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[Brake performance] Standard brakes on Roadster 2.5

Discussion in 'Roadster: Performance' started by widodh, Feb 17, 2012.

  1. widodh

    widodh Model S R231 EU

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    Hi,

    My colleague is on vacation for a couple of weeks, so the Roadster is at my house for that time.

    I drove again a bit today and I noticed right away, the brakes are SO weak on a Roadster.

    I found this thread: Braking issues ...

    Anybody else finding the brake performance of the Roadster really low?

    A car like the Roadster with it's huge acceleration potential should also have a descent deceleration, but it doesn't imho.

    If I compare the braking power to my BMW M5 or Toyota Auris Hybrid the Roadster ends last.

    Did anybody here replace the brake pads or the pistons? If so, with which ones?
     
  2. strider

    strider Active Member

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    I wonder if your colleague didn't properly bed in the brakes? I have found that the stock brakes work fine. The Roadster doesn't stop as fast as my Corvette but I believe this is because the tires are quite small relative to the weight and not related to the brakes at all. My Corvette had much larger tires and only weighed slightly more.

    From: Hawk Performance Brake Pads: Frequently Asked Questions

     
  3. Doug_G

    Doug_G Lead Moderator

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    I find the Roadster's brake pedal takes a bit more force than most cars, which can give you the impression that they are weak. But they actually do stop quite fast... in fact, here's an anecdote to illustrate:

    After getting the Roadster I decided it would be a good idea to take the CASC Race School, and learn how to drive a performance car properly. The first in-car task was an emergency stopping exercise. You drove through a slalom and then into a large puddle, where the head instructor was standing in the middle. You had to aim right for her. At the last moment she'd wave a flag and you had to avoid her in the direction she waved (proper procedure is to slam brakes first to load up the front tires, then steer).

    I had a lot of trouble with this, but not (like half the class) because I balked at trying to run down a middle-aged woman (I figured she knew what she was doing). No, my problem was the Roadster kept stopping way short.

    On the second attempt my in-car instructor asked me to go faster. We stopped short again. The head instructor looked at us and said, "This is going to be interesting. Faster!"

    Finally after several increments in speed, with my in-car instructor reading off the speedometer so I could keep my eyes on the road, we were bearing down on her with what seemed break-neck speed. As in her neck. At the last second she waved the flag, I planted the brakes then turned the wheel, and we slid and ABS-ed our way to our resting point right beside her. Success!
     
  4. NigelM

    NigelM Recovering Member

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    So what was your final speed??
     
  5. Doug_G

    Doug_G Lead Moderator

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    That exact number is a bit fuzzy because it's been almost two years, but it was over 50 kph and we were pretty damned close - a matter of meters - when she waved that flag.

    They do take safety very seriously. CASC regulations set the pit lane speed limit at 60 kph, because that's the threshold above which serious bodily injury is likely. So they weren't going to get me to go that fast. I'm sure she's fast on her feet, if need be, but there's no doubt she's fearless!
     
  6. Mitrovic

    Mitrovic Member

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    First I thought also the brakes are weak. Then I went on a race track with an instructors.
    Now I think that we are just not used to those brakes. We are used to super-servo-assisted brakes you merely touch them and the car brakes. At the roadster you have to slam the brakes really hard, but then, oh boy, it really BRAKES!
     
  7. cinergi

    cinergi Active Member

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    They do require a lot of pedal force but for me I find them a bit weak ... I've had some quick stops ... My STi would have done better. It's probably related to the weight balance and overweight design (for the chassis) of the Roadster. That said its not empirical and 100-0 braking comparisons would be really nice.
     
  8. ggr

    ggr Roadster 537, Sig P85

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    A racing driver friend of mine recently drove the roadster in the local mountains, and pointed out that the brakes are usually cold! They stop just fine after a few uses.
     
  9. frequencydip

    frequencydip Sig 100 - #52

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    I also felt the brakes are under powering. I changed the pads to Carbotech AX6 they are much better initial bite but they squeal just a bit.
     
  10. widodh

    widodh Model S R231 EU

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    I think you are right.

    I took the Roadster out for a drive yesterday and braked really hard a couple of times. Once the brakes were warmed up and all the dust and rust was off, the brake much better. But you have to slam them REALLY hard.

    It seems like the brake-assistance isn't that hard, you have to do a lot your own. My M5 of course has hydraulic brake-assistance which is much more powerful.

    You have to know you have to press the brakes that hard, otherwise you'll be surprised.

    My idea is also that since you use the regen so much, the brakes start rusting and dusting?
     
  11. Doug_G

    Doug_G Lead Moderator

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    That's an excellent point.

    And yes your rotors do tend to get some crap built up on them over time, due to the light usage. Take your car out once in a while and do a bunch of hard stops; that will clean things up.
     
  12. vfx

    vfx Well-Known Member

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    So you were driving straight at her?
     
  13. Doug_G

    Doug_G Lead Moderator

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    Correct. The instructions were to drive straight at her. Only when she waved the flag left or right were we to do the avoidance maneuver. If someone started to lean one way or otherwise jump the gun she'd wave it in the opposite direction.
     
  14. Eberhard

    Eberhard #421 Model S #S32

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    This is my problem too. After 14 moth, i got my rear braking discs and pads replaced. After driving in humid conditions, the pads gets clued to the discs and i have to brake them free with pure force. have anyone an idea using different pads which don't get rusted with the disc together?
     
  15. frequencydip

    frequencydip Sig 100 - #52

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    This happens with just humidity? I always brake hard a few times or drag the brakes before parking if its raining out to make sure they are dry.
     
  16. Eberhard

    Eberhard #421 Model S #S32

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    Thats what I always do, but if don't drive for a few days this no longer helps if the humidity is too high.
     
  17. Roger Reid

    Roger Reid Old but effective

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    I have been running the Carbotech 6 compound for over a year now. These are the best stopping pads I have found for my 2.0. I highly recommend them.

    It would be a shame to scrap an $100,000.00 plus car because you couldn't stop before the impact.
     
  18. brianman

    brianman Burrito Founder

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    Is there any official information (or educated guesses if not) regarding whether this is a Roadster-specific issue or whether we should expect similar human-calibration for the Model S and/or Model X?

    Is this exacerbated by the use of regen much of the time vs. an ICE always using the brakes and thus they "warm faster"?
     
  19. strider

    strider Active Member

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    As the Model S will be a "luxury car" vs a hard-edged sports car I would assume they will have stronger brake assist.

    Yes. On my 60-mile round trip commute I typically touch the brake pedal about 6 times - 2 stop signs, 2 stop lights, and pulling into my parking space/garage - and then it's only to stop the creep from 2mph or so to a stop. I use regen for all the slow and go on the freeway.

    That being said, there was one of those classic Highway 101 "let's all slam on our brakes from 80mph" events the other day and I jammed on the brakes hard. The car stopped very quickly so the brake pads were biting just fine. But I did go through the brake bedding process I described above right after I got the car.
     

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