In article ,
wrote:
On Monday, 8 May 2017 10:50:10 UTC+1, Rod Speed wrote:
"Jim GM4DHJ ..." wrote in message
news
"Rod Speed" wrote in message
...

I blame the passing of asbestos for discs wearing out fast .....

Mine don‘t wear out any faster than they did with asbestos was used.

lucky you ...on aveage every second or third set of pads you need discs
these days ....

I havent needed a set of pads in 10 years and only needed
one set of pads in the previous 45 years with the previous car.

sounds about right for a Crosley.

And since Wodney spends all his time posting here likely only drives a few
miles a year.

--
*Strip mining prevents forest fires.

Dave Plowman London SW
To e-mail, change noise into sound.

"dennis@home" wrote in message
web.com...
On 07/05/2017 21:43, Steve Walker wrote:
On 07/05/2017 13:41, Andy Burns wrote:
Dave Plowman wrote:

Generally, discs need replacing every second set of pads.

That seems to be the way, though the garage generally tells me I've been
"lucky" as modern discs and pads are intended to need replacing at the
same time.

I do my own maintenance and only use a garage for a few things (welding a
sill, replacing a cambelt and replacing a dual-mass flywheel) that would
have cost me more in time off work to do it myself than for them to do
it.

In 30-odd years I have only replaced discs on two cars, both due to
slight warping - I have never worn a disc to the minimum even on cars
that have had numerous replacements of pads and mileages of 160,000+.

Are garages pushing unneccessary changes for profit?

Some will.
My MOT advisory said pads were close to limit but the service guy said
they were not and didn't need doing.

discs wear more than they did before asbestos was removed from the pads.
The pads are harder and need servos to work these days.

As the pads wear the disc, you tend to get a lip on the edge of the disc
which is outside the area rubbed by the pads. My local garage removes the
discs and skims off that lip, as part of the normal car service every 12,000
miles. I'm not sure when I last had new discs, but I'm sure I've had at
least one set of replacement discs (maybe front only) in the 160,000 that
the car has done so far.

The biggest problem is if the pads wear down to the rivets that fasten them
to the backing plates, because the rivets can there score the discs, which
when new discs are usually necessary even if the old discs still have plenty
of thickness. I've only had that happen once on a car: I was going down a
long steep hill and suddenly there was a grinding noise. I wasn't aware of
any loss of braking force, presumably because the other brakes took more
braking force if the worn one stopped braking as effectively.

Luckily my garage could fit me in quickly to replace the discs and pads, but
it was a noisy journey home and to the garage - noisy whenever I braked. It
must have been a back brake because I could also reproduce the grinding
noise by applying handbrake only (which I did as a test).

Every time I have my car serviced they warn me that new pads and/or discs
will be required, but (almost) every time I get the car back an they say
"worn, will need replacing next time" so they haven't worn down yet. I don't
know whether pads have a non-destructive wear-indicator which shows when it
is time to replace them without (at that amount of wear) scoring the discs.

On 08/05/2017 09:54, wrote:
On Monday, 8 May 2017 07:44:27 UTC+1, Jim GM4DHJ ... wrote:

history for SDO7 KNN ......ALWAYS pay the full price for an MOT or you WILL
get ripped off .......

even then you often will. I'm picky about where I take cars for MOTs.


I've used the local Halfords for several years for about half price.
Don't think I've ever had a fail - a few advisories, and I let them fix
a leaking water pump they'd diagnosed once.

--
Cheers, Rob

"Dave Plowman (News)" wrote in message
...
I used to service a police driving instructors car. His brakes were
like new at 40,000 miles.

Glad I never had to drive behind him in traffic. But then he probably
never did drive in heavy traffic.

He used gears - "always be in the right gear to accelerate away again"

I was taught when I learned in the very early 80s to change down through my
gears when coming to rest, because that is what the normal test required at
that time. My instructor had been a Police Class 1 instructor before he
retired and said "once you've passed your test, I'll teach you the *proper*
way to slow down" though unfortunately I never took him up on the extra "now
you've passed" lessons.

But when I was preparing for my IAM advanced test about 10 years later, I
was taught the "Roadcraft" way: as you approach the junction etc, stay in
whatever gear you are in, braking progressively (gently at high speed,
gradually increasing brake pressure as you slow down, then come almost off
the footbrake as you are about to stop to prevent a sudden lurch). Change
into the required gear once you know from the road conditions what that gear
is - if you can see that you can continue without having to stop, you may
need a sixth-to-second change; if you will have to stop, it's
sixth-to-first, so you are in the correct gear to accelerate away again.

