Re: Can anyone tell the difference between rotors and pads (truthfully)?

"hob" <dehoberg@comcast.net> wrote in message news:...[color=blue]
> "Stuart A. Bronstein" <spamtrap@lexregia.com> wrote in message
> news:FEwNf.36318$Jd.11501@newssvr25.news.prodigy.net...[color=green]
> > I found out from another thread that brake rotors can't warp[/color]
>
> Wrong - been certified as a brake expert in Federal and State courts,[/color]
having[color=blue]
> designed and built many kinds of brakes as well as brake testing machines
> for Detroit and Japan, and have done hobby work on race cars for 35[/color]
years -[color=blue]
> rotors warp out of plane.
> And I have pulled off a fair number of rotor plates that were[/color]
definitely[color=blue]
> warped.
>
> From your cite:
>
> "The problem with this diagnosis and repair procedure is that first of all
> is that brake rotors do not warp. "
>
> Wrong. They do, especially the ones that have offset bells. How can that[/color]
be[color=blue]
> if the website says it can't?
>
> Again, from your cite, as they state one sentence beyond where they say it
> does not exist.:
>
> "Brake rotor disc thickness variation or excessive lateral runout, as well
> as drums that are out of round can cause vibrations and pulsations in the
> brake pedal and/or steering wheel. Brake lining material transfer onto[/color]
the[color=blue]
> rotor can also have an effect on this as well."
>
> Check out what they said about the rotor in their excerpts above- "it's[/color]
not[color=blue]
> warped, it really just has its faces warped out of plane" yes, BS
> doubletalk is what you saw on that site.
> " It's not a duck, its really a mallard or its a bird with a green head
> that has webbed feet and quacks":
>
> 1) "Brake rotor disc thickness variation" means the planes of the rotor[/color]
face[color=blue]
> are no longer flat with reference to each other, and if beyond allowable
> limits, each the face of the rotor has warped out of the permitted plane
> with respect to each other. That is called warp. (of the rotor face[/color]
plane,[color=blue]
> the part the shoes contact).
>
> 2) "Excessive lateral runout" means the plane of the rotor face is no[/color]
longer[color=blue]
> in the range of allowed plane, when measured by a runout gauge mounted
> externally to the rotor, and thus the face of the rotor has warped out of
> permitted plane.
> (to make a runout measurement - mount rotor in trued solid axle, set
> preloaded gauge on face, and turn rotor one turn while checking gauge to[/color]
get[color=blue]
> max and min: subtract to get total runout)
> "Excessive lateral runout" can be due to excessive "brake rotor disc
> thickness variation" or bent mounts or twisted rotor.
>
> Rotors are made thin so they can be light and keep fleet/vehicle mpg[/color]
down.[color=blue]
> Even a first year engineering student can tell you how hard braking with
> the linkage turned hard over bends (warps) the rotor bell.
> (imagine 2 tons moving forward trying to go over a tire turned sideways
> with the brake pads locked onto the rotor, a rotor designed for transfer[/color]
of[color=blue]
> force into floating claipers and transversely into the axle.
> Guess how the force gets from the 2 ton moving vehicle mass into the[/color]
tire[color=blue]
> tread in a turn-- through the shoes gripping the rotor and back into the
> axle - forces across the rotor plane, unlike straight ahead braking, where
> the forces are in the rotor plane)
>
> Any experienced engineer will tell you that if there is a problem and it
> goes way when you replace a part, the problem is gone.
> Was the problem the root cause and will it return? Well, if it wasn't[/color]
part[color=blue]
> of the problem, the problem would still be there in some form.
> However, if it is only part of the problem, the problem will later
> manifest the same symptoms (E.g, if the driver brakes hard in corners,[/color]
part[color=blue]
> of the problem, the rotors will again bend/wear the faces so that in time
> the plane of the rotor surfaces are no longer within tolerance, Before the
> driver got in and warped the new rotors, the new rotors were just fine)
>
> ( Logically, when you change the rotor and then the problem goes away,[/color]
the[color=blue]
> problem is gone.)
>
> and it seems[color=green]
> > nobody on this planet can really (reliably) tell the difference between
> > brake friction materials (because there are no standards whatsoever)
> > according to
> > [url]http://www.performanceoiltechnology.com/brakingsystems.htm[/url][/color]
>
>
> the man ought to read the specs in the vehicle manuals, which do indeed[/color]
list[color=blue]
> tolerances for rotors. And he ought to get some in depth background first.
> The internet is full of half-aware self-promoters with partially[/color]
applied[color=blue]
> theories. And AMSOIL, no less.
>
> FWIW - match mounting is a way to limit costly close tolerance machining[/color]
in[color=blue]
> many mating parts- you make hundreds of parts all alike, and then measure
> them - some will be way off and get tossed, most will be within tolerance
> and used according to their tolerance, and some may even be perfect. It's
> cheaper than making each one perfect.
>
> I'll put this quote from them in here for the experienced engineers to get[/color]
a[color=blue]
> chcukle
>
> "DTV is when the rotor thickness is not the same all the way around the
> rotor. DTV is typically caused by lateral runout. DTV can only be[/color]
measured[color=blue]
> with very specialized laboratory testing equipment or with special on
> vehicle capacitance probes."
>
> right.... ( or like a shop caliper or shop "mic", as noted in the
> maintenance manuals.)
>
> Quote - "This [DTV] phenomenon is what many technicians refer to as
> "warping", however they actually think the rotor warped and needs
> replacement."
>
> OK, so what they are saying is that the rotor isn't warped ( and so the
> rotor is true?) and the face of the rotor plane has just warped, and so[/color]
they[color=blue]
> are saying that
> instead of the rotor needing replacing because the thickness varies,[/color]
the[color=blue]
> rotor needs replacing because the thickness varies and the esoteric DTV
> measurements are lab things .(or you could just get refacing done at a[/color]
brake[color=blue]
> shop, if enough material is left).
>
> enough of quoting their home-spun humor....
>[color=green]
> >
> > So, since I have horrible brake-induced wobble in my Toyota 4Runner, how
> > DOES anyone buy the right parts given there are no regulations or
> > standards to protect us?
> >[/color]
>
> There are regulations - Check out the following standards for brake
> materials: DE3A, BEEP, NHTSA FMVSS-105
>[color=green]
> > We may as well close our eyes and choose randomly for all the lack of
> > standards. Which leaves me to my most important question, having to[/color][/color]
trust[color=blue][color=green]
> > in your judgement and experience (which I don't have).
> >
> > Where would YOU buy a good quality rotors & pads for a Toyota 4Runner?
> >[/color]
>
> From Toyota -
> why? aftermarket pads have few, if any standards. New-car brake pads
> (OEM) have to meet NHTSA standards, and thus actually do stop better, are
> more reliable, and the dust around the kids and dogs is less hazardous.
>
> nuff free stuff
>[color=green]
> > Stu[/color]
>
>[/color]

hob wrote:
[color=blue][color=green]
> > Even a first year engineering student can tell you how hard braking with
> > the linkage turned hard over bends (warps) the rotor bell.[/color][/color]

That's just plain silly.

