MOT failed on scored discs

Mot failed and the garage tell me discs and pads need replacing as the discs are scored. Ok will get them fixed - no problem with that. But I thought a failure was/could/should be on insufficient braking effort - the amount of force and the brake balance. The braking is very good even with the discs as described. In fact the reason I was going to change them anyway is because the disc are warped - can feel it under braking especially from speed. As I say, I have no problem with them doing the work or anything like that but my question is can "scored" discs cause an MOT failure even if they work ok (from force point of view). I suppose the answer is an obvious "yes" but like to hear it from the grp.

Reply to
alan
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They seem to have lied to get work. My local Lookers garage were forever telling people that they needed new discs. They also regularly overfilled cars with oil amongst other things. The best was the car that passed an MOT and was sold with a broken track rod end. Or the car released with faulty brakes after some idiot didn't put the rear ones back together correctly. My Trading Standards Office regularly have to send test cars in now. Fortunately the local MSF Ford people are far far better. People in a garage are pressurised to meet sales targets so will lie to meet those targets or they are given warnings. It's all been on various TV consumer shows. Ask them to show you the MOT document that states what they claim. Appeal against their decision and post the name and address of the garage on here. If what you say is true we can all avoid them.

Reply to
Ian

From

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The Testers Manual

3.5 Mechanical Brake Components

Information

A visual and physical check must be carried out on all mechanical components that are visible and accessible.

Method of Inspection

  1. Check the mechanical brake components for

h. the condition and security of brake drums and discs

Reason for rejection

h. a brake disc or drum insecure, cracked or excessively scored, pitted or worn

Reply to
David Taylor

"Ian" gurgled happily, sounding much like they were saying:

See the extract from the tester's manual that David posted. Scored discs can be a fail.

Discs are a consumable these days - two sets of pads to one of discs is not unusual.

No, it didn't. If the TRE was "broken", the car would be physically completely unmovable, let alone undrivable.

They'll have given him the fail sheet, you f****it.

Reply to
Adrian

I've seen several advises for scored discs, but no fails. Does the manual define "excessive", or is it at the examiners discretion? I can see the opening for bigging it up to get the work.

Steve

Reply to
shazzbat

"shazzbat" gurgled happily, sounding much like they were saying:

Examiner's discretion.

Also, don't forget that tester's can't dismantle - so if a disk or pads are hidden behind dustshields or similar, they can't be tested.

As with anything that's discretionary.

Reply to
Adrian

hmmmm and the reasoning behind that statement of lying to get work ?

we can issue a fail for excessively scored brake disc's even though the readings are acceptable.

Reply to
reg

Could you define 'excessive', or how you decide it is?

Reply to
Dave Plowman (News)

At some MoT stations : check bank account/number of jobs booked in.

At others: go by long experience.

Mrcheerful

Reply to
Mrcheerful

Long experience of what? How much information does the average MOT tester have - on the average life of brake disks against the number, depth, position and orienatation of scores. In short ... how does he / know/ whether there's a problem.

M'lud, at this point I would like to introduce Exhibit A: a "grooved" brake disk.

Ian

Reply to
Ian

Ian gurgled happily, sounding much like they were saying:

There's a very big difference between a grooved disk and a scored disk.

Anybody who can't spot that difference from the far side of the workshop shouldn't be working at Kwik-Fit, let alone be an MOT tester.

Reply to
Adrian

the silly thing is: scored discs have more surface area than a smooth/new disc !!

Reply to
Mrcheerful

Err yes. But it's not helpfull.

Reply to
Duncan Wood

Ah, you were there then?

That is all 100% lies you've just made up. Thankfully seen as you don't mention where you are so we don't know where is local to you, your lies are even more meaningless.

Ah the local one. Good. I know where to go now. Of course, if I didn't know 100% of everything you post is lies, then I, well, still wouldn't be any the wiser.

All garages do this do they? But, you're a mechanic, you said so, so surely that includes you? (and a garage owner, TV and electronics salesman, car accessory shop owner, policeman who does accident investigations and several more made up jobs). To say how much of a problem this is, I'm surprised it doesn't come up on here more often than, erm, this one time right now.

