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

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

Frankly I doubt your credentials. But in the event that you are who you
claim you clearly have not grasp the subject of this thread. No one is
interested in what happens to the rotors when there is a catastrophic
axle failure.

[color=blue]
> 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.
>[/color]

Well yes, if the axle gets bent that much so that the calipers are force
to the end of their travel then the rotors absorb the load. But so what.
That's hardly got anything to do with someone who needs a brake job. You
are talking about someone who has totaled their car.

`I agree if the side load is enough to deflect the axle so that the
brake assembly is caused to slide to the end of its travel then there is
definitely a load on the calipers and rotors. But until the axle
deflects that much there will be very little load on the disk because
the calipers are designed to slide sideways. And if your axle does
deflect that much you have a lot more serious problems than just a
rotor. But for normal drivers under normal driving conditions this
doesn't play any role in why rotors don't run true and develop uneven
wear patterns which is the subject of the thread.


-jim

[color=blue]
> 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.[/color]


[color=blue]
> 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=green]
> >
> >[color=darkred]
> > > > (imagine 2 tons moving forward trying to go over a tire turned[/color][/color]
> sideways[color=green][color=darkred]
> > > > with the brake pads locked onto the rotor, a rotor designed for[/color][/color]
> transfer[color=green][color=darkred]
> > > of
> > > > force into floating claipers and transversely into the axle.[/color]
> >
> > The caliper can move freely from side to side (floating calipers). There
> > is no side load at all due to steering.
> >[color=darkred]
> > > > Guess how the force gets from the 2 ton moving vehicle mass into the
> > > tire
> > > > tread in a turn-- through the shoes gripping the rotor and back into[/color][/color]
> the[color=green][color=darkred]
> > > > axle - forces across the rotor plane, unlike straight ahead braking,[/color][/color]
> where[color=green][color=darkred]
> > > > the forces are in the rotor plane)[/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=green]
> > 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=green]
> > 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=green]
> > 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=green]
> > 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=green]
> >[color=darkred]
> > > >
> > > > Any experienced engineer will tell you that if there is a problem and[/color][/color]
> it[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]
> wasn't[color=green][color=darkred]
> > > part
> > > > 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,
> > > part
> > > > of the problem, the rotors will again bend/wear the faces so that in[/color][/color]
> time[color=green][color=darkred]
> > > > the plane of the rotor surfaces are no longer within tolerance, Before[/color][/color]
> the[color=green][color=darkred]
> > > > driver got in and warped the new rotors, the new rotors were just[/color][/color]
> fine)[color=green][color=darkred]
> > > >[/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=green]
> > -jim
> >
> >[color=darkred]
> > > > ( Logically, when you change the rotor and then the problem goes[/color][/color]
> away,[color=green][color=darkred]
> > > the
> > > > problem is gone.)
> > > >
> > > > and it seems
> > > > > nobody on this planet can really (reliably) tell the difference[/color][/color]
> between[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]
> indeed[color=green][color=darkred]
> > > list
> > > > tolerances for rotors. And he ought to get some in depth background[/color][/color]
> first.[color=green][color=darkred]
> > > > The internet is full of half-aware self-promoters with partially
> > > applied
> > > > theories. And AMSOIL, no less.
> > > >
> > > > FWIW - match mounting is a way to limit costly close tolerance[/color][/color]
> machining[color=green][color=darkred]
> > > in
> > > > many mating parts- you make hundreds of parts all alike, and then[/color][/color]
> measure[color=green][color=darkred]
> > > > them - some will be way off and get tossed, most will be within[/color][/color]
> tolerance[color=green][color=darkred]
> > > > and used according to their tolerance, and some may even be perfect.[/color][/color]
> It's[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]
> get[color=green][color=darkred]
> > > a
> > > > chcukle
> > > >
> > > > "DTV is when the rotor thickness is not the same all the way around[/color][/color]
> the[color=green][color=darkred]
> > > > rotor. DTV is typically caused by lateral runout. DTV can only be
> > > measured
> > > > 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]
> the[color=green][color=darkred]
> > > > rotor is true?) and the face of the rotor plane has just warped, and[/color][/color]
> so[color=green][color=darkred]
> > > they
> > > > are saying that
> > > > instead of the rotor needing replacing because the thickness[/color][/color]
> varies,[color=green][color=darkred]
> > > the
> > > > rotor needs replacing because the thickness varies and the esoteric[/color][/color]
> DTV[color=green][color=darkred]
> > > > measurements are lab things .(or you could just get refacing done at a
> > > brake
> > > > 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]
> how[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]
> of[color=green][color=darkred]
> > > > > standards. Which leaves me to my most important question, having to
> > > trust
> > > > > in your judgement and experience (which I don't have).
> > > > >
> > > > > Where would YOU buy a good quality rotors & pads for a Toyota[/color][/color]
> 4Runner?[color=green][color=darkred]
> > > > >
> > > >
> > > > From Toyota -
> > > > why? aftermarket pads have few, if any standards. New-car brake[/color][/color]
> pads[color=green][color=darkred]
> > > > (OEM) have to meet NHTSA standards, and thus actually do stop better,[/color][/color]
> are[color=green][color=darkred]
> > > > more reliable, and the dust around the kids and dogs is less[/color][/color]
> hazardous.[color=green][color=darkred]
> > > >
> > > > nuff free stuff
> > > >
> > > > > Stu
> > > >
> > > >[/color]
> >
> > ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet[/color]
> News==----[color=green]
> > [url]http://www.newsfeeds.com[/url] The #1 Newsgroup Service in the World! 120,000+[/color]
> Newsgroups[color=green]
> > ----= East and West-Coast Server Farms - Total Privacy via Encryption[/color]
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"Emmo" <emmo@austin.rr.com> wrote in news:ZDGOf.5257$gm.1937
@tornado.texas.rr.com:
[color=blue]
> On my '94 Jeep Grand Cherokee, it is important to torque
> the front wheel lugs to 90 foot/pounds.
> If this isn't done, my rotors warp in a very short time...[/color]