[color=blue][color=green]
> > (imagine 2 tons moving forward trying to go over a tire turned sideways
> > with the brake pads locked onto the rotor, a rotor designed for transfer[/color]
> of[color=green]
> > force into floating claipers and transversely into the axle.[/color][/color]

The caliper can move freely from side to side (floating calipers). There
is no side load at all due to steering.
[color=blue][color=green]
> > Guess how the force gets from the 2 ton moving vehicle mass into the[/color]
> tire[color=green]
> > tread in a turn-- through the shoes gripping the rotor and back into the
> > axle - forces across the rotor plane, unlike straight ahead braking, where
> > the forces are in the rotor plane)[/color][/color]

This is fantasy. The wheel is mounted solid to the axle with the rotor
sandwiched between. Even if the axle would deflect it couldn't possibly
deflect enough to exceed the side travel of the calipers. If the car is
sliding sideways the brakes see no load at all because there would be no
force to turn the wheels.
Heat build up is usually what causes rotors to warp. You don't even
have to put the rotor on a car just toss it in a fire and it will warp.
Rust in the ventilation passages can also warp rotors. And frozen
calipers can also warp rotors - not so much because of uneven force
loads but uneven heat loads.
[color=blue][color=green]
> >
> > Any experienced engineer will tell you that if there is a problem and it
> > goes way when you replace a part, the problem is gone.
> > Was the problem the root cause and will it return? Well, if it wasn't[/color]
> part[color=green]
> > of the problem, the problem would still be there in some form.
> > However, if it is only part of the problem, the problem will later
> > manifest the same symptoms (E.g, if the driver brakes hard in corners,[/color]
> part[color=green]
> > of the problem, the rotors will again bend/wear the faces so that in time
> > the plane of the rotor surfaces are no longer within tolerance, Before the
> > driver got in and warped the new rotors, the new rotors were just fine)
> >[/color][/color]


This is nonsense. Excessive braking can result in warped rotors, but
braking on turns has nothing to do with it.

-jim

[color=blue][color=green]
> > ( Logically, when you change the rotor and then the problem goes away,[/color]
> the[color=green]
> > problem is gone.)
> >
> > and it seems[color=darkred]
> > > nobody on this planet can really (reliably) tell the difference between
> > > brake friction materials (because there are no standards whatsoever)
> > > according to
> > > [url]http://www.performanceoiltechnology.com/brakingsystems.htm[/url][/color]
> >
> >
> > the man ought to read the specs in the vehicle manuals, which do indeed[/color]
> list[color=green]
> > tolerances for rotors. And he ought to get some in depth background first.
> > The internet is full of half-aware self-promoters with partially[/color]
> applied[color=green]
> > theories. And AMSOIL, no less.
> >
> > FWIW - match mounting is a way to limit costly close tolerance machining[/color]
> in[color=green]
> > many mating parts- you make hundreds of parts all alike, and then measure
> > them - some will be way off and get tossed, most will be within tolerance
> > and used according to their tolerance, and some may even be perfect. It's
> > cheaper than making each one perfect.
> >
> > I'll put this quote from them in here for the experienced engineers to get[/color]
> a[color=green]
> > chcukle
> >
> > "DTV is when the rotor thickness is not the same all the way around the
> > rotor. DTV is typically caused by lateral runout. DTV can only be[/color]
> measured[color=green]
> > with very specialized laboratory testing equipment or with special on
> > vehicle capacitance probes."
> >
> > right.... ( or like a shop caliper or shop "mic", as noted in the
> > maintenance manuals.)
> >
> > Quote - "This [DTV] phenomenon is what many technicians refer to as
> > "warping", however they actually think the rotor warped and needs
> > replacement."
> >
> > OK, so what they are saying is that the rotor isn't warped ( and so the
> > rotor is true?) and the face of the rotor plane has just warped, and so[/color]
> they[color=green]
> > are saying that
> > instead of the rotor needing replacing because the thickness varies,[/color]
> the[color=green]
> > rotor needs replacing because the thickness varies and the esoteric DTV
> > measurements are lab things .(or you could just get refacing done at a[/color]
> brake[color=green]
> > shop, if enough material is left).
> >
> > enough of quoting their home-spun humor....
> >[color=darkred]
> > >
> > > So, since I have horrible brake-induced wobble in my Toyota 4Runner, how
> > > DOES anyone buy the right parts given there are no regulations or
> > > standards to protect us?
> > >[/color]
> >
> > There are regulations - Check out the following standards for brake
> > materials: DE3A, BEEP, NHTSA FMVSS-105
> >[color=darkred]
> > > We may as well close our eyes and choose randomly for all the lack of
> > > standards. Which leaves me to my most important question, having to[/color][/color]
> trust[color=green][color=darkred]
> > > in your judgement and experience (which I don't have).
> > >
> > > Where would YOU buy a good quality rotors & pads for a Toyota 4Runner?
> > >[/color]
> >
> > From Toyota -
> > why? aftermarket pads have few, if any standards. New-car brake pads
> > (OEM) have to meet NHTSA standards, and thus actually do stop better, are
> > more reliable, and the dust around the kids and dogs is less hazardous.
> >
> > nuff free stuff
> >[color=darkred]
> > > Stu[/color]
> >
> >[/color][/color]

----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
[url]http://www.newsfeeds.com[/url] The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

> This is nonsense. Excessive braking can result in warped rotors, but[color=blue]
> braking on turns has nothing to do with it.[/color]

According to this article (probably the best on the Internet)
[url]http://www.babcox.com/editorial/bf/bf100326.htm[/url]

"Many technicians are under the impression that a "warped" rotor is one
that has too much runout. They also attribute this "warping" to why the
brake pedal pulsates. This is not true. Runout will NOT cause pedal
pulsation in most cases."

So, I'm back to being confused about whether or not brake rotor
pulsation is really caused by "warped" rotors or not. It seems not.

