Had car mot'd today. Car passed, but was amazed seeing the subjectiveness of the brake test.
The car was tested on the rollers with the tester watching a flickery needle on an analogue dial. He judged it was reading 150 on the right and 200 on the left, I reckon the error in this measurement must be at least 20%.
Anyway, he plugs all the numbers in the the famous computerised system and told me it just scraped through on the brake balance, cos the computer 'worked it out' and the max imbalance is 25%. Given that the original reading was taken by eye from a flickery needle, what a ridiculous system! If it was reading 149 on the left it would have failed!
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So, you want to pay more for your MOT tests to cover the cost of yet more test equipment?
Number_Cruncher
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Since the car only just passed the brake test you would probably be being very wise to investigate futher why the 25% inbalance is there.
You can't take any chances with brakes, and just because it's just scraped through the MOT certainly does not mean the brakes are completely problem free.
Requires further investigation.
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Since the car only just passed the brake test you would probably be being very wise to investigate futher why the 25% inbalance is there. You can't take any chances with brakes, and just because it's just scraped through the MOT certainly does not mean the brakes are completely problem free. Requires further investigation.
In fact I know exactly what is causing the 'problem'. What I am highlighting is how subjective the test is and how the 'computer system' seems to overide human judgement.
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I'm highlighting the subjectiveness of the test. If I hadn't been watching the test I would never had known there is a potential problem with the brakes. There was no advisory notice.
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The MOT test is typical of everything else that govt legislation dictates, i.e. there's rules to follow which don't necessarily make sense....
my brother has a m/c garage & repair shop inc MOT's. A couple of months ago he was visited under cover and tested re his MOT testing........ no problem with that you might think...but..
you can only have a certain number of negative marks before you have the MOT entitlement taken away. He received a negative mark for........
..failing a m/c because the front brake disc was worn and had worn beneath the manufacturers recommended limits...
despite this being dangerous (and potentially catastrophic), because this wasn't in the MOT check list, it apparently shouldn't have been a fail....
hmmm, If that was my bike i think i would have liked to know about that one.
oh well 'rules is rules'.
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>>it apparently shouldn't have been a fail....
Absolutely right - if checking the disc thickness isn't in the bike MOT, your brother had no business making that check. At the most, he should have advised if he felt there is a potential problem there.
Number_Cruncher
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aaaaah and therein lies the point............
something inherently dangerous, nah pass it mate, 'cos it's not in the rules.........
but what happens if the rules are flawed, should we not look at why the rules are there in the first place...i.e make the bike safer on the roads........ or shall we just ignore it because the rule maker has got it wrong
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what it is in a nutshell is the opinion of the tester is being eroded by the machinery of central government......
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Of all the cars I have had MoT tested, hardly any have had front brake retardation levels identical or nearly so. Yet they passed, and on the rare occasions when heavy braking was necessary did not misbehave.
Those standards and variations are theren for good reason. If you're racing or trying conclusions on the public roads then get your brakes fettled by an appropriate person by allo means. Otherwise assume if it passes it will pass muster on the road.
Am I becoming an authority toady?
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what it is in a nutshell is the opinion of the tester is being eroded by the machinery of central government......
Not got anything to do with central government.
What is and isn't in the MoT is decided by the guys at VOSA who work with a panel of people from the motor industry (in fact most of the VOSA engineers are ex-industry). Obviously much of the industry would like a very tough test that nothing over about four years old will pass and this has to be moderated in the interests of motorists so that we get something that is sensible but keeps dangerous cars off the road. I think the MoT is pretty fair and balanced and not a bad price either - for a 45 minutes of labour from a pro mechanic.
In terms of brakes, its down to the measured brake performance. A dangerous or corroded disc would fail (would on a car - I'm not familiar with bike test). There is also a pad limit (IIRC about 3mm on front pads and 1.5mm on back pads). Any tester worth his salt will put an advisory on any disc worn enough to start causing concern.
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If you accept that the MOT isn't a complete check of safety, and simply regard it as an inspection, carried out according to some guidelins, apparent problems with the MOT disolve.
I think Mark has put this better than I could -
www.honestjohn.co.uk/forum/post/index.htm?v=e&t=41...1
To carry out a complete, exhaustive, objective safety test would probably require some dissassembly - it would have real difficulty coping with even slight modifications, and the failure rate would be massive. We would end up with a Japanese like system with cars 4 years old being scrapped because the MOT is more expensive than the car is worth. Do you really want a system like that?
What sounds like a good idea today can begin the slippery slope to very expensive annual inspections.
Take measuring disc thickness for example. If you include it in the MOT, you have to include it for all vehicles covered by that class of test - possibly some dismantling required on some models. How do you set a pass fail criterion for each possible type of brake - disc, drum, propshaft mounted? The same is true for lining thickness - would you be happy having your drum brakes stripped down?
The brake efficiency test is an excellent compromise - it checks the basic function of the brakes quickly, and with relatively simple equipment. IMO, this represents real common sense.
People's desire for a more objective MOT would soon dissolve once they found out how expensive it would be.
The law has enough teeth - drivers are responsible for the state of the vehicle they are driving.
Number_Cruncher
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I agree with number cruncher
An mot is a test that checks the vehicle meets minimal saftey requirements and is only good at the time of test, there is no road test carried out.
a car could pass an mot with over inflated tyres as it isnt part of the test to check tyre pressures but as we all know if a car had over inflated tyre the car would be dangerous to drive.
It is down to the driver of the vehicle to make sure the car is a roadworthey condition every time he/she drives it on a public road and NOT an MOT testers.
We just check them every year
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>>. He received a negativemark for........
I don't know when this was, but it's certainly in the checklist now.
". Examine all the mechanical components of the brakes which can be seen without dismantling, looking particularly for:
blah blah blah
"brake disc scoring, pitting or wear;"
A couple of mate's bikes have failed on this. Notable mainly because bike discs are typicaly about £150 to replace. Each. :o(
Cheers
DP
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>> I don't know when this was, but it's certainly in the checklist now. ". Examine all the mechanical components of the brakes which can be seen without dismantling, looking particularly for: blah blah blah "brake disc scoring, pitting or wear;"
Yes, but I think the issue is how much 'wear' before a fail is issued. The manfr might allow for very little wear in setting minimum thickness whereas for the MoT brake performance may be fine with much more wear. Manfr minimum thickness can be quite conservative. I have certainly put cars though with 1mm wear lip either side of a 22mm vented disc and they've gone through without a murmur.
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