When I'm driving I try to lose speed in the first instance simply by lifting
off the power and letting the car slow down by friction and air resistance.
If there's a car behind me, I may press the pedal just enough to put the
lights on. If that doesn't slow me down enough, only then will I brake using
the footbrake. But I'm not one of these people (and I've ridden with them as
a passenger) who believes that your foot should always be on either the
accelerator or the brake, and that it must never be on neither pedal.

The IAM also taught me how (in a car without ABS) to brake in an emergency:
smoothly but quickly apply large pressure on the pedal (but don't stamp on
the pedal - even in an emergency *try* to phase in the braking over a
fraction of a second) and be ready to come off the brake as soon as you
detect any skidding. Ideally (and I reckon you have to be super-human to be
able to do this) keep braking to just before skid-point and then back off to
let the tyres bite - rinse and repeat. But when I tried this "cadence
braking" on a skid pan, I couldn't master it: the instinct in an emergency
is to press the pedal hard and leave it there - schooling yourself to
release the brake pedal slightly while you are rapidly approaching the
hazard is what needs superhuman skills :-)

ABS does the cadence braking for you (that's what the rapid pulsing is in
the pedal). I've only had to use it in anger once: when a child ran out into
the road and I instinctively hit the brake and steered hard right, managing
to steer left again before hitting the opposite kerb. The child's mother
gave me an earful until the driver of the car behind me pointed out that I
had been driving at 20 in a 30 limit because I'd judged that there might be
a hazard, and that I'd started to brake when the football rolled out from
behind the gatepost a couple of seconds before the child had even appeared,
and I'd managed to avoid the child who was on the pavement at the time I
came to rest by the opposite kerb. I think her anger might have been
influenced by the fact that the car two behind me had collided with the one
behind me because *he* was driving too close.

On Monday, 8 May 2017 15:07:18 UTC+1, NY wrote:
"Dave Plowman (News)" wrote in message
...

I was taught when I learned in the very early 80s to change down through my
gears when coming to rest, because that is what the normal test required at
that time. My instructor had been a Police Class 1 instructor before he
retired and said "once you've passed your test, I'll teach you the *proper*
way to slow down" though unfortunately I never took him up on the extra "now
you've passed" lessons.

But when I was preparing for my IAM advanced test about 10 years later, I
was taught the "Roadcraft" way: as you approach the junction etc, stay in
whatever gear you are in, braking progressively (gently at high speed,
gradually increasing brake pressure as you slow down, then come almost off
the footbrake as you are about to stop to prevent a sudden lurch). Change
into the required gear once you know from the road conditions what that gear
is - if you can see that you can continue without having to stop, you may
need a sixth-to-second change; if you will have to stop, it's
sixth-to-first, so you are in the correct gear to accelerate away again.

I think all this business about changing through gears & always being in gear comes from the early days of the driving test when cars were a bugger to get into gear, and needing all your acceleration to avoid someone was a frequent thing. Times have changed a lot. Once you know your vehicle one can go into the right gear in a moment, there's no hanging about - this makes being in gear all the time redundant.


When I'm driving I try to lose speed in the first instance simply by lifting
off the power and letting the car slow down by friction and air resistance.
If there's a car behind me, I may press the pedal just enough to put the
lights on. If that doesn't slow me down enough, only then will I brake using
the footbrake. But I'm not one of these people (and I've ridden with them as
a passenger) who believes that your foot should always be on either the
accelerator or the brake, and that it must never be on neither pedal.

The IAM also taught me how (in a car without ABS) to brake in an emergency:
smoothly but quickly apply large pressure on the pedal (but don't stamp on
the pedal - even in an emergency *try* to phase in the braking over a
fraction of a second) and be ready to come off the brake as soon as you
detect any skidding. Ideally (and I reckon you have to be super-human to be
able to do this) keep braking to just before skid-point and then back off to
let the tyres bite - rinse and repeat. But when I tried this "cadence
braking" on a skid pan, I couldn't master it: the instinct in an emergency
is to press the pedal hard and leave it there - schooling yourself to
release the brake pedal slightly while you are rapidly approaching the
hazard is what needs superhuman skills :-)

It's quite doable. But to be honest I think doing that is the sign of not having learnt how to do it properly. You get a lot more braking effect by only braking as hard as it can take rather than repeatedly skidding & coming off the brakes. So use the candence thing when you really haven't got the hang of the car and/or road coditions, but normally once you release to stop skidding you should be able to judge fairly well how hard to brake. Manual ABS is something you need to practice to get the hang of. Friction is less than stiction, so skidding gets you less braking not more.


ABS does the cadence braking for you (that's what the rapid pulsing is in
the pedal).

