Re: [OT] car brakes

'fu' - art, skill, workmanship - from the Chinese gong(1)fu(1) meaning
art, skill, workmanship.

JG

Robert Lorenzini said:

Peter Cole said:

Cross-drilled seems to be more about looks than anything else. "Vented"
or "ventilated" rotors are another matter. They appear to be reasonably
effective, but it's not a *huge* effect (+40%, rather than 100%).

Vented (cross-drilled or slotted) rotors came from racing brakes
which use pads that boil gasses under heat. This is most noticeable
when bedding green pads and they act just like a tire hydroplaning
until most of the volatiles have disapated.

Bob

Again, what is commonly known as "vented rotors" have nothing to do with
venting the gases from the pads, and unless they are *also* crossdrilled
and/or slotted will have perfectly flat braking surfaces. The venting
is cast into the rotor in the form of spaces between the two braking
surfaces for air to flow.

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

Robert Lorenzini said:

Peter Cole said:

Cross-drilled seems to be more about looks than anything else. "Vented"
or "ventilated" rotors are another matter. They appear to be reasonably
effective, but it's not a *huge* effect (+40%, rather than 100%).

Vented (cross-drilled or slotted) rotors came from racing brakes
which use pads that boil gasses under heat. This is most noticeable
when bedding green pads and they act just like a tire hydroplaning
until most of the volatiles have disapated.

Do you know what gasses these are and how or why they are produced?

Jobst reckons this theory is myth and lore, and it does sound pretty
unlikely, but perhaps if more of the details were explained it wouldn't
seem so implausible.

Nate Nagel said:

Robert Lorenzini said:

Peter Cole said:

Cross-drilled seems to be more about looks than anything else. "Vented"
or "ventilated" rotors are another matter. They appear to be reasonably
effective, but it's not a *huge* effect (+40%, rather than 100%).

Vented (cross-drilled or slotted) rotors came from racing brakes
which use pads that boil gasses under heat. This is most noticeable
when bedding green pads and they act just like a tire hydroplaning
until most of the volatiles have disapated.

Bob

Again, what is commonly known as "vented rotors" have nothing to do with
venting the gases from the pads, and unless they are *also* crossdrilled
and/or slotted will have perfectly flat braking surfaces. The venting
is cast into the rotor in the form of spaces between the two braking
surfaces for air to flow.

Correct, different animal entirely.

Bob

"Ben C" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Robert Lorenzini said:

On Sat, 03 May 2008 21:06:41 GMT, Peter Cole <[email hidden]>

Quoted message said:

Cross-drilled seems to be more about looks than anything else. "Vented"
or "ventilated" rotors are another matter. They appear to be reasonably
effective, but it's not a *huge* effect (+40%, rather than 100%).

Vented (cross-drilled or slotted) rotors came from racing brakes
which use pads that boil gasses under heat. This is most noticeable
when bedding green pads and they act just like a tire hydroplaning
until most of the volatiles have disapated.

Do you know what gasses these are and how or why they are produced?

Jobst reckons this theory is myth and lore, and it does sound pretty
unlikely, but perhaps if more of the details were explained it wouldn't
seem so implausible.

Ben C,
Vented is not cross-drilled or slotted. Vented is:
http://images.outdoorinteractive.net/mgen/530211_oi.jpg
cross-drilled is:
http://www.camarotech.com/images/BrakeRotor_CrossDrilled.jpg
slotted is:
http://ecx.images-amazon.com/images/I/215jYLuKBLL._AA160_.jpg
Don't know about steel or iron brake disk rotors, but the carbon ones used
on F1 racing cars (with carbon pads) don't have cross-drilling or slotting,
but do have venting.
Kerry

Kerry Montgomery said:

"Ben C" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Robert Lorenzini said:

On Sat, 03 May 2008 21:06:41 GMT, Peter Cole <[email hidden]>
wrote:
>
> Cross-drilled seems to be more about looks than anything else. "Vented"
> or "ventilated" rotors are another matter. They appear to be reasonably
> effective, but it's not a *huge* effect (+40%, rather than 100%).
>

Vented (cross-drilled or slotted) rotors came from racing brakes
which use pads that boil gasses under heat. This is most noticeable
when bedding green pads and they act just like a tire hydroplaning
until most of the volatiles have disapated.

