TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker or making a Paypal contribution here: paypal.me/SupportTMC

Flush your brake fluid!

Discussion in 'Roadster: Technical' started by frequencydip, Jan 28, 2012.

  1. frequencydip

    frequencydip Sig 100 - #52

    Joined:
    Dec 11, 2011
    Messages:
    165
    Location:
    Los Angeles
    #1 frequencydip, Jan 28, 2012
    Last edited: Feb 5, 2012
    I flushed my own brakes the other-day and was horrified of how nasty the old fluid was. The fluid has gelled in the real calipers, it was like a thick gooey substance that came out. I flushed the whole system putting in high performance fluid and I noticed a very big difference in braking afterwords. Most likely due to the coagulation of the fluid in the rear calipers. My car is a sig 100 and had 30,000 miles on it. I also inspected the rotors and they had minimal wear and the pads were also in good shape so the fluid didn't gel due to heavy usage of the brakes just age.

    Edit: So far only my car has had this issue, so this seams to be an isolated issue. There does not appear to be an issue with EV's or the roadsters breaks until someone else can confirm the same problem.
     
  2. AnOutsider

    AnOutsider S532 # XS27

    Joined:
    Apr 3, 2009
    Messages:
    11,923
    Perhaps Tesla is so used to not having to do dirty things related to ICE vehicles that they forgot. :smile:
     
  3. S-2000 Roadster

    Joined:
    Apr 10, 2009
    Messages:
    636
    How old is your Roadster, Frequency Dip?
     
  4. hcsharp

    hcsharp Active Member

    Joined:
    Jun 7, 2011
    Messages:
    2,532
    Location:
    Vermont
    Without looking it up, I think I saw in my owner's manual they recommend replacing brake fluid every 2 yrs regardless of miles because it absorbs moisture and forms the corrosive gel that you saw. I think better quality brake fluid might prevent that.
     
  5. dsm363

    dsm363 Roadster + Sig Model S

    Joined:
    May 17, 2009
    Messages:
    18,235
    Location:
    Las Vegas, NV
    Have you notified Tesla? Maybe they simply haven't had enough Teslas that are 2 years old to notice the problem.
     
  6. JRP3

    JRP3 Hyperactive Member

    Joined:
    Aug 20, 2007
    Messages:
    10,098
    Location:
    Central New York
    I've had 10+ year old vehicles that never had the brake fluid changed and I've never seen what you describe. Something seems odd there.
     
  7. frequencydip

    frequencydip Sig 100 - #52

    Joined:
    Dec 11, 2011
    Messages:
    165
    Location:
    Los Angeles
    My Tesla is 25 months old, I have never seen brake fluid like that either even on old cars with lots of usage. I'm willing to bet its substandard brake fluid. I'll contact my Tesla shop on monday to let them know they should at least check other cars.
     
  8. W.Petefish

    W.Petefish Active Member

    Joined:
    Apr 29, 2011
    Messages:
    1,059
    Location:
    North Texas (DFW)
    Ranger Larry said that bleeding the breaks is done once every two years. (If my memory serves me correctly) I may ask if we(he) can do mine today.
     
  9. The_User

    The_User Member

    Joined:
    Jan 31, 2012
    Messages:
    31
    Location:
    Seattle
    Brake fluid is hydroscopic and should be changed/flushed each year. I bleed out the fluid on my buddies 1.0 about a month ago. Luckily things were still liquid, but very dark. Make sure to use DOT4 only. The local dealer here only charges a little over $100 to bleed the brakes which isn't any more than any other car would cost.
     
  10. JRP3

    JRP3 Hyperactive Member

    Joined:
    Aug 20, 2007
    Messages:
    10,098
    Location:
    Central New York
    Since the brakes are a sealed system where is the moisture coming from? Yearly brake flushes? That sounds crazy.
     
  11. Lloyd

    Lloyd Active Member

    Joined:
    Jan 12, 2011
    Messages:
    4,883
    Location:
    San Luis Obispo, CA
    #11 Lloyd, Jan 31, 2012
    Last edited: Jan 31, 2012
    Moisture can come through the seals on the calipers, master cylinder through the breather on the resovoir.
     
  12. dwegmull

    dwegmull 2013 Model S 85

    Joined:
    Oct 8, 2009
    Messages:
    238
    Location:
    Redwood City, California
    Mine is going in for its second annual service this coming Monday (Menlo Park store). I will raise this question and see what happens...
     