Some cars use single circuit ABS. If 3 wheels have good grip & one doesn't, it lets off all 4 brakes. Such systems are a hazard.


NT

In article ,
NY wrote:
The biggest problem is if the pads wear down to the rivets that fasten
them to the backing plates, because the rivets can there score the
discs, which when new discs are usually necessary even if the old discs
still have plenty of thickness. I've only had that happen once on a
car: I was going down a long steep hill and suddenly there was a
grinding noise. I wasn't aware of any loss of braking force, presumably
because the other brakes took more braking force if the worn one
stopped braking as effectively.

I've never ever seen a disc pad with the lining riveted. Even in the 1960s.

--
*A conscience is what hurts when all your other parts feel so good *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
wrote:
I think all this business about changing through gears & always being in
gear comes from the early days of the driving test when cars were a
bugger to get into gear, and needing all your acceleration to avoid
someone was a frequent thing. Times have changed a lot. Once you know
your vehicle one can go into the right gear in a moment, there's no
hanging about - this makes being in gear all the time redundant.

And likely from the days when cars had very poor brakes indeed.

--
*Experience is something you don't get until just after you need it *

Dave Plowman London SW
To e-mail, change noise into sound.

Jethro_uk pretended :
I used to service a police driving instructors car. His brakes were like
new at 40,000 miles.

That is because they are taught to actually drive. No silly racing up
to a junction and banging on the brakes at the last second.

Jim GM4DHJ ... wrote :
three years ago I took my wagon r for a full price mot to a tyre place and it
passed ...two years ago I got an invitation from them for a £20 mot ...i took
it in and they failed it on pads and discs....cost quoted £150....Got the
wife to do it for £30 parts...took it back and they failed it for poor
efficiency and pulling which was a load of ****e I figured they were in the
huff for not getting the job.....I took it to a full price place without
touching anything ...it passed....if you don't believe me look up mot history
for SDO7 KNN ......ALWAYS pay the full price for an MOT or you WILL get
ripped off .......

I always do and I agree - they have to make up for the discounted MOT
somehow, the somehow is usually by finding some chargeable work that
needs doing. If there is none, make something up that needs to be done.
Halfords seems to be one of the worst culprits for doing this I have
come across.

On 08/05/2017 07:44, Jim GM4DHJ ... wrote:

three years ago I took my wagon r for a full price mot to a tyre place and
it passed ...two years ago I got an invitation from them for a £20 mot ...i
took it in and they failed it on pads and discs....cost quoted £150....Got
the wife to do it for £30 parts...took it back and they failed it for poor
efficiency and pulling which was a load of ****e I figured they were in the
huff for not getting the job.....I took it to a full price place without
touching anything ...it passed....if you don't believe me look up mot
history for SDO7 KNN ......ALWAYS pay the full price for an MOT or you WILL
get ripped off .......



That's not true, I have paid half price for MOT for the last 12 years
and have had one fail and that was a headlamp that blew while being tested.
They fitted my spare for free and retested for free there and then.

"Dave Plowman (News)" wrote in message
...
In article ,
NY wrote:
The biggest problem is if the pads wear down to the rivets that fasten
them to the backing plates, because the rivets can there score the
discs, which when new discs are usually necessary even if the old discs
still have plenty of thickness. I've only had that happen once on a
car: I was going down a long steep hill and suddenly there was a
grinding noise. I wasn't aware of any loss of braking force, presumably
because the other brakes took more braking force if the worn one
stopped braking as effectively.

I've never ever seen a disc pad with the lining riveted. Even in the
1960s.

Ok, well whatever was worn caused the pads to score the discs when they were
applied. I assumed that rivets were revealed when the lining wore down, but
evidently I'm wrong with how the scoring was caused.

On 08/05/2017 10:16, Dave Plowman (News) wrote:
In article ,
Jethro_uk wrote:
On Sun, 07 May 2017 09:19:31 +0100, The Natural Philosopher wrote:

On 07/05/17 03:30, alan_m wrote:
On 06/05/2017 22:11, DerbyBorn wrote:

Sounds good to me.
A micrometer and the specification is the proper way of establishing
wear surely though.

But unlikely to be the way the MOT tester "advises" a replacement.


Indeed. Unless you do a huge mileage, uneven disc wear and scoring are
likely to be more of a reason to replace that simple disk thickness..

I used to service a police driving instructors car. His brakes were like
new at 40,000 miles.

Glad I never had to drive behind him in traffic. But then he probably
never did drive in heavy traffic.

I'll bet he was a poor instructor. Given the very short life of brakes on
police cars.


He didn't say it was a police car.

Some police cars have a hard life some don't.

I have yet to have any brake pads fitted to any of my cars, but the wife
has had one set of pads.
The current cars are 8 years and 4 years old now.

