Ridemalibu Motorcycle Rentals & Tours – Los Angeles CA
  1. Ciao Guest - You’ve landed at the ultimate Guzzi site. In SoCal? See the SERVICE tab above for the best in service, tires, tuning and installation of our products or custom work. NEW FORUM REGISTRATIONS REQUIRE EMAIL ACTIVATION - CHECK YOUR SPAM FOLDER. ALWAYS TRY A SEARCH BEFORE STARTING A NEW TOPIC - Most questions you may have are already answered on the Forum with FACTS, NOT OPINIONS. PLEASE DON'T BE A DRIVE-BY POSTER: As a common courtesy, check back if you are posting elsewhere on the web. Note there's decades of Guzzi hands-on experienced help on this site, all whom give endless amounts of their time for free; BE COURTEOUS AND RESPECTFUL! There is zero tolerance on personal attacks and off-site links to other Forums or competing products. Also be sure to click on the Store link also above for our 600+ product inventory, including many of our 100% Made-in-house-USA GTM products and engine kits. We appreciate the consideration, understanding and your business... past and future. Also be sure to see our GTMotoCycles.com custom BUILDS tab above. WE ARE ONLINE ONLY - NO PHONE CALLS MADE OR RECEIVED.

floating brake disc play (on bobbins)

Discussion in 'BNS12 Chat & Tech' started by pswiatki, Apr 15, 2020.

  1. pswiatki

    pswiatki Tuned and Synch'ed

    Joined:
    Aug 26, 2011
    Messages:
    65
    Likes Received:
    13
    Location:
    Wrocław, POLSKA
    Quick question: my bike mechanic said the new discs to be installed on my bike (which I dropped at his service shop together with the cycle) are not as they should be. Specifically: he said there should not be any detectable leeway felt between the centre mount part and the [so called] brake track / outer ring, but there was. So, some play on the floaters (bobbins?) was detected both, axially and radially.

    I read some posts here on the forum and could not confirm the above. Quite the opposite: there could be some play between the parts and - once installed - there could even be some rattling when in motion. The unfortunate thing is I cannot go there and verify the situation because I am far away from the shop and we also have social distancing and travel restrictions in place here in Poland. Anyhow, he is reluctant to install those discs and work on my bike is halted now. I described this to the manufacturer and still awaiting their response.
    Therefore, I seek your advice. It will be very much appreciated!
     
    Last edited: Apr 16, 2020
  2. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

    Joined:
    Oct 28, 2008
    Messages:
    7,733
    Likes Received:
    738
    Location:
    Huntsville, AL
    I tend to agree with your mechanic. There should be some lateral play, but just about none in the direction of rotation of the brake rotor. Excessive play in the direction of rotation may cause a brake rotor failure which can be catastrophic.
     
    pswiatki likes this.
  3. pswiatki

    pswiatki Tuned and Synch'ed

    Joined:
    Aug 26, 2011
    Messages:
    65
    Likes Received:
    13
    Location:
    Wrocław, POLSKA
    Thanks! Good to know. The [German] manufacturer responded and I am not sure what to make of it. They said they never had any problems with their discs, but if the mechanic said he was unsure they (manufacturer) wanted the discs to shipped back to them for inspection. Yet, they did not give me a clear answer if there could be any play on the floaters or no play whatsoever. I only got the info their discs are semi-floating (guess no play allowed!)...
    Well... shipping back and forth may increase the cost greatly, I wonder who's going to pay for that. Dammit! We'll see what happens next.
     
  4. Kubbie

    Kubbie Tuned and Synch'ed

    Joined:
    Aug 15, 2017
    Messages:
    56
    Likes Received:
    8
    Location:
    Florida
    My Triumph has floating rotors (like most bikes nowadays) and you can definitely move the braking surface radially and laterally (look at me using big works) and you can hear them. Pretty sure my other bikes do too. Just haven't played with the others.
     
  5. pswiatki

    pswiatki Tuned and Synch'ed

    Joined:
    Aug 26, 2011
    Messages:
    65
    Likes Received:
    13
    Location:
    Wrocław, POLSKA
    OK, I got the video from the mechanic:



    Clearly the brake track moves around on the floaters.
    The Germans [manufacturer] saw it, too. They want these discs (both exhibit the same behaviour) back in their workshop. Will happen soon. Will see what they say.
     