But we learn more every day about brakes so time will tell for all.
Stu









jim <"sjedgingN0sp"@m@mwt.net> wrote in
news:1141434475_67@sp6iad.superfeed.net:
[color=blue]
>
>
> hob wrote:
>[color=green][color=darkred]
>> > Even a first year engineering student can tell you how hard
>> > braking with the linkage turned hard over bends (warps) the rotor
>> > bell.[/color][/color]
>
> That's just plain silly.
>
>[color=green][color=darkred]
>> > (imagine 2 tons moving forward trying to go over a tire turned
>> > sideways
>> > with the brake pads locked onto the rotor, a rotor designed for
>> > transfer[/color]
>> of[color=darkred]
>> > force into floating claipers and transversely into the axle.[/color][/color]
>
> The caliper can move freely from side to side (floating calipers).
> There is no side load at all due to steering.
>[color=green][color=darkred]
>> > Guess how the force gets from the 2 ton moving vehicle mass into
>> > the[/color]
>> tire[color=darkred]
>> > tread in a turn-- through the shoes gripping the rotor and back
>> > into the axle - forces across the rotor plane, unlike straight
>> > ahead braking, where the forces are in the rotor plane)[/color][/color]
>
> This is fantasy. The wheel is mounted solid to the axle with the rotor
> sandwiched between. Even if the axle would deflect it couldn't
> possibly deflect enough to exceed the side travel of the calipers. If
> the car is sliding sideways the brakes see no load at all because
> there would be no force to turn the wheels.
> Heat build up is usually what causes rotors to warp. You don't
> even
> have to put the rotor on a car just toss it in a fire and it will
> warp. Rust in the ventilation passages can also warp rotors. And
> frozen calipers can also warp rotors - not so much because of uneven
> force loads but uneven heat loads.
>[color=green][color=darkred]
>> >
>> > Any experienced engineer will tell you that if there is a problem
>> > and it
>> > goes way when you replace a part, the problem is gone.
>> > Was the problem the root cause and will it return? Well, if it
>> > wasn't[/color]
>> part[color=darkred]
>> > of the problem, the problem would still be there in some form.
>> > However, if it is only part of the problem, the problem will
>> > later
>> > manifest the same symptoms (E.g, if the driver brakes hard in
>> > corners,[/color]
>> part[color=darkred]
>> > of the problem, the rotors will again bend/wear the faces so that
>> > in time the plane of the rotor surfaces are no longer within
>> > tolerance, Before the driver got in and warped the new rotors, the
>> > new rotors were just fine)
>> >[/color][/color]
>
>
> This is nonsense. Excessive braking can result in warped rotors, but
> braking on turns has nothing to do with it.
>
> -jim
>
>[color=green][color=darkred]
>> > ( Logically, when you change the rotor and then the problem goes
>> > away,[/color]
>> the[color=darkred]
>> > problem is gone.)
>> >
>> > and it seems
>> > > nobody on this planet can really (reliably) tell the difference
>> > > between brake friction materials (because there are no standards
>> > > whatsoever) according to
>> > > [url]http://www.performanceoiltechnology.com/brakingsystems.htm[/url]
>> >
>> >
>> > the man ought to read the specs in the vehicle manuals, which do
>> > indeed[/color]
>> list[color=darkred]
>> > tolerances for rotors. And he ought to get some in depth background
>> > first.
>> > The internet is full of half-aware self-promoters with partially[/color]
>> applied[color=darkred]
>> > theories. And AMSOIL, no less.
>> >
>> > FWIW - match mounting is a way to limit costly close tolerance
>> > machining[/color]
>> in[color=darkred]
>> > many mating parts- you make hundreds of parts all alike, and then
>> > measure them - some will be way off and get tossed, most will be
>> > within tolerance and used according to their tolerance, and some
>> > may even be perfect. It's cheaper than making each one perfect.
>> >
>> > I'll put this quote from them in here for the experienced engineers
>> > to get[/color]
>> a[color=darkred]
>> > chcukle
>> >
>> > "DTV is when the rotor thickness is not the same all the way around
>> > the rotor. DTV is typically caused by lateral runout. DTV can only
>> > be[/color]
>> measured[color=darkred]
>> > with very specialized laboratory testing equipment or with special
>> > on vehicle capacitance probes."
>> >
>> > right.... ( or like a shop caliper or shop "mic", as noted in the
>> > maintenance manuals.)
>> >
>> > Quote - "This [DTV] phenomenon is what many technicians refer to
>> > as
>> > "warping", however they actually think the rotor warped and needs
>> > replacement."
>> >
>> > OK, so what they are saying is that the rotor isn't warped ( and
>> > so the
>> > rotor is true?) and the face of the rotor plane has just warped,
>> > and so[/color]
>> they[color=darkred]
>> > are saying that
>> > instead of the rotor needing replacing because the thickness
>> > varies,[/color]
>> the[color=darkred]
>> > rotor needs replacing because the thickness varies and the esoteric
>> > DTV measurements are lab things .(or you could just get refacing
>> > done at a[/color]
>> brake[color=darkred]
>> > shop, if enough material is left).
>> >
>> > enough of quoting their home-spun humor....
>> >
>> > >
>> > > So, since I have horrible brake-induced wobble in my Toyota
>> > > 4Runner, how DOES anyone buy the right parts given there are no
>> > > regulations or standards to protect us?
>> > >
>> >
>> > There are regulations - Check out the following standards for brake
>> > materials: DE3A, BEEP, NHTSA FMVSS-105
>> >
>> > > We may as well close our eyes and choose randomly for all the
>> > > lack of standards. Which leaves me to my most important question,
>> > > having to[/color]
>> trust[color=darkred]
>> > > in your judgement and experience (which I don't have).
>> > >
>> > > Where would YOU buy a good quality rotors & pads for a Toyota
>> > > 4Runner?
>> > >
>> >
>> > From Toyota -
>> > why? aftermarket pads have few, if any standards. New-car brake
>> > pads
>> > (OEM) have to meet NHTSA standards, and thus actually do stop
>> > better, are more reliable, and the dust around the kids and dogs is
>> > less hazardous.
>> >
>> > nuff free stuff
>> >
>> > > Stu
>> >
>> >[/color][/color]
>
> ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet
> News==---- [url]http://www.newsfeeds.com[/url] The #1 Newsgroup Service in the
> World! 120,000+ Newsgroups ----= East and West-Coast Server Farms -
> Total Privacy via Encryption =----
>[/color]

"Stuart A. Bronstein" <spamtrap@lexregia.com> wrote in message
news:nvaOf.43710$H71.22542@newssvr13.news.prodigy.com...[color=blue][color=green]
> > This is nonsense. Excessive braking can result in warped rotors, but
> > braking on turns has nothing to do with it.[/color]
>
> According to this article (probably the best on the Internet)
> [url]http://www.babcox.com/editorial/bf/bf100326.htm[/url]
>
> "Many technicians are under the impression that a "warped" rotor is one
> that has too much runout. They also attribute this "warping" to why the
> brake pedal pulsates. This is not true. Runout will NOT cause pedal
> pulsation in most cases."[/color]

Runout WILL cause pulsation. Even though the caliper is free to move, it
has mass, and to move it takes energy. The quicker it has to move, the more
pronounced is the effect. Force is still equal to mass time acceleration.

And you WILL feel it in the pedal. And by truing the rotor, it will go
away.

And when you get some idiot with a torque stick/torque wrench installing
a wheel, WILL likely return.

On Sat, 04 Mar 2006 06:31:47 GMT, "Stuart A. Bronstein"
<spamtrap@lexregia.com> wrote:
[color=blue][color=green]
>> This is nonsense. Excessive braking can result in warped rotors, but
>> braking on turns has nothing to do with it.[/color]
>
>According to this article (probably the best on the Internet)
>[url]http://www.babcox.com/editorial/bf/bf100326.htm[/url]
>
>"Many technicians are under the impression that a "warped" rotor is one
>that has too much runout. They also attribute this "warping" to why the
>brake pedal pulsates. This is not true. Runout will NOT cause pedal
>pulsation in most cases."
>
>So, I'm back to being confused about whether or not brake rotor
>pulsation is really caused by "warped" rotors or not. It seems not.
>
>But we learn more every day about brakes so time will tell for all.
>Stu[/color]

Confused? Why? Fucking take your car in and have the rotors
machined, and when the pulsation stops, you can fucking bet it is
because the pads now have a flat surface to grip.

