Brake disc corrosion?

DangerMousy

DangerMousy

Joined
May 29, 2016
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Hampshire
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43,352
MH
Carthago C-Line
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Since 2016
I'm not too mechanically minded when it comes to vehicles so can someone tell me....from these photos, are the brake discs badly corroded (the motorhome is less than 3 years old).
When I compare them to the discs on our own MH the wear pattern is significantly different....our's don't have the thick outer strip of corrosion and the wear pattern is much more even.

Brakes.jpg
 
Can't tell from the photos you need to take the wheels off and measure the disc thickness with a caliper, manufacturers normally give minimum disc thickness in the manual.
Or if you are not happy with them change them.
 
So you wouldn't worry about the surface corrosion or the wear pattern?
Its not our MH, just one we are maybe going to look at. At the moment I'm going through the photos in detail to make notes on things we need to look at when viewing.
 
You always get surface corrosion only needs to be left a couple of weeks without using. The top pic looks like the pads not fully contacting often good drive and applying the brakes a speed sorts it out but unless strip it down and look at the pads & pistons no way of being certain. Nowadays with non-asbestos pads discs are consumable. If you are thinking of buying the van get a reduction just in case it needs new calipers.
 
The top pic is more of a concern than the bottom one , job to tell if just surface rust or irregular worn disc pattern . What you want to see is a discernible small margin at each edge that is heavily corroded , and then a large area between that is obviously just recent surface rust if been sat for a while . You also need to look at pad thickness they should all be similar , if not points to sticky piston . This can also be indicated by narrow variations in the wear pattern eg a bit like pic 1 . A reasonable length test drive with use of the brakes frequently should give you a better indication .

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Discs soon start to look rusty if a vehicle stands for a while in our damp climate.
Usually a drive on a clear road hammer the brakes a good few times and they will shine up again. However...Our Mercedes just over 3 years old shocked me on the first MOT.
The inside surfaces of the front discs were badly corroded and we had to replace them.
 
tacr2man said:
The top pic is more of a concern than the bottom one , job to tell if just surface rust or irregular worn disc pattern . What you want to see is a discernible small margin at each edge that is heavily corroded , and then a large area between that is obviously just recent surface rust if been sat for a while . You also need to look at pad thickness they should all be similar , if not points to sticky piston . This can also be indicated by narrow variations in the wear pattern eg a bit like pic 1 . A reasonable length test drive with use of the brakes frequently should give you a better indication .
Click to expand...

Agreed the top picture doesn’t look right.

Needs checking IMHO
 
you used to be able to get discs recut on a lathe, but the replacement cost is now much less, so not worth it
 
Living near the sea our discs rust up overnight, modern discs & pads are rubbish but environmentally friendly .

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Thanks all, I think you've confirmed my initial gut feeling that its something that needs looking into.....brakes are not something I want to take a chance with.
As its less than 3 years old there's no MOT history to check so I think it would definitely be worth paying for a pre-purchase inspection and ask them to specifically check the brakes.
 
You need to take it for a test drive, and use brakes as you normally would. Then after the drive see what the discs look like.

It is possible that the vehicle was valeted ready for the photos to be taken. If so they probably sprayed the wheels with wheel cleaning acid which will rust a disc as soon as it dries, if after that they have just moved it for the photos to be taken, it won’t have had chance to clean its discs.
 
If you haven't used the van much, it can be death to pads. We only got nine nights away all of last year instead of the usual 50+ and the van wasn't getting a weekly run either. The brakes felt very spongy and there clearly was an increase in stopping distance. I couldn't get to look at it myself, so took it to the guy who MOT's it for us. The pads had actually started to delaminate, a common problem he reckoned if they don't get warmed up with use, to drive out any moisture ?
 
Landy Andy said:
You need to take it for a test drive, and use brakes as you normally would. Then after the drive see what the discs look like.

It is possible that the vehicle was valeted ready for the photos to be taken. If so they probably sprayed the wheels with wheel cleaning acid which will rust a disc as soon as it dries, if after that they have just moved it for the photos to be taken, it won’t have had chance to clean its discs.
Click to expand...
Top picture.. Most of the outer circumferance of the disc is polished, the inner half is rusty.
If the brakes had been applied after washing the light surface rush would have rubbed off evenly.
Plus the other side is 90% polished..... Applying the brakes would clean each disc, not just one and half the other no matter how light or heavy the braking.

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pappajohn said:
Top picture.. Most of the outer circumferance of the disc is polished, the inner half is rusty.
If the brakes had been applied after washing the light surface rush would have rubbed off evenly.
Plus the other side is 90% polished..... Applying the brakes would clean each disc, not just one and half the other no matter how light or heavy the braking.
Click to expand...
Yes that's exactly what concerned me - the pattern of the corrosion looks odd to me. I'm no expert but I went out and checked the discs on our own MH and in comparison whilst there's some surface corrosion on our's, its evenly spread over the surface. We're going to look at it tomorrow so will pay attention to the way it feels when braking and what the discs look like after the a drive. And if we decide to go ahead then we'll definitely get pre-purchase inspection done.

Its also an auto - neither of us have ever driven a comformatic before....I understand from reading various sources that its going to be very different to our BMW auto so that should be interesting.
 
Its quite possible that its simply been standing at the dealers for ages and just moved a few yards, check it after a drive and insist that it goes through a workshop if you decide to have it.
 
Norman Jones said:
Its quite possible that its simply been standing at the dealers for ages and just moved a few yards, check it after a drive and insist that it goes through a workshop if you decide to have it.
Click to expand...
Its for sale via MH Depot rather than a dealer so if things need doing I'd rather negotiate a discount and get them fixed myself locally (so I know its done properly). It had a habitation and full mechanical service in September so I doubt the brakes are actually dangerous, but nevertheless I want them checking further. The hab check was green/good for everything except the auxiliary battery which was amber/advisory which I expect this means it isn't holding a charge properly - so we'll need to negotiate to budget for a new one.
 
probably it's fine, if it had been mistreated those alloys wouldn't look so good.
 

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