  13. Lloyd

    Lloyd Active Member

    Joined:
    Jan 12, 2011
    Messages:
    4,883
    Location:
    San Luis Obispo, CA
    Fluid on my BMW gets changed every year by BMW at their cost while under warrenty.
     
  14. JRP3

    JRP3 Hyperactive Member

    Joined:
    Aug 20, 2007
    Messages:
    10,098
    Location:
    Central New York
    If moisture can come through the caliper seals wouldn't brake fluid leak out of them? Are they building master cylinders differently now? I don't remember seeing a breather on any master cylinder, they always had a sealed cover with no vent. I've just never encountered the brake fluid dynamics that some of you are describing.
     
  15. Lloyd

    Lloyd Active Member

    Joined:
    Jan 12, 2011
    Messages:
    4,883
    Location:
    San Luis Obispo, CA
    it's a piston with with a wiper seal. Each time it goes each way a little moisture has the opportunity to be absorbed by the fluid. This is especially true in rain and moist environments. It is not as completely sealed as you might think.
     
  16. S-2000 Roadster

    Joined:
    Apr 10, 2009
    Messages:
    636
    There are many things to consider.

    For one, when the atmospheric pressure (temperature) changes, the difference has to come from somewhere, and usually some part of the brake system pulls in "air" - but note that air always has some amount of water vapor. So, it's not pulling in water, per se, but pulling in air that eventually condenses into water.

    Four wheel drive vehicles have to design around this because often the systems are under water, and the pressure changes will suck in water through every available avenue. Such systems have venting at a high point in the vehicle so that it's easier for air to come in up high than for water to come in down low. But the point is that if they could just make it "perfectly" sealed then they wouldn't bother with all of this venting, which just provides evidence that perfect seals are not really feasible in consumer or even most military vehicles. Note, the venting I am describing is not for brake lines, but it should illustrate the difficulty in making perfect seals on any system that is exposed to environmental changes.

    For another thing, there are many grades of brake fluid, up to DOT 5 and DOT 6, I recall. Some of these are better than the DOT 4 that is in the Roadster, but they're also more expensive and more trouble to deal with. In other words, there is nothing substandard about the Tesla Roadster brakes, it's on par with the bulk of vehicles out there.
     
  17. JRP3

    JRP3 Hyperactive Member

    Joined:
    Aug 20, 2007
    Messages:
    10,098
    Location:
    Central New York
    But the fluid issues reported and the change intervals are not standard from my experience. In fact I've had a number of off road vehicles that regularly went in deep water and mud and I never saw excessive water or gelling in the brake fluid and never did yearly brake flushes. In most cases unless I had to change system components they never got a full flush and never had any issues, and this was with regular DOT3 fluid. I'm just mystified by the fluid change intervals some of you seem to think are standard. If some mechanic suggested to me a yearly brake fluid flush I'd think he was trying to rip me off and I'd never go back there again, but I've never heard of such a thing before. Maybe the DOT 4 and up fluids are more sensitive to moisture?
     
  18. W.Petefish

    W.Petefish Active Member

    Joined:
    Apr 29, 2011
    Messages:
    1,059
    Location:
    North Texas (DFW)
    FYI Ranger says, "The fluid (brake) is bled every two years." and that if you are seeing fluid gelling you have some sort of contamination in the fluid. (And should call Tesla Service)
     
  19. Lloyd

    Lloyd Active Member

    Joined:
    Jan 12, 2011
    Messages:
    4,883
    Location:
    San Luis Obispo, CA
    All brake fluid absorbs moisture, that is their intention. It prevents water from accumulating in the system and creating steam when hot and affecting braking ability, or corrosion internal to the calipers or master cylinder. High performance cars are usually more sensitive to this due to the higher temperatures, generated. Street vehicles with normal operation are not as critical. I bleed my wife's car every couple of years. Airplanes are bled annually. I took my M6 on the track with a professional race team. They insisted on bleeding the brakes after the racing run and returning the car to the street!
     
  20. The_User

    The_User Member

    Joined:
    Jan 31, 2012
    Messages:
    31
    Location:
    Seattle
    Heat cycling is what causes most of the moister to develop and allow contaminants into the brake fluid along with seals, cap, vent etc. As some have mentioned, track use is the most critical because brake fluid has an incredibly high boiling point. Water of course, does not. Little particles of water can boil and tadda, they can compress! Ever gotten brake fade? That's a part (not all) of why brake fade happens.

    These are $100k cars, spending $100 or so to care for part of a system that has such an impact on safety seems non-debatable to me.
     

Share This Page