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Have the brakes on the P85D been upgraded to match the power?

Discussion in 'Model S' started by MarcG, Nov 23, 2014.

  1. MarcG

    MarcG Active Member

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    It seems a lot of focus has been put on the P85D's amazing acceleration, but I haven't heard or read much talk about its braking ability.

    Common sense and aftermarket tuning generally dictates that when an engine is upgraded, or more generically power output is greatly enhanced, so too should the braking systems (bitter/bigger rotors, calipers, pads, etc.)

    When I test drove the 85 and P85 back-to-back, I could sense that the brakes on the P85 were struggling to keep up with the extra power. While driving through some twisty hilly roads, I got a mushy feeling out them that could have gotten me in trouble if I was pushing harder.

    Anyway, I just hope Tesla gave this some good thoughts, but if anyone has any inside information on the P85D brakes before the first customer cars have been delivered, please do share.
     
  2. Aargau

    Aargau Member

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    Theoretically dual motors can slow down the car more than a single electric motor could. Stopping distance measured at 113 feet 60-0. However, AWD and turning on the safety assist should ensure that you don't get into trouble.

    22 Cars that Stop from 60 MPH in Less Than 100 Feet - Motor Trend
     
  3. lolachampcar

    lolachampcar Active Member

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    MarcG,

    It seems the answer to your question was at the very front of the article. Simply shod your PD with Michelin Cups and you're home free with your brake upgrade. This will not address what I can only assume is your fade problem but I'm not sure there is much to be done apart from perhaps some AP600.
     
  4. Firewired

    Firewired Member

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  5. lolachampcar

    lolachampcar Active Member

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    I believe all MS got those as it is the technology that helps to enable (or is required to enable) the autopilot function. It was unclear if the change in brake master affects stopping distance. My guess is it will not.
     
  6. andrewket

    andrewket 2014 S P85DL, 2016 X P90DL (soon 100)

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    This. The physical braking force or characteristics such as fade I don't believe have changed, unfortunately.
     
  7. Saghost

    Saghost Active Member

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    Perceived fade might, though. With the new electromechanical system that is on every current build/Autopilot car, Tesla can dynamically adjust the boost any way that they choose to, so if they wanted, there's no reason they couldn't 'hide' the fade - increase the brake force to compensate for the reduced friction as the brakes heat.

    I'm not sure that would be wise, though - while it would give consistent performance, it might encourage people to keep pushing the system hard until it breaks.
    Walter
     
  8. MarcG

    MarcG Active Member

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    #8 MarcG, Nov 24, 2014
    Last edited: Nov 24, 2014
    Thanks for the article. Unfortunately it only talks about the ability of the car to stop itself thanks to the "all-new electromechanical braking system", not the improvements made to the physical components of the brakes themselves (rotors, pads, calipers..)

    Also, it really irks me when news articles get their facts wrong:

    Forward-looking camera, yes.
    Forward-looking long-range radar, yes.
    360-degree short-range ultrasonic sensors, yes.
    But "12 forward-looking long-range utrasonic sensors"? No!!
     
  9. redox

    redox Member

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    I'm not sure why this is common sense: when you hit the brakes you want to decelerate from a given speed. The braking power is what will control this deceleration. It's quite independent from how fast you got to that speed: whether you get to 60 MPH in 5 or 3.2 seconds, you're at 60 MPH when you hit the brakes, which is what matters (from laws of physic's standpoint).

    It's true that cars with lots of power are traditionally marketed at people who like "performance driving" (whatever that means), so it's not uncustomary to pair lots of acceleration power with higher end braking systems, but it's not really necessary unless the current brakes aren't performing well on the current models (so it'd be a worthwhile upgrade for all models).

    -- Greg
     
  10. mspohr

    mspohr Active Member

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    I don't know why you would expect higher motor power to require bigger brakes. Stop and go are two different things and most people don't try to do both at the same time. Brakes are sized by the mass of the car and the top speed. These are the same for the P version and the standard S version.
     
  11. gg_got_a_tesla

    gg_got_a_tesla Model S: VIN P65513, Model 3 Res Holder

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    Some of the veteran EV owners on here may be able to answer this: isn't brake fade quite possible with EVs where the friction brakes are not used as often given regen? Isn't it advisable to do some hard friction braking from highway speeds to near-zero - like when coming off an off-ramp - to get the brakes in good shape?