Hi Emmo,
I agree and disagree (now that I've done some research).
I agree one should do a three pass tightening of the lug nuts, which, in
the case of the six-lug-nut 1998 Toyota 4Runner, is 84 foot pounds.

FIRST PASS: While the truck is in the air, tighten three lug nuts by hand
in a triangle pattern; then tighten the other three in a reverse triangle
pattern.

SECOND PASS: Back on the ground, tighten the second lug nut triangle to 1/2
the recommended torque (42 foot pounds for a 1998 Toyota 4Runner); then do
the same for the first triangle set of lug nuts.

THIRD PASS: Finally, tighten the first triangle to full torque; and then
the second triangel to full torque.

Of course, this assumes the hub was cleaned of all rust and was greased
with synthetic Mobil 1 grease to prevent rust creep (pushing out of the
rotors like tree roots push out a sidewalk or curb).

However, now that I've learned enough to be dangerous, I will disagree with
your assertion that the rotors will "warp" if you tighten lug nuts
incorrectly. Many articles have shown that brake discs almost never warp.
What people call warp is really disk thickness variation or rotor thickness
variation caused by the pad deposition being different on various parts of
the rotor.

See a more detailed explanation in the following reference:
[url]http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml#[/url]

Stu

"Stuart A. Bronstein" <spamtrap@lexregia.com> wrote in message
news:A3LOf.18881$rL5.17151@newssvr27.news.prodigy.net...[color=blue]
> However, now that I've learned enough to be dangerous, I will disagree
> with
> your assertion that the rotors will "warp" if you tighten lug nuts
> incorrectly. Many articles have shown that brake discs almost never warp.
> What people call warp is really disk thickness variation or rotor
> thickness
> variation caused by the pad deposition being different on various parts of
> the rotor.[/color]

Dear Stuart,
I know for a fact, that incorrectly tightening lugnuts will
warp rotors. (even brand new rotors).
I can prove it on just about any vehicle.
(not just hubless types)
Those websites are just playing on words mostly and also
must not know that even a 0 thickness variation can still have a
warp in the rotor if the wheels are not properly tightened.
You really should not listen to websites as if they are law..
Since if you do.
There are websites that have proof of many other things
that are far more silly than the "rotors can not warp" bologna
you are reading.


