Tippy

I have read the article in the past.

I guess Society of Automotive Engineers have always had this scenario wrong........

Here is an exert from Wikipedia. Before you shoot it down as not being credible, look at the references after the summary.


Warping is often caused by excessive heat, which softens the metal and allows it to be reshaped. The main causes of overheating are: undersized/overmachined brake discs, excessive braking (racing, descending hills/mountains), "riding" the brakes, or a "stuck" brake pad (pad touches disc at all times).

Another cause of warping is when the disc is overheated and the vehicle is stopped. When keeping the brakes applied, the area where the pads contact the disc will cause uneven cooling and lead to warping.

^ Crosley Firsts. Retrieved on 2006-05-20.
^ WHAT MAKES A CLASSIC CAR?. CLASSIC CAR. Auto Lemon. Retrieved on 2006-05-20.
^ The Avanti - Born in Palm Springs. Retrieved on 2006-05-20.
^ Henry, Alan (1985) "Brabham, the Grand Prix Cars" p. 163 Osprey ISBN 0-905138-36-8
^ Abdelahamid, M. K. (1997), "Brake judder analysis: Case studies", SAE, Technical Paper Series, no. 972027.
^ de Vries, A. et al. (1992), "The brake judder phenomenon", SAE Technical Paper Series, no. 920554.
^ a b Engel, G., H. et al. (1994), "System approach to brake judder", SAE Technical Paper Series, no. 945041.
^ Gassmann, S. et al. (1993), "Excitation and transfer mechanism of brake judder", SAE Technical Paper Series, no. 931880.
^ Jacobsson, H. (1996), "High speed disc brake judder – the influence of passing through critical speed", In EuroMech – 2nd European Nonlinear Ocillation Conference, Prague, no. 2, pp. 75–78.
^ Jacobsson, H. (1997), "Wheel suspension related disc brake judder", ASME, no. DETC97/VIB-4165, pp. 1–10.
^ Jacobsson, H. (1998), "Frequency Sweep Approach to Brake Judder, Licentiate of engineering", Chalmers University of Technology Sweden.
^ Jacobsson, H. (1999), SAE Technical Paper Series, no. 1999-01-1779, pp. 1–14.
^ Stringham, W. et al. (1993), "Brake roughness – disc brake torque variation", rotor distortion and vehicle response, SAE Technical Paper Series, no. 930803.
^ Thoms, E. (1988), "Disc brakes for heavy vehicles", IMechE, pp. 133–137.
^ Anderson, E., et al. (1990), "Hot spotting in automotive friction systems", Wear, v. 135, pp. 319–337.
^ Barber, R., J. et al. (1985), "Implications of thermoelastic instabilities for the design of brakes", Jnl. Tribology., v. 107, pp. 206–210.
^ Inoue, H. (1986), Analysis of brake judder caused by thermal deformation of brake discs, SAE Technical Paper Series, no. 865131.
^ a b Rhee, K., S. et al. (1989), "Friction–induced noise and vibration of disc brakes", Wear, v. 133, pp. 39–45.
^ Kim, M.-G. et al. (1996), "Sensitivity analysis of chassis system to improve shimmy and brake judder vibration on the steering wheel", SAE Technical Paper Series, no. 960734

1999Porsche911

Regardless of what the "wikopinion" says, if you have ever been involved in the process of hardening metals, you would understand that a rotor is much to hard (as evidenced by it's cracking) to warp from the reletively low temperatures you created while braking, unless you can get them to above 2000F. Becoming "out of round" is not warping and can only be caused by improper installation.

rcronin

Now with some extra thought on this topic, it came to my mind that when I ran club racing with sport bikes that every few races we pulled the rotors off and took them to be bead blasted to remove the pad material build up. I didn't have any judder issues but with the heat induced to the rotors, I had some extra build up of material.
Once blasted I was able to bed in new pads and the world was anchored yet again.
I wonder if getting new pads and having these rotors blasted would be the short answer cure? Should would be the cheapest.

LVDell

You bet your **** I do! Hence the reason anecdotal evidence like the stuff Cory is subscribing to really throws my panties into a tizzy.

AND FOR THE LOVE OF GOD......QUICK CITING WIKI AS A SOURCE!!!! There is a reason we have BANNED it as a reference at the university as well as many across the USA.

1999Porsche911

You used to be able to by carbon steel pads for just this purpose, however, many modern pads are hard enough to accomplish the same thing.

