Mind you, the OP's quote to get the work done is pretty good (assuming it's using official VAG discs and pads) - around £40 cheaper than I've had from anyone round here.

Also begs the question as to why my garage noted the rust and offered a quote for replacing discs and pads. And further the garage today said 'I wouldn't bother changing the discs until early next year as there will be further corrosion due to salt on the road during the winter'!

 

The garage is ready to make a little profit from an ignorant consumer.

 

Rust on the non-swept part of the disk is quite normal. Unless the swept area of the disc is badly scored and approaching the minimum thickness, it does not need to be replaced. If scored and there is enough thickness left, it can be trued up in a lathe - standard equipment in a well equipped repair shop.

I had similar problem with my elegance 4x4 DSG. Initially no joy from dealer or Skoda but I persisted and they agreed to pay half the cost which I didn't feel was too bad as the car had done 23000miles. However feel more cosmetic than a defect.

TP reckons it's a fault caused by the calipers sticking - see posts 8, 10 & 12 of the linked thread. According to him, it's not the unswept part of the disk that's rusting, that part of the disk is supposed to be swept but isn't because the calipers stick.

Why would they fit discs that are 25mm bigger than they need to be?

It's not only Skoda that have such a problem. Both my SZ5 rears had to have rotors and pads replaced due to the latter having been assembled incorrectly...at the factory.

 

 

 

 

 

Just back from my early morning dump run and visit to my dealership to see what Yetis are in. I looked at the 3 S/H ones on the forecourt and all had new rear rotors and pads fitted. A S/H vehicle awaiting prep showed some signs of the problem but only minor.

Is this something new? I've had my Yeti for four years and the rear discs are swept completely.

 

It is probably due to sticking ( see TP's post ) as they wouldn't fit discs bigger than the pads, it doesn't make sense to do so.

 

Also you don't need to take the wheel off to see if the disc is shiney all over.

Worth repeating that the appearance of discs is not in itself a factor in determining pass or fail.

Yeap!  As above.  When my Yeti was acquired at 3 years old, the rear disks looked as the OP.  Outer 10mm of swept face corroded and pitted, but worked fine. I guess they had not seen much hard use for a while?  Selling dealer said not to worry as they "all like that", pointing to another s/h Yeti on the forecourt.

 

Now its another 13 months / 22,000 miles older, and clearly now getting enough use to un-jam the sliders, as the corroded area is now gradually being cleaned up by the pads.  Not touched them myself, just "used" them now and again.  That said, SWMBO is regular driver, and if anything she is harder on the brakes (and most other parts) than self - little "mechanical sympathy".

 

The Snow Monster has just sailed through its second MOT like that, with rears working fine on the test machine. So I'm not about to "fix" them just yet.

I know I am resurrecting an old thread, but I have a similar issue and am not clear on the exact problem despite having read a dozen threads about it on this forum.

 

I have about 12 mm of rust around the outer edge of my rear discs (Bosch callipers) despite the pads actually covering the full width (to within 1 mm or so) of the metal. They passed the last MOT in April like this so not concerned about that, but am concerned that it will only get worse if I do nothing about it.

 

 

Does this mean that the callipers are sticking and that I should strip them down, clean and regrease them?

 

I've no issue with doing this as I have done so on my Octavia, but want to make sure that this is the problem before I go about taking them apart on the Yeti.

 

Whilst the calliper and pads are off the vehicle, should I look at getting the discs skimmed to remove the rust or will this disappear fairly quickly once the callipers are sliding properly (assuming that this is the problem?

Clean the calipers and fit new rotors and pads. 

 

Just done my Audi £66 2 new rotors and pad sets...a no brainer.

I have about 12 mm of rust around the outer edge of my rear discs (Bosch callipers) despite the pads actually covering the full width (to within 1 mm or so) of the metal. They passed the last MOT in April like this so not concerned about that, but am concerned that it will only get worse if I do nothing about it.

 

 

Does this mean that the callipers are sticking and that I should strip them down, clean and regrease them?

 

I've no issue with doing this as I have done so on my Octavia, but want to make sure that this is the problem before I go about taking them apart on the Yeti.

 

Whilst the calliper and pads are off the vehicle, should I look at getting the discs skimmed to remove the rust or will this disappear fairly quickly once the callipers are sliding properly (assuming that this is the problem?

The callipers will hold the pads in relation to the centre of the hub so as long as they are sliding OK it will not make ant difference to the pads position on the disk.

If cleaning the carrier to help the calliper to slide do not use any grease as it will attract grit and you will have more wear than leaving it clean and dry.

The bit that does the sliding where the calliper is bolted on should not want re-greasing if the bellows seals are OK.

I do think that the pads are sweeping a few mm towards the centre though, but if the pads are correct and fitted OK the only thing that can change that is calliper or carrier.

Its safer and probably cheaper to fit new disks rather than have them skimmed, or gently tapping at 45 degrees to the edge of the disc with a lump hammer will remove most of that rust then just clean it up with a file and wire brush to reuse if within service limits that should be stamped on the disk..

Thanks for the advice.

The discs are well within limits of thickness and I believe the pads are as well although am not certain.

The outer pads, the ones I can see through the wheel, are within a millimetre or two of the edge of the disc, so are in the correct position, but are obviously not pressing hard enough on the discs to clear the rust or to grip.

I have noticed the rust spreading slowly inwards so I think I'll strip down the calipers and see what's what.

Mine on my Fabia looked OK but the inside was a bit past it, think I renewed them just in time.

 

I think Urrell makes a very valid point. The outer face/pads of my rear discs looked 'as new', but the inner face and pads were beyond acceptable wear limit. The inner face/pad is not easy to check visually without removing the wheel, a point taken on board by my dealer

Exactly, the outer pad was only just over half worn and making full contact with the disk whereas the inner was down to the metal and you can see the state of the disk.

I had not had the wheel off but was acting on an advisory from the MOT that should probably have been a fail.

Valid points. I was thinking about the thickness of the disc with my comment above.

If you remove & clean callipers/pads yearly it helps no end with this problem. It’s an easy DIY job.

Clean out old grease from off the sliders, as this stuff gets a bit goopy after a while, & sticks the calliper slide. Re copper slip slider.

Clean up carrier with wire brush & file, (where rusty) copper slip area of b/pad contact on slider. (Obviously not the surface of the pad where it meets the disc)

The brake pad must be able to move freely in the carrier, otherwise the pads sticks, and then the disc starts to corrode.

Finally check that the calliper moves freely on its slider.

Surface clean the brake pad with emery cloth.

Clean up all parts with spray Brake Cleaner.