On Monday, 8 May 2017 16:20:20 UTC+1, NY wrote:
"Dave Plowman (News)" wrote in message
...
In article ,
NY wrote:
The biggest problem is if the pads wear down to the rivets that fasten
them to the backing plates, because the rivets can there score the
discs, which when new discs are usually necessary even if the old discs
still have plenty of thickness. I've only had that happen once on a
car: I was going down a long steep hill and suddenly there was a
grinding noise. I wasn't aware of any loss of braking force, presumably
because the other brakes took more braking force if the worn one
stopped braking as effectively.

I've never ever seen a disc pad with the lining riveted. Even in the
1960s.

Ok, well whatever was worn caused the pads to score the discs when they were
applied. I assumed that rivets were revealed when the lining wore down, but
evidently I'm wrong with how the scoring was caused.

I've seen riveted drum brake linings, can't remember what on though. Glue is better, but I don't know what sort of glue they use, must be impressive stuff.


NT

On 08/05/2017 13:28, Dave Plowman (News) wrote:
In article ,
Jethro_uk wrote:
On Mon, 08 May 2017 10:16:38 +0100, Dave Plowman (News) wrote:

In article ,
Jethro_uk wrote:
On Sun, 07 May 2017 09:19:31 +0100, The Natural Philosopher wrote:

On 07/05/17 03:30, alan_m wrote:
On 06/05/2017 22:11, DerbyBorn wrote:

Sounds good to me.
A micrometer and the specification is the proper way of
establishing wear surely though.

But unlikely to be the way the MOT tester "advises" a replacement.


Indeed. Unless you do a huge mileage, uneven disc wear and scoring
are likely to be more of a reason to replace that simple disk
thickness..

I used to service a police driving instructors car. His brakes were
like new at 40,000 miles.

Glad I never had to drive behind him in traffic. But then he probably
never did drive in heavy traffic.

He used gears - "always be in the right gear to accelerate away again"

As the saying goes, a worn gearbox and clutch are much more expensive to
replace than a set of pads. And changing gear purely to slow the car does
cause unnecessary wear on the box and clutch. And uses more fuel and
causes more pollution.

Not true.
You can change gear and not do any extra wear on the clutch or gearbox
if you do it properly.
The engine does the braking and it will be running anyway.
It won't be using any fuel while slowing so where does the extra
pollution come from?


I'll bet he was a poor instructor. Given the very short life of brakes
on police cars.

Operational cars have a different lifestyle.

Yes. They drive under real road conditions.

One of the courses he taught was royal protection - the idea is the
passengers don't know they are in a car - it should accelerate and
decelerate imperceptibly. They used a *very* shallow dish on the bonnet
with a ball bearing in it (and a copper alongside it to pick it up )

As I said, glad he doesn't drive in London.


You don't have to drive like an idiot just because you are in London.

dennis@home was thinking very hard :
That's not true, I have paid half price for MOT for the last 12 years and
have had one fail and that was a headlamp that blew while being tested.
They fitted my spare for free and retested for free there and then.

I had Halfords make up a spurious reason to fail and repair, yet passed
it with a very obvious fault that was pointed out to them by me before
the MOT.

On 08/05/2017 15:07, NY wrote:

ABS does the cadence braking for you (that's what the rapid pulsing is
in the pedal). I've only had to use it in anger once: when a child ran
out into the road and I instinctively hit the brake and steered hard
right, managing to steer left again before hitting the opposite kerb.
The child's mother gave me an earful until the driver of the car behind
me pointed out that I had been driving at 20 in a 30 limit because I'd
judged that there might be a hazard, and that I'd started to brake when
the football rolled out from behind the gatepost a couple of seconds
before the child had even appeared, and I'd managed to avoid the child
who was on the pavement at the time I came to rest by the opposite kerb.
I think her anger might have been influenced by the fact that the car
two behind me had collided with the one behind me because *he* was
driving too close.

That road must have been very slippy to take over two seconds to stop
from 20mph.

A car that just about passed the MOT should take a maximum of about 1.7
seconds.

It would travel about 25 feet so it was a narrow road too.

A modern car would do it in less than a second and travel less than 15 feet.

NY expressed precisely :
The biggest problem is if the pads wear down to the rivets that fasten them
to the backing plates, because the rivets can there score the discs, which
when new discs are usually necessary even if the old discs still have plenty
of thickness. I've only had that happen once on a car: I was going down a
long steep hill and suddenly there was a grinding noise. I wasn't aware of
any loss of braking force, presumably because the other brakes took more
braking force if the worn one stopped braking as effectively.

