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Len, I can tell you in the service station as a kid, we turned our own. More than once I turned rotors that were quite far from factory true.
I did too, heck I still take rotors in to have turned. I was on another forum and the concensus was that it's not the rotor that warps but brake pad dust & dirt that sticks to the rotor?

Supposedly you can clean it off and keep on driving?:WTF Must be this new school stuff. :laughing:
 

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We have had this discussion here before and it all boils down to your interpretation of the word warped. I have had the Rotors on my Z06 changed because they were Per Chevrolet they were "Warped and Cracked". (The dictionary says. WARPED: to turn or twist out of or as if out of shape; especially : to twist or bend out of a plane.).

To me that is what all these Brake experts describe when they talk about brakes pulsing, coning, or becoming thicker or thiner in spots.

I do not understand Why it is so important to them not to use the word warped. By any other name the Brake Rotor still needs repaired in some manner.

My 2cents.....:huh:
 

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OK, I have owned this '72 here for some 12 years, street driven daily....i'ts my hotrod, and I enjoy hell out of it, working on it, allthough it reminds me of a BOAT sometimes.....as in Break Out Another Thousand.....well afterall it IS iron surrounded by FIBARGLASSSSSSSS.....???

anyway....the brakes issue falls into very simple terms for me, over the years....number UNO....SS lined calipers, TWO...O ring pistons and toss the springs, THREE, NEW FRESH HOSES....., FOUR....HYDRABOOST......
the rotors are so far down the list as to be allmost inconsequential unless you are RACING...then it's all bets off....

IMO, buy new rotors as I did for a swelled brake hose NOT releasing drivers front pressure and a some 60 mile limp home with the LF tire hating life....and the car all OVER the road at 35 mph....I can say that....

buy NAPA front rotors and new VBP Orings/hoses/local stockish pads...and have OVER with it....

BTDT, the rears are far more 'sensitive' than the fronts...why I dunno, I suspect because of the slop in the 'HUB' type because of IRS...there is no purchase on the bearings...so any slop there is harder on rotors, well , DUH....
 

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The author of the article specifically refers to Ford products. Maybe they don't warp....;)

I agree the whole affair may be a matter of the definition of "warped." Ford racers may have a defintion the rest of us don't share.

Regardless of whether they "warp," Corvette rotors can, and do, get out of true. When they do, you've got brake problems on the near horizon.

:thumbsup:
 

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This uneven deposition results in thickness variation (TV) or run-out due to hot spotting that occurred at elevated temperatures.
I think this is the key. Thickness variation, what I called unparallel surface when I was in the business, is usually what happens. I guess it is a form of warp ....

Part of the rotor wears faster than the rest of the rotor thus causing a pulsing pedal.

My .02 :thumbsup:
 

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If we assume that what is said in this article is correct then I'm not sure that our "old" way of thinking was wrong, just the reasons behind it. In other words, when we perceived that the pumping was the result of warped rotors, we turned them. It really doesn't matter if it is the shape of the metal or the un-evenness of deposition that causes it, turning will cure it.

This article does, however, explain something that has always bothered me. When you turn a rotor, I've always noticed that the warping returned fairly quickly in relative terms. Conventional wisdom was that the rotors were thinner from having been turned. They aren't that much thinner though and it always bothered me that there was so much effect from such a small relative reduction in thickness.
 

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personally I can`t believe Carroll Smith would say "There is no such thing as a warped rotor"......Chrysler products are notorious for having thin rotors that warp and have to be replaced...type "Jeep rotors" into your browser and see what comes up. I have a 99 Chrysler Concord (wifes DD) ...pedal pulsated at 34K mi, went to Chrysler thinking warranty!!!! service writer says warped rotors, next breath rotors are a "wear" item.....NO warranty on wear items. Warped rotors DO exist.
...redvetracr
 

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If notors don't warp or another way of saying the same thing, become 'out of round' why is it necessary to have a minimum thickness and if not within that number YOU must replace. And why replace if they dont warp? They should be good forever with this mans logic. No more cutting rotors, just let that pedal jump all over the place. The guy that wrote this article needs to go out in the real world :laughing:
 

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When I was a parts manager at a major auto repair chain that has since gone belly up (Monkey Wards), it was SOP to store the brake rotors on edge so they didn't warp IN THE BOX, and to put a "clean up cut" on every rotor that was installed. Reason? Warped right from the factory or during shipment. I think the author of that article must live in a very special place...FANTASY ISLAND!!! :laughing: :laughing:

Dep
 

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I think this article has been pulled out of it's context I only read the top bit though. Like Howard said, it's not just someone who wrote that. If you have any interest in racing and racing engineering you know damn well who carroll smith is. Engineer to win, tune to win, drive to win, prepare to win and his fastener hardware books are some of the most valuable pieces of info you can find.

Now, why do I think it's taken out of context? Because it most likely refers to RACING primarily, where dyno bedded rotors are commonplace. What you do NOT see in racing (or the driver is plain stupid) is people braking hard and then standing waiting for the traffic light with the foot on the brake (something hardly to avoid w/ an automatic), what this does is it insulates part of the rotor where the rest cools. You can usually see this where you see the outline of the pad on the rotor. Sort of like branding. You will leave a mark of pad material on the rotor and you will feel it every time you brake if you get a severe enough imprint. The friction coeff. of that area will be different from the rest.
That's however not a warped rotor, it's jut an improperly bedded rotor. I'm convinced however warped rotors do exist, in fact I have 1 warped rotor on my daily driver now. It's a cheap rotor but it's fairly new, brakes were properly broken in and I never keep my foot on the brake. There's no visible stains from uneven bedding (although you can't always see that) It's a non vented rear rotor, they're pretty thin. You can hear it chirp chirp when driving at slow speeds and a dial indicator will show the runout on BOTH sides of the disc.

Now breaking in new pads and rotors is important to form an even boundary layer (pad material transferred into rotor so you have a similar surface on both sides) if you mess it up and heat cycle the rotors you're screwed, you'll have to have the rotors turned or use some pads that are more abrasive to remove the old layer.

As for the minimum thickness, the pad is not the only thing that wears, so does the rootr so you will have a minimum thickness to deal with, even if you don't have them resurfaced
 

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stopped reading the article part way thru, on purpose -- obviously carol sith is pulling somebody's leg, i don't need b/s clutter in my limited cranial cavity.

i have driven some street cars well over 100k, using soft pads so that the pads wear out and the rotors never do -- never got a ''build-up'' of pad material on a rotor...a few months ago, the wif's cart had extreme pedal pulsation, i threw on new front rotors (cheaper than turning) and left the OLD pads on cause they looked ok -- NO pulsation or vibes since.

breaking in new rotors, or pads really does make the car stop better, so i do do it, but the theories in stoptech's article are just do-do (as in doggie)
 

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I turn my new rotors before I put them on just to make sure they are true. I get it done for free so I don't see a reason not too.
 

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When I was running bikes we bead blasted the rotors whenever we changed pad compounds to get the old friction material off the ductile iron or stainless....

Also we used fixed calipers and floated the rotors with special buttons/bolts so that they could move side to side...

FWIW
 
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