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This is a discussion on Brake Rotor Life?? within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; I put EBC Greenstuff pads on at 30,000 miles and changed the rotors at 70k, just because of wear not ...

  1. #16
    Registered User perfusionista's Avatar
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    I put EBC Greenstuff pads on at 30,000 miles and changed the rotors at 70k, just because of wear not any issues. Now at 76k I'm going to replace the front pads but the rears still are fine. I do a lot of highway driving, but otherwise I'm pretty hard on the brakes.

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  3. #17
    Registered User AKESREX's Avatar
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    Brakes 101

    I internally debated whether I wanted to step into this but here goes......
    1) There's no such thing as a warped rotor.
    2) What you "feel" as a pedal pulsation is actually a buildup of pad material on the rotor.
    3) In the brake industry, this buildup is called thickness variation (TV for short).
    4) The usual solution to remove TV is by turning the rotors, providing a fresh rotor surface.
    5) Unfortunately, the physics of brakes implies a calorific (heat) equation. Removing mass
    from the rotor makes them heat up quicker and you tend to get that wonderful material
    buildup (TV) all the more quicker.
    6) The material buildup is called "Cementite." It may of may not be visible to the naked
    eye. If present, you will pick it up as a pulsation in the brake pedal and you will hear it
    being removed on a brake lathe as the cutter is hitting the hard spots on the rotor.
    7) Material transfer from the brake pad is a big issue. You need pad formulas that
    don't tranfer material, provide long life, don't chew up the rotor and have a high Mu or
    co-efficient of friction. Getting all that into a brake pad is quite a feat.
    8) The tire manufacturer Sumitomo was the vendor that supplied the brake pads
    originally on the WRX. They do an OK job, but they do transfer material and they are
    pretty aggressive on the rotors.

    There is an excellent white-paper writeup on Brake Tech's site that is an eye-opener-
    http://www.stoptech.com/whitepapers/...otors_myth.htm


    Lawrence
    Akebono Brake Corporation
    (supplier to Subaru, Toyota, Nissan,
    Honda, Ford, GM, D-Chrysler and others)

  4. #18
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    I have 45K miles and turned the rotors once when they had a bad vibration at about 25K miles. Been good ever since. Pads were good lat time I checked them. I do have a history of being good on brakes though. Went over 95K on my last car before needing brake pads. I'm not exactly an easy driver either, just easier on the brakes I guess.

  5. #19
    Registered User rickyh's Avatar
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    I replaced my rotors and pads at 42k. I put stoptech slotted rotors, axxis ultimate pads and stainless steel lines with motul fluid. the difference is startling. I changed everything cuz I had a bad experience with the brakes fading to nothing after two hard stops in a row.

  6. #20
    Registered User Richie03's Avatar
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    I replaced my OEM rotors at 22k with chp slotted rotors. I ruined the stock rotors by applying medium pressure while at stoplights when the rotors were very hot from agressive braking. This caused the oem brake pads to stencil a pattern on the rotors. I was unaware of what I was doing to my rotors and now I use my ebrake at stop lights when I think the rotors are hot.

    I hope this post keeps others from making the same mistake I have made.

  7. #21
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    Im in the same boat as WRCfan, 3k miles and pulsating like crazy! BTW, did the dealer charge you or did they cover it under warranty?

  8. #22
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    question about the stoptech rotors. should i go with slotted or drilled?

  9. #23
    Registered User AKESREX's Avatar
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    Given that choice, I'd opt for the slots. If the rotors are designed correctly, that's the best
    way to go. There is a "correct" way to do the slots. If they're being machined, using the
    right broach when making the slots goes a long ways toward getting it "correct."
    Too wide a slot is not a good thing, too deep a slot- obviously not good. Techique is
    also important. Do the slots go all the way to the edge of the rotor? That's really not
    the greatest technique to use. Great technique to achieve rotor fatigue & failure
    We have found that the wrong slots contribute greatly toward greatly increased brake
    pad wear. Kinda a cheese-grater effect on the pads, if you will
    Drilled rotors provide lots of good places (the holes) for stress-risers, also known as
    future cracks in your new rotors. Drilling holes in rotors also removes mass or weight
    from the rotor. Mass is part of the calorific (heat) equation..... rotors are used to
    dissipate heat, therefore it's not a good idea to remove mass from a rotor. With drilled
    rotors, there are always exceptions- holes already cast into the rotor or going to a
    much larger rotor than stock, but with cast holes. The former "solution" still removes
    weight from an otherwise stock-sized rotor and the latter "solution" looks nice and will
    perform, but ain't cheap

