Warped 2006 4runner rotors 200 miles....

Discussion in 'The Garage' started by Matt fe2o3, Feb 10, 2014.

  1. ohgood

    ohgood Long timer

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    i'm not saying you're wrong, but


    it seems very odd that RUST will wipe right off with one or two applications driving around the block but cosmoline will not ?

    i've had axle grease on my rotors before from a wheel bearing change (accidents happen) that i didn't realize. it actually made it's way all the way around the rotor, filled all the holes evenly, and only made the brakes less usable. after i realized that mistake, a pressure washer (to blast out the holes) and then brake cleaner was the fix. i can't imagine a car's rotors, with so much more material, would warp from a thin coat of cosmoline.

    but, i'm wrong

    a lot :lol3
    #21
  2. jachard

    jachard Been here awhile

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    Are you guys bedding in your rotors/pads correctly? Many times a symptom of "warping" is just bad brake pad material transfer to the new rotors. New rotor/pad procedure should be as follows:

    Installation:
    1. Rotor surfaces should be THOROUGHLY cleaned prior to install.
    2. Hub mating surface should be cleaned with a wire wheel prior to install.
    3. Wheel lug nuts should be properly torqued, using a torque wrench, not an air gun.

    Bed In on the Road:
    1. Perform 3 runs from ~30MPH to 10MPH with each run gradually increasing brake pressure.
    2. Repeat above procedure using 60MPH down to 20MPH.
    3. Drive around after so as to allow the brake components to cool back down.

    I've followed this procedure and never had any issues on all of my vehicles( race cars, bikes, trucks etc.)

    Cheers, James
    #22
  3. Matt fe2o3

    Matt fe2o3 Been here awhile

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    Well as an update to my 4Runner, the replacement rotors seem spot on. A few days or driving around and they fell exactly like they should be.

    I was also surprised that the rotors "warped" in such little time due to the coating left on?, certainly as another poster pointed out that to the point of hitting the guards did not add up.

    I did look at the rotors that came off and there did seem to be some dark areas on the right rotor, but nothing that indicated "oh wow".

    So whatever was done, it has been undone and the brakes seem fine. Perhaps he put the pads in backwards.... or one dropped down put of position. Somewhere here on ADV there is a picture of exactly that (backwards).... Good grief.

    Anyway I guess I chalk one up to the "I dunno God" and keep monitoring.
    #23
  4. concours

    concours WFO for 41 years

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    Come North to the rust belt... where we replace rotors TWICE as frequently as the sunny South. The Iron oxide, which is much harder than any of the host materials destroys rotors. The creeping rust causes "thunder" (noise/vibration/pulsation) without EVER having an overheating event, etc.
    So, yes, the light dusting of rust from a rain polishes right off... but it doesn't stop there. :clap
    #24
  5. concours

    concours WFO for 41 years

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    NAPA calls it "premium" to differentiate between the horrid shit price leader meant to compete with AutoDrone $20 rotors, or so my local Napa store manager explained. I'm not a big NAPA fan, but reference them due to widespread availability/familiarity.
    #25
  6. gmiguy

    gmiguy You rode a what to where?

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    From a friend who has 10+ years experience with the fundamental design, failure analysis, and testing of automotive disc brakes:

    "The rotor metallurgy and dimensional control on el-cheapo rotors is fine for daily drivers. Rotor warping on a street-driven vehicle is almost certainly not a parts-quality issue. Proper lug torque and bed-in is essential."

    I know that he and his similarly experienced co-workers all run cheap Chinese rotors on their street cars, and treat upgraded street car rotors as little more than a punchline.
    #26
  7. ohgood

    ohgood Long timer

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    I'll trust your rust is a more frequent replacement if worn rotors, but how does it warp them ?

    and the cosmoline bit ?
    #27
  8. concours

    concours WFO for 41 years

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    It's uneven, and the friction coefficient is less than the iron, so the slip/grab scenario again, resulting in uneven heating/wear. This is hard core rust, well adhered, not just the light orange dusting from rain. It's black, usually worse on the back (tin shield) side. If a car is short tripped in the winter, it's not uncommon to have to shatcan rotors 2yo, with 10K miles. :huh
    #28
  9. H96669

    H96669 A proud pragmatist.

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    Lets see....GM POS rotors, failed from corrosion at less than 10,000 miles?? I am up to my third pair of fronts and I should do the rear soon.