*************************
Dave

"Stuart A. Bronstein" <spamtrap@lexregia.com> wrote in
news:nvaOf.43710$H71.22542@newssvr13.news.prodigy.com:
[color=blue][color=green]
>> This is nonsense. Excessive braking can result in warped rotors, but
>> braking on turns has nothing to do with it.[/color]
>
> According to this article (probably the best on the Internet)
> [url]http://www.babcox.com/editorial/bf/bf100326.htm[/url]
>
> "Many technicians are under the impression that a "warped" rotor is
> one that has too much runout. They also attribute this "warping" to
> why the brake pedal pulsates. This is not true. Runout will NOT cause
> pedal pulsation in most cases."
>
> So, I'm back to being confused about whether or not brake rotor
> pulsation is really caused by "warped" rotors or not. It seems not.
>
> But we learn more every day about brakes so time will tell for all.[/color]

If that is the best on the web then it must be true.

Well, no it isn't.

In a perfect world a warped rotor would not cause pulsations.

However, a warped rotor will rapidly wear at the high spots (wear tends
to occur in brakes off position), which will rapidly create DTV (Disc
thickness variation) which will cause BTV (brake torque variation) even
in a perfect car.

But, the callipers don't slide smoothly in the real world, so I suspect
you'll pick up a warped rotor via the pedal even if there is no DTV.

So, now you can get them to correct that article.

Cheers

Greg Locock

DTJ <none@nowhere.com> wrote in news:g17k02pllgnipo1po1p6o9u9olc54hkj4o@
4ax.com:[color=blue][color=green]
>>According to this article (probably the best on the Internet)
>>[url]http://www.babcox.com/editorial/bf/bf100326.htm[/url]
>>
>>"Many technicians ... attribute "warping" to why the
>>brake pedal pulsates. This is not true.[/color][/color]
[color=blue]
> Confused? Why? Fucking take your car in and have the rotors
> machined, and when the pulsation stops, you can fucking bet it is
> because the pads now have a flat surface to grip.[/color]

Hi Dave,

According to more than one well-informed article, that's exactly what most
technicians do, and, that's exactly the wrong approach.
[url]http://www.babcox.com/editorial/bf/bf100326.htm[/url]

I am just looking to find the proper way to resolve this problem long term
and, just the uneducated technician who thinks high octane gas is "better"
gas, there's a lot of ignorance posing as fact out there.

I'm simply trying to properly diagnose, isolate, and repair my first case
of brake pedal pulsation at highway speeds on a Toyota 4Runner truck.

I'm realizing neither machining the rotors nor simply replacing them will
solve the problem, long term. I'm getting closer to the answer though, with
your help, and I hope those who read this thread in the future benefit.

Stu

Stuart A. Bronstein wrote:
snip[color=blue]
> According to more than one well-informed article, that's exactly what
> most technicians do, and, that's exactly the wrong approach.
> [url]http://www.babcox.com/editorial/bf/bf100326.htm[/url]
>
> I am just looking to find the proper way to resolve this problem long
> term and, just the uneducated technician who thinks high octane gas
> is "better" gas, there's a lot of ignorance posing as fact out there.
>
> I'm simply trying to properly diagnose, isolate, and repair my first
> case of brake pedal pulsation at highway speeds on a Toyota 4Runner
> truck.
>
> I'm realizing neither machining the rotors nor simply replacing them
> will solve the problem, long term. I'm getting closer to the answer
> though, with your help, and I hope those who read this thread in the
> future benefit.
>
> Stu[/color]

It seems to me you've found one article that you want to believe over all
the other articles available, as well as the advice from learned
technicians, based on their education and experience. Many of these techs
I've read in this thread are either experts in the field of brakes or are
Master Diagnostic Technicians, which would lead one to believe the majority
opinion of these is true.
Are you possibly overanalyzing your situation?
davidj92

"Stuart A. Bronstein" wrote:
[color=blue]
> I'm realizing neither machining the rotors nor simply replacing them will
> solve the problem, long term.[/color]

What do you mean by "long term". As far as I can tell you are resisting
the idea of fixing your brakes because eventually they will require
fixing again. If you are hard on the brakes you can expect to have to
repair them quite often. If you put your mind to it you can easily wear
your brakes out in days.
Nevertheless, if you develop a pulsation in the brakes and you replace
the pads and rotors you can reasonably expect that to fix the problem
and it should last as long as the originals did if you drive the same as
before. Anybody who knows what they are doing will also make sure the
calipers and pistons are clean, that they move freely and are generally
in good working order and if not they should be fixed also.
In most cases buying replacement rotors costs the same or very little
more than having the rotors turned so just buy the rotors and you won't
have to worry about the rotors not being turned properly. That should
address most of the worries from the article you are so fond of.

-jim

----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
[url]http://www.newsfeeds.com[/url] The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

"davidj92" <davidj92REMOVE@sigecom.net> wrote in
news:l9GdndF_XfPAvpbZRVn-gw@sigecom.net:
[color=blue]
> It seems to me you've found one article that you want to believe over
> all the other articles available ... [you should] believe the majority
> opinion ... is true.[/color]


Hi David,

Actually I found many articles, some with conflicting ideas.

For example, some say we should replace with softer brake pads, others
say we should always true brand new rotors, other say never true rotors
off the vehicle, others say use the parking brake instead of the pedal
when stopped at a light due to cooling differences, etc.

The majority is often wrong, by the way. The majority will tell you, in
and of itself, that high octane gas is "better" gas just like the
majority of chiropracters will tell you your spine needs "adjustment".

There is only one truth, and I'm simply searching for that one truth.

Here's a quick summary to date of some of those articles
Stu


What causes high-speed brake induced shimmy?

Vibration felt in the steering wheel only when the brakes are
applied is not a front end alignment problem, but a brake problem.
[url]http://www.trustmymechanic.com/besttires.html[/url]

The steering wheel is vibrating because the front brake
rotors are warped (we call this vibration "shimmy").
[url]http://www.trustmymechanic.com/brakewarp.html[/url]

Cold judder occurs primarily as a result of a non-uniform
circumferential rotor (friction ring) thickness, which causes a
cyclic variation in the brake torque output during braking (1 -
2). These microscopic variations in the cross-sectional thickness
of the disc brake rotor, axiomatically referred to as Disc Thickness
Variations (D.T.V. or R.T.V. (Rotor Thickness Variation)) may arise
during rotor manufacture as a product of the machining process
(typical manufactured D.T.V. < 7 m), or, as laboratory and field
trial testing have demonstrated, may be generated throughout their
lifetime in-service.
[url]http://www.eurac-group.com/technote4.htm[/url]

Warping can be caused by excessive heat build up, which softens the
metal ... however with most ventilated discs ... the sensation of
warped brakes (wheel shimmy under braking) most often is a matter of
a brake pad material operating outside of its designed temperature
range and it has left a thick(er) than normal deposit in one area
of the disc surface, creating a "sticky" spot that will grab every
revolution of the disk. In cars with automatic transmissions the
driver applies brakes when the car is stopped ... the brake pads
remain in contact with the disc and the discs will cool unevenly
.... leading to warping.
[url]http://en.wikipedia.org/wiki/Disk_brake[/url]

