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  • Braking judder

    Hey all, so I have always had a bit of brake judder, but it's recently got a lot worse - front bushes are new, and the disks aren't warped (confirmed by Munich Legends).

    There is no judder under any circumstances other than medium-hard braking. If I stamp on the pedal, there's no judder.

    So is it possible the floating mechanism on the front pads has corroded or something? If that's the case, can I just soak the disks in some sort of solvent overnight to free it up?

    I've tried getting them quite hot on a run, and it doesn't seem to have solved the problem.

    What else might it be?

    I've just spent c.£2k on an InspII, 4 tyres (not yet fitted), bushes and other stuff, so another £300+ on front disks is not really something I want to spend! I will if I have to though - it just means my colour coding and new steering wheel will have to wait.

    Thanks.
    Last edited by breezer; 04-04-2012, 10:27 PM.

  • #2
    You may find that your wheels are just unbalanced! once you get your new tyres on chances are it may go...

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    • #3
      Originally posted by kwoffa View Post
      You may find that your wheels are just unbalanced! once you get your new tyres on chances are it may go...
      Thanks, it makes sense to try this first, as it's easier. However, there's no wobbling at any speed when I'm not braking - wouldn't wheel imbalances show up at other times?

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      • #4
        Any brake judder under braking is ALWAYS your discs/pads. There are internet myths abound about worn ball joints and tie rods etc that cause it, these can only exacerbate the judder, not cause it. Your discs won't be warped but the judder will be caused by pad material on the disc causing uneven friction/judder.

        Brake judder is the bane of my life, having gone from super smooth brakes for 5years to judder on my new set of discs and pads it was doing my head in!! I cooked some pads on them on a trackday and they started to judder and it's taken ages to get rid of it. However some Carbone Lorraine RC6 pads seems to have cleaned them up and they seem smooth again.

        What pads are you running?

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        • #5
          Could also be there rear brakes, did they check both or just the fronts.

          Jason
          BMW e21 track car
          Z3M (S62)
          2.8 Z3 Coupe
          Ariel Atom
          GT86 race car
          Ferrari 348 Challenge
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          • #6
            C_W - sorry to hear you're also suffering. It's really spoiling the car for me at the moment. Everything else mechanical is perfect, but this is seriously intrusive! I'm running OEM pads.

            ML checked all 4 for warping as part of the inspection II.

            The car gets used about once a month (for a long run of c.100-150miles between properties), which I imagine is bad for the brakes...I wonder if REALLY getting them hot (e.g. emergency stop from 70mph - repeat) would clean them off?

            In your experience is it more likely to be pad material than a stuck floating mechanism?
            Last edited by breezer; 05-04-2012, 11:22 AM.

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            • #7
              Yes most likely pad deposits causing the judder. I'm now convinced it's black magic as I have the exact same setup as I have run before perfectly smooth but now it's not on this set of discs.

              It's very hard to clean off manually with sandpaper and skimming doesn't really work on the floating discs, what you need is some really aggressive pads like RC6 which will condition the surface. I'm hoping I can now go back to my Pagid RS29s now the discs are "clean".

              EBC Yellowstuff come (or used to come) with a special bed in coating which was essentially a very abrasive top coating on the pad which cleaned the disc up ready for bedding. For normal or fast road use they are good pads IMO.

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              • #8
                Originally posted by c_w View Post
                Yes most likely pad deposits causing the judder. I'm now convinced it's black magic as I have the exact same setup as I have run before perfectly smooth but now it's not on this set of discs.

                It's very hard to clean off manually with sandpaper and skimming doesn't really work on the floating discs, what you need is some really aggressive pads like RC6 which will condition the surface. I'm hoping I can now go back to my Pagid RS29s now the discs are "clean".

                EBC Yellowstuff come (or used to come) with a special bed in coating which was essentially a very abrasive top coating on the pad which cleaned the disc up ready for bedding. For normal or fast road use they are good pads IMO.
                Thanks for the heads up. I guess an electric sander would also not work?

                If you're reverting to normal pads, can I buy or rent your RC6s? EBC yellows are £110 a pair, which hurts considering my OEM pads are still pretty new.
                Last edited by breezer; 05-04-2012, 12:41 PM.

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                • #9
                  Originally posted by breezer View Post
                  I wonder if REALLY getting them hot (e.g. emergency stop from 70mph - repeat) would clean them off?
                  I understand it's better NOT to come to a stop. i.e. repeat 60-10mph several times.

                  ps: Don't forget to check your mirrors
                  Not actually in the least bit fat

                  2000 S50 Titanium Silver / Black
                  ACS Suspension, Exhaust & Type III Wheels
                  Simota carbon air intake | Strong Strut Front Brace

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                  • #10
                    Originally posted by Fat Tony View Post
                    I understand it's better NOT to come to a stop. i.e. repeat 60-10mph several times.

                    ps: Don't forget to check your mirrors
                    I still remember the emergency stop part of my driving test!

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                    • #11
                      i changed the discs on mine due to judder. swapped them for some old part worn discs i had from my m3 evo (i think thats what they were!) and it fixed the issue.

                      how do they check the discs for warping?

                      Click here to email me

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                      • #12
                        Originally posted by indy View Post
                        i changed the discs on mine due to judder. swapped them for some old part worn discs i had from my m3 evo (i think thats what they were!) and it fixed the issue.

                        how do they check the discs for warping?
                        Dunno, but they said they measured the surface somehow, and they gave me a pretty precise set of readouts iirc.

                        At a guess, could you just put a straight edge to them and see?

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                        • #13
                          Originally posted by breezer View Post
                          Dunno, but they said they measured the surface somehow, and they gave me a pretty precise set of readouts iirc.

                          At a guess, could you just put a straight edge to them and see?
                          Not accurate enough to give precise measurements - would have thought a dial gauge against the disc being spun on a lathe i would imagine.
                          2002 '52 S54 - Titanium Silver with 18" BBS LMs, AP Racing BBK, KW V3, H&R anti roll bars & ACS flippers (previously 2000 'X' S50 - Arctic Silver)

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                          • #14
                            Originally posted by breezer View Post
                            Thanks for the heads up. I guess an electric sander would also not work?

                            If you're reverting to normal pads, can I buy or rent your RC6s? EBC yellows are £110 a pair, which hurts considering my OEM pads are still pretty new.
                            You should be able to ge tthe yellows cheaper than that, sure around £75-80 on ebay. You could try an eletric sander but make sure you move it in a uniniform pattern to minimise risk of give the disc runout.

                            I'm removing the RC6s as I want to minimise wear to save them for trackdays.

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                            • #15
                              Originally posted by c_w View Post
                              You should be able to ge tthe yellows cheaper than that, sure around £75-80 on ebay. You could try an eletric sander but make sure you move it in a uniniform pattern to minimise risk of give the disc runout.

                              I'm removing the RC6s as I want to minimise wear to save them for trackdays.
                              Ah okay, thanks anyway!

                              I took it for a 'hot run' and the judder is a bit better actually. I should probably just try doing that for a few more times, then try the sander next. New pads will be the 3rd attempt, and new disks the final shot.

                              Thanks for your help.

                              I sometimes (well, my bank account does) wish I didn't keep buying these toys! My FL400R is now playing up too - it needs a crank case rebuild. Maybe time to do a 4-stroke bike engine conversion?!

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