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My brakes need a morning coffee some days....

Discussion in 'Model S' started by MacLeodMX, Jan 12, 2014.

  1. MacLeodMX

    MacLeodMX Member

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    Weird behaviour on a few mornings makes me wonder if this is expected. Didn't happen last winter, though.
    Unpredictable - happens in cold and not so cold days. Actually, come to think of it, this only happens when the regenerative braking is disabled.
    So it's like I don't have brakes - stepping on mush as I go through the first intersection of the day.
    This is a very heavy car to slow down.They absolutely return to normal after the frantic 20 second pumping exercises.
    Anyone else have this? I'm not getting any " car needs service" messages. Should I "work" the brakes before I even start off? This is a P85 with 13000km on the odo.
     
  2. MassX1317

    MassX1317 Addicted to TMC

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    Call Tesla immediately and don't drive the car! If your car isn't braking when it should and causing you to enter intersections unintentionally you are putting yourself and others at risk. I'm sure they will come out right away with a loaner for you.
     
  3. Discoducky

    Discoducky Active Member

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    This sounds much more like the pads heating up. I live on a hill about 400ft up from the highway and about a mile of coasting. Without regen on cold mornings I need to use the brakes and it isn't until the bottom where they cease to be "squishy". This scenario sounds the same.
     
  4. howardc64

    howardc64 Member

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    Curious what pads Tesla uses. In all the other car's I've had, pad material and the disc rotor itself can make a huge difference in bite. Difference in cost is quite big between the low and high quality stuff and there isn't any visual way to distinguish. I'm not saying Tesla used low quality brakes. Just noting the difference can be huge.

    On the Tesla... I'm on standard regen most of the time so really aren't familiar with the Tesla brake's bite. There is the feature to turn to regen to low, I wonder if using this setting will give us a better feel for this brake system's bite.
     
  5. Alysashley79

    Alysashley79 Member

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    Can you try setting your pack to be done charging about 30 minutes before you leave so your regen won't be disabled? That's what I've done as I descend from 2100' to sea level in the morning. My brakes are a bit squishy in the morning but I usually go a bit fast when I'm alone on the road and stomp on them hard once or twice if I don't have the regen.
     
  6. strider

    strider Active Member

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    If the pedal is soft (ie the pedal travels really far) then you need to have Tesla bleed your brakes. If the pedal is firm but the car doesn't slow down then it is pad/rotor interaction. You could have some rust built-up on the rotors from snow/ice melting over night and it takes a bit to scrub them.

    We had a really bad problem with this on the Roadster as the Lotus pads they used were made for higher heat and since we hardly use our brakes they would gunk up and then not work. The solution was to switch to these:
    Carbotech Performance Brakes

    The 1521 or AX6 compound. Excellent bite even when cold and with our limited brake use. Also with the 1521 compound there is essentially zero brake dust. I am currently working on getting them to support the Model S.

    Not saying you should have to buy new brake pads for your car but just saying there is a better option out there for the "hard pedal but car won't slow down" problem.
     
  7. kbeckley

    kbeckley Member

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    Amazing that I experienced the exact same issue over the past week here in Toronto. Didn't experience this last year either. It has been cold so no initial regen and initially if feels like there is no brake. The pedal goes almost to the floor to get any stopping. If you pump it a few times and then it feels normal. I'll call Tesla and see what they say.
     
  8. muleferg

    muleferg Member

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    On the Nissan Leaf the brake fluid is changed yearly.
     
  9. howardc64

    howardc64 Member

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    #9 howardc64, Jan 13, 2014
    Last edited: Jan 13, 2014
    Brake fluid is designed to absorb moisture. Many shops suggest 2 year change interval for wet climate regions. Might be overkill but is a peace of mind. Don't want to have moisture inside the lines corroding your lines+system.

    On non EV/hybrid cars, bleeding is pretty easy. I use a pressure bleeder and can do it quickly. However, on EV/hybrids, I think the factory diagnostic tool is necessary to open up each circuit for bleeding.

    Know if Carbotech 1521 is ceramic since it quotes low dust operation? I find low dust is highly desirable for street use if want to avoid black wheels all the time :)

    I live by a steep 1/2 mile down hill, different types of pads definitely release different temperature and different bite. A lot of rotor warpage problems when cheap pads are used. Sounds like Tesla didn't pick the best combo at least for the Roadster. With such powerful regen stopping power, most drivers probably don't notice it.

    Looks like typical premium sedan replacement pad manufacturer like Akebono and EBC don't yet make pads for the Model S.
     
  10. strider

    strider Active Member

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    Tesla needs to bleed the brakes.

    Nothing special because it's an EV - They recommend a diagnostic tool for all cars w/ ABS, ESP, etc to manually cycle the pumps that run those systems or you end up w/ pockets of old fluid.
    With the Roadster Tesla just used the pads and rotors that Lotus already had for the Elise and they are a "high-performance" pad suited for higher heat operation. We need pads that work when cold since we don't use our brakes that much. That's why we like the Carbotech's as they are built for Autocross which requires pads that work hard when cold and through a wide heat spectrum.

    The carbotechs are ceramic. You can read more here: Carbotech Performance Brakes: About Us

    On my Corvette and other ICE's I was a big fan of Hawk pads but I think the way we use brakes in our cars (ie we rarely use them) requires something different than your standard "performance" pad.

    I am buying a set of Model S pads to send to Carbotech on Wednesday so they can measure them and see if they can provide fitment. I'll keep the forum updated. Most likely in this thread: Brake dust
     
  11. Gizmotoy

    Gizmotoy Active Member

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    Basically a big +1 to this whole comment and strider's subsequent comment. You either have air in your brake lines, have a brake fluid leak, the hydraulic pump is bad, or you are otherwise low on fluid. In any case, it needs serviced immediately.

    Some pad compounds are extremely poor when cold and take several stops on a cold morning before they warm up and achieve good bite, but I don't think Tesla or any OEM would ever use such a pad on a mass market (non-high-performance/race) vehicle. So that leaves this firmly in the "not normal" range, and it needs looks at.
     
  12. ImperialG

    ImperialG Member

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    I had the same issue when the temperature fell to 4 degrees in New Jersey. I was rolling out of the driveway and nothing happened when I pressed the brakes. I had to use A LOT of force to push the brakes and still it barely slowed the car. The brakes were basically inoperable for the first mile that I drove. Eventually, it seems that the pads heated up and started to work again. It has only happened once, so I'm not too sure if it's cause for alarm yet, or if I can even reproduce the issue for the service center.
     
  13. VolkerP

    VolkerP EU Model S P-37

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    When I pump the brake pedal, I can hear some machinery running intermittently from the car's front end. I think Model S has a vacuum pump that supplies pneumatic assistance to manual brake pedal. Same as the Roadster has. In conventional car, when ICE is not running, the vacuum buffer is exhausted after a few brake cycles. Pedal gets harder to push to yield same braking effect. So different behavior from what was described in OP.

    If the brake pedal goes all the way without producing stopping power, I think it indicates some problem in the hydraulic brake lines. Could be air or moisture. Have your car checked ASAP.
     
  14. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    My driveway has quite a slope plus a sharp turn into the alley and I've never had a problem (coldest has been -10 C). I'd agree there is a problem with the braking system in the OP's car.
     
  15. mnx

    mnx 2013 P85

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    The loaner I have while my car is in for it's annual service seems to have much better initial bite when applying the brakes.
     

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