Do you know what gasses these are and how or why they are produced?

Jobst reckons this theory is myth and lore, and it does sound pretty
unlikely, but perhaps if more of the details were explained it wouldn't
seem so implausible.

Ben C,
Vented is not cross-drilled or slotted. Vented is:
http://images.outdoorinteractive.net/mgen/530211_oi.jpg
cross-drilled is:
http://www.camarotech.com/images/BrakeRotor_CrossDrilled.jpg
slotted is:
http://ecx.images-amazon.com/images/I/215jYLuKBLL._AA160_.jpg

Yes I did realize that but no harm in clarifying it. I heard the point
of the slotting is to break up glaze on the pads.

Kerry Montgomery said:

"Ben C" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Robert Lorenzini said:

On Sat, 03 May 2008 21:06:41 GMT, Peter Cole <[email hidden]>
wrote:
> Cross-drilled seems to be more about looks than anything else. "Vented"
> or "ventilated" rotors are another matter. They appear to be reasonably
> effective, but it's not a *huge* effect (+40%, rather than 100%).
>
Vented (cross-drilled or slotted) rotors came from racing brakes
which use pads that boil gasses under heat. This is most noticeable
when bedding green pads and they act just like a tire hydroplaning
until most of the volatiles have disapated.

Do you know what gasses these are and how or why they are produced?

Jobst reckons this theory is myth and lore, and it does sound pretty
unlikely, but perhaps if more of the details were explained it wouldn't
seem so implausible.

Ben C,
Vented is not cross-drilled or slotted. Vented is:
http://images.outdoorinteractive.net/mgen/530211_oi.jpg
cross-drilled is:
http://www.camarotech.com/images/BrakeRotor_CrossDrilled.jpg
slotted is:
http://ecx.images-amazon.com/images/I/215jYLuKBLL._AA160_.jpg
Don't know about steel or iron brake disk rotors, but the carbon ones used
on F1 racing cars (with carbon pads) don't have cross-drilling or slotting,
but do have venting.

What do you call this type of rotor:
<http://farm3.static.flickr.com/2249/2163925995_f7a5dd2a3b.jpg?v=0>?

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful

In article <[email hidden]>,

Robert Lorenzini said:

Peter Cole said:

Cross-drilled seems to be more about looks than anything else. "Vented"
or "ventilated" rotors are another matter. They appear to be reasonably
effective, but it's not a *huge* effect (+40%, rather than 100%).

Vented (cross-drilled or slotted) rotors came from racing brakes
which use pads that boil gasses under heat. This is most noticeable
when bedding green pads and they act just like a tire hydroplaning
until most of the volatiles have disapated.

What is the chemical composition of the boiling gasses?
Do the boiling gasses come from the pads?

--
Michael Press

Quoted message said:

Quoted message said:

Peter Cole said:

Cross-drilled seems to be more about looks than anything else. "Vented"
or "ventilated" rotors are another matter. They appear to be reasonably
effective, but it's not a *huge* effect (+40%, rather than 100%).

Quoted message said:

Robert Lorenzini said:

Vented (cross-drilled or slotted) rotors came from racing brakes
which use pads that boil gasses under heat. This is most noticeable
when bedding green pads and they act just like a tire hydroplaning
until most of the volatiles have disapated.

Michael Press said:

What is the chemical composition of the boiling gasses?
Do the boiling gasses come from the pads?

Counterintuitive, isn't it? This guy thinks it happens:
http://www.innerauto.com/Auto_Part/Brake_Disc/

I'm not convinced ('gas' goes in the little hole??) or that taking one's
foot off a brake can break it.

