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Brake linings (attn MonsterMork)

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bungeejumper
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Brake linings (attn MonsterMork)

#163902

Postby bungeejumper » September 3rd, 2018, 1:09 pm

Whoops, red face moment here at Bungee Towers. I took my four year old Toyota in for its second MOT and got a Do Not Drive because the rear disc pads were down to 1.6 millimetres, and I hadn't known about it. The car's last main-dealer service (last Christmas) hadn't flagged anything up, and I'd only done about 8,000 miles since then, and there had been no dashboard warning lights, and the car had been stopping perfectly all through my last 2,500 mile thrash through France. And, FWIW, my discs were in perfect and unmarked condition - it was just the pads that needed changing?

So - on the strict understanding that I'm not trying to duck my responsibility to keep the car roadworthy - what could I have done to head off this black mark on my car's record?

Could I/should I have taken a caliper measurement of my brake pad thicknesses every few months, in the hopeful confidence that my visible pads (the outer ones) would have matched those on the inside edge of the wheel discs?

Or should I have known, as the RAC website says, that the minimum MOT-allowable pad thickness varies from car to car (from maybe 3mm down to 1.2mm), and that the true allowable thickness is stamped on the car's wheel discs? Where I'm really not likely to go looking for it?

I mean, come on guys, what's a punter supposed to do? All I can say is thank goodness for the MOT, and god bless all who sail in her.

MonsterMork, as an MOT tester I would be glad of your views. Please don't spare my blushes, I'd really like to know. :)

BJ

swill453
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Re: Brake linings (attn MonsterMork)

#163909

Postby swill453 » September 3rd, 2018, 1:27 pm

Surely if you really don't want your car to fail its MOT for the wear on the brake pads, then the answer is to measure them yourself before submitting to the test? And if you can't, then get a professional to do it for you.

I'm sure the likes of Kwikfit etc. do free brake checks, other "professionals" are available.

Scott.

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Re: Brake linings (attn MonsterMork)

#163911

Postby Snorvey » September 3rd, 2018, 1:30 pm

My scooter went into the dealers last week because the rear brake was sounding like a bacon slicer. It turns out the pads were worn right down and one of them was metal on metal.

Anyone who rides a bike knows that almost all of the stopping is done with your front brake, so I wasn't overly concerned (although he changed the front set as well)..... but he only MOT'd it in March and I've only done about 1000 miles on it since then.

I know I should check them regularly, but you'd think if they were good in March, they'd be good 6 months later (particularly the rear set)

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Re: Brake linings (attn MonsterMork)

#163929

Postby swill453 » September 3rd, 2018, 2:12 pm

Snorvey wrote:I know I should check them regularly, but you'd think if they were good in March, they'd be good 6 months later (particularly the rear set)

I guess that's the problem with relying solely on the MOT. If they were (just) legal and they stopped the bike within spec 6 months ago, then you'd be told nothing about them.

Scott.

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Re: Brake linings (attn MonsterMork)

#163944

Postby vrdiver » September 3rd, 2018, 3:31 pm

swill453 wrote:
Snorvey wrote:I know I should check them regularly, but you'd think if they were good in March, they'd be good 6 months later (particularly the rear set)

I guess that's the problem with relying solely on the MOT. If they were (just) legal and they stopped the bike within spec 6 months ago, then you'd be told nothing about them.

Scott.

I use a local garage for service and MOT. I chat with the owner, who goes through any work I've had done, and he always tells me two things: what I've had done, and what he thinks I will need next. E.g. my last MOT he told me the brake pads were good for "at least another 1,000 miles, bring it in when you've done that and we''ll take another look". Ditto tires etc. during a service.

If you can find a garage you trust, then they are worth going back to and becoming a regular; I've been to Quickfit once.

VRD

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Re: Brake linings (attn MonsterMork)

#163991

Postby GoSeigen » September 3rd, 2018, 8:07 pm

vrdiver wrote:I use a local garage for service and MOT. I chat with the owner, who goes through any work I've had done, and he always tells me two things: what I've had done, and what he thinks I will need next. E.g. my last MOT he told me the brake pads were good for "at least another 1,000 miles, bring it in when you've done that and we''ll take another look". Ditto tires etc. during a service.

If you can find a garage you trust, then they are worth going back to and becoming a regular; I've been to Quickfit once.