Ask them to show you the MOT document? I usually get myself a copy of that when I leave... The OP could appeal against their decision if you like, but as he mentions he was changing the discs anyway because they were warped, it would seem a bit of a pointless exercise that's just gonna cause him a load of hassle.

Reply to
DanB

Doesn't matter. Unless it can be shown that scoring detracts from the braking performance in some way, it should not be the sole excuse for an MOT fail. Mike.

Reply to
Mike G

My thoughts. All discs get scored with use. If the scoring takes them below the spec thickness then I suppose a fail is fair enough. But if it doesn't and the performance is fine it seems to me like a stupid reg. As do any which aren't strictly defined.

Reply to
Dave Plowman (News)

Agreed. All discs get scored in use as bits of grit get into the pads. It doesn't affect anything greatly and the pad surfaces stay matched to the disc ones. I've never seen a disc that I would call 'unusually' deeply scored because the wear evens out as the grit gets pulverised. It might mean a change of both parts when one wears out but until then it doesn't strike me as a reasonable MOT fail. It's one of those grey areas that gives an unscrupulous garage an ideal opportunity to try and make work for themselves.

One way of avoiding that is don't go to an MOT station that also does repairs and especially not one that specialises in brake and suspension repairs like a Kwik Fit.

Reply to
Dave Baker

"Dave Baker" gurgled happily, sounding much like they were saying:

Unfortunately, some disks DO get _badly_ scored - due to being used with utterly knackered pads.

I'm very surprised that you've not seen 'em - I've certainly seen 'em looking like a freshly ploughed field.

Reply to
Adrian

As 'ploughed field' isn't a term that capable of being scientifically quantified I wouldn't like to surmise what you mean by it however I've not only seen plenty of scored disks I've machined plenty true again and the scoring is rarely as deep as it looks. If the disk is still within the recommended overall wear limits then the scoring usually skims out after a few thou of machining.

In fact I take those wear limits with a pinch of salt too because I think they have more to do with the manufacturer wanting to sell you another set of disks than any real safety concerns. 2mm on a 20mm thick disk is an average limit but there's still a ton of meat left on them at that and no danger of a pad popping out or anything. I did once see a front set on a Peugeot 205 that were 5 mm worn and not far from breaking through into the ventilation ducts though. That was one where I told the owner I wasn't taking it out onto the road and if he had any sense he wouldn't either.

However I had no qualms about skimming the disks on my Focus which when I bought it at 34k miles were already about down to the 2mm limit and then putting them back on with new pads. To someone brought up on cars that hardly ever showed disk wear I think it's a bit rich having to change them with every set of pads as you seem to have to nowadays. 15,000 miles later they're still fine and in fact don't seem to have worn much further but then I'm very light on brakes.

We had this conversation last year and I'm quite sure the disk material doesn't need to wear as fast as it does. The stainless steel ones on my motorbikes don't wear at all and car ones didn't wear much 30 years ago but they seem to use very soft cast iron these days. A slightly better material might last the life of the car but that would be bad for corporate profits. It might also be down to modern non asbestos pad material but who knows.

However, back to the original point. I've never seen disks where the scoring alone was any reason to stop them working efficiently enough to be safe on the road and pass an MOT load test. I'm not saying that it isn't possible to get them to that state if you leave them on with the pads worn down to the steel backing for long enough but any car that passes the roller test ought not to be a fail unless the disks are horribly unusually worn.

Reply to
Dave Baker

"Dave Baker" gurgled happily, sounding much like they were saying:

I've seen a rear disc from a CX Safari that had actually worn past that - one side had little wafer-thin bits attached to the vents. The other side had cracks...

When they do, how much do they cost to replace?

When they did, how much did they cost to replace?

I seem to recall replacing the disks on my first CX - they were slightly below the wear limit - with a new boxed pair I'd bought off somebody at an event for "only" about £60 for the pair - 15yrs ago. Front disks "never wear", I was told, "hideously expensive new". Strange how the fade from speed reduced massively after changing 'em.

People sell second-hand DS disks. You can't get 'em new, and they really DON'T ever wear. Just as well, since they're the bit they hung off the factory ceiling and built the rest of the car around...

And how much do they cost to replace?

Sod all. Pattern vented disks for my Saab are £20 each. Certainly, the braking improved when I replaced the ones that were on the car - they were a couple of mm below the wear limit.

Reply to
Adrian

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