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?

"DerbyBorn" wrote in message
2.222...

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?

so mercedes etc can sell you discs ......

I am given to understand its to stop the material breaking up around the
outside because its still thick enough to hold the rest together.

Not that I know a lotabout cars, but that seems to be the reason people are
given.
Brian

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"Jim GM4DHJ ..." wrote in message
news

"DerbyBorn" wrote in message
2.222...

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?

so mercedes etc can sell you discs ......

"Brian Gaff" wrote in
news
I am given to understand its to stop the material breaking up around
the outside because its still thick enough to hold the rest together.

Not that I know a lotabout cars, but that seems to be the reason
people are given.
Brian


Mmmm! Hoop Stress.

On Sat, 06 May 2017 17:41:55 +0000, 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?


****wit.

When the pads wear enough, the lips will meet and prevent the pad from
contacting the disc.

On 06/05/17 18:57, Walter wrote:
On Sat, 06 May 2017 17:41:55 +0000, 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?


****wit.

When the pads wear enough, the lips will meet and prevent the pad from
contacting the disc.

****wit. The pads would be down to metal before they met


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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?



The lip is the indication that the disks need replacing. If the pads
were larger you wouldn't get an easily seen indication of the thinness
of the disks.

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On 5/6/2017 7:13 PM, alan_m wrote:
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?



The lip is the indication that the disks need replacing. If the pads
were larger you wouldn't get an easily seen indication of the thinness
of the disks.

The right answer, IMHO

On 06/05/2017 20:30, newshound wrote:
On 5/6/2017 7:13 PM, alan_m wrote:
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?



The lip is the indication that the disks need replacing. If the pads
were larger you wouldn't get an easily seen indication of the thinness
of the disks.

The right answer, IMHO

Sorry, I don't agree! You often get some rust on the outer bit of the
disk, outside where the pad rubs, making any lip look a lot thicker than
it really is. Besides which, disks are allowed to wear quite a lot
before they need replacing. There's quite a substantial lip on mine, but
the disks are still within spec when measured with a micrometer.
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On 06/05/17 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?

cos then they'd put a lip on the pads instead


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The Natural Philosopher wrote:

On 06/05/17 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?

cos then they'd put a lip on the pads instead

I am sure you are right. Secondly it would produce an axial force on
the pad, thirdly it would render part of the pad unused. Fourthly, and
I think most importantly, movements of the pad against the edge of the
disc would shatter the outer few millimeters of the pad material (which
has little tensile strength) so you would be back to the bearing surface
of the pad being inside the perimeter of the disc quite quickly.

--

Roger Hayter

(Roger Hayter) wrote in
:

The Natural Philosopher wrote:

On 06/05/17 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?

cos then they'd put a lip on the pads instead

I am sure you are right. Secondly it would produce an axial force on
the pad, thirdly it would render part of the pad unused. Fourthly,
and I think most importantly, movements of the pad against the edge of
the disc would shatter the outer few millimeters of the pad material
(which has little tensile strength) so you would be back to the
bearing surface of the pad being inside the perimeter of the disc
quite quickly.


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

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.


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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..


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diverted our attention away from what really matters to our existential
survival, to indulging in navel gazing and faux moral investigations
into what the world ought to be, whilst we fail utterly to deal with
what it actually is.

In article ,
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.

At least some cars have the minimum thickness stamped on the disc hub.

Generally, discs need replacing every second set of pads.

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Dave Plowman London SW
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In article 2,
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?

The entire pad needs to be in contact with the disc. If it overlapped it,
the differential in heat would cause it to break up.

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

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.

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