    The first time I went to the GM dealer and they turned them/installed new pads. Under some sort of warranty/good faith from them they don't usually cover corrosion issues.:evil

    In any case they wouldn't install new rotors.:D They warped shortly after, I couldnt fix it myself from lack of time and not wanting to do that outside in the winter so I kept driving in the salt.

    Less than 10,000 miles later they looked like that, good old "Pig Iron".:lol3

    [​IMG]

    I am trying something with the new pair of cheap chinese I just installed, may or may not extend their life. I'll know for sure in a year or so.:wink:
    #29
  10. concours

    concours WFO for 41 years

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    Thanks for posting the images of crusty rotors... :clap hard to imagine for those not in the salt belt. :huh
    #30
  11. MrBob

    MrBob Certified Geezer

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    This can be problematic. Factory specs for my AWD van call for a hundred pounds on the nuts but I'm convinced that cranking them to spec contributes to warping. What to do?
    One study that I read stated that warped discs are more often discs with deposits of brake pad material that cause grabbing.
    #31
  12. SteelJM1

    SteelJM1 Undercover KTM rider

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    Yeah thats usually the case. Its definitely whats going on on my car. Im going to try different pads for when its Big Overhaul time in 15k miles.

    This is the only car ive ever had problems with. And ive done dozens of brake jobs.

    As far as your lug specs, do them in stages, preferably with the wheel in the air. 50, then 75, then 100 and see if that helps.

    Sent from my Tandy 1000 mobile using DOS
    #32
  13. H96669

    H96669 A proud pragmatist.

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    I got more if you want....the quite expensive and apparently very good Akebonos brake pads where the rust got between the friction pads and backing plate and then lifted the pads off the plate.:eek1:eek1:eek1

    Third set of pads/rotors at less than 40,000 miles. One front wheel bearing last december where the shop commented on the rust/hard to remove bearing and then way overcharged me and returned the car with a rubbing brake shield.:puke1

    And just yesterday drove it again, forgot to turn on the music only to realize the other wheel bearing is whining.:puke1 More $$$$ but kind of hoping that one is the source of the "now constantly on" ABS fault lights. Hoping because the shop with the good code reader can't find any fault codes.:eek1

    I don't have a puller for DIY but the local guy will do the job for about half what them city guys charged me.And unlike the "city" shop will answer my questions on the provenance of them wheel bearings, he recently got me motorcycle wheel bearings that I sent back as they were from China.....and got me some better ones from Bulgaria and Argentina but I do trust SKFs.:rofl
    #33
  14. concours

    concours WFO for 41 years

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    I had some NAPA "Premium" rotors develop pulsing/thumping, hard spots in the iron.
    [​IMG]

    [​IMG]

    [​IMG]
    #34
  15. troidus

    troidus Long timer

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    This. I run the nuts down snug with my fingers, making sure the wheel is seated evenly, then come up to torque in three stages. Then I make one more pass to make sure that final tightening didn't cause any of the others to loosen. The first one will often loosen up as the other four are brought up to spec.
    #35
  16. big-t

    big-t Been here awhile

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    This is a classic example of warped rotors,although the term "warped" is misleading.
    The problem starts with rotor runout or wobble.The rotors develop thin spots on one side from the pads brushing the same spot each revolution.Then as the pads squeeze the rotor while rotating they hit the thick and thin spots causing the pulsating sensation.
    Most mfgs only allow a .0005 variation in rotor thickness all the way around.

    The cure is to bolt the rotors to the hubs and check them with a dial indicator to get them to less than .003 runout by cleaning the mating surfaces or rotating the rotors to a different lug position.

    worst case you may have to have them trued with an on the car lathe.

    I bought one of these http://www.procutusa.com/ when they first came out years ago and it has cured any come back issues.In fact most auto mfgs are requiring their dealerships to have one.
    #36
  17. SteelJM1

    SteelJM1 Undercover KTM rider

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    Perhaps ill try that, a shop with an on-car lathe. Hopefully its ok to let the subaru AWD system rotate in the air like that.
    #37
  18. showkey

    showkey Long timer

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    BIGT Wins^^^^^^^^^^^^^^^^^^^ the entire system must be "trued" as an assembly.

    Very very common industry wide problem...........and is why the on car lathe was invented.........any other solution is just random luck in parts variation. Variation is not code for quality or lack of it due to tolerance stacking when multiple parts are assembled.

    Plus the clown at the tire store with the air gun set at 300 ft lbs is a whole another variable.
    #38