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  • brake problems after the 'Ring....

    First of all,
    Hello to everyone. I've recently bought my first Z3mcoupe (after having owned a 2.8 coupe for 2-3 years). I'm obviously really happy with it and have actually used this forum on and off for general information about the z3m in the past few years.

    I have a question though...

    I recently took the z3m to Nurburgring and while it was a great experience the brakes started acting up halfway through both of my laps. They started to vibrate quite hard during braking. This effect went away after holding back and coasting for the next 2-3 kilometer of the track. The next lap, however, same thing. After the laps the discs seemed to be slightly red / amber...but all seemed well otherwise. On the way home, however, the ABS light came on and has not come off. A specialist I spoke to suggested that I probably warped my discs but that seems counter-intuitive since the vibration actually went away...? The only other point to note is that prior to this trip, the brakes squeaked quite often during regular road-driving. Someone else suggested that the pads / discs may have ‘crystallised’ prior to me buying due to consistent slow driving and that explains a) why they squeaked and b) why they failed as they did…

    Any advice / thoughts would be greatly appreciated since the specialist suggested new discs and yelllowstuff pads. I'll probably install the pads anyway but I'm not convinced it's my discs that are damaged!?

    Thanks in advance for any wisdom!
    Adgild

  • #2
    Originally posted by adgildio View Post
    First of all,
    Hello to everyone. I've recently bought my first Z3mcoupe (after having owned a 2.8 coupe for 2-3 years). I'm obviously really happy with it and have actually used this forum on and off for general information about the z3m in the past few years.

    I have a question though...

    I recently took the z3m to Nurburgring and while it was a great experience the brakes started acting up halfway through both of my laps. They started to vibrate quite hard during braking. This effect went away after holding back and coasting for the next 2-3 kilometer of the track. The next lap, however, same thing. After the laps the discs seemed to be slightly red / amber...but all seemed well otherwise. On the way home, however, the ABS light came on and has not come off. A specialist I spoke to suggested that I probably warped my discs but that seems counter-intuitive since the vibration actually went away...? The only other point to note is that prior to this trip, the brakes squeaked quite often during regular road-driving. Someone else suggested that the pads / discs may have ‘crystallised’ prior to me buying due to consistent slow driving and that explains a) why they squeaked and b) why they failed as they did…

    Any advice / thoughts would be greatly appreciated since the specialist suggested new discs and yelllowstuff pads. I'll probably install the pads anyway but I'm not convinced it's my discs that are damaged!?

    Thanks in advance for any wisdom!
    Adgild
    Adgild,

    The yellow stuff pads have an abrasive coating when new, which cleans off all the glazing from your discs, left by your old pads. I expect that's all you need.

    I'd highly recommend fitting some DIY brake ducts such as those I've made in the photos below. My brakes discs consistently run more than 30 degs C cooler than OEM brakes without the ducts (instant comparison with other MCs doing the same track). I recently measured my front brake temperature after braking from 145mph (Yellow Stuff pads) and it was more than 250 degs C. Goodness knows what it would be without the ducting! I'd also put some DOT5.1 brake fluid in your system, and whilst you're about, fit braided brake and clutch hoses.


    /// Exdos ///
    "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

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    • #3
      Originally posted by adgildio View Post
      since the specialist suggested new discs and yelllowstuff pads.
      Just had this combo fitted about 700 miles ago and get squeaking...don't do much stop start driving though.

      Comment


      • #4
        The judder will be from bad disc/pad combination; do you know what pads are currently fitted? You might be ok leaving the discs (it's rare for them to properly "warp" - it's usually down to the pad smearing on the disc causing the vibration or overheating) as you found they went ok once they cooled down. But if you really want have a brake overhaul then new discs are always worth a go (they solved a very slight vibration I had when braking) and they've been perfect since fitting new discs and having done 4 trackdays with them plus a trip to the 'Ring. They're difficult to skim so don't bother trying that.

        I can't recommend Yellows enough for smooth braking; they're by no means the best pad available but they are good value at £72 compared to other pads. I have the same cooling duct setup as Exdos and with Yellows the brakes were faultless at the 'Ring - no fade and absolutely no judder. I've previously been in the Coupe with DS2500 pads and they juddered after a couple of corners (without cooling ducts though).

        The ABS light is a red-herring, probably triggered by a large amount of brake dust build up or the vibration; I'd try removing and cleaning the sensors and try that (the light resets automatically when the sensor is fine)
        Last edited by c_w; 19-08-2008, 05:24 PM.

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        • #5
          Good post Exdos.

          On another note; with your brake duct mod - doesn't the brake shield block some of the cooling air flow to your discs/pads?
          Last edited by h4pry; 19-08-2008, 04:29 PM.
          Out: 99 S50 Titan Silver V876 KKO
          In: 98 S50 Estoril.......

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          • #6
            Originally posted by h4pry View Post
            Good post Exdos.

            On another note; with your brake duct mod - doesn't the brake shield block some of the cooling air flow to your discs/pads?
            Below are two photos that I took when replacing the front discs.

            As you can see, the OEM front discs are a "floating" design. This means that the cast iron disc is suspended by spokes from the aluminium hub centres, and that there is a gap for air to pass between disc and hub. The discs have curved vanes, so that when the wheel rotates, they act as air-impellers pulling air between the two faces of the disc so that both faces of the disc are cooled evenly. The dust plate will actually direct more air into the centre of the disc so that the impeller will work better. If it wasn't there, then air would tend to "wash" over the outside of the inner face of the disc rather than pass inside the disc. IMHO, the MC's OEM discs are about the most sophisticated cast iron discs around.