--
James M Driscoll Jr
Spaceman

"jim" <"sjedgingN0sp"@m@mwt.net> wrote in message[color=blue]
> hob wrote:[color=green]
> > I have designed and built several of the machines that test wheels,
> > tires, and linkages on motor vehicles for Ford and GM,[/color][/color]
[color=blue]
> Frankly I doubt your credentials. But in the event that you are who you
> claim you clearly have not grasp the subject of this thread. No one is
> interested in what happens to the rotors when there is a catastrophic
> axle failure.[/color]
[color=blue]
> rotor. But for normal drivers under normal driving conditions this
> doesn't play any role in why rotors don't run true and develop uneven
> wear patterns which is the subject of the thread.
>
>
> -jim[/color]

Jim, the man claims to have built rigs... I have no problem with this. If he
had claimed he was responsible for interpreting results from the rigs....

Is the cross posting a little heavy ?

BTW to the original poster, the organ grinder at Toyota insures that
genuine Toyota spares are good.
Don't be to worried about what the monkey says :-)

Regards Jonathan.

..
..
========
========
Spaceman wrote:[color=blue]
> "Stuart A. Bronstein" <spamtrap@lexregia.com> wrote in message
> news:A3LOf.18881$rL5.17151@newssvr27.news.prodigy.net...[color=green]
> > However, now that I've learned enough to be dangerous, I will disagree
> > with
> > your assertion that the rotors will "warp" if you tighten lug nuts
> > incorrectly. Many articles have shown that brake discs almost never warp.
> > What people call warp is really disk thickness variation or rotor
> > thickness
> > variation caused by the pad deposition being different on various parts of
> > the rotor.[/color]
>
> Dear Stuart,
> I know for a fact, that incorrectly tightening lugnuts will
> warp rotors. (even brand new rotors).
> I can prove it on just about any vehicle.
> (not just hubless types)
> Those websites are just playing on words mostly and also
> must not know that even a 0 thickness variation can still have a
> warp in the rotor if the wheels are not properly tightened.
> You really should not listen to websites as if they are law..
> Since if you do.
> There are websites that have proof of many other things
> that are far more silly than the "rotors can not warp" bologna
> you are reading.
>
>
> --
> James M Driscoll Jr
> Spaceman[/color]
============
============
I agree with Stuart,
he has learned enough to be dangerous.

I agree with Spaceman,
it is very easy to warp a rotor during tightening of lug nuts.

I've done it.
More than once.
Not recently.
Not in the last year.
Not in the last 15-20 years.
But..I've done it.

why....??......
because I too was onced learn'ed enough to be dangerous.






~:~
MarshMosnter
~wonders why it takes 3 threads to diagnose a symptom~

"Marsh Monster" <MarshMonster2624@aol.com> wrote in
news:1141604743.621888.84060@e56g2000cwe.googlegroups.com:[color=blue]
> he has learned enough to be dangerous.
> it is very easy to warp a rotor during tightening of lug nuts.
> MarshMosnter wonders why it takes 3 threads to diagnose a symptom[/color]

Hi Marsh Monster,

The three related threads were a result of each other.

THREAD #1: Why does my 4Runner vibrate when I apply the brakes?
THREAD #2: What replacement pads should we use for this 4Runner?
THREAD #3: How do we test piston retraction?

The actual titles of those only somewhat related threads are:
#1: Bad shimmy upon heavy braking Toyota 4Runner (why?)
#2: Can anyone tell the difference between rotors and pads (truthfully)?
#3: Can anyone check whether brake pistons move freely?

What I found out, thanks to you, from each thread was:
#1: I have DTV which is being felt in the front steering & pedal.
#2: A DIY can not tell the difference between pads so go OEM.
#3: There is no tool that can test brake piston movement.

As stated, I've learned a lot (enough to be argumentative :) ... but I
still don't understand what's wrong with the referenced method of torquing
the lug nuts half way first.

What is wrong with torquing them to 1/2 torque in a triangle pattern in two
passes and then repeating the two pass triangle pattern for the full torque
value?

Is that wrong?

