How do people warp their brake rotors anyway?

[BarracksSi]

I literally have not warped the brake rotors in any of my three Civics since my first one (a DX hatch), and that was back in 1990, mere months after I got it. Then, I didn't warp them for the remaining 5 years & 120,000 miles I had it, and I didn't warp the brakes on my '86 Si over the 100K+ miles I had it, and haven't warped the EP's rotors (not yet, anyway).

When I did warp 'em in the DX, it was because I would brake hard, and then keep pressure on the brake pedal even after I stopped. After learning that they warped because of my treatment, I started braking differently, and I've never had problems since.

Once I'm stopped, I don't press very hard on the pedal at all -- just enough to turn on the brake lights, and maybe a bit more if I'm on a slope.

If, for whatever reason, I have to stand on my brakes to stop in a hurry, or decelerate quickly from highway speeds, I make sure to be gentle to them once I've stopped. Sometimes, I'll let up on the pedal and the car roll a few inches so that the pads aren't squeezing the same spot for very long.

It just kills me to hear that people warp their rotors so quickly. More energy goes into braking than accelerating, ya know. Going from 60 to zero is a lot faster, so that's a lot of abuse going into those discs. Just be good to 'em, and they'll last.

[myeverlovinsir]

I think you answered it correctly, the stock rotors are easily overheated under hard braking and will fade. When you have overheated rotors the pressure you put on them at a stop will create a warp effect. I had my front stock rotors warp and there is no correction except to have them shaved and it's a pain to adjust the pad thickness to compensate. The stock brakes are not made for high endurance for sure. Get a big brake kit if you need the stopping power and even if you don't think you do, they will save you one day!
I know I would be dead in the water with the braking power of the stock rotors and pads on my setup.;)

[BarracksSi]

No, that's not the answer --

The answer is to not beat the shit out of the brakes by squeezing the hell out of them after coming to a stop. That prevents the rotors from cooling evenly, and that is what causes any rotor -- not just stock rotors -- to warp.

Like I said, after I first replaced my rotors due to ME warping them (they don't just warp on their own), I was able to last over 100,000 miles without warping them ever again, and that was just on that car. I went over 100,000 miles without warped rotors on my second Civic, and although I'm only at about 24,000 miles on my EP, there is absolutely zero hint of rotor warpage.

And these miles have all been on regular Honda discs.

[Slip_Angle]

I've read that the warping of rotors is a industry myth. According to this link, your rotors don't warp. What actually happens is that the pads overheat and transfer pad material onto the rotor, which causes the pulsating brake pedal. When the rotors are "turned" at the shop they actually remove the pad material that was transfered to the disc.

I've learned that when applying the brakes hard (especially at auto-x events) you need to let the car roll forward a bit every 10-20 seconds to let the air flow through the disc and pads so the heat dissipates.

Link: http://www.stoptech.com/whitepapers/warped_rotors_myth.htm

[myeverlovinsir]

Originally posted by BarracksSi
No, that's not the answer --

The answer is to not beat the shit out of the brakes by squeezing the hell out of them after coming to a stop. That prevents the rotors from cooling evenly, and that is what causes any rotor -- not just stock rotors -- to warp.

Like I said, after I first replaced my rotors due to ME warping them (they don't just warp on their own), I was able to last over 100,000 miles without warping them ever again, and that was just on that car. I went over 100,000 miles without warped rotors on my second Civic, and although I'm only at about 24,000 miles on my EP, there is absolutely zero hint of rotor warpage.

And these miles have all been on regular Honda discs.

Don't know if you even read what I said, but I agreed with you. I don't worry about my braking power anymore since the wilwoods have went on.;)

[BarracksSi]

Originally posted by CDN-SiR-02
I've read that the warping of rotors is a industry myth.

Hey, even better. Either way, I believe that "warped rotors" (even though it's surely burnt pad material) is still primarily the fault of the driver. It certainly was MY fault before I changed my methods.

[Slip_Angle]

BarracksSi: Ya, I completely agree with you. I do wonder though if cheap rotors can be a factor as well? I'm thinking they may develop hot spots under normal braking situations and cause pad material to transfer at the hot spot..

[BarracksSi]

I don't know if the nature of braking can allow rotors to develop hot spots. Being under severe load through many revolutions at a time, the rotors should begin heating pretty evenly. Plus, I still brake pretty hard these days (even more so after getting Mugen SS), with the only difference between now and 1990 being that I don't mash the brakes when I'm sitting still after a hard stop.

It does make sense that squishing piping hot brake pads against the rotor would transfer material. The thought never occurred to me, but I think it's correct after all.

The worst my EP's brakes ever felt was when it was parked at an air base for 6 weeks with the parking brake engaged. Every part of the rear rotors corroded (of course - no big deal) except for the areas under the brake pads. I'd feel them grind, then feel smooth for a split second, then grind again. It took a few days for the brakes to feel completely normal again.