VRD


Nice idea in theory until the garage changes ownership (but not staff) without your knowing and one day your bill is far higher than previously. Happened to me when I took my banger in for a service and MOT: got a shock, was charged effectively £125 for just the MOT part. Since then I go to Kwikfit: latest MOT £25 after they knocked off a tenner for keeping me waiting.


GS

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Re: Brake linings (attn MonsterMork)

#164002

Postby ten0rman » September 3rd, 2018, 9:16 pm

Re: Kwikfit.
Many years ago, I was somewhat concerned about my brakes - can't remember why, so whilst on holiday I called in a KwikFit who were offering free brake checks. New disks, new pads, new cylinder, new this, new that. So I tried to cherry pick - nothing doing, it was all or nothing, so I chose nothing, knowing that I was due for MOT in a few weeks time.
Strangely, it passed with flying colours, so I asked about the leaky cylinder - we don't dismantle and it isn't leaking outside the drum. And what about the disks? Have you been to Kwikfit? Yes. And thus I got a tirade of how they prey on people. In my case, the disks were indeed well within the stated wear limits for that vehicle, apparently what KW did was to measure them, and if they show any wear at all, they are worn out! I've never been back to KW since then.

I use a small independant, and have done for 20+ years. The owner openly admits that being in a small village, he has to do a reasonable job as otherwise word gets round and he goes out of business. It is a family business, husband & wife team plus a couple of other mechanics. He does all my servicing and MOT's and always warns me if something's coming up that might cause problems, even if it's satisfactory at the moment. Also, anything that needs doing at either an MOT or a service is usually done there and then. Now ok, plenty of opportunity for a fiddle, you might think. Not so, I've known him turn down work because he has not had the problem demonstrated to him! I can't see him selling up, easing up perhaps in about 10 or so years, so I have every confidence that he will see me out.

Back to Kwikfit. As I said, the above event happened a long time ago. I have no idea what they are like today, it may well be that they are much better behaved today, indeed I would hope they are.

BJ,
My Avensis had the rear brake pads changed at 50299 miles in Nov 2016 at a cost of 23.20 + VAT + labour. According to my records, this was during a service. The previous MOT, performed at 39772 miles in May 2016 made no mention of the brakes. In October 2017, at 62071 miles, the front discs and pads were changed. This was shortly after the previous service (August 2017) at which it was noted that they had about 2000 miles left on them. Again, the previous MOT (May 2017) and 56409 miles made no mention of wear. The car currently has 74000 miles on it.

Regards,

ten0rman

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Re: Brake linings (attn MonsterMork)

#164011

Postby scottnsilky » September 3rd, 2018, 10:33 pm

I was a motor mechanic for 20 years and have worked on cars most of my adult life, I wonder myself how thick the pad lining is on the Peugeot I bought a year ago. It is unreasonable to expect an ordinary car owner will know the thickness of brake pad lining on their car. If your car has alloy wheels and the spokes are thin enough, you can just see the outer brake pad inside the caliper. I can on mine but still can't really assess the thickness of lining. If I can't, how can the less technically minded person? It may be possible with the aid of a mirror, especially a dentist's type with a long stem. ( I've just remembered I have such a tool, I'll check tomorrow) My experience of owners is one service per year and MoT test at the same time, that service would involve removing the wheels to check brake pads even if the car had passed it's test an hour ago. One sign worn out pads will show is brake fluid level in the master cylinder. As the pads wear, fluid passes down the pipe to fill the caliper as the piston moves to make up for the thinner pad and the fluid level in the master cylinder will be lower.

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Re: Brake linings (attn MonsterMork)

#164077

Postby DrFfybes » September 4th, 2018, 9:41 am

ten0rman wrote:Re: Kwikfit.
Many years ago, I was somewhat concerned about my brakes - can't remember why, so whilst on holiday I called in a KwikFit who were offering free brake checks. New disks, new pads, new cylinder, new this, new that. So I tried to cherry pick - nothing doing, it was all or nothing, so I chose nothing, knowing that I was due for MOT in a few weeks time.
[...]

Back to Kwikfit. As I said, the above event happened a long time ago. I have no idea what they are like today, it may well be that they are much better behaved today, indeed I would hope they are.



I think things have changed, especially with KF, however when MrsF took her Z4 to the main dealers for a service and mentioned a sticky handbrake they quoted £1500 or so for a complete rear brake replacement due to a leaky caliper, and charged over £100 for a strip and clean.