Pads don't have rivets, the are glued on. Same with modern brake shoes
too. I suspect when you were down to the steel backing plate that the
braking effect wasn't reduced by much.

On 08/05/2017 14:44, NY wrote:
"dennis@home" wrote in message
web.com...
On 07/05/2017 21:43, Steve Walker wrote:
On 07/05/2017 13:41, Andy Burns wrote:
Dave Plowman wrote:

Generally, discs need replacing every second set of pads.

That seems to be the way, though the garage generally tells me I've
been "lucky" as modern discs and pads are intended to need replacing
at the same time.

I do my own maintenance and only use a garage for a few things
(welding a sill, replacing a cambelt and replacing a dual-mass
flywheel) that would have cost me more in time off work to do it
myself than for them to do it.

In 30-odd years I have only replaced discs on two cars, both due to
slight warping - I have never worn a disc to the minimum even on cars
that have had numerous replacements of pads and mileages of 160,000+.

Are garages pushing unneccessary changes for profit?

Some will.
My MOT advisory said pads were close to limit but the service guy said
they were not and didn't need doing.

discs wear more than they did before asbestos was removed from the pads.
The pads are harder and need servos to work these days.

As the pads wear the disc, you tend to get a lip on the edge of the disc
which is outside the area rubbed by the pads. My local garage removes
the discs and skims off that lip, as part of the normal car service
every 12,000 miles. I'm not sure when I last had new discs, but I'm sure
I've had at least one set of replacement discs (maybe front only) in the
160,000 that the car has done so far.

The biggest problem is if the pads wear down to the rivets that fasten
them to the backing plates, because the rivets can there score the
discs,


I haven't seen pads with rivets for years.


Every time I have my car serviced they warn me that new pads and/or
discs will be required, but (almost) every time I get the car back an
they say "worn, will need replacing next time" so they haven't worn down
yet. I don't know whether pads have a non-destructive wear-indicator
which shows when it is time to replace them without (at that amount of
wear) scoring the discs.

I believe it has been law for many years that cars have a warning system
to show worn pads. Its used to be a copper stud set into the pad
connected to a wire that shorts to the disk and lights a lamp.
Mine is indicated by the computer but I expect its still a copper stud.
The biggest failure mode is the wire falling off the pad.

On 06/05/2017 18:41, DerbyBorn wrote:

Why don't they make the pads just a bit bigger so that they don't allow a
lip to develop on the periphery of the disc?

Heat?
Would the outer edge of the disk get hottest as it's rotating fastest?
Therefore having extra metal beyond the pad gives a bit of a heat buffer
zone to both dissipate heat as it's generated and give a grater cooling
surface and more even temperature under the pad it's self, I think the
reasons aren't just down to a single "because" but the entire
combination of suggested reasons.

Jim GM4DHJ ... formulated the question :
also have you noticed that over the years advisories come and go on
subsequent mots to the same car.....one year it can be front nearside brake
pipe slightly corroded then it disappears ......happens with loads of slight
faults....buggers up your private sale second hand price though...advisories
should be banned .....

Well, they maybe ought to be listed on a sheet of paper, rather than
made public on the site.

Each inspector will have their own favourite faults they look for, each
will have a different opinion on what is and is not worth flagging up.
I don't think the get access to the list of advisories when a vehicle
is presented for testing.

On 08/05/2017 16:30, wrote:

I've seen riveted drum brake linings, can't remember what on though. Glue is better, but I don't know what sort of glue they use, must be impressive stuff.

Think the shoes were riveted on my Mk2 Cortina, definitely seen a lot of
riveted shoes in the past as the rivet holes used to accumulate a
build-up of dust which we'd wilfully blow out with the air-line until
such practice became frowned upon.

"dennis@home" wrote in message
b.com...
The biggest problem is if the pads wear down to the rivets that fasten
them to the backing plates, because the rivets can there score the discs,


I haven't seen pads with rivets for years.

I believe it has been law for many years that cars have a warning system
to show worn pads. Its used to be a copper stud set into the pad connected
to a wire that shorts to the disk and lights a lamp.
Mine is indicated by the computer but I expect its still a copper stud.
The biggest failure mode is the wire falling off the pad.


Could it be the copper stud embedded in the pad that causes the scoring of
the disc in the same way that (in the olden days) rivets would do.

I checked the warning light when I experienced the symptom, knowing about
brake pad warning wires/studs, and the light (the same one as used for
handbrake-on) did not light, so it may be that the wire had fallen off since
the last time the brakes have been checked and passed for another X thousand
miles.