These guys just say 'ducted', which is what I thought this conversation
was about earlier:
http://www.lexus.com/models/IS/features/performance/fourwheel_disc_brakes.html

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971
** Posted from http://www.teranews.com **

A Muzi said:

Quoted message said:

Quoted message said:

Peter Cole <[email hidden]> wrote:
> Cross-drilled seems to be more about looks than anything else. "Vented"
> or "ventilated" rotors are another matter. They appear to be reasonably
> effective, but it's not a *huge* effect (+40%, rather than 100%).

Quoted message said:

Robert Lorenzini said:

Vented (cross-drilled or slotted) rotors came from racing brakes
which use pads that boil gasses under heat. This is most noticeable
when bedding green pads and they act just like a tire hydroplaning
until most of the volatiles have disapated.

Michael Press said:

What is the chemical composition of the boiling gasses?
Do the boiling gasses come from the pads?

Counterintuitive, isn't it? This guy thinks it happens:
http://www.innerauto.com/Auto_Part/Brake_Disc/

I'm not convinced ('gas' goes in the little hole??) or that taking one's
foot off a brake can break it.

If gas did come off the pad where it touched the disk then it would have
nowhere to go except to try and squeeze round the edge of the pad or
build up into a sort of bubble. Either way the gas pressure would try to
push pad and disk apart. The holes would prevent that happening.

So I can see how the holes would work if the gas is there.

And just because I don't know what gas would come off brake pads doesn't
mean no gas does. After all what I don't know about brake pads would
fill a book.

Tom Sherman said:

Kerry Montgomery said:

"Ben C" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

On 2008-05-04, Robert Lorenzini <[email hidden]> wrote:
> On Sat, 03 May 2008 21:06:41 GMT, Peter Cole <[email hidden]>
> wrote:
>> Cross-drilled seems to be more about looks than anything else. "Vented"
>> or "ventilated" rotors are another matter. They appear to be reasonably
>> effective, but it's not a *huge* effect (+40%, rather than 100%).
>>
> Vented (cross-drilled or slotted) rotors came from racing brakes
> which use pads that boil gasses under heat. This is most noticeable
> when bedding green pads and they act just like a tire hydroplaning
> until most of the volatiles have disapated.
Do you know what gasses these are and how or why they are produced?

Jobst reckons this theory is myth and lore, and it does sound pretty
unlikely, but perhaps if more of the details were explained it wouldn't
seem so implausible.

Ben C,
Vented is not cross-drilled or slotted. Vented is:
http://images.outdoorinteractive.net/mgen/530211_oi.jpg
cross-drilled is:
http://www.camarotech.com/images/BrakeRotor_CrossDrilled.jpg
slotted is:
http://ecx.images-amazon.com/images/I/215jYLuKBLL._AA160_.jpg
Don't know about steel or iron brake disk rotors, but the carbon ones used
on F1 racing cars (with carbon pads) don't have cross-drilling or slotting,
but do have venting.

What do you call this type of rotor:
<http://farm3.static.flickr.com/2249/2163925995_f7a5dd2a3b.jpg?v=0>?

Eyecandy.
** Posted from http://www.teranews.com **

In article <[email hidden]>,

Ben C said:

A Muzi said:

Quoted message said:

> Peter Cole <[email hidden]> wrote:
>> Cross-drilled seems to be more about looks than anything else. "Vented"
>> or "ventilated" rotors are another matter. They appear to be reasonably
>> effective, but it's not a *huge* effect (+40%, rather than 100%).

Quoted message said:

Robert Lorenzini <[email hidden]> wrote:
> Vented (cross-drilled or slotted) rotors came from racing brakes
> which use pads that boil gasses under heat. This is most noticeable
> when bedding green pads and they act just like a tire hydroplaning
> until most of the volatiles have disapated.

Michael Press said:

What is the chemical composition of the boiling gasses?
Do the boiling gasses come from the pads?