It was still binding so we went to an independent about 10 miles away who took us under the car and said "see that leak?".. "No?"..."No, neither can we".

2 years and 2 MOTs later all is still well. Since then I've heard of an elderly neighbour being told her wheels were buckled at the first service and quoted over a grand for new ones, fortunately she had the sense to go to KF who told her the correct term was "kerbed" and one had a slight flats pot from a pothole but nothing to worry about.

Last week I had a flat battery - ATS tested it and said there was 780A left (about 85%) and to replace it. "Nothing in stock, but I've ordered one for tomorrow in case you want it".I went to KF as well who had 3 people on it, tested it under load, starting, ancillaries on, declared it was at 85% and said it is fine but with all the lights and demisters going the alternator was marginal.

Paul

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Re: Brake linings (attn MonsterMork)

#164080

Postby bungeejumper » September 4th, 2018, 9:54 am

Thanks for all the great replies, fellas, I feel a bit less stupid already. :D

Scottnsilky's comment about the brake fluid level going down reminded me of an experience I had with my Passat. One dark night, out in the country lanes, the car started making an ominous bonging noise from the dashboard every time I turned a right hand corner. No other warnings. Since it was after midnight, I checked everything and then drove home slowly and carefully.

In the morning, it all became clear. Brake pad wear had lowered the fluid level to the point where the fluid level warning was sounding intermittently. So why only on right hand bends? Centrifugal force was lowering the fluid level on one side of the master cylinder so that the sensor was exposed, but not on the other! Jeepers, and I was hardly pulling big Gs. (Not my style, and especially not after midnight.)

The pads, FWIW, were well within their limits - they had maybe 25% still to go. And the garage said it seemed to be because the master cylinder simply wasn't big enough to accommodate the travel from the front pads. And the bonging noise? It wasn't even in the owner's manual. It was just VW's own inimitable way of telling me that the level needed checking. Sure enough, when I got the discs and pads changed the fluid level returned to normal. It never happened again. You live and learn.

BJ

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Re: Brake linings (attn MonsterMork)

#164101

Postby GoSeigen » September 4th, 2018, 11:16 am

bungeejumper wrote:Thanks for all the great replies, fellas, I feel a bit less stupid already. :D
[...]
Centrifugal force was lowering the fluid level on one side of the master cylinder

BJ


Correction. Newtonian inertia was lowering the fluid level on one side of the master cylinder....

Just trying to make you feel stupid again ;-)


I felt extremely foolish a few years back when I bought a used Ford Focus from my landlord without having it checked over. He'd left it standing for a year but then driven it for a few weeks before I bought it, so I assumed he'd had it serviced himself. Bad mistake. Two weeks later going down a steep local hill the brakes failed -- probably the brake fluid had absorbed water while the car was standing, lowering its boiling point -- foot went to the floor with no braking effect at all and a few seconds later, having turned the air blue, I ploughed into the back of a hapless driver who'd pulled into my path. My torment was increased by the police investigating me for dangerous driving and my insurer failing to test the brake fluid and not believing my story!

I've recently changed front and rear discs and pads, better change the fluid too before something else bad happens...


GS

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Re: Brake linings (attn MonsterMork)

#164615

Postby DrFfybes » September 6th, 2018, 12:08 pm

bungeejumper wrote: And the bonging noise? It wasn't even in the owner's manual. It was just VW's own inimitable way of telling me that the level needed checking. S

BJ


Safety features not in the manual can be irritating.

On some 90s Toyotas the brake level warning light comes on if a brake light has failed, but it takes an application of the brake to register, so if the brake pedal is pressed when you start the car, it doesn't come on.

Of course it comes on the first time you brake, and resets after you turn off the engine. So if you get out, check the levels/grovel under looking for leaks/try and look at the pads, then it goes off, until next time you brake.

That would have been nice to mention in the manual.

Paul

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Re: Brake linings (attn MonsterMork)

#164623

Postby bungeejumper » September 6th, 2018, 12:40 pm

DrFfybes wrote:Safety features not in the manual can be irritating.

On some 90s Toyotas the brake level warning light comes on if a brake light has failed, but it takes an application of the brake to register, so if the brake pedal is pressed when you start the car, it doesn't come on.