    For the OP, it may have been that the P85 was coincidentally suffering from some brake fade owing to this?!
     
  12. ArtInCT

    ArtInCT Always Learning

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    #12 ArtInCT, Nov 24, 2014
    Last edited: Nov 24, 2014
    Brake fade can occur in the various parts of the brake system which may become over-heated due to sustained or frequent heavy brake application. Most commonly, fade is caused the gassing of the friction material in the disc brake pad as it and the rotors become very hot due to braking. This can cause one of the four disc brake assemblies to become less efficient, which in turn essentially cascades to the other three discs as they try to do more than their fair share of work. Often times, the front brake assemblies have a designed in breaking bias and get asked to do a larger share of the work.

    There are many remedies to brake fade with performance in mind. Slotted or drilled disc rotors allow gasses to escape between the pad and rotor, various ceramic brake pad compounds which are more resistant to gassing, larger and finned brake calipers and discs which offer more friction surface and cooling surface, and brake fluids which can withstand heat buildup. Also more air flow to the calipers and discs is/could employed as well.

    The model S is a very heavy car and stopping it repeatedly, on a curvy downhill switchback from high speed will probably display brake fade eventually (as it would on most cars).

    In "normal" driving situations, with normal weight in the model S I suspect there is no fade what so ever.
     
  13. PlanB

    PlanB Banned

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    I read this weekend that it is supposed to have the "best brakes in industry". I know that my new P85's brakes are amazingly better then my previous Tesla.
     
  14. point1

    point1 Member

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    I doubt fade will be a problem since it's hard to push the car, if it can't make more than 1/3 of a lap at the Nurburgring I have a hard time seeing the brakes would start fading during any kind of use. (Except from maybe riding down a mountain pass really fast, but even then it would perform better than most large sedans due to it's regenerative braking).
     
  15. Victory

    Victory Member

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    I've always thought the same as the OP until I read your comment. It makes so much sense now that I think about it. Faster acceleration doesn't necessarily mean you need bigger brakes. The only reasoning I can see behind that is if you accelerate so fast that you may not have time to notice your surroundings before-hand so you may need a faster stop in case something is in your way last minute.
     
  16. MarcG

    MarcG Active Member

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    It's quite simple, really: take the same road or track, and do an apples-to-apples comparison between a standard S85 and a P85D. Accelerating from the exit of a previous corner to the next corner will yield higher speeds with the more powerful machine, so if you don't upgrade the brakes then you have to start slowing down earlier since you'll have achieved a higher speed at the same braking point (which is the marker on the track where you are used to begin your braking phase).
     
  17. wycolo

    wycolo Active Member

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    Unless it is the battery that limits regen to the same figure that the single motor has.
    --
     
  18. marchyman

    marchyman Member

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    Huh? Braking is about traction. Can the current brakes trigger the ABS system? If so you've got enough braking power. More won't help.
     
  19. MarcG

    MarcG Active Member

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    Ok, I'll try to explain it a little differently. Let's suppose the following points exist on a road or track:

    A = Apex of the first corner/turn/bend in the road
    B = Braking point ahead of second corner/turn/bend

    The theory is that you start accelerating at point A and keep your foot in the accelerator pedal until point B, at which point you break to get ready for the next corner.
    In a P85D, you would reach point B with HIGHER speed than if you were in a P85/S85/S60. So to turn into corner 2 safely, you'll need either:

    1. more braking power, since at point B you're carrying more speed than in a P85/S85/S60, OR
    2. to start braking EARLIER than point B, if your brakes are the same as a P85/S85/S60
     
  20. tezco

    tezco Sig P85

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    Lets just hope that Tesla hits a happy medium between excellent braking for the average P85D driver vs costly over design for the few that want to turn this sedan into a track machine. If the latter becomes feasible with better engine and inverter cooling etc, I'm sure that aftermarket solutions will appear. Does the average owner want to travel around with heavy rotors and calipers, or pay an extra k or two for something state of the art, when something more earthly will satisfy all of their daily needs?
     

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