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Doing a brake job myself help please

Discussion in 'Model S' started by Bheuring, Mar 20, 2017.

  1. DarkMatter

    DarkMatter Member

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    Also: just realized that it's added as a service item because electric vehicles won't need brake jobs due to pad wear very often. Those (done properly) will also include a fluid change, and most other cars would need one every five years or less. Of course when the pad change is not needed any more you still should change the fluid to prevent corrosion of the internal components.
     
  2. bcsteeve

    bcsteeve Member

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    Good point, and if water absorption is the concern then that may very well be the reason I've never run into this.

    I should be clear that I've had my cars serviced regularly. "Inspect brake system" is always par for the course, but as far as I'm aware, they've never changed the fluid. That's true on my current Honda, which I now see it *is* right there on the service intervals that it should be changed every 3 years. I suspect that the dealership inspects it (or not) and feel it is still in acceptable condition. They have entries on my sheet for "inspected and filled washer reservoir" (along with a $9 charge... seriously?) so I'm sure they'd note it (and charge it) if they replaced the brake fluid.

    Now that this is on my radar, I'll be sure to ask. I'm due for a service really soon (just about to roll over 100,000km).
     
  3. DarkMatter

    DarkMatter Member

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    In some countries they actually test the boiling point of the brake fluid. In North America, it's not tested, just inspected with the Mark 1 Eyeball. That's why it ends up on the service schedule at a given interval. Dealerships are happy to skip services they think you will never notice (like brake fluid) while recommending services you don't need (like really short intervals on transmission fluid).
     
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  4. Don85D

    Don85D Member

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    I don't have one but there is a brake fluid tester that measures water content. It might be possible to delay brake fluid change using this device but after BMW ownership of cars and motorcycle with the 2 year recommended flush I do it for all of our vehicles.
     
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  5. Gamma195

    Gamma195 Member

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    Might as well throw my two cents in here. I am an ASE certified mechanic. Used it to put myself through college then used that to be a maintenance officer in the Army. Let's put a few of these incorrect comments to rest...

    1. Brakes are easy. Yes they are. They are only a step above oil change. But we don't teach people how to get dirty anymore. Don't believe me? Just see the declining mechanical scores on military entrance exams. Do brakes take some basic knowledge? Yep, but not a ton.

    2. Pad and Rotors need to be worked on as a set. If you put new rotors on you have to replace the rotors (if the are warped or below tolerance) or at a minimum have the rotors turned. This is to create a new machined surface to mate the new pads and rotors. Its possible to skip turning, but you run the risk of premature warpage due to metal hot spots. As a rule of thumb, most rotors can be turned at least once. Also, just by new brake hardware (the clips). They are cheap and reusing old clips is Primary reason brakes rattle.

    3. Brake fluid. Here it is kids, brake fluid is hydroscopic, meaning absorbs water. The minor impact is a spongy brake feel. The real impact is water creates rust. Rust in the master cylinder, caliper body, Pistons (both master and caliper) and inside brake lines. This produces pitting and allows fluid to bypass seals. This is all bad. So change it. DOT 4 is slightly better than DOT3, but all fluids are good for no more than 3 years. With an auto bleeder pulling out the old fluid is easy. Two people can do it by hand by just manually bleeding for an extended period.

    4. Differences between old and new. Some newer cars have some added steps for bleeding (computer controlled parking brake retraction, abs system bleeding, etc). That's about the only stuff you need to research that may be different make to make or model to model.

    And on a personal note... working on your own car is fun as hell and cheaper too. Now, I am not so eager to start, say, working on the high voltage battery, but brakes shouldn't kill you. If you're nervous or haven't done it before, find a friend who has, or take a class at your local community college. Might even turn into a hobby!

    Plus, contrary to popular millennial beliefs, chick's still dig dudes that can actually build and fix things with their own two hands!
     
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  6. Don85D

    Don85D Member

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    My one addition to your list is to pump the brakes until the pedal is hard before putting the car in Drive after a brake job. Those first few feet with no brakes can be a big surprise.
     
  7. tls

    tls Member

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    Do you mean to say, every new set of pads means replacement or (at a minimum) turning of the rotors? That seems pretty extreme.

    I've done a lot of brakes over the years including on single-disc motorcycles where you really notice (particularly on the front) and I have never had a problem doing pads without rotors unless the rotor measured out as warped or was obviously grooved.

    What I have had plenty of trouble with is warped rotors from uneven lug torque. I had a Volvo where it seemed like I'd go through 4 rotors a year until I wised up and started retorquing the lugs with my own wrench every time someone had a wheel off...
     
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  8. Don85D

    Don85D Member

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    It's my understanding that rotors on most cars are already at the minimum thickness when the car is new. The assumption is that when the pads need replacing so do the rotors. This actually works out OK as rotors are not expensive and the resulting brake job makes the customer very happy.

    I have been guilty of cleaning and keeping older rotors especially those that are cross drilled. On my old truck that philosophy has worked well but for newer Japanese cars in our family the rotors are changed with every change of pads.
     