Oh indeed, but they still keep on doing it. On Passats like mine (and maybe still, for all I know?), your rear windscreen wash/wiper wouldn't work if your bonnet catch was misbehaving. And your front wipers wouldn't do much either. The reason was/is that VW wipers are recessed into the bonnet, so that they'll foul the bonnet panel if the bonnet is even a little bit open. (or is wrongly suspected of being open.) The result is that your rear wipers won't work until they've asked permission from the front grille. :lol:

Less obvious was that the 12V dashboard sockets on my old Focus wouldn't work if the glovebox illumination bulb had failed. So your satnav goes off, and so does everything else, and you don't know why. Don't ask me how I know. I never did get to the reasoning behind that one. ;) I mean, come on, how often do you check your glovebox illumination?

BJ

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Re: Brake linings (attn MonsterMork)

#164663

Postby Watis » September 6th, 2018, 1:53 pm

On a ten year old Toyota Yaris - the one with the digital speedometer display (a great idea IMHO) there is a button which cycles a subsidiary display through such things as the temperature, MPG and miles of fuel left in the tank.

This button is also used to adjust the time of the clock. The first time I needed to change the clock, it took three weeks to achieve - and at first I didn't know why it had worked on that attempt.

The manual states that a long press of the button would initiate the time change function. But all that happened was that it reset whatever the display was showing at that time.

What the manual omitted to mention was that the display needs to be showing the temperature - which can't be reset - to trigger the time change function!

Watis

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Re: Brake linings (attn MonsterMork)

#164862

Postby MonsterMork » September 7th, 2018, 11:30 am

bungeejumper wrote: the RAC website says, that the minimum MOT-allowable pad thickness varies from car to car (from maybe 3mm down to 1.2mm), and that the true allowable thickness is stamped on the car's wheel discs?

BJ


Complete and utter bollox. :roll:

The minimum thickness for brake pads on class 3, 4, 5 and 7 vehicles (ie: motor tricycles, cars and vans etc) is 1.5mm, irrespective of the make or model. There is no set limit for the thickness of the discs, the rule being "A brake disc or drum must be significantly worn before you should reject it. Being worn below the manufacturer’s recommended limits isn't a reason in itself.". Follow the linky to section 1.1.13 for pads, and 1.1.14 for the discs:
https://www.mot-testing.service.gov.uk/ ... ion_1.1.13

Please note, however, that the minimum standard for the MoT may not be the minimum standard as stated by the vehicle manufacturer, so if you have a crash and your brakes are ok for an MoT you might still get scuppered by your insurers for being below the manufacturers limits ....

As for the allowable thickness being on the discs it is not for the pads, it is for the disc itself, and not all disc manufacturers stamp it onto the discs, as they may be used on multiple vehicles from multiple manufacturers, each of whom may have different service limits even though the disc itself is the same. If shown then it will be stamped onto either the outer edge, the outer centre face, or inner centre face, not on the actual braking surface itself. The only way of finding out is to jack the vehicle up, safely support it, remove the wheel, then strip the brakes (pads, carrier and caliper), then remove the disc, then hope that the info you want is stamped on the disc and hasn't been eaten away by corrosion. Or alternatively look in the owners manual or online for the service limits for your vehicle :D

Could I/should I have taken a caliper measurement of my brake pad thicknesses every few months, in the hopeful confidence that my visible pads (the outer ones) would have matched those on the inside edge of the wheel discs?


Realistically the best thing to do is to, say, once a month, have a quick look through the wheels at your brakes. Unless you really do want to faff about with a full strip-down! Most (but by no means all) cars have just enough visibility to see the condition of the pads and discs, and whilst you might not quite be able to see the pad material itself, the backing plate is in most cases visible and should give you and idea of the depth of the pad (it will be the distance 'twixt backing and disc). Note, however, that Scottnsilky made a very valid reply earlier, even for us wot do it for a living it can be nigh on impossible to gauge properly just by looking from the outside, and checking the brake fluid level can be a good indicator as to pad wear.

Usually the inner pad should wear at the same rate as the outer (the one you can see), although they can, and do, seize or partially stick leading to a difference in wear, more so (in my experience) on vehicles which combine the handbrake and brake caliper (eg: modern Mini's). The only way of checking the inner pad is from under the vehicle, or stripping the brakes.

Some cars have rear drum brakes fitted, and there is no way of measuring brake wear on these without a full strip-down.

It is entirely possible, and happens all too often, that worn brakes will still pass the brake test at MoT time. Many, many times I have seen vehicles in for MoT and service, pass the brake test with no problem, and then find the brakes actually have little life left when stripped for inspection as part of the service afterwards.