Stu

<HLS@nospam.nix> wrote:
[color=blue]
>
> "Stuart A. Bronstein" <spamtrap@lexregia.com> wrote in message
> news:nvaOf.43710$H71.22542@newssvr13.news.prodigy.com...[color=green][color=darkred]
> > > 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.[/color]




The article says runout will not cause pedal pulsation if there's no
fluid movement. Read the article in full.



[color=blue]
> 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.[/color]



I've noticed the article does not mention *steering wheel* vibration.
I'm guessing steering wheel vibration could occur for exactly the
reasons you list above, and even if no pulsation is evident at the
pedal. I had just this happen with my Integra last year.


[color=blue]
>
> And you WILL feel it in the pedal. And by truing the rotor, it will
> go away.[/color]


Truing the rotor will make pedal pulsation go away, but *how* you go
about truing it is the whole point of the Babcox article.


[color=blue]
>
> And when you get some idiot with a torque stick/torque wrench
> installing a wheel, WILL likely return.[/color]



As the article says towards the very end...

[email]HLS@nospam.nix[/email] wrote:
[color=blue]
> 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.[/color]

At last, a voice of sanity in a silly discussion!

"jim" <"sjedgingN0sp"@m@mwt.net> wrote in message
news:1141593546_2681@sp6iad.superfeed.net...[color=blue]
>
>
> hob wrote:[color=green]
> >
> > "jim" <"sjedgingN0sp"@m@mwt.net> wrote in message
> > news:1141434475_67@sp6iad.superfeed.net...[color=darkred]
> > >
> > >
> > > hob wrote:
> > >
> > > > > Even a first year engineering student can tell you how hard[/color][/color][/color]
braking[color=blue][color=green]
> > with[color=darkred]
> > > > > the linkage turned hard over bends (warps) the rotor bell.
> > >
> > > That's just plain silly.[/color]
> >
> > It is only silly to those without brake engineering experience who[/color][/color]
assume[color=blue][color=green]
> > transverse forces into the rotor disc are negligible, or who attend[/color][/color]
pretty[color=blue][color=green]
> > 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[/color][/color]
you[color=blue][color=green]
> > that there are forces imparted transversely to the rotor disc when the
> > linkage is not straight ahead and the brakes are applied.[/color]
>
> Frankly I doubt your credentials. But in the event that you are who you
> claim you clearly have not grasp the subject of this thread. No one is
> interested in what happens to the rotors when there is a catastrophic
> axle failure.[/color]

The forces are present whenever the wheel is not parallel to the
direction of travel (e.g., turning into a driveway and/during braking).
My example was to help you see the forces transverse to the rotor face -
the forces are dramatically manifested when the wheel is hit when turned
off the direction of travel.
They are felt as a sin of the angle between wheel and direction of travel
when the brake is applied.
[color=blue]
>
>[color=green]
> > 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[/color][/color]
is[color=blue][color=green]
> > turned off the vehicle centerline axis at impact clearly shows the disk
> > assembly damage.
> >[/color]
>
> Well yes, if the axle gets bent that much so that the calipers are force
> to the end of their travel then the rotors absorb the load.[/color]

The calipers in braking in turns see more than a pure lateral force that
moves the cliper on the pins - they also see vertical forces because of the
deflections of the axle, bearings, and mounts

But so what.[color=blue]
> That's hardly got anything to do with someone who needs a brake job. You
> are talking about someone who has totaled their car.
>[/color]

No, the forces of which I speak are present whenever the wheel is not
parallel to the direction of travel. They only bring the metal above its
proportional limit (and then warp the face out of plane) when those forvces
are great enough.