  9. jjh1234

    jjh1234 Member

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    There are three rotor thickness numbers to look at. New thickness, Minimum Refinish thickness and Discard thickness. The New thickness will be substantially larger than the other two. Minimum Refinish thickness will be the minimum thickness after refinishing that will still support one more set of brake pads before reaching the discard thickness. Rotors legally must be discarded when they reach the Discard thickness. The discard thickness is usually stamped in the hat of the rotor itself.

    Many people will just replace rotors with the pads instead of resurfacing them if the price difference is not too great. There are, however, some pretty expensive rotors out there that would make a good case for resurfacing the old ones, especially if they are still rather thick and only need light resurfacing. Some light passenger car rotors are <$30, whereas high end cars, trucks and larger SUV can be >$100.

    My own experience is that resurfaced rotors are more susceptible to warping with spirited driving since they are thinner than new and cannot hold as much heat, or from other consequences of resurfacing.
     
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  10. Gamma195

    Gamma195 Member

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    Because people were asking about bleeding...

    Bleeding is pretty simple, but it is a process. It is best to bleed all four wheels if you have cracked any of the bleed valves. Some may argue against that, especially if you are only working on one caliper, but sometimes and air bubble can get past.

    Auto bleeders often don't get it all, so I prefer manual bleeding. Just remember to do all four wheels working around the car. Your helper pumps the brakes then hold the pedal down. You Crack the bleeder, and then tighten it BEFORE he let's up on the pedal. Other wise you suck air back in.

    As for the turning the rotors, if they are not warped then you're only taking thousands of an inch of to get past the surface glazing. The glazing is the tempering of the steel due to heat and friction. You can skip it, but you will get more warping not less. This is due to hot spots (i.e. over tempered areas) causing a non uniform heat distribution. What is true, is if you turn the rotors substantially below minimum thickness they will warp quicker. But the whole reason they put that measurement on there is just for that reason. They are designed to be resurfaced. Be aware though that most crappy mechanic shops will tell you your brakes are warped often to sell you new rotors. If in doubt make them put a runout gauge on them and show you.

    A note about purchasing rotors at an auto parts store. Make them show you how they store them. They are supposed to stack them like pancakes, but most store them vertically like library books for ease of access. I kid you not, if they are stored vertically they will slightly warp over time. I have turned many a new rotor right out of the box that was stored that way.

    And I have personally turned a couple hundred rotors as a mechanic and none of them came back warped. At least not until they were below thickness.

    For the record, you do the exact same thing for clutch flywheels. Nothing will make you mad quicker than spending all day replacing a transmission just to get instant clutch chatter from hot spots.
     
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  11. Don85D

    Don85D Member

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    The low price of rotors has made turning them obsolete, at least in my neighbourhood. Here there is only one shop remaining with the lathe required and they have to find it for my job. In the end, the rotor warps again and I give up to buy new which I should have done in the first place. My theory about warped rotors is that they are not heat stress relieved during manufacture. The cross drilled rotors that I purchased as an upgrade have lasted much longer. It may be the cost reduced manufacturing and metallurgy that is causing rotor warping.

    I now consider rotors to be a disposable item after one set of pads.

    There is another factor where salt/brine is used on roads in winter. In the old days vehicles came with disk brakes on the front and drum brakes on the back. This was ideal as road debris and low braking requirements on the rear didn't affect brake operation. I spend most of my time cleaning rusty parts on rear disk brakes and ensuring that they work freely. It's an annual check when mounting winter tires. The old design of drums brakes on the back had merit.

    My comments are for common daily use low priced vehicles so there are exceptions and dry garage storage is a benefit if available. Mostly these daily drivers sit outdoors for their entire life and brake maintenance is a constant effort.
     
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  12. sakimano

    sakimano Member

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    I dare you to start a thread about wheel spacers :)
     
  13. gavine

    gavine Petrol Head turned EV Enthusiast

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    A couple of car enthusiasts that I work with love my Tesla but they said would never buy an EV because you can't really modify them. These guys are obsessed with modifying their engines. Headers, superchargers, chips/programmers, etc. etc. Then they get tired of the car when no more mods are available and they take a bath when they sell.....they get none of that money back in added value.
     
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  14. Don85D

    Don85D Member

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    I observe the same addiction with new Harley owners who feel a need to add optional chrome parts, remove parts to be chromed and in general add extra weight to the motorcycle. Eventually they have every option available and go into remorse. I ride a BMW and there are no options except for the riding gear that keeps us safe.

    Car tuners and those who restore classic cars also pay dearly for the enjoyment and they lose when they sell. On the other hand, entertainment and comradeship can be worth a lot so I'm not knocking those that customize their vehicles. Pride of ownership is always nice to see.
     
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  15. DarkMatter

    DarkMatter Member

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    Tuning can be super fun on old cars, since the tapestry is more wide open. It's not something you do to get money back.
     
  16. ⚡️ELECTROMAN⚡️

    ⚡️ELECTROMAN⚡️ Fritterer and waster of hours in an off hand wayer

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