Tippy

Anecdotal? A Society of Automotive Engineers stating this as fact is anecdotal?

My creditibility and the facts supporting me is higher than anyone on my opposition.

StopTech, a relatively new company versus 40+ years of brake rotor knowledge?

And like I said Dell (knowing you are a Professsor), before you shoot down the reference, consider its references.

LVDell

It's not the reference that I am shooting down, it is the source that "holds" the reference. If I wanted to I could march right on over to Wiki and change that entry as I see fit. Stop Tech has a good rep in the industry (brakes) but citing Wiki when you have NO IDEA if the info is 100% accurate or not is a bad habit to get into. Just because the society of some engineers name is used doesn't make it real. But go ahead and believe it.

I assume you ahve read this from Stop Tech on their OWN website that there is no instances verified by them of a single warped disc?

The term "warped brake disc" has been in common use in motor racing for decades. When a driver reports a vibration under hard braking, inexperienced crews, after checking for (and not finding) cracks often attribute the vibration to "warped discs". They then measure the disc thickness in various places, find significant variation and the diagnosis is cast in stone.

When disc brakes for high performance cars arrived on the scene we began to hear of "warped brake discs" on road going cars, with the same analyses and diagnoses. Typically, the discs are resurfaced to cure the problem and, equally typically, after a relatively short time the roughness or vibration comes back. Brake roughness has caused a significant number of cars to be bought back by their manufacturers under the "lemon laws". This has been going on for decades now - and, like most things that we have cast in stone, the diagnoses are wrong.

With one qualifier, presuming that the hub and wheel flange are flat and in good condition and that the wheel bolts or hat mounting hardware is in good condition, installed correctly and tightened uniformly and in the correct order to the recommended torque specification, in more than 40 years of professional racing, including the Shelby/Ford GT 40s – one of the most intense brake development program in history - I have never seen a warped brake disc.

1999Porsche911

Sorry, but referneces are meaningless especially when they can't be verified. Go back and read medical journals from the 50's and you'll find all sorts of witchcraft cures that either proved worthless or even deadly. BUT, they were all sanctioned by the worlds most repsectable people.

Tippy

Ok, so I have to believe you guys reference but you dont have to believe mine? I give up, there is no need to carry on then. I am reading Engineering papers other than the ones from Wikis site and you guys are reading StopTechs website. Funny, no one respects Ford on this board until it favors them, especially 35 year old info.....................the GT-40 program?

Here is another paper on the possiblility of brake shudder:
http://www-personal.umich.edu/~jbarber/TEI.html
Take it for what its worth, probably nothing here.

1999Porsche911

MY reference is actually working with metal, from smelting to softening and hardening. If you want proof, take your "warped" rotors off and give them to a good machine operator. Have him only remove the 80% of the high spot and collect the material. You will not find disc metal in the sample.

You can then post your finding on Wikopinion and maybe someday, someone will use your test as a reference.

BTW: I did not link you to Shoptech for a reference, but because they pretty much had what I I was too lazy to explain to you. Since I know ALL things knowable, there is never a need for me to post references.

.

LVDell

Time for me to jump ship. Damn, sometimes I wish I was just ignorant so I didn't get into these discussions.

Tippy

Funny you mentioned this, I was going to say the same thing. You have to do analysis to check for content. This is the only 100% guaranteed, signed, sealed, and delivered way to determine.

But since none of us are going to do this test for the sake of the debate, we are both right, and both wrong. We all are going off of someone elses data. That, no one can deny.

1999Porsche911

Been there, done that. Summer of 1975. Testing completed by engineer from Sperry Univac in Danbury, CT.

There IS only one correct answer. I will not be so bold as to say that you are wrong, but I am definately right.

Tippy

[QUOTE=1999Porsche911;4576662]Been there, done that. Summer of 1975. Testing completed by engineer from Sperry Univac in Danbury, CT.

You witnessed or read about? If you read about the test, give me the link, I would love to be proved wrong so all I have to do is use glass cleaner and tissue on my rotors to get rid of the current shudder I have.Just kiddin'

Tippy

Sorry this is such an inconvenience for you. I was told one thing, you were told another. We have opposite opinions that came from hearsay, neither of us actually tested a rotor.

Oh, and by the way, you were the one who said never to turn rotors. If you are not taking away parent metal of the rotor when they are being turned, what is the big deal?

Your just removing brake pad material getting back to the rotor.