[Slip_Angle]

I was thinking.. If during a rotor's manufacturing process the metals that make up the rotor are not evenly distributed this could cause hot spots under normal breaking. The reason I think this is because we purchased a new set of rotors for our 90 accord, which began pulsating within a month. I know they were very cheap no name type rotors and I wondered if the manufactor was producing rotors made from cheap metals that weren't "mixed" well.

For example: (And I have no idea what rotors are made from) If the rotor's content was intended to be an evenly distributed mix of 75% mild steel and 25% copper, but the copper bunched up in one area of the rotor, this may cause it to heat up quicker in that area and get hotter than the rest of the rotor. This may produce the results I was talking about.

Another theory would be that the rotor's content "mates" poorly with the pads and promotes transfer of pad material. Possibly an abrasive rotor or chemical reaction. Again, associated with cheaper rotors...

Just a theory. I'll ask google :)

[DrtyTexan]

ive been told that if your brakes are very hot and you spray them with a hose it will cause them to warp. is that true or just an urban legend?

[dofu]

i always thought that braking while hard cornering warps the rotors?

[sonic imperial]

The honda service advisor told me that warped rotors are common among import cars because they use cheaper, thinner rotors to begin with. I am not an aggressive driver and I have tried extremely hard not to warp my rotors but it still happens on average every 11,000 miles. I owned a 2001 accord and they warped just as fast. I drive 22 miles to work each day on an open highway with a few stoplights and it's impossible not to brake quickly every now and then when the light happens to catch you. I do not sit on the brakes though while stopped. It's weak mechanical parts IMO, they don't make them like they used to.

[BarracksSi]

Originally posted by CDN-SiR-02
(And I have no idea what rotors are made from)

Lots and lots of 'em are made from iron. Cheap (a lot cheaper than carbon, too), solid, good resistance to heat.

I still wonder why I've gone over 250,000 miles of driving without getting pulsating brakes.

[BlairSpeed]

This is a good thread. I've actualy learned something today! :cool:

Oh and some good links to brake kits on ebay: Click me! (http://motors.search.ebay.com/02-Civic-Si_eBay-Motors_W0QQfromZR8QQsacategoryZ6000QQsamotorscateg orymapZ6000QQsocustoverrideZ1QQsosortorderZ2QQsoso rtpropertyZ2)

[zum_zum]

man. there are a lot of questions on here. i wanted to pass on a little experience and knowledge:

it IS possible to warp rotors. the metal distorts. i have warped rotors at track events, i.e. multiple 30 minute session of HARD left-foot braking, deep corner driving. i am not a rookie at these things either. if your rotors are hot, AVOID HOSING THEM WITH WATER. rapid cooling can cause the rotors to warp, even crack.

it is true you can develop hot spots if you leave the calipers clamped, but this is under extreme conditions. similarly, if you are going to store your car, or leave is parked for a long time (weeks), DO NOT use the parking brake.

big brake kits are unnecessary. modern, 4 disc systems are more than adequate for these size cars. if you want to improve the braking, get GOOD slotted rotors, better pads with a high friction coefficient, switch to braided stainless lines, and flush your fluid regularly with a GOOD brake fluid.

some rotors warp quicker that others. it is usually because of their metallurgy. a lot of parts stores sell two different brands of rotors at different prices. the cheaper rotors are made with pot metals and are inherently inferior. personally, i think the braking system is the most crucial saftey equipment on the car, so scrimping yields less performance and puts you at greater risk when you REALLY need the brakes the most.

be careful with the brake fluid. some newer dot 4 or 5 are a silicone formula which may not work with your braking system. just because it's exotic or sold in an expensive sports car, doesn't mean it should go in yours. i will try to find a good article on that. i found it in a bmw forum a while back. motil is excellent, but valvoline synthetic is good and easily available without breaking the bank.

if you want to go with a high-performance rotor, consider a slotted rotor. the slots do not go through the rotor, compromising the structure. cross-drilled rotors can develop stress fractures and can actually shatter as a result at speed. you may not even see the fractures. i have seen this on my own car (miata) it's pretty scary and sobering.

autocross runs barely last more than a minute, and the speeds are relatively low. it is hard to get enough heat into full race pads to use them effectively, let ablone warp the stock equipment. i would be more concerned with keeping the intake and engine temps down.

regular caliper maintenance is also a must, especially those of you in the snow belt and desert/dusty areas. if the calipers are not checked regularly, the lubricants that allow them to pivot on their slides/guides can gum up from foreign particles or repeated heat cycles. they will start to "hang" or stick, with will cause them to drag the pads on the rotors, wearing out the pads and warping the rotors.

finally, if you are replacing the pads, PLEASE spend the extra $5 on new hardware (clips and springs). these can also have adverse effects on the pads and braking system too.

[BarracksSi]

Originally posted by zum_zum
man. there are a lot of questions on here. i wanted to pass on a little experience and knowledge:

Good post -- most of it I kinda knew, but it's still better to see good information like that.

Speaking of big brake kits (mainly the ones for just the front) --

Car and Driver just put out an issue under the title of "Boost" *LINK* (http://caranddriver.com/boost), and they wrote an article describing how big brake kits might do more harm than good. I'll try to sum it up in less than two hundred words...

