Announcement

Collapse
No announcement yet.

Forum Top Advertisment

Collapse

Brake shimmy/judder/vibration only after brakes are heated up at the track

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #16
    When I installed the PFC I had slightly used PFC 2 piece front rotors and OEM used rear rotors, all were resurfaced, but used with OEM and carbotech pads respectively. I have followed all guidelines for bedding in, but it took a really long time until they started to work properly. My guess at the time was that PFC are really sensitive to old deposits even after resurfacing.

    Comment


    • #17
      So... there a direct connection between braking vibrations and correctly bedded in pads?
      How can I do?

      Comment


      • #18
        Based on your description, it sounds like you have pad deposits on the rotors. Make sure you aren't applying the brakes in the paddock after a track session as that can easily leave an imprint on your rotors. Here's a good article that discusses the issue in more detail:

        -Warped- Brake Disc and Other Myths

        I recommend trying to re-bed them when cold, effectively try to scrape the deposits off with a few hard 100-40 stops.

        Comment


        • #19
          Originally posted by ban25 View Post
          Based on your description, it sounds like you have pad deposits on the rotors. Make sure you aren't applying the brakes in the paddock after a track session as that can easily leave an imprint on your rotors. Here's a good article that discusses the issue in more detail:

          -Warped- Brake Disc and Other Myths

          I recommend trying to re-bed them when cold, effectively try to scrape the deposits off with a few hard 100-40 stops.
          Thanks, I've read a lot of these. I've tried bedding on the street, on my first session out, after a while I decided to just go and run what I brung. These Winmax W6 are the only ones that do this after only 1 session.

          Is it possible that I never got them hot enough to bed them correctly?
          When I first got them, I did around 4 or 5 100+ mph to ~30 mph hard braking stops on the freeway. I never did get them to fade.

          Next I took them to CVR, shaking all day (during hard braking) after the first session (Most noticeable braking for turn #8 (braking before left-off-camber turn running CW). I realized it was bumpy on the left side of the track, but later on, I avoided this area while braking and the vibrations persisted.

          Next I took them to Buttonwillow, shaking all day after the first session. When I think about it, I only noticed it vibrating while braking before the sweeper (#13CW), but never before buttonhook. Weird.
          How can I do?

          Comment


          • #20
            Pad material transfer defintiely can cause a vibration. On our 240Z we were using Porterfield R-4 pads in front and they would easily overheat (mostly due to poor rear brake performance). When too hot they get gummy and leave material on the rotots. When we changed to Raybestos ST-43 pads there was a disconcerting virbration for a few laps until the deposits on the rotors wore off.

            Sanding the rotos to remove old pad material is recommend, at least by some pad suppliers, when changing pads.
            Last edited by beermanpete; 01-25-2016, 03:59 AM.

            Comment


            • #21
              Found slight play in my wheel bearing. I'll swap it out and do a track day and hopefully get to the bottom of this. Thanks for the responses!
              How can I do?

              Comment


              • #22
                Now we're talkin!

                Comment


                • #23
                  Originally posted by BANKAI View Post
                  Found slight play in my wheel bearing. I'll swap it out and do a track day and hopefully get to the bottom of this. Thanks for the responses!
                  May fix your problem, but I doubt it. E36 ain't a miata
                  Last edited by bawareca; 01-25-2016, 07:45 PM.

                  Comment


                  • #24
                    Originally posted by bawareca View Post
                    May fix your problem, but I doubt it. E36 ain't a miata
                    I'm trying to be positive... hahaha
                    How can I do?

                    Comment


                    • #25
                      Nothing negative in my comment either, just a different platforms. BMWs have a real wheel bearings, not ones from a scale model. If this problem was existing with the track BMWs I am sure I would have heard of it. My front hubs came from a 96 150k miles M3 and according to the data this car is pulling consistently over 1.5g with no ill effects so far. Rears are original from the 1987 325i with over 240 k on the clock.
                      Anyway i will be curious to hear the result.

                      Comment


                      • #26
                        Originally posted by bawareca View Post
                        Nothing negative in my comment either, just a different platforms. BMWs have a real wheel bearings, not ones from a scale model. If this problem was existing with the track BMWs I am sure I would have heard of it. My front hubs came from a 96 150k miles M3 and according to the data this car is pulling consistently over 1.5g with no ill effects so far. Rears are original from the 1987 325i with over 240 k on the clock.
                        Anyway i will be curious to hear the result.
                        My front bearings are SKF and only about a year old (Nov 2014), but I run a 20mm spacer to clear my wheel and suspension. This still only gives me like 1-2mm gap between the tire and the spring.
                        Still seems excessive (premature bearing failure)... went with F.A.G. this time, we'll see how long this lasts.
                        Last edited by BANKAI; 01-26-2016, 10:37 AM. Reason: added "premature"
                        How can I do?

                        Comment


                        • #27
                          If it isn't the pads/rotors, that wheel bearing + the thick spacers would be my best guess. I ran two different sets of wheels on the e30. The wide, low offset wheels were really sensitive in the steering wheel irregularities that the other set wouldn't transmit. I ran THR FCABs and the entire front steering assembly was brand new, right down to the steering guibo. It took me a while to figure it out and I became REALLY good at swapping front hubs. I got it to about 15-20 minutes a side. I grew tired of doing that so I sprung for FAG assemblies and it helped a lot (I was using NAPA assemblies before)

                          The other vibration I had was in the driveline, the rear u joints on the driveshaft were worn. That one took me a lot longer to diagnose.
                          Last edited by Force McCocken; 01-28-2016, 10:25 AM.
                          Yer pal,
                          Force

                          Comment


                          • #28
                            Originally posted by Force McCocken View Post
                            If it isn't the pads/rotors, that wheel bearing + the thick spacers would be my best guess. I ran two different sets of wheels on the e30. The wide, low offset wheels were really sensitive in the steering wheel irregularities that the other set wouldn't transmit. I ran THR FCABs and the entire front steering assembly was brand new, right down to the steering guibo. It took me a while to figure it out and I became REALLY good at swapping front hubs. I got it to about 15-20 minutes a side. I grew tired of doing that so I sprung for FAG assemblies and it helped a lot (I was using NAPA assemblies before)

                            The other vibration I had was in the driveline, the rear u joints on the driveshaft were worn. That one took me a lot longer to diagnose.
                            Giving me hope! Thank you! Of course, now my car is throwing codes for random misfire, which is like looking up symptoms for AIDS. Everything and anything can be the cause. Good thing I went through this exercise before when my fuel pump was on its way out. I know what to expect.
                            How can I do?

                            Comment


                            • #29
                              My '95 m3 had a number of electrical gremlins too. I think it depends on how OCD you are with the warning lights. Me, personally, very much. Pull the codes and look for common issues. Don't forget one of our members here is a BMW electrical specialist.
                              Yer pal,
                              Force

                              Comment


                              • #30
                                Originally posted by Force McCocken View Post
                                My '95 m3 had a number of electrical gremlins too. I think it depends on how OCD you are with the warning lights. Me, personally, very much. Pull the codes and look for common issues. Don't forget one of our members here is a BMW electrical specialist.
                                I'm sure I suffer from OCD to a degree, but sometimes during these random misfires, I lose a cylinder or 2, so it's pretty noticeable. I usually shut my car off and back on and it usually fixes the issues... temporarily.
                                How can I do?

                                Comment

                                Working...
                                X