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


Wrong - been certified as a brake expert in Federal and State courts, having 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 years - rotors warp out of plane. And I have pulled off a fair number of rotor plates that were definitely 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 be 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 the rotor can also have an effect on this as well."
Check out what they said about the rotor in their excerpts above- "it's not 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 face 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 plane, the part the shoes contact).
2) "Excessive lateral runout" means the plane of the rotor face is no longer 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 get 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 down. 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 of force into floating claipers and transversely into the axle. 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 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 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 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, the problem is gone.)
and it seems

the man ought to read the specs in the vehicle manuals, which do indeed list tolerances for rotors. And he ought to get some in depth background first. 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 machining in 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 a 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 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 the rotor is true?) and the face of the rotor plane has just warped, and so they are saying that instead of the rotor needing replacing because the thickness varies, the rotor needs replacing because the thickness varies and the esoteric DTV 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....

There are regulations - Check out the following standards for brake materials: DE3A, BEEP, NHTSA FMVSS-105

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

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I can't tell the difference between my head and my ass.
But my ass tells me that rotors warp and pads do not.
My ass also says that rotors rotate and pads do not.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
It should also tell you that pads can glaze over and lead to hot spots of rotors which can warp the rotors. Pads can be a big factor in rotor warpage.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I think its told me that before.... sometimes I listen ...sometimes I don't
sometimes it says that on a front wheel drive if the wheels are not torqued correctly (lug nuts) that ii can lead to rotor warpage..
The ASS knows... :)
Just a little humor :)
Sometimes my ass gets really pissed when the rotors warp on the accord, but then it remembers that the accord been many miles...between brake work.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.