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Stop here! Let's talk about brakes

Kirstie_HKirstie_H Posts: 10,890
Do you know or suspect you've got brake trouble? Got a tip? Talk about it here.

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  • well... here's one. My old car had a strange brake problem. It was hard to detect even by the garage mechanics. It was only noticeable when the car has been running more than 10 minutes and with the A/C on. I would noticed that the brake pedal would really became looser as I braked more.... repeated brakings.

    The mechanic had to open the whatchamacallit and found that the fluids were leaking inside! So if you feel that your brake pedal gradually becoming "depressing" then have it check out as soon as possible :)
  • Kirstie_HKirstie_H Posts: 10,890
    I used to have an Altima, and even when new the brakes squeaked a lot. The shop said it was because of the type of pads used and roughed them up occasionally to kill the noise, but it was still really annoying. I haven't had that problem on any of my vehicles since. Is this folklore that he was sharing with me?

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  • It's true that some new disc brakes will generate unnerving noises. I believe that there are some sort of brake sprays that you could buy to reduce that noise. Check it out at an auto parts. That should help.
  • shiposhipo Posts: 9,152
    Back in the early to mid 1970's, I learned to turn a fair wrench learning on the cars of my own and my friends in college who could not afford to pay a professional to keep them running. I was fortunate in that I bought most of the parts that I needed at a local shop that had a Geezer (as he called himself) working there who had been working on cars since the late 1920's and had more tricks up his sleeve than a magician.

    He taught me that the “Sure-Fire” way to eliminate disk-brake squeal was to slap a piece of high quality “Duct-Tape” on the back of each pad before mounting them inside the caliper. Since that time, I have used that technique on well over 100 cars (through the mid 1980’s) and have never had anybody complain about noisy brakes again.

    Interesting side note, since 1980 I have never had a car that had the infamous “Brake Squeal”, however, in the mid 1990’s, I had the opportunity to develop the Customer Service system for MBUSA. During the development process, I was working with a lot of live data, and noticed that a fairly common complaint from MB owners was brake noise. I suspect that Duct-Tape might just solve their problem, however, I am “just a programmer”, what do I know about cars? ;-)

    Best Regards,
    Shipo
  • * The vehicle pulls to one side when the brakes are applied.
    * The brake pedal sinks to the floor when pressure is maintained.
    * You hear or feel scraping or grinding during braking.
    * The "brake" light on the instrument panel is lit.
  • shiposhipo Posts: 9,152
    It sounds like you have 1 or 2 different problems.

    First, the pulling to one side, the pedal sinking to the floor and the "Brake" suggests to me that you have air and/or water in your brake lines, more on this later.

    Second, the Grinding you hear might imply worn brake pads where the metal backing plate (or their rivets if so equipped) is grinding on the disk rotor; it might also be simple pad shimmy. The difference is that worn pads can be fatal when your brakes fail all together, while pad shimmy is simply annoying.

    Back to your brake fluid. Brake fluid has a tendency to absorb water over time; BMW recommends a complete fluid replacement every two years because of this. When a sufficient quantity of water builds up in your brake fluid, you have two problems. The first is that under braking, your brakes generate LOTS of heat, and any water in the brake fluid is likely to boil. When that happens you essentially end up with a bubble (which is compressible like air) and loss of pressure on the brake pads for that wheel. The second problem is rust; there are plenty of parts inside a brake system that can rust under prolonged exposure to water. The most serious is the pistons used to actuate disk brakes, if they rust, they will be unable to move freely and as a result, you will not get full stopping power on that wheel. Air in the brake lines is in some ways worse, it is compressible and when you push the brake pedal, the air in the line compresses and the brake pads do little if anything to stop the car.

    If I were you, and if I intended on keeping the car beyond an hour from now, I would get the car to a shop for a complete 4-wheel brake job including new caliper seals and a complete brake fluid replacement.

    I hope this helps.

    Best Regards,
    Shipo
  • joe3891joe3891 Posts: 759
    I would say your pads are worn out & you popped a piston o-ring due to excessive piston travel.Better get them fixed ASAP.
  • brorjacebrorjace Posts: 588
    kirstie, brake pads are asked to do a lot of things ... and it is not uncommon for them to squeak and squeal a bit here and there. It may be annoying, but as long as the friction material is not worn out, they are fine. OEM pads are usually the best all around bet for most cars but you are also well off getting the best grade of friction material from Bendix, Raybestos or Ferodo America (The Spectra Premium brand). Usually, they have an OE replacement grade and that's your best choice.

    Excessive brake squeal is usually caused by vibration between the pad's backing plate and the caliper's piston. This is why shipo's trick works ... although I'd prefer a material more resistant to heat than regular old duct tape. Better brake pad sets come with anti-squeal shims. A membrane anti-squeal goo is also available.