    Akebono Brake Corporation

  10. #24
    Registered User turbo_bxr's Avatar
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    Quote Originally Posted by AKESREX
    Given that choice, I'd opt for the slots. If the rotors are designed correctly, that's the best
    way to go. There is a "correct" way to do the slots. If they're being machined, using the
    right broach when making the slots goes a long ways toward getting it "correct."
    Too wide a slot is not a good thing, too deep a slot- obviously not good. Techique is
    also important. Do the slots go all the way to the edge of the rotor? That's really not
    the greatest technique to use. Great technique to achieve rotor fatigue & failure
    We have found that the wrong slots contribute greatly toward greatly increased brake
    pad wear. Kinda a cheese-grater effect on the pads, if you will
    Drilled rotors provide lots of good places (the holes) for stress-risers, also known as
    future cracks in your new rotors. Drilling holes in rotors also removes mass or weight
    from the rotor. Mass is part of the calorific (heat) equation..... rotors are used to
    dissipate heat, therefore it's not a good idea to remove mass from a rotor. With drilled
    rotors, there are always exceptions- holes already cast into the rotor or going to a
    much larger rotor than stock, but with cast holes. The former "solution" still removes
    weight from an otherwise stock-sized rotor and the latter "solution" looks nice and will
    perform, but ain't cheap

    Akebono Brake Corporation
    if you go with stock style rotors with the same internal vanes then dont worry about the right direction . i put mine opposite of the box labels . i even asked stop-tech thierself. its ok as long as thier not aero vanes.

  11. #25
    Registered User turbo turtle's Avatar
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    With my '02 WRX, I'm at 75k miles and tomorrow I'll be installing my 3rd set. Had StopTech OEM replacements, but those only lasted slightly longer than the stockers.... That's what a few runs down at SCR will do to ya! I'll now be trying cryo-treats

    ~Dan
    "Not just a turtle, a SNAPPING turtle!"

  12. #26
    Registered User AKESREX's Avatar
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    That's a good way to go because it actually improves the rotor at the molecular
    level. Lots of issues with rotor performance are immediately addressed

  13. #27
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    I'm almost at 50K on my OEM brakes.
    I enjoy driving it hard but not as hard as some of you guys.
    My WRX is just a daily driver. ( I do have a car that I pound on that is much faster than the WRX, but that is another subject.)

    Any way, my question is this:
    I noticed that the Subie parts dept have Hi-perf parts from the factory, including rotors.
    Has anyone tried these and are they any good?
    I was just going to order those and put them on myself.
    Advice?
    Thanks.

    WR

  14. #28
    Registered User turbo_bxr's Avatar
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    Quote Originally Posted by WR Wreck's
    I'm almost at 50K on my OEM brakes.
    I enjoy driving it hard but not as hard as some of you guys.
    My WRX is just a daily driver. ( I do have a car that I pound on that is much faster than the WRX, but that is another subject.)

    Any way, my question is this:
    I noticed that the Subie parts dept have Hi-perf parts from the factory, including rotors.
    Has anyone tried these and are they any good?
    I was just going to order those and put them on myself.
    Advice?
    Thanks.

    WR
    never saw them/ heard of them

  15. #29
    Registered User Digo's Avatar
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    I have 15k kms and I'm on my second set. I have just distryed them in Interlagos. Stock rotors do not handle extreme conditions like a 10 lap race in a F1 cicrcuit :P I'll buy my 3rd set next week.
    04 Track Seeker RED WRX
    05 Silver Peugeot 307

    http://img437.imageshack.us/img437/6847/mamao4ls.jpg

  16. #30
    Registered User cyrilgrey's Avatar
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    Quote Originally Posted by Fixxxer
    Warping is usually caused by the brake rotor getting hot and then suddenly cooling off (driving through a deep puddle, etc). The surface of the rotor will actually warp, hence the term "warping." Since the surface of the rotor is no longer perfectly flat, when you step on the brakes, the car won't come to a smooth stop. Instead, it will "pulsate" to a stop. It's the same feeling as when you try to stop on a bicycle that has a wheel that's a little bit out of shape.
    No.
    http://www.stoptech.com/tech_info/wp...rakedisk.shtml


    "Myth # 1 BRAKE JUDDER AND VIBRATION IS CAUSED BY DISCS THAT HAVE BEEN WARPED FROM EXESSIVE HEAT.


    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. I have seen lots of cracked discs, (FIGURE 1) discs that had turned into shallow cones at operating temperature because they were mounted rigidly to their attachment bells or top hats, (FIGURE 2) a few where the friction surface had collapsed in the area between straight radial interior vanes, (FIGURE 3) and an untold number of discs with pad material unevenly deposited on the friction surfaces - sometimes visible and more often not. (FIGURE 4)

    In fact every case of "warped brake disc" that I have investigated, whether on a racing car or a street car, has turned out to be friction pad material transferred unevenly to the surface of the disc. This uneven deposition results in thickness variation (TV) or run-out due to hot spotting that occurred at elevated temperatures.

    In order to understand what is happening here, we will briefly investigate the nature of the stopping power of the disc brake system...................................."
    Last edited by cyrilgrey; 10-08-2005 at 07:59 AM.
    "..are wont to seize upon people about the beginning of Autumn; and sometimes also sooner, according to the temper of the foregoing Summer, whether they had been hotter, or cooler: & they some years rage so violently, as that they last the greatest part of the said seasons, miserably afflicting people all that while, and destroying many of them - Exterminated by the Bloody Flux
    Dysentery in Eighteenth-Century Naval and Military Medical Accounts
    "

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