            /// Exdos ///
            "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

            Comment


            • #7
              Interesting as sounds a bit like my brakes, which give quite a lot of vibration when braking moderately...ok if you just brake lightly.

              I did fry them a bit on a track day a while back (December) - at which they went rather grumbly and whirry, but they seemed fine when cooled down...and have done until recently.

              From speaking to local garage they reckon I have warped the discs, and will measure them if I take it in (but were recommending I go for EBC disks and pads ;-)

              If they are warped (and I'll get a 2nd opinion) is it worth skimming the discs first, anyone any experience of this?

              Saw this on web: http://www.skimmydiscs.co.uk/

              Chap with one of the machines said it could come back if I have warped them on track (as disc will have a "hot spot" on it)...but could be worth a go as a lot cheaper than discs and pads.

              Any hints/tips recommended!

              PS Discs and pads are not that old, so don't really want to replace unless necessary.
              -------------------------
              Ex Ex Ex: 1998 M Coupé, Estoril/Estoril+Black. HK+ MD+CD Changer, roof, side bags, lamp wash.
              Ex Ex: 1998 M3 Evo Coupé, Estoril / Blk with all the toys.
              Ex: 2004 Z4 3.0i, Silver / blk with no roof.
              Now: 2003 M3 CSL, Silver Grey, lots of carbon fibre.

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              • #8
                What an amazing response! Thanks a million to all who responded; really appreciated. I'm going to properly clean the brakes and the sensor first, see what happens. Then I'll take it from there and will probably buy the pads anyway.

                Another quick question: If I'm using the car 90% for road use and may take it on the track 2-3 times per year would the yellows be better or the reds?

                Thanks again all of you! Really appreciated!

                Comment


                • #9
                  Originally posted by adgildio View Post
                  What an amazing response! Thanks a million to all who responded; really appreciated. I'm going to properly clean the brakes and the sensor first, see what happens. Then I'll take it from there and will probably buy the pads anyway.

                  Another quick question: If I'm using the car 90% for road use and may take it on the track 2-3 times per year would the yellows be better or the reds?

                  Thanks again all of you! Really appreciated!
                  We're a helpful lot on here!

                  I can't see what cleaning the sensor will do: it only shows when there is 3mm of pad material left.

                  How are you going to clean the brakes? What parts are you going to clean?

                  I had Red stuff pads for over 10k miles of hard driving on the twisties and I found them to be excellent. Some claim they're rubbish though.

                  The Yellow stuff pads are very good indeed at stopping the car, but I've no idea how durable they will be though or damaging to the discs. I don't find them noisy, nor are they poor at stopping the car when cold. I've done about 1200miles with them so far and about 350 miles of that has been very hard driving indeed.

                  FYI, I had to replace the original discs after 28k miles when they had reached their minimum thickness (as stamped on to the hub centres). I've no idea how many miles others get out of their discs.
                  Last edited by exdos; 19-08-2008, 08:39 PM.
                  /// Exdos ///
                  "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

                  Comment


                  • #10
                    Exdos you've been quiet recently - I was waiting for one of your more involving posts !
                    Ex 2001 S54
                    New cars:
                    Lotus Carlton
                    350Z

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                    • #11
                      Originally posted by danp View Post
                      I did fry them a bit on a track day a while back (December) - at which they went rather grumbly and whirry, but they seemed fine when cooled down...and have done until recently.

                      From speaking to local garage they reckon I have warped the discs, and will measure them if I take it in (but were recommending I go for EBC disks and pads ;-)
                      I've had similar - had the brakes vibrating badly whilst on track, then they were fine on the road, and then a consistent judder (hot and cold) came back when on the road. I was actually on the way to getting my brakes skimmed when the problem disappeared completely, so I didn't bother getting it done.

                      EBC pads are worth considering, but don't go for the discs: as exdos says, the OEM ones are really very good, and the EBC ones will almost certainly be a step backwards.

                      If they are warped (and I'll get a 2nd opinion) is it worth skimming the discs first, anyone any experience of this?

                      Saw this on web: http://www.skimmydiscs.co.uk/
                      BMW says that the floating discs on the MC must not be skimmed, and I've heard other people say that skimming floating discs, as on the MC, doesn't really work, but I've never had a good explanation of why.

                      Paul

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                      • #12
                        Exdos,
                        If it was your car, what are the first three steps you'd take?
                        Adgildio

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                        • #13
                          My advice would be to try getting them skimmed first and maybe try some DS2500 pads with them and the third step would be to paint the calipers blue
                          Last edited by c_w; 20-08-2008, 08:07 AM.

                          Comment


                          • #14
                            Originally posted by exdos View Post
                            We're a helpful lot on here!

                            I can't see what cleaning the sensor will do: it only shows when there is 3mm of pad material left.

                            How are you going to clean the brakes? What parts are you going to clean?
                            It's the ABS light that is on so it's the ABS sensors that are worth cleaning.

                            Comment


                            • #15
                              Originally posted by c_w View Post
                              ... the third step would be to paint the calipers blue
                              Ex 2001 S54
                              New cars:
                              Lotus Carlton
                              350Z

                              Comment

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