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Brake Performance Issues in wet weather?

Discussion in 'Model S: Driving Dynamics' started by scaesare, Apr 30, 2014.

  1. scaesare

    scaesare Active Member

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    #1 scaesare, Apr 30, 2014
    Last edited: May 1, 2014
    MOD NOTE: I'm editing this asking for the mods to delete this thread, as I had not initially seen another thread already covering this, so to avoid duplication I've copied my info there. Thanks.

    OK, so I'm resurrecting this from earlier in the month.

    I got the weird brake feeling again a few times with the heavy rains the last couple of days. When I initially hit the brakes for the first couple of seconds it feels very much like either air in the lines, or "brake fade" if you've ever had it: the calipers just don't seem to be grabbing. After a few moments it will then start to grab and slow me down.

    I did some testing, and here are my observations:

    - It appears to happen when the car is first driven after sitting in wet conditions for a bit (a couple of hours).

    - After the first instance or two in a driving session it stops being as prevalent (but can still happen to some extent)

    - It does not appear to be tires losing traction/hydroplaning: I had a section of parking lot where I could test and under identical conditions it would happen the first time, but not subsequent times

    - It is not the ABS system. I can feel that kick in, and deliberately engaged it during testing to compare... this is different.

    - I've not had it happen in dry conditions


    I've never had a disc brake car act like this when in good order. It's very disconcerting in that it it can easily double stopping distance when it happens if in mid-speed traffic.

    I'm wondering if the same rust/scale build-up that we notice on the rotors, and that may cause them to stick when parked over night, might be reacting with the moisture and preventing good brake-bad friction until it's been "scuffed off" after the first few braking applications in a given session?

    Has anybody else experienced anything like this?
     
  2. mibaro2

    mibaro2 Member

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    My car is a few weeks old. It has been raining here for the past 2 days, and my car was parked out in the rain all day today.
    The only thing different that I noticed when I drove it was my brakes squeaking. Other that that, the braking was fine.
    Could be that my car is new and won't show your symptoms until it has a few more miles on it.
    My .02 cents.
     
  3. Xenoilphobe

    Xenoilphobe Active Member

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    your brakes are wet if you use regen the motor is the braking element so the wet rotors are not really being used
     
  4. SeminoleFSU

    SeminoleFSU Member

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    #4 SeminoleFSU, Apr 30, 2014
    Last edited: Apr 30, 2014
    There have been numerous discussions on brake fade in wet conditions. Just do a search (top right)... IIRC, it has to do with water being directed onto the discs and lack of brake use in general because of regen. An owner who complained a lot wrote about a mod they did on his sig model s to help deflect water away or something
     
  5. scaesare

    scaesare Active Member

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    True, however the initial wet brake application in the S feels drastically different than all of the other disc brake vehicles I've ever driven or owned.
     
  6. yobigd20

    yobigd20 Well-Known Member

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    there is a brand new TSB Tesla just released that replaces the rotors with heavier rotors and brand new brake pads to address the braking issue and brake squeaking issue. I just had my rotors replaced last week and haven't had these issues since.
     
  7. scaesare

    scaesare Active Member

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    Thanks yobigd20, I just read the other thread on this and my experience is identical.

    I should also point out that the service center flushed my brake system to address this when I first mentioned it here (they proactively called me about my posting here). I'll give them another ring...
     

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