I'm intrigued that a lot of people have done large mileages without needing
new discs, because on all the cars that I have had, brake discs tend to be
needed roughly every three times that the pads need changing. And that's
with fairly gentle progressive braking (ie not rushing up to lights at 60
and then slamming hard on at the last moment).

I presume it makes a difference if you live in hilly country: even with
engine braking to take some of the braking load, you will still use your
brakes more than if you live in flat terrain. Mind you, modern learners are
taught not to use engine braking on a long hill, but to stay in a fairly
high gear and rely entirely on brakes - that's what my nephew said he was
told, anyway.

I wouldn't like to descend Porlock Hill, Rosedale Chimney or Park Rash using
only my brakes, without going down into maybe third or second to give at
least *some* engine braking.

On 08/05/17 16:30, wrote:
On Monday, 8 May 2017 16:20:20 UTC+1, NY wrote:
"Dave Plowman (News)" wrote in message
...
In article ,
NY wrote:
The biggest problem is if the pads wear down to the rivets that fasten
them to the backing plates, because the rivets can there score the
discs, which when new discs are usually necessary even if the old discs
still have plenty of thickness. I've only had that happen once on a
car: I was going down a long steep hill and suddenly there was a
grinding noise. I wasn't aware of any loss of braking force, presumably
because the other brakes took more braking force if the worn one
stopped braking as effectively.

I've never ever seen a disc pad with the lining riveted. Even in the
1960s.

Ok, well whatever was worn caused the pads to score the discs when they were
applied. I assumed that rivets were revealed when the lining wore down, but
evidently I'm wrong with how the scoring was caused.

I've seen riveted drum brake linings, can't remember what on though. Glue is better, but I don't know what sort of glue they use, must be impressive stuff.


epoxy of a kind.



NT



--
All political activity makes complete sense once the proposition that
all government is basically a self-legalising protection racket, is
fully understood.

On Monday, 8 May 2017 17:13:31 UTC+1, NY wrote:
"dennis@home" wrote in message
b.com...

Could it be the copper stud embedded in the pad that causes the scoring of
the disc in the same way that (in the olden days) rivets would do.

copper versus steel, I doubt it.

I checked the warning light when I experienced the symptom, knowing about
brake pad warning wires/studs, and the light (the same one as used for
handbrake-on) did not light, so it may be that the wire had fallen off since
the last time the brakes have been checked and passed for another X thousand
miles.

I'm intrigued that a lot of people have done large mileages without needing
new discs, because on all the cars that I have had, brake discs tend to be
needed roughly every three times that the pads need changing. And that's
with fairly gentle progressive braking (ie not rushing up to lights at 60
and then slamming hard on at the last moment).

I presume it makes a difference if you live in hilly country: even with
engine braking to take some of the braking load, you will still use your
brakes more than if you live in flat terrain. Mind you, modern learners are
taught not to use engine braking on a long hill, but to stay in a fairly
high gear and rely entirely on brakes - that's what my nephew said he was
told, anyway.

I wouldn't like to descend Porlock Hill, Rosedale Chimney or Park Rash using
only my brakes, without going down into maybe third or second to give at
least *some* engine braking.

Old vehicles can and did run out of brakes on long descents. And the gravel pits for out of control trucks, I've not seen one since the 80s. Teaching people to rely entirely on the brakes, well I wouldn't.


NT

On Monday, 8 May 2017 17:18:11 UTC+1, The Natural Philosopher wrote:
On 08/05/17 16:30, tabbypurr wrote:

I've seen riveted drum brake linings, can't remember what on though. Glue is better, but I don't know what sort of glue they use, must be impressive stuff.


epoxy of a kind.

I'd like to know what kind can survive those kind of temps. Car accessory shop high temp epoxy is hopeless even at 70C.


NT

On 08/05/17 17:21, wrote:
Old vehicles can and did run out of brakes on long descents.

I've run out of brakes on a rather pad-worn Opel Manta braking from ahem
120mph to a standstill....


Most cars will do one emergency stop from their top speed. It takes
something like a Porsche to do unlimited stops without time to cool the
brakes.



--
€œBut what a weak barrier is truth when it stands in the way of an
hypothesis!€�

Mary Wollstonecraft

In article ,
www.GymRatZ.co.uk wrote:
On 08/05/2017 16:30, wrote:

I've seen riveted drum brake linings, can't remember what on though. Glue is better, but I don't know what sort of glue they use, must be impressive stuff.

Think the shoes were riveted on my Mk2 Cortina, definitely seen a lot of
riveted shoes in the past as the rivet holes used to accumulate a
build-up of dust which we'd wilfully blow out with the air-line until
such practice became frowned upon.