  6. GT-Rx®

    GT-Rx® Administrator Staff Member GT di Razza Pura

    Joined:
    Jul 1, 2009
    Messages:
    11,033
    Likes Received:
    3,223
    Location:
    Malibu
    Side to side is perfectly normal, as is the button rotation with a full floating rotor. You actually want that to help with axis deflection from side to side difference with the forks. OEM is "semi" float (hardly visible). The issue would be in the direction of rotation; If there were any movement there, it would be very bad.
     
    john zibell likes this.
  7. pswiatki

    pswiatki Tuned and Synch'ed

    Joined:
    Aug 26, 2011
    Messages:
    65
    Likes Received:
    13
    Location:
    Wrocław, POLSKA
    Thank you very much for your answer, Todd. Exactly. The manufacturer said they use semi-floating "bearings" (as they call the floaters) - they call their discs semi-floating. If so, nothing really matches.
    Thus, it will be best for them to check the discs. Hope it will happen fast because I am currently wasting time - could have been riding already :) Everything else is all good to go.
     
  8. Brett

    Brett Tuned and Synch'ed GT Contributor

    Joined:
    Apr 7, 2012
    Messages:
    90
    Likes Received:
    13
    Location:
    Edson
    Dare I ask what make these are?
     
  9. pswiatki

    pswiatki Tuned and Synch'ed

    Joined:
    Aug 26, 2011
    Messages:
    65
    Likes Received:
    13
    Location:
    Wrocław, POLSKA
    For now, let's say: a German mfg.
     
  10. GuzziMoto

    GuzziMoto GT Reference GT Contributor

    Joined:
    Nov 7, 2008
    Messages:
    1,861
    Likes Received:
    256
    Location:
    B'more, Md
    The video doesn't clearly show any bad play. There may be bad play (play in the direction of rotation) but I don't see it in the video. The play shown, side to side and being able to rotate the float buttons that locate the disk to the carrier, are normal and not a problem. That is how floating, or semi-floating, rotors work.
     
    john zibell likes this.
  11. pswiatki

    pswiatki Tuned and Synch'ed

    Joined:
    Aug 26, 2011
    Messages:
    65
    Likes Received:
    13
    Location:
    Wrocław, POLSKA
    Alright, thank you for your input. The MFG however, saw the video and requested the discs back for inspection. Will post the end result here. By the way: yes, there is play in the direction of rotation. It may not be clearly visible, but it is audible. Perhaps video conversion and processing done by YT on the original material caused this issue. On the original one can see play in both directions.
     
  12. pswiatki

    pswiatki Tuned and Synch'ed

    Joined:
    Aug 26, 2011
    Messages:
    65
    Likes Received:
    13
    Location:
    Wrocław, POLSKA
    So, here's the update. Discs went back to the manufacturer. They checked and said play (in either direction) was within tolerance. One was closer to the limit and they replaced it so that both rotors would be more equal. Then they sent the rotors back to the workshop. The bike is ready, I shall pick it up on Friday. Since I have ~320 km to cover on the way back home, I will be able to have some impression of how the discs behave. The manufacturer promises no judder. Well.. will see about that.
    By the way: I am a bit puzzled because they do have all the approvals from the regulatory bodies (who are pretty restrictive in Germany as far as I know) and they also are ISO quality certified. They say they know the stuff and shared info they make parts for racing as well. So they know their craft. Very interesting.
     
  13. scottmastrocinque

    scottmastrocinque Scott Mastrocinque GT Famiglia

    Joined:
    Jun 26, 2011
    Messages:
    738
    Likes Received:
    390
    Location:
    Findlay, Ohio
    I just checked my Stelvio, 1200 Sport, Centauro, and California Vintage. All have bobbin mounted semi-floating rotors. All move axially about .5 - 1.0mm forwards or backwards with respect to wheel rotation. None have significant vertical movement up off of the bobbins. In that regard, they are all less than .5mm movement.

    I have seen many full floating rotors on racing Ducati’s that moved significantly like yours in the video. It’s not unusual as they were designed with that movement.