----
The secret to shortest stopping distances is to make sure the brake system slows all four tires at their peak levels simultaneously -- that is, without locking up.

They calculated that at 1.00 g of deceleration force, a vehicle will have a 74/26 dynamic front-to-rear weight distribution. A 2500 lb car would also require exactly 2500 lbs of total braking force to achieve that same 1 g. Using the 74/26 dynamic-weight-distribution split, the front tires will have to handle 1850 pounds of braking force, and the rears need to generate 650 pounds.

Stay with me, here... ;)

The Stoptech big brake kit they're using as an example generated 62.7% more front-wheel braking force than the stock. In other words, the kit will make the front tires lock up at lower brake line pressures because of all that force.

C&D: "Although this may sound like a good thing, the rear brakes continue on along as if nothing had ever happened. This is where the fun begins."

If the stock front brakes originally reached their lockup point at a brake pressure of 1500 psi, then the big-brake kit would reach their lockup point at 922 psi (62.7% of 1500). The front brakes will still be generating 1850 lbs of force at the tires' contact patches, but the rear brakes are getting a LOT less pressure at their calipers than before.

Follow this --

Given a typical proportioning valve, when the stock front brakes were at 1500 psi, the rear brakes will be at about 875 psi. With the kit, and its lower lockup pressure of 922 psi at the front, the rear brakes will only receive 586 psi. This means that instead of generating 650 lbs of force, the rears now only get to generate 435 lbs of force.

Now...

Instead of the stock system's ability to generate 2500 total pounds of force (1850 front & 650 rear), the modified system can now only generate 2285 pounds (1850 front plus 435 rear). This ultimately is a decrease of nine percent of force, which translates into 0.91 g of deceleration.

Nine percent doesn't seem like much, but for a 70-0 stop, what was a distance of, say, 164 feet is now increased to 180 feet.

The big brake kit does generate more decelerative force for a given amount of pedal effort, but only up to a certain point. Then, its force is already great enough to lock up the front tires, and the system can't contribute any more force to braking. In the meantime, the stock system can eventually produce more braking force at higher pedal efforts.

To be done properly, and possibly decrease stopping distances, a brake kit should also include proportionally-designed rear brake upgrades, or front caliper pistons of smaller cross-section to offset the torque effects of the bigger rotor.

---

Anyway, so that's what C&D says in the April issue of Boost. Less than 200 words? I'm not gonna count 'em all...

[zum_zum]

very nice article.

[GoneImport]

I'm getting an almost violent vibration that seems localized to the right front under breaking (of course the higher the pedal effort the worse the vibration) at speeds over ~50 mph. I'm not sure if the rotors are warped or suffering from excessive brake material deposits, but I'll pursue having them turned first.

My challenge is repeated braking at speeds of 70-85 during my 40 minute commute each way to work. These crazy Texas drivers in their SUVs tailgate each other and then panic brake when they get off their cell phone and realize they're about the rear-end the SUV they've been tailgating. I miss European driver lane discipline.

Now after all that, what I really need to know is who is really pleased with their slotted or cross drilled rotors. I'm not looking to go with a pricey brake kit, as this is my commuter. I don't want to flame or be flamed but my visceral automotive exhilaration is provided by a serious V8 powered American car.

[mhx]

you can easily warp rotor's.. This can happen say if your driving on the freeway you brake hard.. say some1 cuts you off or something.. so you heat your brakes a bit.. then hey 2miles down the freeway it starts to rain..... boom.. and your just about to exit the freeway.. and somehow theres 1/2in of rain on the road.. u go to get off the free and use your brakes hard.. and boom mass cooling on a really hot surface can warp metal.

[TrippZ]

after reading all this i want to invest in steel lines, slotted rotors, and new pads... and i can paint my calipers while im at it too! :)

[TrippZ]

well ladeda, look what i found about 20 seconds after this...

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33564&item=7907202572&rd=1

[GoneImport]

According to Honda service, my rotors were warped. They called my wife to let them know they wouldn't cover the repairs under warranty and said that it would cost ~$130 to turn them. She told them no thanks and that I was going to replace them with aftermarket performance rotors to avoid this in the future. They decided to turn them under warranty so I should be good for another 15-20K miles before I need to upgrade. I bought both my Hondas from them about a year ago so they probably don't want to risk losing a customer over 130 bucks.

Maybe I'll upgrade to the S2000 instead. They've dropped one on the lot to $29,650... mighty tempting - only thing that keeps me from buying it right now is the thought of using such a sweet car for commuting.

[BarracksSi]

... only thing that keeps me from buying it [the S2K] right now is the thought of using such a sweet car for commuting.

But imagine how sweet the commuting would be if you had it.... :D :D

That's a bummer about your dealer not covering the warped rotors. Did other dealerships tell you the same thing?

[zum_zum]

not an s2k, but i have a miata i use for commuting sometimes. it can be little inconvenient if you need to carry something large home (rarely). great for unwinding on athe way home from a stressful day, though. :D