Wheel shimmy during braking is often caused by thickness variation
of the rotor disc. If the rotor has runout, a thin spot will develop
by the continuous touch touch touch as the rotor turns while the
brakes are not applied. When this thickness variation increases to
approximately 0.007 inch, the pulsation can be felt by the driver.
[url]http://en.wikipedia.org/wiki/Disk_brake[/url]

The accepted cause of brake-induced vibrations is disc thickness
variation. Disc thickness variation generated by off-brake running,
uneven transfer of lining material to the disc surface, disc
corrosion, and distortion of the disc under thermal loading. The
variations in rotor disc thickness cause the brake fluid pressure
in the caliper to fluctuate, resulting in torque variations.
[url]http://support.mscsoftware.com/cgi-bin/kb_files/Ford_Brake_Roughness_[/url]
2001_NAUC.pdf

Pre-loaded wheel bearings have no end play to "absorb" hub and rotor
run-out. Hence, almost 100% of any axial run-out of the hub and
brake rotor are transmitted to the brake pads. This axial run-out or
wobble in the rotor causes the brake pads to wear the rotor unevenly
over time, producing two sections of the rotor, 180 degrees apart,
where the rotor thickness becomes thinner than the other two sections.
This difference in thickness is called Disk Thickness Variation or DTV.
[url]http://www.rtitech.com/latheinfo.htm[/url]

In general, any run-out greater than 0.002" (50 microns) will
lead to an increase in DTV of about 0.0004" (10 microns) in about
3000-5000 miles. In most cars, when DTV reaches 0.0004" (10 microns)
or only 4 ten-thousandths of an inch, the driver will complain of
pedal pulsation, steering wheel shimmy, or brake shudder. The most
important fact to consider here is that the installation of the
wheel will almost always increase hub/rotor run-out by 0.001-0.0015"
(25-40 microns), even if the lug nuts are carefully torqued.
[url]http://www.rtitech.com/latheinfo.htm[/url]

jim <"sjedgingN0sp"@m@mwt.net> wrote in
news:1141580792_2413@sp6iad.superfeed.net:[color=blue]
> What do you mean by "long term". ...
> Anybody who knows what they are doing will also make sure
> the calipers and pistons are clean, that they move freely and are
> generally in good working order and if not they should be fixed also.
> In most cases buying replacement rotors costs the same or very
> little more than having the rotors turned so just buy the rotors[/color]

Hi Jim,

You are the words of wisdom.
- I will replace the rotors (I already ordered them from the best Toyota
Internet dealership in the USA according to these newsgroups).
- I will replace the pads and hardware too (already ordered them too).
- I agree it is important to check that the four pistons in each caliper
are moving freely as the disc thickness variation (DTV) is what caused the
runout in the first place (not heating & cooling warpage).

I'm not just interested in fixing my brakes (otherwise I'd just take them
to any mechanic on the block). I'm interested in learning why it happened
and how to prevent it from happening in the future. And how to diagnose
the problem properly.

For example, if I follow your (correct) advice to check caliper and piston
movement, it begs the question (which is NOT in the shop manuals)!

How does one check that the front 2 calipers & 8 pistons move freely?

Stu

On many vehicles, such as my '94 Jeep Grand Cherokee, it is important to
torque the front wheel lugs to a specified point, on my Jeep it is 90
foot/pounds. If this isn't done, my rotors warp in a very short time...

"Stuart A. Bronstein" <spamtrap@lexregia.com> wrote in message
news:m_FOf.56512$dW3.24778@newssvr21.news.prodigy.com...[color=blue]
> "davidj92" <davidj92REMOVE@sigecom.net> wrote in
> news:l9GdndF_XfPAvpbZRVn-gw@sigecom.net:
>[color=green]
>> It seems to me you've found one article that you want to believe over
>> all the other articles available ... [you should] believe the majority
>> opinion ... is true.[/color]
>
>
> Hi David,
>
> Actually I found many articles, some with conflicting ideas.
>
> For example, some say we should replace with softer brake pads, others
> say we should always true brand new rotors, other say never true rotors
> off the vehicle, others say use the parking brake instead of the pedal
> when stopped at a light due to cooling differences, etc.
>
> The majority is often wrong, by the way. The majority will tell you, in
> and of itself, that high octane gas is "better" gas just like the
> majority of chiropracters will tell you your spine needs "adjustment".
>
> There is only one truth, and I'm simply searching for that one truth.
>
> Here's a quick summary to date of some of those articles
> Stu
>
>
> What causes high-speed brake induced shimmy?
>
> Vibration felt in the steering wheel only when the brakes are
> applied is not a front end alignment problem, but a brake problem.
> [url]http://www.trustmymechanic.com/besttires.html[/url]
>
> The steering wheel is vibrating because the front brake
> rotors are warped (we call this vibration "shimmy").
> [url]http://www.trustmymechanic.com/brakewarp.html[/url]
>
> Cold judder occurs primarily as a result of a non-uniform
> circumferential rotor (friction ring) thickness, which causes a
> cyclic variation in the brake torque output during braking (1 -
> 2). These microscopic variations in the cross-sectional thickness
> of the disc brake rotor, axiomatically referred to as Disc Thickness
> Variations (D.T.V. or R.T.V. (Rotor Thickness Variation)) may arise
> during rotor manufacture as a product of the machining process
> (typical manufactured D.T.V. < 7 m), or, as laboratory and field
> trial testing have demonstrated, may be generated throughout their
> lifetime in-service.
> [url]http://www.eurac-group.com/technote4.htm[/url]
>
> Warping can be caused by excessive heat build up, which softens the
> metal ... however with most ventilated discs ... the sensation of
> warped brakes (wheel shimmy under braking) most often is a matter of
> a brake pad material operating outside of its designed temperature
> range and it has left a thick(er) than normal deposit in one area
> of the disc surface, creating a "sticky" spot that will grab every
> revolution of the disk. In cars with automatic transmissions the
> driver applies brakes when the car is stopped ... the brake pads
> remain in contact with the disc and the discs will cool unevenly
> ... leading to warping.
> [url]http://en.wikipedia.org/wiki/Disk_brake[/url]
>
> Wheel shimmy during braking is often caused by thickness variation
> of the rotor disc. If the rotor has runout, a thin spot will develop
> by the continuous touch touch touch as the rotor turns while the
> brakes are not applied. When this thickness variation increases to
> approximately 0.007 inch, the pulsation can be felt by the driver.
> [url]http://en.wikipedia.org/wiki/Disk_brake[/url]
>
> The accepted cause of brake-induced vibrations is disc thickness
> variation. Disc thickness variation generated by off-brake running,
> uneven transfer of lining material to the disc surface, disc
> corrosion, and distortion of the disc under thermal loading. The
> variations in rotor disc thickness cause the brake fluid pressure
> in the caliper to fluctuate, resulting in torque variations.
> [url]http://support.mscsoftware.com/cgi-bin/kb_files/Ford_Brake_Roughness_[/url]
> 2001_NAUC.pdf
>
> Pre-loaded wheel bearings have no end play to "absorb" hub and rotor
> run-out. Hence, almost 100% of any axial run-out of the hub and
> brake rotor are transmitted to the brake pads. This axial run-out or
> wobble in the rotor causes the brake pads to wear the rotor unevenly
> over time, producing two sections of the rotor, 180 degrees apart,
> where the rotor thickness becomes thinner than the other two sections.
> This difference in thickness is called Disk Thickness Variation or DTV.
> [url]http://www.rtitech.com/latheinfo.htm[/url]
>
> In general, any run-out greater than 0.002" (50 microns) will
> lead to an increase in DTV of about 0.0004" (10 microns) in about
> 3000-5000 miles. In most cars, when DTV reaches 0.0004" (10 microns)
> or only 4 ten-thousandths of an inch, the driver will complain of
> pedal pulsation, steering wheel shimmy, or brake shudder. The most
> important fact to consider here is that the installation of the
> wheel will almost always increase hub/rotor run-out by 0.001-0.0015"
> (25-40 microns), even if the lug nuts are carefully torqued.
> [url]http://www.rtitech.com/latheinfo.htm[/url][/color]

