PP brake pad temp range?

Discussion in 'Road Course, Track, Autocross, HPDE' started by lugz, Mar 7, 2018.

  1. DickR

    DickR Well-Known Member

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    Why not? It makes sense to me if the root cause is something like running out of M/C cylinder or booster travel (i.e. bottoming) as opposed to a simple M/C to caliper "ratio" change in the direction of more effort. Note that I have no practical experience to support my guess. :doh:
     
  2. Norm Peterson

    Norm Peterson corner barstool sitter

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  3. OP
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    lugz

    lugz Well-Known Member

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    Same question I had. Never signed up for FB, and not about to now. :D
     
  4. BmacIL

    BmacIL Enginerd

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    #84 BmacIL, Apr 19, 2018
    Last edited: Apr 19, 2018
    That's not how a properly functioning and bled hydraulic system works, though. Brake fluid compressibility is extremely low and if your system is bled properly, master cylinder travel just goes into increasing the line pressure. I find it extremely unlikely that the <10% change in total piston surface area (between the full set of front calipers) is enough to require a different master cylinder to function properly. Yes, the PP master cylinder probably has a larger displacement, but that is done to provide margin by design at the limits (old fluid, some air in the system, still can exert enough pressure to stop the car). As an engineer in the auto industry, I would be shocked if their margins were that small to not be able to take up that change. I could be wrong, but I also know Ford engineering. Also, the GT350 MC is identical to the base, non-PP GT.

    I find their conclusions difficult to agree with, especially when there are numerous folks on this very forum who have changed to these brakes and used them on track without issue.

    Here's the video on YT:
    [ame]
     
  5. DickR

    DickR Well-Known Member

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    Thanks very much for the technical explanation!!!!

    Question: Is there any chance that if the root cause isn't the very likely incorrect bleeding or bedding that the problem is ABS calibration? I don't really understand how brake balance works in these cars. Could the change in front have caused the rears to lock prematurely so ABS does the equivalent of what many call "ice mode"?

    Another question: Where do you stand on your braking issue? Do you have the "bad" external vane inlet rotors?

    Thanks!
     
  6. J.P.B.

    J.P.B. Member

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    For those thinking about if it might still be possible to stick with the base GT brakes....

    - Steve Garvin (Chief Engineer) at DBA says that they are now exploring the possibility of changing the tooling to change the vent port on their rotors to the inside.

    - If you can't wait for that, you can contact Mark Fowler at Bear, and he can set up their Eradispeed+ 2 piece rotors with slots only (off the shelf they come drilled and slotted). He has confirmed that the vent vanes are on the inside. Those rotors save some weight too.

    I have no links of any kind with either company; just sharing a summary of some recent discussions I had with both.
     
  7. DR_

    DR_ Well-Known Member

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    Good info, thanks. I want to keep the base GT calipers as they fit the ethos of my build.
     
  8. J.P.B.

    J.P.B. Member

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    @DR I hear you. I am very happy with my current 18" wheels (18x10 at all four corners, and only 23.5 lbs each) and tires; I don't really want to change them.

    When I figure the cost of the brake and rotor upgrade, and the master cylinder, and the bigger wheels and tires, it's starting to look very expensive (even if the upgraded brakes and rotors are bargain NTOs).

    Sure the Eradispeed+ 2-piece look expensive. But it seems like it should be less in the long run. Plus the whole package (aluminium hat rotors, 4 pistons callipers, 23.5 lb wheel) is looking like it will be substantially lighter than anything I can afford if I were to upgrade to the 6 pistons callipers. I am guessing that the lower rotational mass and the much better cooling with 2-piece rotors could each have noticeable effects. The price ($745.00) is no longer looking so bad. Now I just need to start saving up!
     
  9. BmacIL

    BmacIL Enginerd

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    You're welcome :)
     
  10. BmacIL

    BmacIL Enginerd

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    Oh by the way, I had seen this quite a while ago, but was recently reminded: the GT350 master cylinder is the same as the base GT (non PP). The claim is BS.
     
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  11. J.P.B.

    J.P.B. Member

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    THAT is very good to know!
     
  12. Optimum Performance

    Optimum Performance Well-Known Member
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    So out of curiosity how much interest would there be in something like this..if it were available? :shrug: 30806168_10211777858702581_8718743409579668821_o.jpg
     
  13. BmacIL

    BmacIL Enginerd

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    Would love it, but probably not the price, at least at the moment.
     
  14. Norm Peterson

    Norm Peterson corner barstool sitter

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    How hard could it be to cast up 1-piece rotors with the air inlet on the back side? I bet they'd even come in a little lighter than the non-PP design, since the hat portion wouldn't have to be as deep. Better back-side airflow ought to more than compensate for the longer heat path from disc to hub in the front-side design.


    Norm
     
  15. BmacIL

    BmacIL Enginerd

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    See post 89 and 90 :)
     
  16. Norm Peterson

    Norm Peterson corner barstool sitter

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    Even without an aluminum hat section, a rotor with back-side air inlet should end up being lighter. The aluminum-hat 2-piece should be better at insulating the hubs against brake heat, though.


    Norm
     
  17. Optimum Performance

    Optimum Performance Well-Known Member
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  18. F0J

    F0J Well-Known Member

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    Let me say that I really appreciate all the technical talk about the non-PP brakes. I took it hard on the OEM rotor+pads for one lap and after 3 transitions I lost all confidence (on 265/45R18 RE71R). I've since installed data acq so we'll have video and live data the next time I go out. My local track (Gimli) has a nice run-off on the first turn after the long straight and I'm not afraid to pucker up.

    The system has to be somewhat salvageable. I have GLOC 12&10s but I haven't installed them since I read they get too hot and I hadn't yet bought another set of rotors or installed cooling because, well, time (my second son was born) and money (we bought a bigger house with a shop). I'd even consider setting up some kind of IR sensor on the rotor.
     
  19. OP
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    lugz

    lugz Well-Known Member

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    There should be a series of sticky threads in this forum - one should be what to do about non-pp brakes. Guess we veered off the original subject a bit, but I don't mind. Might be hard for someone searching for info to find it though.
     
  20. DR_

    DR_ Well-Known Member

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    Want to add that I did a two day track event at Eagle's Canyon, which is very hard on brakes, and the 14" non-PP rotors and calipers with Powerstop Track Day pads held up really well. I was not on the stickiest rubber (340TW Firestone Indy 500) and more importantly I did not try to threshold brake every braking zone of every lap.
     
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