They were riveted on my Anglia. Somwhere in the depth so my garage I have
a jig to hold everything in place while I bashed the rivets. I had waht
were known as "competition linings" which didn't fade as much as the
ordinary ones

--
from KT24 in Surrey, England

In article , NY
wrote:
"dennis@home" wrote in message
b.com...
The biggest problem is if the pads wear down to the rivets that fasten
them to the backing plates, because the rivets can there score the
discs,


I haven't seen pads with rivets for years.

I believe it has been law for many years that cars have a warning
system to show worn pads. Its used to be a copper stud set into the
pad connected to a wire that shorts to the disk and lights a lamp.
Mine is indicated by the computer but I expect its still a copper stud.
The biggest failure mode is the wire falling off the pad.


Could it be the copper stud embedded in the pad that causes the scoring
of the disc in the same way that (in the olden days) rivets would do.

I checked the warning light when I experienced the symptom, knowing about
brake pad warning wires/studs, and the light (the same one as used for
handbrake-on) did not light, so it may be that the wire had fallen off
since the last time the brakes have been checked and passed for another
X thousand miles.

I'm intrigued that a lot of people have done large mileages without
needing new discs, because on all the cars that I have had, brake discs
tend to be needed roughly every three times that the pads need changing.
And that's with fairly gentle progressive braking (ie not rushing up to
lights at 60 and then slamming hard on at the last moment).

I presume it makes a difference if you live in hilly country: even with
engine braking to take some of the braking load, you will still use your
brakes more than if you live in flat terrain. Mind you, modern learners
are taught not to use engine braking on a long hill, but to stay in a
fairly high gear and rely entirely on brakes - that's what my nephew
said he was told, anyway.

I wouldn't like to descend Porlock Hill, Rosedale Chimney or Park Rash
using only my brakes, without going down into maybe third or second to
give at least *some* engine braking.

A friend, doing somewhat more than the legal limit on the M1 found some
cones coming up rather quickly, so he changed down a gear. That caused
engine breaking.

--
from KT24 in Surrey, England

wrote in message
...
Old vehicles can and did run out of brakes on long descents. And the
gravel pits for out of control trucks, I've not seen one since the 80s.
Teaching people to rely entirely on the brakes, well I wouldn't.

Blue Bank on the A169 Pickering-Whitby road has one
https://goo.gl/maps/CBsehEUQDcv, and almost every time I go past I see fresh
ruts in the sand as if something has used it. And it's a pretty puny hill.
Sutton Bank on the A170 Thirsk-Helmsley road has an unofficial escape route
(not signposted) as a gap in the crash barrier and a flat section on the
outside of one of the tight bends.

Steeper 1:3 hills (Rosedale Chimney near Rosedale Abbey) and the two either
side of Littlebeck (just off Blue Bank) tend not to have them, but maybe
that's because lorries don't tend to use them.

"The Natural Philosopher" wrote in message
news
On 08/05/17 17:21, wrote:
Old vehicles can and did run out of brakes on long descents.

I've run out of brakes on a rather pad-worn Opel Manta braking from ahem
120mph to a standstill....


Most cars will do one emergency stop from their top speed. It takes
something like a Porsche to do unlimited stops without time to cool the
brakes.

I remember a for-schools physics programme on TV about energy, and they
mounted a camera under a car (a Mark I "dogbone" Ford Escort IIRC) and
repeatedly took it up to 70 and braked hard a few times (on a racetrack).
And by the end the discs were glowing bright cherry red. Mind you, that may
have been in the days of asbestos in brake pads :-(

On 08/05/17 17:23, wrote:
On Monday, 8 May 2017 17:18:11 UTC+1, The Natural Philosopher wrote:
On 08/05/17 16:30, tabbypurr wrote:

I've seen riveted drum brake linings, can't remember what on though. Glue is better, but I don't know what sort of glue they use, must be impressive stuff.


epoxy of a kind.

I'd like to know what kind can survive those kind of temps. Car accessory shop high temp epoxy is hopeless even at 70C.


Well no it isn't.


You have to know how to use epoxy.

1/. It requires and exact ratio to mix, otherwise it will end up
'rubbery' as some will not set.

2/. It requires absolutely 100% mixing, which is hard to do at room
temperature

3/. Because of the above, its works best if stoved at a temperature well
above room. It goes runny, mixes better, and sets much faster.

Average epoxies will do 100C no problem if used as above. Getting to
300C is harder and requires a special brew.

There are literally thousands of 'epoxy' formulations with widely
varying characteristics available in the professional and industrial arena.



NT



--
€œBut what a weak barrier is truth when it stands in the way of an
hypothesis!€�

Mary Wollstonecraft

On 08/05/17 17:28, charles wrote:
A friend, doing somewhat more than the legal limit on the M1 found some
cones coming up rather quickly, so he changed down a gear. That caused
engine breaking.