Brakes wot are squealing when applied need to be looked at by a professional (unless you are a competent spanner slinger yourself) pronto, see my previous post about a brake issue ....

If you are at all unsure then head for your local independant garage, main dealer, brakes/tyres/zorsts retail barn etc and ask them to have a look for you. They might try to sell you new brakes when you might not actually have needed them (some places have quite a reputation for this!), but generally speaking they are unlikely to say everything is fine if they find your brakes really are stuffed, as they could find themselves liable if there was an unfortunate incident ....

got a Do Not Drive because the rear disc pads were down to 1.6 millimetres,


Ooooh, strictly speaking the tester has been a naughty boy and may get points on his ticket, as the limit is, as previously stated, 1.5mm, but hey, wot is a whole one tenth of a millimetre between friends? :lol: Would anyone out there like to guess how we measure brake thickness at the MoT?

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Re: Brake linings (attn MonsterMork)

#166299

Postby DrFfybes » September 14th, 2018, 12:49 pm

bungeejumper wrote:Less obvious was that the 12V dashboard sockets on my old Focus wouldn't work if the glovebox illumination bulb had failed. So your satnav goes off, and so does everything else, and you don't know why. Don't ask me how I know. I never did get to the reasoning behind that one. ;) I mean, come on, how often do you check your glovebox illumination?
BJ


I took the bulb out of mine - the button that switches it off presses on a soft part of the lid, so it wears and the light stays on, melting the holder, which also houses the boot and fuel cap release buttons (yup, in the glove box).

There are also a number of bleeps when the ignition is turned off - it varies in number and does not seem to be documented anywhere. I once asked the dealer what this meant.
"How many beeps"
"Thirteen this morning"
"Oh, that means it is Tuesday"
"But it's Saturday"
"Ahhh, your clock''s wrong".

Paul

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Re: Brake linings (attn MonsterMork)

#166723

Postby 88V8 » September 16th, 2018, 2:46 pm

GoSeigen wrote:
bungeejumper wrote:...probably the brake fluid had absorbed water while the car was standing, lowering its boiling point.


Well, you're ahead of most people in knowing that bit of arcana.

But isn't it annoying how in moments of braking crisis we don't think to grab the handbrake.

Anyway, due as you say to water absorption, brake fluid should be changed every two years, regardless of mileage. And on our cars, it is, usually by me.
That also minimises corrosion in the system, thus the seals last longer.
On our cars. just a matter of bleeding the fluid at each corner until it comes out clean.
Modern cars no duobt complexify this simple task in some way, jobs for the garage boys eh what.

As to pad thickness, two of our cars no longer need an MOT. Happily, they don't have disc brakes. One less thing to worry about.

V8

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Re: Brake linings (attn MonsterMork)

#166745

Postby Slarti » September 16th, 2018, 5:38 pm

88V8 wrote:
GoSeigen wrote:But isn't it annoying how in moments of braking crisis we don't think to grab the handbrake.


Even more annoying that, for many of us, that is no longer an option.

I'd hate to think what would happen if, in a braking emergency, I pushed the button that applies the parking brake. Shattered disks?


Slarti

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Re: Brake linings (attn MonsterMork)

#166750

Postby GoSeigen » September 16th, 2018, 6:11 pm

88V8 wrote:
GoSeigen wrote:
bungeejumper wrote:...probably the brake fluid had absorbed water while the car was standing, lowering its boiling point.


Well, you're ahead of most people in knowing that bit of arcana.

But isn't it annoying how in moments of braking crisis we don't think to grab the handbrake.


Yes, I simply assumed that as the footbrake wasn't working the handbrake wouldn't either. I only found out about the fluid arcania when I consulted the mechanic afterwards.


Slarti wrote:Even more annoying that, for many of us, that is no longer an option.

I'd hate to think what would happen if, in a braking emergency, I pushed the button that applies the parking brake. Shattered disks?


Agree -- the joys of drive-by-wire!

Probably the car would just refuse to apply it's brakes because it is moving. Wouldn't like to experiment though!


GS

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Re: Brake linings (attn MonsterMork)

#166788

Postby swill453 » September 16th, 2018, 8:23 pm

Out of curiosity I tried my electronic handbrake while (slowly) rolling to a halt. It refused to do anything until I was stopped.

Scott.


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