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Thread: machined brakes + pads = terrible

  1. #1
    Join Date
    Mar 2009
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    Default machined brakes + pads = terrible

    Got my brakes machined under recommendation of the service manager and got new Hawk HPS front pads put on. Are they meant to feel really really crap when i start out or should it be a instant feeling of great breaking.

    Because, at the moment my brakes feel like utter rubbish.

    Is there a bedding in period where everything tightens up and becomes responsive?

    I followed to instructions on running the pads in i.e get to 60, break to 10, rinse and repeat 6 - 10 times. then do 2 stops from 35km/h to 0 with heavier brake pressure.

    But they still feel worse then when i had my worn pads, and apparent warped discs.

  2. #2

    Default

    sometimes better brake pads with have a shiny outer coating which is not as grippy as the material underneath. it takes up to 1000miles for some bpads to wear in.
    they shouldnt feel crap tho. they should still stop good and feel solid. they will get much better with age. also, try changing your brake fluid to something like motul dot 5.1 or something thereabouts. much better brake feel and more resistant to overheating.
    Last edited by MaN|aC; 01-06-2009 at 11:47 AM.

  3. #3
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    Default

    Oh fair enough. So over time they should get better. I got the Mobil Dot 4 Hi Temp MOBIL 4 brake fluid put in.

    Ill suss it out over time and see how it goes. It has only been 1 day.

    Thanks for that

  4. #4

    Default

    it took around 100 - 200 kms of driving for mine to bed in. Give it time.

    It wouldn't hurt to get a can of brake cleaner and give it a good spray. Just incase the mechasic had greasy hands while putting them in.

  5. #5
    Join Date
    Dec 2008
    Location
    Carindale
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    Default

    Because i like to think im the next shumacher, i somtimes may drive my car hard around corners etc!
    the result!
    at 40,000, new pads, new discs!!
    at one stage i was using the handbrake to help me stop!!
    The grinding was not good!! hahah, all up inc the sevice around the 1400 mark... ouch!! um.. credit sir??

  6. #6

    Default

    On Friday night I installed Hawk HPS pads front and rear. Apparently the MPS 3 and 6 use the same pads in the front (HB 549 F.702).

    The crappy feeling you have might be rotor contamination as suggested, or it could be the bedding in procedure gone wrong. A couple of things i did differently, which you might want to consider at your next pad change:

    1. After machining the rotors I ran them with used pads for a while to bed in the surface.
    2. To bed in the pads I drove the car completely normally. No special procedure.

    The first point is nice to do but I regard the second point as essential. Race pads like DS11 that don't work until they reach 600 degrees need a special bedding in procedure, street pads do not.

    The bedding in procedure is like walking a tight rope. If you get the pads slightly too hot the pad material will be damaged and the only way to fix them is to machine about 3mm off the surface. This is a common occurrence and I've done it myself a few times.

    It's safer to just drive the car normally and avoid heavy braking for about a week. That way the pads will bed in nicely and be at their optimum, with no risk of being damaged.

    Gone to Volvo


  7. #7
    Join Date
    Nov 2008
    Location
    NSW
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    Default

    I think Dug has the Hawk Pads, maybe he has some input on how he bedded in his pads.....

  8. #8

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    My understanding of the bedding process is to match the pad surface to the disk surface. Even after machining, there could still be some high and low spots on the surface. If hard braking occurs, you could get uneven heating of the pad and causing damage.

    haha Nasa, when i first got my pads in they were squalling like a whore and i too did to old hand brake trick

  9. #9

    Default

    More on why we need to bed in brakes:

    A new set of pads that has not been temperature stabilised will be at risk of "green fade". This occurs when the organic material boils off rapidly as a gas or liquid when first heated. This material then acts as a lubricant between the pad and rotor causing a severe loss of braking ability. It also has a tendency to re-solidify on the rotor surface causing glazing.

    Pad makers include instructions for bedding in for liability reasons, so that Joe Average doesn't change his pads then drive down a mountain pass and kill himself when green fade occurs.

    Leaving aside the liability issues, if we are sensible and know what we are doing, we'll get a better result by just driving around normally for a few days, avoiding mountainous descents, high speed stops and high risk bedding in procedures until the pads achieve thermal stability.

    This is after all what happens with new cars.

    So why don't pad makers sell pads that are already thermally stabilised I hear you ask? Because as Birdhouse indicated, news pads need to be soft enough to conform to the unique characteristics of the rotor surface relatively quickly. After being thermally stabilised the pad material becomes much harder.
    Last edited by kmh001; 02-06-2009 at 01:29 PM.

    Gone to Volvo


  10. Default

    I wrote off my first car, got brand new brakes, the very next morning a car stopped really suddently in front of me, I slammed on the brakes, car didnt stop and BAM ... I was young, it was a ford ... no loss
    Last edited by blackbetty; 02-06-2009 at 01:43 PM.

  11. #11
    Join Date
    Nov 2008
    Location
    Brisbane
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    494

    Default

    Lol @ bb

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