Well indeed. That's why you use brakes instead, brakes don't break under
braking.


--
Truth welcomes investigation because truth knows investigation will lead
to converts. It is deception that uses all the other techniques.

"Michael Chare" wrote in message
news
On 08/05/2017 07:31, Jim GM4DHJ ... wrote:
"Rod Speed" wrote in message
...


"Jim GM4DHJ ..." wrote in message
news
"Steve Walker" wrote in message
news On 07/05/2017 13:41, Andy Burns wrote:
Dave Plowman wrote:

Generally, discs need replacing every second set of pads.

That seems to be the way, though the garage generally tells me I've
been "lucky" as modern discs and pads are intended to need replacing
at
the same time.

I do my own maintenance and only use a garage for a few things
(welding
a sill, replacing a cambelt and replacing a dual-mass flywheel) that
would have cost me more in time off work to do it myself than for them
to do it.

In 30-odd years I have only replaced discs on two cars, both due to
slight warping - I have never worn a disc to the minimum even on cars
that have had numerous replacements of pads and mileages of 160,000+.

Are garages pushing unneccessary changes for profit?

SteveW

I blame the passing of asbestos for discs wearing out fast .....

Mine don’t wear out any faster than they did with asbestos was used.
lucky you ...on aveage every second or third set of pads you need discs
these days ....



My problem has been rust on the surface of the discs leading to potential
MOT failure. It is hard to know just how much rust will be tolerated. The
difficulty I had replacing replacing pads and discs was getting the piston
to retract. I had to buy a special tool on ebay.

I just use two big tyre levers ....

"Rod Speed" wrote in message
...


"Jim GM4DHJ ..." wrote in message
news

"Rod Speed" wrote in message
...


"Jim GM4DHJ ..." wrote in message
news
"Steve Walker" wrote in message
news On 07/05/2017 13:41, Andy Burns wrote:
Dave Plowman wrote:

Generally, discs need replacing every second set of pads.

That seems to be the way, though the garage generally tells me I've
been "lucky" as modern discs and pads are intended to need replacing
at the same time.

I do my own maintenance and only use a garage for a few things
(welding a sill, replacing a cambelt and replacing a dual-mass
flywheel) that would have cost me more in time off work to do it
myself than for them to do it.

In 30-odd years I have only replaced discs on two cars, both due to
slight warping - I have never worn a disc to the minimum even on cars
that have had numerous replacements of pads and mileages of 160,000+.

Are garages pushing unneccessary changes for profit?

SteveW

I blame the passing of asbestos for discs wearing out fast .....

Mine don’t wear out any faster than they did with asbestos was used.

lucky you ...on aveage every second or third set of pads you need discs
these days ....

I havent needed a set of pads in 10 years and only needed
one set of pads in the previous 45 years with the previous car.
you have the wrong second name then ......

On Mon, 8 May 2017 09:21:53 -0700 (PDT), wrote:



Old vehicles can and did run out of brakes on long descents. And the gravel pits for out of control trucks, I've not seen one since the 80s.

Perhaps it is a County thing, Dorset still has them in places such as
entering Chideock traveling eastwards.

Sign for it
https://goo.gl/maps/t1Evssbyrqw

Graveled area,
https://goo.gl/maps/CqaWFwaqvHS2

I have seen wheel marks in it , in more recent times I suspect they
were from the equipment such as a JCB that tidys the gravel and build
some of it up into ridges .

G.Harman

who remembers brake shoes with rivets in them ? .....

"Harry Bloomfield" wrote in message
news
dennis@home was thinking very hard :
That's not true, I have paid half price for MOT for the last 12 years and
have had one fail and that was a headlamp that blew while being tested.
They fitted my spare for free and retested for free there and then.

I had Halfords make up a spurious reason to fail and repair, yet passed it
with a very obvious fault that was pointed out to them by me before the
MOT.

the garage I use now at full price failed me for indicators bulbs not
coloured enough so the replaced the bulbs and then passed it at no extra
charge...now there is a garage you can trust .....

who needs disc brakes anyway...the drum brakes on my '63 mini 850 and '66
mustang coupe were just fine ...tee hee

On 08/05/17 17:51, Mobilohm ... wrote:
who remembers brake shoes with rivets in them ? .....


I do.


--
You can get much farther with a kind word and a gun than you can with a
kind word alone.

Al Capone

"The Natural Philosopher" wrote in message
news
On 08/05/17 17:51, Mobilohm ... wrote:
who remembers brake shoes with rivets in them ? .....


I do.


they made a lovely mess of the drum when they wore down .....