When I viewed my car before I bought it, I was not in the least surprised to find that all four brake discs were very rusty, given that the car was 16 months old but had only done 4000 miles. But it was a good price, and I accepted that I might have to have new discs fitted at some point. The question now is ~ after what mileage should I hope for the discs to be substantially rust-free? My motoring is mostly on winding rural roads, with some hills, and requires an above average number of brake applications. I have now done 800 miles in under 4 weeks and I expected the discs to be largely OK ~ but they?re not. What is most apparent is that they are not cleaning up evenly ~ the worst of the discs is still noticeably rusty on the innermost (i.e. nearest to the centre) 50% of the face while the outermost (i.e. nearest to the outside diameter) 50% is virtually rust-free. Is this sort of thing normal, and can I expect the discs to eventually clean up completely. Or should I start saving up now for some new discs? I don?t notice anything substandard about the degree of braking available, although I have not tried an emergency stop.
(I realise that my questions may be seen as being similar to asking ?How long is a piece of string??!)
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L\'escargot by name, but not by nature.
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A simple answer is that the rust will remain on the discs where the pads don't make contact. Your pads may make contact with the outer 50% of the disc.
The proof of the pudding is in the eating. Get a braking efficiency test done to make sure your brakes are OK.
I am also going to move this thread to technical where you'll get some more answers.
Hugo - BR Moderator
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i returned to pick my toyota up from a service, and they said "the bad news is the disks were rusted very badly and needed replacing, the good news is weve done it for free and put new pads on at the same time under guarantee"
seems toyota 3 year guarantee is worth more than some
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I really wouldnt worry about this.
As long as the brakes dont judder, (due to possible warping of the discs), they will clean themselves up.
Personally, I would find a quiet highish speed downhill stretch of road and do some moderately heavy braking to clean the discs and bed the pads in.
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You should only have approx 1mm of rust on inside.outside of disc.on both sides. being area not contacted by pad..If you have rust in contact area of pad.their is a problem. many reasons why.But you need to get it looked at..50% contact area lost is a lot of braking power
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Steve
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Once there's a clean band on the disk for the pad to contact then that will be doing all the braking. The reminder of the rust tends to rub away the pad as you drive so that part of the pad never gets chance to clean the rust down to clean metal.
Are rusty disks an MOT failure, or do they just rely on the efficiency test?
Chances are you'll get away with it if the brakes seem OK, but if you have a serious accident and the police look at your you could be in a *lot* of trouble.
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Is it under warranty??
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Steve
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Is it under warranty?? -- Steve
It has the balance of Ford's 3 year warranty ~ i.e. up to July 2006. However, I would imagine that they will say that the rust is the result of the car having stood idle for a long period of time (which it obviously had) and not due to manufacturing defects. Nevertheless, I will ask my local Ford dealer whether I can claim under the warranty.
Thanks, steve.o, for pointing out this possibility. It might save me a load of dosh.
--
L\'escargot by name, but not by nature.
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You can speed up the process by using medium emery paper on a flat piece of wood, to get rid of the worst of the rust.
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If they are not evenly clearing, there is a chance the pads are not as free as they should be, ie stuck to the pistons in the calipers. Can't really say what is best, as I can't see the discs and pads, but new pads, backs greased, fitted to well cleaned up calipers may be what is needed. You do need to check all the bits of the caliper that should move, do. You will need an assistant for this as pushing brake pedal with the pads removed is a recipe for disaster, unless done very carefully. (Hint - BIG screwdrivers can make a pad replacement and allow you to push the piston back after you have checked it.)
If the car stops in a straight line, and feels ok, I might be tempted to do the equivelent of an Italian tune up on the brakes, but the risk factor must be allowed for here.
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I had a car that was like this if it was unused for a week and left outside. A dozen miles of energetic driving was enough to clear the rust. I'd suspect either sticking pads or single-sided calipers with sliding pins that need cleaning and lube.
If the rust has gone as far as becoming flaking rust rather than just surface rust then it will just grind the pad material away so will never get worn off by brake use.
Martin
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As well as checking for free movement in the calipers and pins, it may be worth chipping off any rust growths around the rim of the disks, which could contact the pads.
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