On Sun, 05 Mar 2006 18:21:06 GMT, "Stuart A. Bronstein"
<spamtrap@lexregia.com> wrote:
[color=blue]
>"davidj92" <davidj92REMOVE@sigecom.net> wrote in
>news:l9GdndF_XfPAvpbZRVn-gw@sigecom.net:
>[color=green]
>> It seems to me you've found one article that you want to believe over
>> all the other articles available ... [you should] believe the majority
>> opinion ... is true.[/color]
>
>
>Hi David,
>
>Actually I found many articles, some with conflicting ideas.
>
>For example, some say we should replace with softer brake pads, others
>say we should always true brand new rotors, other say never true rotors
>off the vehicle, others say use the parking brake instead of the pedal
>when stopped at a light due to cooling differences, etc.
>
>The majority is often wrong, by the way. The majority will tell you, in
>and of itself, that high octane gas is "better" gas just like the
>majority of chiropracters will tell you your spine needs "adjustment".
>
>There is only one truth, and I'm simply searching for that one truth.
>
>Here's a quick summary to date of some of those articles
>Stu
>
>
>What causes high-speed brake induced shimmy?[/color]


Generally the last 3 articles pretty well nail it, while many of the
others contain truth.

Rotor quality is one BIG variable - and todays rotors are not "aged"
before finishing. The "green" castings relieve after machining - so
often arive out of true from the factory.
Warpage, in itself, seldom causes pedal pulsation OR steering shimmy
unless it is quite sizeable. Thickness variation causes problems even
if very close in tolerance.
Vented rotors often have "callapse" problems, where several "fins"
move in tolerance as the rotor ages, or in use.
Particularly in the "salt belt" todays pads often cause a "glaze" on
the rotors, which traps moisture and pits the rotor away. When it
pits, the oxide layer expands behind the glaze, clausing "blisters"
that cause pulsations.

Machining the rotor temporarily solves the problem, but reduced
thickness and mass makes warpage more likely.

As for surfacing new rotors, SOME need surfacing. On Car machining
will usually give you a truer disk - but since runout is NOT the big
problem, off-car machining on a good lathe will sometimes give better
parallellism than on-car machining, where vibrations can have an
effect.
Pad composition is one thing you CAN change to prevent or greatly
reduce break pulsation problems. Anything with an iron metallic is
going to cause problems in salt-belt areas. Brass metallic is MUCH
better, from early Toyota experience, and carbon metallic or ceramic
pads have proven to be a great improvement in my experience with later
model Ford and GM vehicles.

Carbon Metallic pads on my 90 Aerostar improved rotor life by over
400%, and pad life by 100% over factory parts. Brake effectiveness was
also GREATLY improved - allowing me to actually lock the front wheels
on dry pavement, which was absolutely impossible with the factory
pads.[color=blue]
>
>Vibration felt in the steering wheel only when the brakes are
>applied is not a front end alignment problem, but a brake problem.
>[url]http://www.trustmymechanic.com/besttires.html[/url]
>
>The steering wheel is vibrating because the front brake
>rotors are warped (we call this vibration "shimmy").
>[url]http://www.trustmymechanic.com/brakewarp.html[/url]
>
>Cold judder occurs primarily as a result of a non-uniform
>circumferential rotor (friction ring) thickness, which causes a
>cyclic variation in the brake torque output during braking (1 -
>2). These microscopic variations in the cross-sectional thickness
>of the disc brake rotor, axiomatically referred to as Disc Thickness
>Variations (D.T.V. or R.T.V. (Rotor Thickness Variation)) may arise
>during rotor manufacture as a product of the machining process
>(typical manufactured D.T.V. < 7 m), or, as laboratory and field
>trial testing have demonstrated, may be generated throughout their
>lifetime in-service.
>[url]http://www.eurac-group.com/technote4.htm[/url]
>
>Warping can be caused by excessive heat build up, which softens the
>metal ... however with most ventilated discs ... the sensation of
>warped brakes (wheel shimmy under braking) most often is a matter of
>a brake pad material operating outside of its designed temperature
>range and it has left a thick(er) than normal deposit in one area
>of the disc surface, creating a "sticky" spot that will grab every
>revolution of the disk. In cars with automatic transmissions the
>driver applies brakes when the car is stopped ... the brake pads
>remain in contact with the disc and the discs will cool unevenly
>... leading to warping.
>[url]http://en.wikipedia.org/wiki/Disk_brake[/url]
>
>Wheel shimmy during braking is often caused by thickness variation
>of the rotor disc. If the rotor has runout, a thin spot will develop
>by the continuous touch touch touch as the rotor turns while the
>brakes are not applied. When this thickness variation increases to
>approximately 0.007 inch, the pulsation can be felt by the driver.
>[url]http://en.wikipedia.org/wiki/Disk_brake[/url]
>
>The accepted cause of brake-induced vibrations is disc thickness
>variation. Disc thickness variation generated by off-brake running,
>uneven transfer of lining material to the disc surface, disc
>corrosion, and distortion of the disc under thermal loading. The
>variations in rotor disc thickness cause the brake fluid pressure
>in the caliper to fluctuate, resulting in torque variations.
>[url]http://support.mscsoftware.com/cgi-bin/kb_files/Ford_Brake_Roughness_[/url]
>2001_NAUC.pdf
>
>Pre-loaded wheel bearings have no end play to "absorb" hub and rotor
>run-out. Hence, almost 100% of any axial run-out of the hub and
>brake rotor are transmitted to the brake pads. This axial run-out or
>wobble in the rotor causes the brake pads to wear the rotor unevenly
>over time, producing two sections of the rotor, 180 degrees apart,
>where the rotor thickness becomes thinner than the other two sections.
>This difference in thickness is called Disk Thickness Variation or DTV.
>[url]http://www.rtitech.com/latheinfo.htm[/url]
>
>In general, any run-out greater than 0.002" (50 microns) will
>lead to an increase in DTV of about 0.0004" (10 microns) in about
>3000-5000 miles. In most cars, when DTV reaches 0.0004" (10 microns)
>or only 4 ten-thousandths of an inch, the driver will complain of
>pedal pulsation, steering wheel shimmy, or brake shudder. The most
>important fact to consider here is that the installation of the
>wheel will almost always increase hub/rotor run-out by 0.001-0.0015"
>(25-40 microns), even if the lug nuts are carefully torqued.
>[url]http://www.rtitech.com/latheinfo.htm[/url][/color]