[color=blue]
> `I agree if the side load is enough to deflect the axle so that the
> brake assembly is caused to slide to the end of its travel then there is
> definitely a load on the calipers and rotors. But until the axle
> deflects that much there will be very little load on the disk because
> the calipers are designed to slide sideways. And if your axle does
> deflect that much you have a lot more serious problems than just a
> rotor. But for normal drivers under normal driving conditions this
> doesn't play any role in why rotors don't run true and develop uneven
> wear patterns which is the subject of the thread.
>
>
> -jim
>
>[color=green]
> > The rotor bell on a jeep wrangler is an excellent example for
> > illustration. Its linkage allows a greater angle off the vehicle axis[/color][/color]
than[color=blue][color=green]
> > 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.[/color]
>
>
>[color=green]
> > 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[/color][/color]
the[color=blue][color=green]
> > axle-caliper-pin-rotor disk loop.
> > When the caliper is turned sideways to the direction of vehicle[/color][/color]
travel[color=blue][color=green]
> > and engaged, the momentum and resultant forces are no longer in the[/color][/color]
plane of[color=blue][color=green]
> > the rotor disk face, but rather across, and they become moments across[/color][/color]
the[color=blue][color=green]
> > bolts and keys, reacted into the face of the rotor (and across the face[/color][/color]
of[color=blue][color=green]
> > the disc itself) and the axle.
> > Hard turns and heavy braking will definitely warp that disk out of[/color][/color]
plane[color=blue][color=green]
> >
> > The manifestation of transverse load is more pronounced in offset rotor
> > discs and with off-road where the greater limits lock to lock allow[/color][/color]
greater.[color=blue][color=green]
> >[color=darkred]
> > >
> > >
> > > > > (imagine 2 tons moving forward trying to go over a tire turned[/color]
> > sideways[color=darkred]
> > > > > with the brake pads locked onto the rotor, a rotor designed for[/color]
> > transfer[color=darkred]
> > > > of
> > > > > force into floating claipers and transversely into the axle.
> > >
> > > The caliper can move freely from side to side (floating calipers).[/color][/color][/color]
There[color=blue][color=green][color=darkred]
> > > is no side load at all due to steering.
> > >
> > > > > Guess how the force gets from the 2 ton moving vehicle mass into[/color][/color][/color]
the[color=blue][color=green][color=darkred]
> > > > tire
> > > > > tread in a turn-- through the shoes gripping the rotor and back[/color][/color][/color]
into[color=blue][color=green]
> > the[color=darkred]
> > > > > axle - forces across the rotor plane, unlike straight ahead[/color][/color][/color]
braking,[color=blue][color=green]
> > where[color=darkred]
> > > > > the forces are in the rotor plane)
> > >
> > > 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[/color][/color]
receiving[color=blue][color=green]
> > a force deflects, the amount of deflection depending on the geometry,[/color][/color]
the[color=blue][color=green]
> > input force, and the material.
> > There is no such thing as "solid" in engineering, there is only[/color][/color]
relative[color=blue][color=green]
> > deflection.
> >
> > The wheel is is mounted to the axle through a flexible bolt pattern[/color][/color]
and[color=blue][color=green]
> > the axle is a small diameter shaft that does deflect. A lot less[/color][/color]
straight[color=blue][color=green]
> > ahead than when turning.
> > It particularly deflects when the moment it sees is increased from[/color][/color]
the[color=blue][color=green]
> > weight and braking dynamic force acting in a plane parallel to the[/color][/color]
vehicle[color=blue][color=green]
> > 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[/color][/color]
of[color=blue][color=green]
> > travel which causes the moment from the tread gripping the road to no[/color][/color]
longer[color=blue][color=green]
> > 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[/color][/color]
wheel[color=blue][color=green]
> > 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=darkred]
> > > deflect enough to exceed the side travel of the calipers. If the car[/color][/color][/color]
is[color=blue][color=green][color=darkred]
> > > sliding sideways the brakes see no load at all because there would be[/color][/color][/color]
no[color=blue][color=green][color=darkred]
> > > force to turn the wheels.[/color]
> >[color=darkred]
> > > 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[/color][/color]
stable[color=blue][color=green]
> > part.
> >
> > However, it is easier to bend a heated piece of metal than a cool[/color][/color]
one -[color=blue][color=green]
> > 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=darkred]
> > > have to put the rotor on a car just toss it in a fire and it will[/color][/color][/color]
warp.[color=blue][color=green]
> >
> > Not if you keep the face-plane vertical.
> >[color=darkred]
> > > 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[/color][/color]
the[color=blue][color=green]
> > disc face unevenly.
> > A rotor that has frozen calipers will heat a "high spot" on one side[/color][/color]
of[color=blue][color=green]
> > the disc, and that high spot is easier to abrade when hot, so indirectly[/color][/color]
the[color=blue][color=green]
> > heat allowing more wear can contribute - but it is not the heat itself.
> >[color=darkred]
> > >
> > > > >
> > > > > Any experienced engineer will tell you that if there is a problem[/color][/color][/color]
and[color=blue][color=green]
> > it[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]
> > wasn't[color=darkred]
> > > > part
> > > > > of the problem, the problem would still be there in some form.
> > > > > However, if it is only part of the problem, the problem will[/color][/color][/color]