Counterintuitive, isn't it? This guy thinks it happens:
http://www.innerauto.com/Auto_Part/Brake_Disc/

I'm not convinced ('gas' goes in the little hole??) or that taking one's
foot off a brake can break it.

If gas did come off the pad where it touched the disk then it would have
nowhere to go except to try and squeeze round the edge of the pad or
build up into a sort of bubble. Either way the gas pressure would try to
push pad and disk apart. The holes would prevent that happening.

So I can see how the holes would work if the gas is there.

And just because I don't know what gas would come off brake pads doesn't
mean no gas does. After all what I don't know about brake pads would
fill a book.

What gas evolves, what is its chemical composition,
and its partial pressure?

--
Michael Press

"Tom Sherman" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Kerry Montgomery said:

"Ben C" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

On 2008-05-04, Robert Lorenzini <[email hidden]> wrote:
> On Sat, 03 May 2008 21:06:41 GMT, Peter Cole <[email hidden]>
> wrote:
>> Cross-drilled seems to be more about looks than anything else.
>> "Vented"
>> or "ventilated" rotors are another matter. They appear to be
>> reasonably
>> effective, but it's not a *huge* effect (+40%, rather than 100%).
>>
> Vented (cross-drilled or slotted) rotors came from racing brakes
> which use pads that boil gasses under heat. This is most noticeable
> when bedding green pads and they act just like a tire hydroplaning
> until most of the volatiles have disapated.
Do you know what gasses these are and how or why they are produced?

Jobst reckons this theory is myth and lore, and it does sound pretty
unlikely, but perhaps if more of the details were explained it wouldn't
seem so implausible.

Ben C,
Vented is not cross-drilled or slotted. Vented is:
http://images.outdoorinteractive.net/mgen/530211_oi.jpg
cross-drilled is:
http://www.camarotech.com/images/BrakeRotor_CrossDrilled.jpg
slotted is:
http://ecx.images-amazon.com/images/I/215jYLuKBLL._AA160_.jpg
Don't know about steel or iron brake disk rotors, but the carbon ones
used on F1 racing cars (with carbon pads) don't have cross-drilling or
slotting, but do have venting.

What do you call this type of rotor:
<http://farm3.static.flickr.com/2249/2163925995_f7a5dd2a3b.jpg?v=0>?

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful

Tom,
I don't know - maybe high void-ratio rotationally slotted but transversely
compliant?
And, pretty as it is, it doesn't have the mathematical artistry of:
http://www.rider-inc.com/Ti_Rotor_Pics/QM_Rotors/Ti_QM_Rotor_Frnt.jpg
Kerry

Kerry Montgomery said:

"Tom Sherman" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Kerry Montgomery said:

"Ben C" <[email hidden]> wrote in message
news:[email hidden]...
> On 2008-05-04, Robert Lorenzini <[email hidden]> wrote:
>> On Sat, 03 May 2008 21:06:41 GMT, Peter Cole <[email hidden]>
>> wrote:
>>> Cross-drilled seems to be more about looks than anything else.
>>> "Vented"
>>> or "ventilated" rotors are another matter. They appear to be
>>> reasonably
>>> effective, but it's not a *huge* effect (+40%, rather than 100%).
>>>
>> Vented (cross-drilled or slotted) rotors came from racing brakes
>> which use pads that boil gasses under heat. This is most noticeable
>> when bedding green pads and they act just like a tire hydroplaning
>> until most of the volatiles have disapated.
> Do you know what gasses these are and how or why they are produced?
>
> Jobst reckons this theory is myth and lore, and it does sound pretty
> unlikely, but perhaps if more of the details were explained it wouldn't
> seem so implausible.

Ben C,
Vented is not cross-drilled or slotted. Vented is:
http://images.outdoorinteractive.net/mgen/530211_oi.jpg
cross-drilled is:
http://www.camarotech.com/images/BrakeRotor_CrossDrilled.jpg
slotted is:
http://ecx.images-amazon.com/images/I/215jYLuKBLL._AA160_.jpg
Don't know about steel or iron brake disk rotors, but the carbon ones
used on F1 racing cars (with carbon pads) don't have cross-drilling or
slotting, but do have venting.