*** Free account sponsored by SecureIX.com ***
*** Encrypt your Internet usage with a free VPN account from [url]http://www.SecureIX.com[/url] ***

"Stuart A. Bronstein" wrote:[color=blue]
>
> jim <"sjedgingN0sp"@m@mwt.net> wrote in
> news:1141580792_2413@sp6iad.superfeed.net:[color=green]
> > What do you mean by "long term". ...
> > Anybody who knows what they are doing will also make sure
> > the calipers and pistons are clean, that they move freely and are
> > generally in good working order and if not they should be fixed also.
> > In most cases buying replacement rotors costs the same or very
> > little more than having the rotors turned so just buy the rotors[/color]
>
> Hi Jim,
>
> You are the words of wisdom.
> - I will replace the rotors (I already ordered them from the best Toyota
> Internet dealership in the USA according to these newsgroups).
> - I will replace the pads and hardware too (already ordered them too).
> - I agree it is important to check that the four pistons in each caliper
> are moving freely as the disc thickness variation (DTV) is what caused the
> runout in the first place (not heating & cooling warpage).[/color]

Well, I'm not sure I trust your analysis. It is quite likely that in one
way or another heat was a major factor that led to the problem
developing. That put another way, if you drive so that the brakes
never get hot it's likely they will last a very long time. All the
energy in a car moving at 70 mph goes into the brakes when you make a
sudden stop. You don't want to put your hand on the discs after doing
that. And if your rotors are truly not the same thickness that didn't
happen all at once - it happened over time and quite a number of things
could have started the process most all of them related to heat,
followed by rust, salt and dirt.
I assume you feel that your brakes needed replacement sooner than they
should have. That points to the driver as the most likely cause. Some
drivers regularly have to replace brakes every 10000 miles others can
get 100000 miles (altho that may be hard to do where salt plays a big
role in the deterioration of brakes). Also, some cars tend to have
brakes that last longer and take more abuse than others.
[color=blue]
>
> I'm not just interested in fixing my brakes (otherwise I'd just take them
> to any mechanic on the block). I'm interested in learning why it happened
> and how to prevent it from happening in the future. And how to diagnose
> the problem properly.
>
> For example, if I follow your (correct) advice to check caliper and piston
> movement, it begs the question (which is NOT in the shop manuals)!
>
> How does one check that the front 2 calipers & 8 pistons move freely?[/color]


In order to change the brake pads and rotors you need to move the
calipers and pistons to their wide open position of there travel. You
should be able to tell if they are able to move normally. Rust of course
is what usually causes sticking problems. Disc brake pistons don't have
much clearance so it doesn't take much to jam them up.

----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
[url]http://www.newsfeeds.com[/url] The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

"jim" <"sjedgingN0sp"@m@mwt.net> wrote in message
news:1141434475_67@sp6iad.superfeed.net...[color=blue]
>
>
> hob wrote:
>[color=green][color=darkred]
> > > Even a first year engineering student can tell you how hard braking[/color][/color][/color]
with[color=blue][color=green][color=darkred]
> > > the linkage turned hard over bends (warps) the rotor bell.[/color][/color]
>
> That's just plain silly.[/color]

It is only silly to those without brake engineering experience who assume
transverse forces into the rotor disc are negligible, or who attend pretty
weak schools.

I have designed and built several of the machines that test wheels,
tires, and linkages on motor vehicles for Ford and GM, and I can assure you
that there are forces imparted transversely to the rotor disc when the
linkage is not straight ahead and the brakes are applied.
Hi-speed photos of wheels heeling in hard braking turns show that that
cute little axle shaft holding on the wheel is aided in resisting total
failure by the caliper-and-disk. Looking at an accident where the wheel is
turned off the vehicle centerline axis at impact clearly shows the disk
assembly damage.

The rotor bell on a jeep wrangler is an excellent example for
illustration. Its linkage allows a greater angle off the vehicle axis than
on-road passenger vehicles, and the rotor is mounted off the axis of the
rotor disc. The mounting flange connecting the bell to the axle is
relatively thin material that is expected to deflect enough so as not to
reach the proportional limit.
Notice the size of the hold-down bolts and key-slider of the caliper
relative to the size of the axle and consider the moments imparted into the
axle-caliper-pin-rotor disk loop.
When the caliper is turned sideways to the direction of vehicle travel
and engaged, the momentum and resultant forces are no longer in the plane of
the rotor disk face, but rather across, and they become moments across the
bolts and keys, reacted into the face of the rotor (and across the face of
the disc itself) and the axle.
Hard turns and heavy braking will definitely warp that disk out of plane

The manifestation of transverse load is more pronounced in offset rotor
discs and with off-road where the greater limits lock to lock allow greater.
[color=blue]
>
>[color=green][color=darkred]
> > > (imagine 2 tons moving forward trying to go over a tire turned[/color][/color][/color]
sideways[color=blue][color=green][color=darkred]
> > > with the brake pads locked onto the rotor, a rotor designed for[/color][/color][/color]
transfer[color=blue][color=green]
> > of[color=darkred]
> > > force into floating claipers and transversely into the axle.[/color][/color]
>
> The caliper can move freely from side to side (floating calipers). There
> is no side load at all due to steering.
>[color=green][color=darkred]
> > > Guess how the force gets from the 2 ton moving vehicle mass into the[/color]
> > tire[color=darkred]
> > > tread in a turn-- through the shoes gripping the rotor and back into[/color][/color][/color]
the[color=blue][color=green][color=darkred]
> > > axle - forces across the rotor plane, unlike straight ahead braking,[/color][/color][/color]
where[color=blue][color=green][color=darkred]
> > > the forces are in the rotor plane)[/color][/color]
>
> This is fantasy. The wheel is mounted solid to the axle with the rotor
> sandwiched between.[/color]

You apparently are not familiar with force analysis. Any material receiving
a force deflects, the amount of deflection depending on the geometry, the
input force, and the material.
There is no such thing as "solid" in engineering, there is only relative
deflection.

The wheel is is mounted to the axle through a flexible bolt pattern and
the axle is a small diameter shaft that does deflect. A lot less straight
ahead than when turning.
It particularly deflects when the moment it sees is increased from the
weight and braking dynamic force acting in a plane parallel to the vehicle
axis an inch from the axle shaft mount arm in straight-ahead braking;
increased due to
1) the increased moment due to the wheel turned across the direction of
travel which causes the moment from the tread gripping the road to no longer
be "next to " the mounting plane in the plane of the wheel, but rather
across the plane of the disc: twenty times as great because of the
tread-to-mount distance of a transversely directed
(turned-to-plane-of-travel) force at the tread compared to the tread-to
mount-distance of an axially directed (straight-ahead-travel)force.
and
2) a greater dynamic braking input (greater from the leading turned wheel
getting more of the vehicle-braking dynamic forces from the resultant
moment, similar to the front wheels having more force than the rear in a
straight-shead stop)

Even if the axle would deflect it couldn't possibly[color=blue]
> deflect enough to exceed the side travel of the calipers. If the car is
> sliding sideways the brakes see no load at all because there would be no
> force to turn the wheels.[/color]
[color=blue]
> Heat build up is usually what causes rotors to warp.[/color]

Materials science one - heating steel does not warp steel- it removes
residual stresses of manufacture - annealing, etc. -and makes a more stable
part.