    Given that the manufacturer is giving you the green light, I’d relax and see how they feel. You might be surprised how well they work.

    I will be Interested in your feedback!
     
  14. pswiatki

    pswiatki Tuned and Synch'ed

    Joined:
    Aug 26, 2011
    Messages:
    65
    Likes Received:
    13
    Location:
    Wrocław, POLSKA
    Sure, I will provide feedback Friday afternoon your time, I think. I got scared by this comment from Todd (see above, earlier in the thread):
    But something was telling me the parts could not be as bad as my mechanics were telling me. The manufacturer confirmed all was good (I have a feeling they were pretty surprised by my mechanics' claims the parts were not as expected and that they would be reluctant to install those).

    When you say the play was 0.5 or 1 mm you mean at the bobbin itself, or - say - the edge of the disc? It makes a huge difference. To answer another comment on the video I posted - it's not easy to capture that play between the disc and bobbins, but once I am back with the bike I shall try to capture a video with a macro lens installed on my camera - it should show everything clearly.

    As a matter of fact, I think the play I can detect is a fraction of a millimetre. But it's very subjective and lack tools to measure that with any greater precision. Well.... not that I really need to know that as long as the front brake performs as expected.
     
    Last edited: May 19, 2020
    scottmastrocinque likes this.
  15. scottmastrocinque

    scottmastrocinque Scott Mastrocinque GT Famiglia

    Joined:
    Jun 26, 2011
    Messages:
    738
    Likes Received:
    390
    Location:
    Findlay, Ohio
    BTW - You live in a BEAUTIFUL and ancient city! I will add it to my list of European cities to visit next time I am in Europe.
     
    pswiatki likes this.
  16. pswiatki

    pswiatki Tuned and Synch'ed

    Joined:
    Aug 26, 2011
    Messages:
    65
    Likes Received:
    13
    Location:
    Wrocław, POLSKA
    Thank you much! I like it very much, too. I spent a large part of my life here and just recently came back to the city I got to know so well when I was at the university and earlier when I was a little kid. I am very happy, although for the past 17 years I lived in Kraków, which is also very old and is the historical capital city of POLSKA.
     
    scottmastrocinque likes this.
  17. scottmastrocinque

    scottmastrocinque Scott Mastrocinque GT Famiglia

    Joined:
    Jun 26, 2011
    Messages:
    738
    Likes Received:
    390
    Location:
    Findlay, Ohio
    Found this too...

    “True full-floaters move on the carriers, this allows them to self-center in the caliper for reduced brake drag and "float" unimpeded for unrestricted expansion and contraction during repeated thermal cycling. The only serious down side is a bit of rattle that reminds you these are indeed full-floaters.”

    These are the Ducati racing rotors I was speaking about. They are supposed to do this!

     
    pswiatki and john zibell like this.
  18. pswiatki

    pswiatki Tuned and Synch'ed

    Joined:
    Aug 26, 2011
    Messages:
    65
    Likes Received:
    13
    Location:
    Wrocław, POLSKA
    Oh... thank you much for sharing this video. My rotors are not anywhere near that much of play on the bobbins. Much smaller play on mine. Well.. two more days and I will test the brakes to see how everything works (new rotors, new pads, new pump).
     
    Last edited: May 20, 2020
    scottmastrocinque likes this.
  19. pswiatki

    pswiatki Tuned and Synch'ed

    Joined:
    Aug 26, 2011
    Messages:
    65
    Likes Received:
    13
    Location:
    Wrocław, POLSKA
    OK, came back home with brakes working really well. Discs do not have as much play [detectable by hand at least] as I thought they would. No judder or any other "special" effects. Brake lever needs some adjustment, but that's just personal preference, nothing more.
    Of course, since nothing can be perfect, something had to happen during the ride and it did (big time).
    But it is a subject for another thread. No worries though. I am OK and did not crash or anything of that nature.
     
    scottmastrocinque likes this.
  20. pswiatki

    pswiatki Tuned and Synch'ed

    Joined:
    Aug 26, 2011
    Messages:
    65
    Likes Received:
    13
    Location:
    Wrocław, POLSKA

Share This Page