later[color=blue][color=green][color=darkred]
> > > > > manifest the same symptoms (E.g, if the driver brakes hard in[/color][/color][/color]
corners,[color=blue][color=green][color=darkred]
> > > > part
> > > > > of the problem, the rotors will again bend/wear the faces so that[/color][/color][/color]
in[color=blue][color=green]
> > time[color=darkred]
> > > > > the plane of the rotor surfaces are no longer within tolerance,[/color][/color][/color]
Before[color=blue][color=green]
> > the[color=darkred]
> > > > > driver got in and warped the new rotors, the new rotors were just[/color]
> > fine)[color=darkred]
> > > > >
> > >
> > >
> > > 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=darkred]
> > > -jim
> > >
> > >
> > > > > ( Logically, when you change the rotor and then the problem goes[/color]
> > away,[color=darkred]
> > > > the
> > > > > problem is gone.)
> > > > >
> > > > > and it seems
> > > > > > nobody on this planet can really (reliably) tell the difference[/color]
> > between[color=darkred]
> > > > > > brake friction materials (because there are no standards[/color][/color][/color]
whatsoever)[color=blue][color=green][color=darkred]
> > > > > > according to
> > > > > > [url]http://www.performanceoiltechnology.com/brakingsystems.htm[/url]
> > > > >
> > > > >
> > > > > the man ought to read the specs in the vehicle manuals, which do[/color]
> > indeed[color=darkred]
> > > > list
> > > > > tolerances for rotors. And he ought to get some in depth[/color][/color][/color]
background[color=blue][color=green]
> > first.[color=darkred]
> > > > > The internet is full of half-aware self-promoters with[/color][/color][/color]
partially[color=blue][color=green][color=darkred]
> > > > applied
> > > > > theories. And AMSOIL, no less.
> > > > >
> > > > > FWIW - match mounting is a way to limit costly close tolerance[/color]
> > machining[color=darkred]
> > > > in
> > > > > many mating parts- you make hundreds of parts all alike, and then[/color]
> > measure[color=darkred]
> > > > > them - some will be way off and get tossed, most will be within[/color]
> > tolerance[color=darkred]
> > > > > and used according to their tolerance, and some may even be[/color][/color][/color]
perfect.[color=blue][color=green]
> > It's[color=darkred]
> > > > > cheaper than making each one perfect.
> > > > >
> > > > > I'll put this quote from them in here for the experienced[/color][/color][/color]
engineers to[color=blue][color=green]
> > get[color=darkred]
> > > > a
> > > > > chcukle
> > > > >
> > > > > "DTV is when the rotor thickness is not the same all the way[/color][/color][/color]
around[color=blue][color=green]
> > the[color=darkred]
> > > > > rotor. DTV is typically caused by lateral runout. DTV can only be
> > > > measured
> > > > > with very specialized laboratory testing equipment or with special[/color][/color][/color]
on[color=blue][color=green][color=darkred]
> > > > > 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[/color][/color][/color]
as[color=blue][color=green][color=darkred]
> > > > > "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[/color][/color][/color]
so[color=blue][color=green]
> > the[color=darkred]
> > > > > rotor is true?) and the face of the rotor plane has just warped,[/color][/color][/color]
and[color=blue][color=green]
> > so[color=darkred]
> > > > they
> > > > > are saying that
> > > > > instead of the rotor needing replacing because the thickness[/color]
> > varies,[color=darkred]
> > > > the
> > > > > rotor needs replacing because the thickness varies and the[/color][/color][/color]
esoteric[color=blue][color=green]
> > DTV[color=darkred]
> > > > > measurements are lab things .(or you could just get refacing done[/color][/color][/color]
at a[color=blue][color=green][color=darkred]
> > > > brake
> > > > > shop, if enough material is left).
> > > > >
> > > > > enough of quoting their home-spun humor....
> > > > >
> > > > > >
> > > > > > So, since I have horrible brake-induced wobble in my Toyota[/color][/color][/color]
4Runner,[color=blue][color=green]
> > how[color=darkred]
> > > > > > DOES anyone buy the right parts given there are no regulations[/color][/color][/color]
or[color=blue][color=green][color=darkred]
> > > > > > standards to protect us?
> > > > > >
> > > > >
> > > > > There are regulations - Check out the following standards for[/color][/color][/color]
brake[color=blue][color=green][color=darkred]
> > > > > materials: DE3A, BEEP, NHTSA FMVSS-105
> > > > >
> > > > > > We may as well close our eyes and choose randomly for all the[/color][/color][/color]
lack[color=blue][color=green]
> > of[color=darkred]
> > > > > > standards. Which leaves me to my most important question, having[/color][/color][/color]
to[color=blue][color=green][color=darkred]
> > > > trust
> > > > > > in your judgement and experience (which I don't have).
> > > > > >
> > > > > > Where would YOU buy a good quality rotors & pads for a Toyota[/color]
> > 4Runner?[color=darkred]
> > > > > >
> > > > >
> > > > > From Toyota -
> > > > > why? aftermarket pads have few, if any standards. New-car[/color][/color][/color]
brake[color=blue][color=green]
> > pads[color=darkred]
> > > > > (OEM) have to meet NHTSA standards, and thus actually do stop[/color][/color][/color]
better,[color=blue][color=green]
> > are[color=darkred]
> > > > > more reliable, and the dust around the kids and dogs is less[/color]
> > hazardous.[color=darkred]
> > > > >
> > > > > nuff free stuff
> > > > >
> > > > > > Stu
> > > > >
> > > > >
> > >
> > > ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet[/color]
> > News==----[color=darkred]
> > > [url]http://www.newsfeeds.com[/url] The #1 Newsgroup Service in the World![/color][/color][/color]
120,000+[color=blue][color=green]
> > Newsgroups[color=darkred]
> > > ----= East and West-Coast Server Farms - Total Privacy via Encryption[/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]
=----