What do you call this type of rotor:
<http://farm3.static.flickr.com/2249/2163925995_f7a5dd2a3b.jpg?v=0>?

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful

Tom,
I don't know - maybe high void-ratio rotationally slotted but transversely
compliant?
And, pretty as it is, it doesn't have the mathematical artistry of:
http://www.rider-inc.com/Ti_Rotor_Pics/QM_Rotors/Ti_QM_Rotor_Frnt.jpg
Kerry

More "eye candy"
** Posted from http://www.teranews.com **

Robert Lorenzini said:

Quoted message said:

Cross-drilled seems to be more about looks than anything else.
"Vented" or "ventilated" rotors are another matter. They appear to
be reasonably effective, but it's not a *huge* effect (+40%, rather
than 100%).

Quoted message said:

Vented (cross-drilled or slotted) rotors came from racing brakes
which use pads that boil gasses under heat. This is most noticeable
when bedding green pads and they act just like a tire hydroplaning
until most of the volatiles have disapated.

Be more skeptical with these old storied of "gas bearing", something
that occurred with drums and was not gas as understanding of brakes
verified. If there were any truth to the gas idea, all passenger cars
sold in the last decade or more do not have cross drilling that are
found only on vehicles sold as racing sport machines such as MTB's,
"Sports cars", and Motorcycles.

How does the brake know on what type vehicle it is performing? How do
car companies get away with smooth surface disks with no gas vents for
family cars, trucks, commercial aircraft and high speed trains?

http://en.wikipedia.org/wiki/Brake_fade#Fade_in_drum_brakes

Jobst Brandt

aka Jobst Brandt said:

[...]
How does the brake know on what type vehicle it is performing? How do
car companies get away with smooth surface disks with no gas vents for
family cars, trucks, commercial aircraft and high speed trains?

The manufactures get away with using smooth surfaced brake rotors since
the buyers are not looking to use the brakes as status symbols.

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful

Ben C said:

A Muzi said:

Quoted message said:

> Peter Cole <[email hidden]> wrote:
>> Cross-drilled seems to be more about looks than anything else. "Vented"
>> or "ventilated" rotors are another matter. They appear to be reasonably
>> effective, but it's not a *huge* effect (+40%, rather than 100%).

Quoted message said:

Robert Lorenzini <[email hidden]> wrote:
> Vented (cross-drilled or slotted) rotors came from racing brakes
> which use pads that boil gasses under heat. This is most noticeable
> when bedding green pads and they act just like a tire hydroplaning
> until most of the volatiles have disapated.

Michael Press said:

What is the chemical composition of the boiling gasses?
Do the boiling gasses come from the pads?

Counterintuitive, isn't it? This guy thinks it happens:
http://www.innerauto.com/Auto_Part/Brake_Disc/

I'm not convinced ('gas' goes in the little hole??) or that taking one's
foot off a brake can break it.

If gas did come off the pad where it touched the disk then it would have
nowhere to go except to try and squeeze round the edge of the pad or
build up into a sort of bubble. Either way the gas pressure would try to
push pad and disk apart. The holes would prevent that happening.

So I can see how the holes would work if the gas is there.

And just because I don't know what gas would come off brake pads doesn't
mean no gas does. After all what I don't know about brake pads would
fill a book.

Dear Ben,

If you google for "disc brakes" "outgas" -excessive, you'll eliminate
much of the echoing of a familiar passage.

Browsing will suggest that there's some oversimplification of an
apparently problem well-known from the 1960s.

People often mention problems with organic pads that tended to outgas
on Formula One cars with early disc brakes.

The trouble was not that the gas pushed the pad away from the rotor.

What happened was that at high temperatures, the gas and the particles
eroding from the pad would mix and form a slick surface--a horrible
glazing effect rather than a gas layer.

