myth of warped disks

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Danny D. wrote, on Wed, 05 Nov 2014 07:55:59 +0000:

This is the key!
Everyone thinks they're a diagnostic genius when they replace rotors and their "warp" magically instantly goes away.
Yet, they start to complain about the car's brakes when the warp comes back, over time.
They don't realize, most of the time, THEY are the reason.
The short term problem is the same, whether it's really a warped rotor or if the rotor has simple DTV, for example.
But, the long-term solution is totally different - but you can't get there, until you understand what caused the vibration in the first place.
And, it wasn't warp (as in potato chip).
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Danny D. wrote:

Hi, Don't believe rotor disc can be warped? Days when they used cast rotor, warp story was never around. To reduce weight(?) they started using light weight rotor. When lug nuts were over tightened, things started happening. Now every one pays attention to lug nut torque.
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On Wednesday, November 5, 2014 11:06:46 AM UTC-5, Tony Hwang wrote: When lug nuts were over tightened, things started

Sadly, that has not been my experience. Overtorqued lug nuts are the norm.
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Thanks. I'l give your tips a try. I have noticed that the oscillation is not always there, so your explanations make sense.
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I have measured warp on street-use rotors, but that warp was a _consequence_ of some other problem. People drive around with bad steering bushings, they get severe shimmy, and when they get that shimmy on braking it causes uneven rotor wear, etc.
So, I'd say you're kind of correct and kind of incorrect. --scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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On 11/4/2014 12:46 AM, J Burns wrote:

Well, by golly, if you read it on the internet, it must be true.
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On 11/5/2014 8:20 AM, Mike wrote:

Well, by golly, NOW we really have a problem. It's also been said that simply because it's on the internet doesn't meant that it's true.
Damn... I feel so conflicted.;)
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On 11/5/2014 9:41 AM, Unquestionably Confused wrote:

Wait till a couple days after voting day, and the confusion will settle down to a bit of harping by the radio hosts.
And, I approved this message.
- . Christopher A. Young Learn about Jesus www.lds.org .
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TimR wrote, on Wed, 05 Nov 2014 08:40:39 -0800:

And that would cause, most likely, runout, not warp (as in a potato).
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Scott Dorsey wrote, on Wed, 05 Nov 2014 08:01:56 -0500:

It's not "me", it's the record. https://www.google.com/search?q=myth+warped+rotors
However, it begs the question.
How did you measure this warp?
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Mayayana wrote, on Wed, 05 Nov 2014 07:54:13 -0500:

As you rebed the brakes the pad deposits can change, and what oftne happens is that the "character" of the vibration changes (either the speed at which it starts and stops, or severity, or whatever).
That's a good clue that you're dealing with deposition and not some mechanically different problem, such as warp.
Rebedding would *never* change the character of warp. Rebedding *often* changes the character of what people "call" warp.
The long term solution is different when there's real warp involved from when it's merely DTV or BTV due to uneven pad deposition.
Good luck. Let us know how it works out. Once you understand this beast, you can drive with more finesse on the brakes.
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Mike wrote, on Wed, 05 Nov 2014 09:20:59 -0500:

Nobody is saying that except you.
Specifically, we provided a ton of good references, and we all know you can find hundreds of thousands of Internet references where people actually think their street rotors warped.
You're the only one saying that it's true because YOU read it on the net.
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Danny D. wrote, on Wed, 05 Nov 2014 19:05:00 +0000:

I apologize for my tone. It bothered me that Mike took things wholly out of context, but, I should have simply ignored the post.
I apologize for not being civil.
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With a dial indicator of course. Although the sort of problem caused by uneven wear can be detected even with a micrometer because the thickness varies. --scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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On Wed, 5 Nov 2014 07:55:59 +0000 (UTC), "Danny D."

We ALL know a cold is caused by a virus - but what experts like you forget is that virus is always around - and in most cases it does not make you sick because yourimune system fights it off. One way your body kills virii is by the use of HEAT. That's what a fever is from - your body fighting off an invader.
Lowering your body temoerature can reduce your body's ability to fight off the infection - thereby CAUSING you to CATCH a cold.
Does the cold temperature and wet CAUSE the cold???? Nope. But that does not mean going out in the cold and wet without a hat and cold is a smart move and will not increase the likelihood of you catching a cold????? Only a fool believes that.

The only long term solution to genuinely warped rotors is to use high quality, well engineered parts and don't overheat them. Not overheating them requires proper service and maintenance and proper driving habits.
Poor quality parts, insufficient maintenance, OR bad driving habits CAN cause genuine warping - as well as the problems you insist are the ONLY common and misdiagnosed cause of brake pulsations generally referred to as "warped rotors"
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On Wed, 5 Nov 2014 07:59:51 +0000 (UTC), "Danny D."

You still do not know the definition of warp. Warpage is distortion of the shape of the rotor from external (and usually thermal) forces. Doesn't matter if it is "classic" potato chip, "ruffles" or what you call "run-out". What defines warpage is what causes it. Warpage does NOT include material deposit or wear, or corrosion damage.
Distortion from heat DOES happen on street driven vehicles - and it is much more common on a vehicle after the rotors have been cut to "correct" "warpage" by any definition because cutting the rotor reduces it's thermal mass, it's stiffness, and therefore it's resistance to overheating and warpage.
It is also more common a vehicles towing a trailer or otherwize operating under higher than normal load conditions or higher speeds.
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wrote:

IMPROPERLY torqued wheels does not necessarily mean overtorqued. Unevenly torqued, and not sequentially torqued can also cause a problem. Unevenly torqued is more dangerous than overtorqued when it comes to disk warpage or runout. (and USUALLY torque problems cause a runout condition which can often be remedied by simply retorquing the wheel PROPERLY if caught on time.
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On Wed, 5 Nov 2014 07:20:17 +0000 (UTC), "Danny D."

You really ARE a bloody idiot, aren't you??? You expect a mechanic to take and keep pictures of every repair he has done in his lifetime? When cameras on cel-phones (heck, even wireles phones) didn't exist - and nor did digital cameras. Even Polaroids were a novelty for halt that time - and we DID photograph some uncommon warranty problems and attach the polaroids to the warranty claims.

Do you have a picture of yourself being born, to prove you are not an alien and were not hatched????
Give it a rest already. You are in WELL over your depth.

And you have still not told us the difference, in your jaundiced eye, between run-out and warpage.
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On 5 Nov 2014 08:01:56 -0500, snipped-for-privacy@panix.com (Scott Dorsey) wrote:

And loose or worn suspension parts will NOT cause warpage or runout. They MIGHT cause uneven wear. However, driving with shimmying brakes CAN cause suspension component wear
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On Wed, 5 Nov 2014 07:25:02 +0000 (UTC), "Danny D."

I DID read them. I could have written half of them.

Your definition is NOT a definition. - so how could I change the definition. You have still not defined warpage, other than to say it is not runout and vaguely referring to a "potato chip"

That is YOUR "expert".
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