Mileage verification?

Not likely to be useful, I think.

Brake disks wear out and are replaced. How often depends on how the vehicle is driven. More short journeys in traffic will need more stops. Greater acceleration implies greater braking so a more aggresive style will also cause more wear. A taxi probably needs new disks every year.

Clues such as mileages recorded at recent MOTs and service history are probably a better indication.

+1

Hi all,

Just been thinking about a novel way to verify odometer readings and thought I'd cast it out for feedback. There are lots of clues that we all know about that can indicate the veracity of the purported mileage of a vehicle: extent of wear on pedal rubbers, shininess of steering wheels and gear levers, sagginess of upholstery and so on and so on. But how about the thickness of brake discs? We can obtain the original thickness of the discs from online sources or service manuals and we can subtract from that the thickness today (using an accurate micrometer of course). The result of that should, I would have thought, provide a far more accurate figure for the true mileage covered by the vehicle than any of the more subjective methods we're accustomed to using. Your thoughts?

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People who drive around fast are likely to use up brakes and clutches at an alarming rate.

People who don't drive like that are likely to have cheap motoring and little wear and tear on such items.

I therefore can't see any viable correlation between brake wear and mileage.

Gareth.

Of course. Most cars will have had new discs long before you get worn pedal rubbers or sagging upholstery. Likely several sets.

The most money to be made by clocking a car is when it is near new. So before the first MOT.

Wot a load of crap!

I often drive as if my hair is on fire and the hounds of hell are after me. I still haven't got rid of a front disc with a slight wobble after about 4 years and the clutch is original at 233k.

You need data from owners who keep their cars for a long time.

I bought a new Focus in 200, and had it 10 years and 100k miles. It needed two new sets of discs in that time. The interior was indistinguishable from new.

Chris

Brakes not if they can drive. The art of driving fast is to not slow down and hold speed though the curves (need to equip yourself with an adequate car). Someone that brakes for oncoming vehicles (yes I see this example of driving test failure at lest once a week) will clearly have a much poorer brake life than someone that maintains pace.

Clutches no. There is no wear related to speed (unless the clutch is already gone to the point it slips). Ability to change gear cleanly and match revs is what determines clutch life. It's more likely to be incompetent slow drivers (you know the ones that are too incompetent to achieve the speed limit) that don't have any idea what a clutch is other than a pedal they have to press that wreck a clutch than a competent but fast driver. Of course there are plenty of incompetent drivers that use excessive speed, they are the ones that have single vehicle accidents and put gaps in hedgerows.

[correction]

*2000* !!!

Chris

Utterly useless. Discs are a disposable component. Some cars will get through several sets of discs in their lifetime.

Tim

Thanks for proving you don't own a car.

Yes. 50k is a decent mileage for a set of discs. Some makers say to change them with the pads. So perhaps 30k or so.

Trouble is, a brake disc with a significant lip at the rim (I don't know what the actual figure is) is an MOT fail. So you have to replace them every few years anyway. In fact, mine don't seem to last as long as the pads. I can only assume they don't make them like they used to. Or maybe they were always like that, and it's something to do with time seeming to go faster as you get older?

Clutch life tends to be determined by how many starts from rest you do. No matter how well you change gear you can't eliminate wear when starting off. So a car which cruises the motorway will likely have a much longer clutch life than one used in town. And the same sort of thing applies to brakes. The way the car is driven can have a big influence - but traffic conditions are outside the control of the driver.

I believe the change to asbestos-free pads meant that the discs had to be changed to a "softer" material, hence the fact that disc replacement seems to be the norm these days rather than the exception.

Tim

[...]

Yeah, MOT stations that do repairs will tell you that.

However, check 'Reason for rejection (h) and (i):

My (non-repair MOT) station tells me that unless the disc is visibly cracked, it can't be a fail, only an advisory. The degree of wear is not testable because to do so would require dismantling.

I've measured discs with a significant lip before replacing pads, and found the disc to only be 50% worn

Chris.

Thanks for proving you don't own a brain.

True, true. However (and this is a key plank of my assertion) in my particular case, the discs in question are OEM and were never fitted to anything other than factory-fresh cars. So I know these discs have witnessed *all* the miles the car has ever done. Had that not been the case, then you're correct to point out what would have been an obvious flaw in the idea.

Well that's interesting, thanks. I take it to the same ATS I've been going to for ever, because it only costs £30 booked online, they know me by now, and they nearly always just pass it (2003 Fiesta). If they do say the discs need replacing (which I'd guess is every 4 or 5 years), I do it myself - eventually they'll get the idea.