Drilling holes through the discs may allow the gas and powdered
residue to escape before forming a film on the pad, or the holes may
simply help to scrape the stuff off, leaving a clean pad surface to
press against the rotor.

Many articles claim that modern pads have eliminated this problem and
that the drilling is now merely cosmetic.

Other articles suggest that competition level braking can still lead
to the problem.

Here's a typical passage leading up to a description of the problem in
the last sentence:

"Manufacturers define the performance -- the grippiness -- of their
brakepads by measuring the Mu, a function of the material coefficient
of friction over temperature. Pads are said to have rising, linear or
digressive rates, based on the Mu. A digressive rate pad means you
have to push harder to maintain the friction of the brakepad on the
rotor. A rising rate means you have to push less as the braking effect
increases. A linear rate means you maintain the same pressure. The
friction increases with temperature in a rising rate pad. Linear Mu
means the friction value is maintained as the temperature increases.
Many performance pads show rising friction values as the temperature
goes up, then drop off as the temperature reaches a point where the
pad outgasses, and powders, reducing the friction with the breakdown
film."
http://www.lemd.com/motorsport/previous.cfm?id=25

So it doesn't seem to be a matter of the gas pressing the pad away
from the rotor. It's the combination of very hot gas and powdered pad
forming a glaze on the surface of the pad.

Cheers,

Carl Fogel

Quoted message said:

Robert Lorenzini said:

Quoted message said:

Cross-drilled seems to be more about looks than anything else.
"Vented" or "ventilated" rotors are another matter. They appear to
be reasonably effective, but it's not a *huge* effect (+40%, rather
than 100%).

Quoted message said:

Vented (cross-drilled or slotted) rotors came from racing brakes
which use pads that boil gasses under heat. This is most noticeable
when bedding green pads and they act just like a tire hydroplaning
until most of the volatiles have disapated.

Be more skeptical with these old storied of "gas bearing", something
that occurred with drums and was not gas as understanding of brakes
verified. If there were any truth to the gas idea, all passenger cars
sold in the last decade or more do not have cross drilling that are
found only on vehicles sold as racing sport machines such as MTB's,
"Sports cars", and Motorcycles.

How does the brake know on what type vehicle it is performing? How do
car companies get away with smooth surface disks with no gas vents for
family cars, trucks, commercial aircraft and high speed trains?

Obviously the requirements are different. The brakes on a racing car
operate in a higher temperature range altogether since they need a much
higher dissipation power. They also need to be warmed up, but brakes on
a passenger car need to work well from cold.

Disks on trains is an interesting one. I doubt trains brake down hills
(and in any case they don't go down steep hills). They just have to stop
at the stations. The disks may work as heat sinks rather than as
continuous dissipators, hence you probably want them big and heavy.

Quoted message said:

Robert Lorenzini said:

Quoted message said:

Cross-drilled seems to be more about looks than anything else.
"Vented" or "ventilated" rotors are another matter. They appear to
be reasonably effective, but it's not a *huge* effect (+40%, rather
than 100%).

Quoted message said:

Vented (cross-drilled or slotted) rotors came from racing brakes
which use pads that boil gasses under heat. This is most noticeable
when bedding green pads and they act just like a tire hydroplaning
until most of the volatiles have disapated.

Be more skeptical with these old storied of "gas bearing", something
that occurred with drums and was not gas as understanding of brakes
verified. If there were any truth to the gas idea, all passenger cars
sold in the last decade or more do not have cross drilling that are
found only on vehicles sold as racing sport machines such as MTB's,
"Sports cars", and Motorcycles.

How does the brake know on what type vehicle it is performing? How do
car companies get away with smooth surface disks with no gas vents for
family cars, trucks, commercial aircraft and high speed trains?

http://en.wikipedia.org/wiki/Brake_fade#Fade_in_drum_brakes

Jobst Brandt

Because they CAN.
They can get "adequate" braking with plain rotors
** Posted from http://www.teranews.com **