However, it is easier to bend a heated piece of metal than a cool one -
and any forces across the plane of the heated disc are more prone to
deforming the disc.

If you wish to warp a rotor, put in the force when the rotor is heated.
Heating a rotor will only warp it if it has residual stresses from
manufacturing that were not removed before truing.

You don't even[color=blue]
> have to put the rotor on a car just toss it in a fire and it will warp.[/color]

Not if you keep the face-plane vertical.
[color=blue]
> Rust in the ventilation passages can also warp rotors. And frozen
> calipers can also warp rotors - not so much because of uneven force
> loads but uneven heat loads.[/color]

Not because of uneven heat loads per se, but because the calipers wear the
disc face unevenly.
A rotor that has frozen calipers will heat a "high spot" on one side of
the disc, and that high spot is easier to abrade when hot, so indirectly the
heat allowing more wear can contribute - but it is not the heat itself.
[color=blue]
>[color=green][color=darkred]
> > >
> > > Any experienced engineer will tell you that if there is a problem and[/color][/color][/color]
it[color=blue][color=green][color=darkred]
> > > goes way when you replace a part, the problem is gone.
> > > Was the problem the root cause and will it return? Well, if it[/color][/color][/color]
wasn't[color=blue][color=green]
> > part[color=darkred]
> > > of the problem, the problem would still be there in some form.
> > > However, if it is only part of the problem, the problem will later
> > > manifest the same symptoms (E.g, if the driver brakes hard in corners,[/color]
> > part[color=darkred]
> > > of the problem, the rotors will again bend/wear the faces so that in[/color][/color][/color]
time[color=blue][color=green][color=darkred]
> > > the plane of the rotor surfaces are no longer within tolerance, Before[/color][/color][/color]
the[color=blue][color=green][color=darkred]
> > > driver got in and warped the new rotors, the new rotors were just[/color][/color][/color]
fine)[color=blue][color=green][color=darkred]
> > >[/color][/color]
>
>
> This is nonsense. Excessive braking can result in warped rotors, but
> braking on turns has nothing to do with it.
>[/color]

See above. And hard braking during turns is the main cause of passenger
vehicle rotor damage.
[color=blue]
> -jim
>
>[color=green][color=darkred]
> > > ( Logically, when you change the rotor and then the problem goes[/color][/color][/color]
away,[color=blue][color=green]
> > the[color=darkred]
> > > problem is gone.)
> > >
> > > and it seems
> > > > nobody on this planet can really (reliably) tell the difference[/color][/color][/color]
between[color=blue][color=green][color=darkred]
> > > > brake friction materials (because there are no standards whatsoever)
> > > > according to
> > > > [url]http://www.performanceoiltechnology.com/brakingsystems.htm[/url]
> > >
> > >
> > > the man ought to read the specs in the vehicle manuals, which do[/color][/color][/color]
indeed[color=blue][color=green]
> > list[color=darkred]
> > > tolerances for rotors. And he ought to get some in depth background[/color][/color][/color]
first.[color=blue][color=green][color=darkred]
> > > The internet is full of half-aware self-promoters with partially[/color]
> > applied[color=darkred]
> > > theories. And AMSOIL, no less.
> > >
> > > FWIW - match mounting is a way to limit costly close tolerance[/color][/color][/color]
machining[color=blue][color=green]
> > in[color=darkred]
> > > many mating parts- you make hundreds of parts all alike, and then[/color][/color][/color]
measure[color=blue][color=green][color=darkred]
> > > them - some will be way off and get tossed, most will be within[/color][/color][/color]
tolerance[color=blue][color=green][color=darkred]
> > > and used according to their tolerance, and some may even be perfect.[/color][/color][/color]
It's[color=blue][color=green][color=darkred]
> > > cheaper than making each one perfect.
> > >
> > > I'll put this quote from them in here for the experienced engineers to[/color][/color][/color]
get[color=blue][color=green]
> > a[color=darkred]
> > > chcukle
> > >
> > > "DTV is when the rotor thickness is not the same all the way around[/color][/color][/color]
the[color=blue][color=green][color=darkred]
> > > rotor. DTV is typically caused by lateral runout. DTV can only be[/color]
> > measured[color=darkred]
> > > with very specialized laboratory testing equipment or with special on
> > > vehicle capacitance probes."
> > >
> > > right.... ( or like a shop caliper or shop "mic", as noted in the
> > > maintenance manuals.)
> > >
> > > Quote - "This [DTV] phenomenon is what many technicians refer to as
> > > "warping", however they actually think the rotor warped and needs
> > > replacement."
> > >
> > > OK, so what they are saying is that the rotor isn't warped ( and so[/color][/color][/color]
the[color=blue][color=green][color=darkred]
> > > rotor is true?) and the face of the rotor plane has just warped, and[/color][/color][/color]
so[color=blue][color=green]
> > they[color=darkred]
> > > are saying that
> > > instead of the rotor needing replacing because the thickness[/color][/color][/color]
varies,[color=blue][color=green]
> > the[color=darkred]
> > > rotor needs replacing because the thickness varies and the esoteric[/color][/color][/color]
DTV[color=blue][color=green][color=darkred]
> > > measurements are lab things .(or you could just get refacing done at a[/color]
> > brake[color=darkred]
> > > shop, if enough material is left).
> > >
> > > enough of quoting their home-spun humor....
> > >
> > > >
> > > > So, since I have horrible brake-induced wobble in my Toyota 4Runner,[/color][/color][/color]
how[color=blue][color=green][color=darkred]
> > > > DOES anyone buy the right parts given there are no regulations or
> > > > standards to protect us?
> > > >
> > >
> > > There are regulations - Check out the following standards for brake
> > > materials: DE3A, BEEP, NHTSA FMVSS-105
> > >
> > > > We may as well close our eyes and choose randomly for all the lack[/color][/color][/color]
of[color=blue][color=green][color=darkred]
> > > > standards. Which leaves me to my most important question, having to[/color]
> > trust[color=darkred]
> > > > in your judgement and experience (which I don't have).
> > > >
> > > > Where would YOU buy a good quality rotors & pads for a Toyota[/color][/color][/color]
4Runner?[color=blue][color=green][color=darkred]
> > > >
> > >
> > > From Toyota -
> > > why? aftermarket pads have few, if any standards. New-car brake[/color][/color][/color]
pads[color=blue][color=green][color=darkred]
> > > (OEM) have to meet NHTSA standards, and thus actually do stop better,[/color][/color][/color]
are[color=blue][color=green][color=darkred]
> > > more reliable, and the dust around the kids and dogs is less[/color][/color][/color]
hazardous.[color=blue][color=green][color=darkred]
> > >
> > > nuff free stuff
> > >
> > > > Stu
> > >
> > >[/color][/color]
>
> ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet[/color]
News==----[color=blue]
> [url]http://www.newsfeeds.com[/url] The #1 Newsgroup Service in the World! 120,000+[/color]
Newsgroups[color=blue]
> ----= East and West-Coast Server Farms - Total Privacy via Encryption[/color]
=----