Mileage verification?

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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Cursitor Doom wrote:

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.
--
Graham J


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On 7/30/2017 10:47 PM, Graham J wrote:

+1
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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.
--
*You never really learn to swear until you learn to drive *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On Mon, 31 Jul 2017 00:14:42 +0100, Dave Plowman (News) wrote:

Wot a load of crap!
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Al wrote:

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
--
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Chris Whelan wrote:
[correction]

*2000* !!!
Chris
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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.
--
*If love is blind, why is lingerie so popular? *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Thanks for proving you don't own a car.
--
*I'm already visualizing the duct tape over your mouth

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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On Mon, 31 Jul 2017 11:06:09 +0100, Dave Plowman (News) wrote:

Thanks for proving you don't own a brain.
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Seems no one else has one on here either then - apart from Mr Doom who you agree with. You make a very nice couple.
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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"Cursitor Doom" wrote in message
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?
**********************************************************
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.
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Gareth Magennis wrote:

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.
--
Scott

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On 31-Jul-17 12:09 AM, Gareth Magennis wrote:

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.
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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.
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"Dave Plowman (News)" wrote in message wrote:

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.
--


*************************************************************


Yeahbut, starting from rest and flooring the throttle each time is
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Unless you've got a pretty weedy car, doing that is going to result in hitting the car in front in traffic?

I'm a pensioner. ;-) Careful use of the clutch isn't age related. And if you wish to do a fast getaway, it's up to you.

But not the gearbox, if you do that often. You'd need to match engine speed to within a fraction of an RPM to avoid stress to the box.
--
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On 01-Aug-17 12:20 AM, Dave Plowman (News) wrote:

Unless you have a crash box it's not clutchless, just a different clutch. This poor little thing. https://qph.ec.quoracdn.net/main-qimg-e87e14d61f1580adad8163258c3be792-c What you are doing is buggering the weedy little metal to metal cone clutch on the synchromesh. The cone clutch is only designed to bring the layshaft, input shaft and clutch disk up/down to speed. Adding the inertia of the flywheel, pressure plate and crank to that is a massive overload.

Unless you have a stock of 2nd hand gearboxes, gearbox rebuilds and parts to replace worn synchro are way more expensive than a clutch kit. To replace the synchro cone you have to replace the gear, gears have to be replaced as sets and that means if it meshes with a gear that is fixed on a shaft with other gears (like the layshaft) then you are replacing every gear that meshes with the gears on that shaft. For a 5 speed RWD box 1st, 2nd and 3rd are usually fixed on the lay shaft and have to be replaced as a set. On FWD 5+ speed indirect gearboxes there can be as many as 4 gears fixed on one shaft.

Only gearbox that can take clutch less changes are dog boxes (motorcycle and race cars). It's still abuse, eventually a shift is missed and it chips the edge off a dog tooth. Strip the box, stone the burr off.
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I remember my Vespa recommending clutchless changes. But it had a spring drive in the transmission to reduce the impact on the dogs. There are springs in most clutch plates which have a similar effect - but aren't going to stop wear on the synchro.
--
*On the other hand, you have different fingers*

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"Dave Plowman (News)" wrote in message wrote:

I remember my Vespa recommending clutchless changes. But it had a spring drive in the transmission to reduce the impact on the dogs. There are springs in most clutch plates which have a similar effect - but aren't going to stop wear on the synchro.
******************************************************************
Well my method is (was) to match the revs in neutral whilst pushing lightly on the gear lever. When they are perfectly matched the gear lever just slides in gently with no jolt or grind at all.
Just like magic, hence the smug grin ensuing. If it doesn't go in smoothly, then it just doesn't go in at all.
I first learnt to do this in my parents' Triumph Herald, which didn't have synchromesh on first gear. I was able to get it up the steep driveway without stopping, and the gearbox never fell out once.
But perhaps I won't do that much any more on my Focus.
Gareth.
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