==========
==========
Stuart A. Bronstein wrote:[color=blue]
> "Marsh Monster" <MarshMonster2624@aol.com> wrote in
> news:1141604743.621888.84060@e56g2000cwe.googlegroups.com:[color=green]
> > he has learned enough to be dangerous.
> > it is very easy to warp a rotor during tightening of lug nuts.
> > MarshMosnter wonders why it takes 3 threads to diagnose a symptom[/color]
>
> Hi Marsh Monster,
>
> The three related threads were a result of each other.
>
> THREAD #1: Why does my 4Runner vibrate when I apply the brakes?
> THREAD #2: What replacement pads should we use for this 4Runner?
> THREAD #3: How do we test piston retraction?
>
> The actual titles of those only somewhat related threads are:
> #1: Bad shimmy upon heavy braking Toyota 4Runner (why?)
> #2: Can anyone tell the difference between rotors and pads (truthfully)?
> #3: Can anyone check whether brake pistons move freely?
>
> What I found out, thanks to you, from each thread was:
> #1: I have DTV which is being felt in the front steering & pedal.
> #2: A DIY can not tell the difference between pads so go OEM.
> #3: There is no tool that can test brake piston movement.
>
> As stated, I've learned a lot (enough to be argumentative :) ... but I
> still don't understand what's wrong with the referenced method of torquing
> the lug nuts half way first.
>
> What is wrong with torquing them to 1/2 torque in a triangle pattern in two
> passes and then repeating the two pass triangle pattern for the full torque
> value?
>
> Is that wrong?
>
> Stu[/color]
===========
===========
Stu,
addressing your last question.......
I find nothing wrong with that tightening proceedure.


Personally, I jest stick my Ingersol on em and have at it.
every day.
every week.
every year.
for many,many,many years.


and...like I stated earlier, i don't warp rotors.
use to.
sometimes.
once or twice.
on occasion.
but.....not for the last 15-20 years.

The proceedure you listed will work.
It's slow as snot run'n up a sand hill.
But...it'll work.



~:~
Marsh
~:~