    Even if installed properly with the correct shim material, some high-performance pads can make a racket ... especially at low speed. Hey, that's what you get for installing the latest, super high-temp carbon fiber racing friction on your daily driver! >;^)

    --- Bror Jace
  • I didn't mean to ask for help... it was a list of possible brake symptoms. But I am sure that someone will appreciate the feedbacks though :)

    My current car is running just fine... not a problem... love it!
  • brorjacebrorjace Posts: 588
    Bigen, Turning the rotor is a good idea in order to remove light scratching/scoring by the old pads and any contaminents that got into the works ... but I'll only do it once.

    For those that don't know, as rotors are turned they become thinner and more prone to warping. I have 110,000 miles on a '95 Honda Civic. I changed my front pads at 90,000 miles (a bit premature) and had the rotors turned. The aftermarket pads I got (Spectra Premium) still seem fine but the next time I do brakes I'm going to use a light carbon-fiber pad (probably Raybetsos Brute-Stop) and let them use up the remainder of the originbal rotors. That should last the car well into 200,000+ miles.

    --- Bror Jace
  • shiposhipo Posts: 9,152
    Not all cars have "Wear Sensors" (little metal tabs usually mounted on the pad itself) which "sing out" when the pad(s) have worn enough to allow them to come in contact with the rotor. In the not too distant past, many cars had brakes that were designed for stopping power as the most important design element, while noise control wound up a distant last on the priority list (Mercedes used to have this problem on a lot of cars), as a result, brand new pads can squeal given the right circumstances. The squealing is caused when the pad vibrates against the rotor during a braking event (just like brakes on a bicycle), hence, using the old standard Duct Tape or other suitable sticking compound to stabilize the pad will reduce or eliminate the noise in most cases.

    Manufacturers have employed many methods over the years to quiet disk brake systems. I have seen adhesives, metal tabs that grab the middle of the piston and tapered or asymmetric piston faces just to name a few of the methods currently in use. It seems that these efforts have been largely successful, as now, the only times I hear brake noise is when I watch a movie and the sound engineer has dubbed brake squeal onto a car that is stopping. ;-)

    Best Regards,
    Shipo
  • wtd44wtd44 Posts: 1,211
    I read your #9 above, and could hear "Dueling Banjos" in the background. (:^>
    Tell us more about "Brute-Stop" by Raybestos, please. Is that a new grade? I've had great luck with other Raybestos pads, but have not heard of that one.
  • brorjacebrorjace Posts: 588
    Shipo, you're giving some good advice, but keep in mind, some friction material (both really cheap and really high-performance) is just plain noisy and it has nothing to do with the plate. That sound is more of a grating/grinding sound akin to the noise made by a rusty rotor.


    Oh, and don't forget the slot running down the middle of the friction material. That's supposed to quiet the pads down as well by giving the 'puck' of friction material enough flexibility to better mate with the rotor. As you probably know, uneven pressure can cause the slight vibration between the backing plate and the piston.


    wtd44, Brute Stop came out about a year ago and a half ago. They are Raybestos' entry in the high-performance market ... but I've seen very little marketing of them to date. Maybe they are concentrating on the domestic muscle market (even though I know they make them for my Honda)? When first introduced, they advertised they are a carbon fiber formula but that language has been pulled off their site. For more info:


    http://www.raybestos.com/brutestop.htm


    My silly little Honda Civic goes through a set of front pads every 80-100,000 miles and I just did my brakes a year ago so I'm not expecting to need anything for a while, but if/when I do, I'm going to take a good, hard look at the Brute Stop grade.


    --- Bror Jace

  • wtd44wtd44 Posts: 1,211
    I'll check the URL you suggested. I think the pads I found so good on an Explorer I had, were named "SUPER STOP."
  • brorjacebrorjace Posts: 588
    I'm not too familiar with the Raybestos line. I know that one grade they consider to be their OEM replacement ... in that it most closely resembles the characteristics of typcial factory materials. That's usually a safe one to go with ... and it might be their "Super Stop".

    I don't know if Raybestos makes a 'bad' brake pad .... but I'm not that familiar with their lower line of friction.

    After a rush 10-15+ years ago to equip all cars with semi-metallic pads, there has been a retreat to organic compounds (asbestos), kevlar and soft-metallics like copper, brass, bronze, etc ... These don't put up with high-performance driving very well but they are quiet, kind to the rotor and last a long, long time. Really abrasive semi-metallic are most often found in the high-performance aftermarket.

    --- Bror Jace
  • spokanespokane Posts: 514
    Ten years ago, Honda brakes had a reputation of being very sensitive to disc runout and resurfacing needed to be done with an on-car lathe in order to be reasonably certain of smooth braking performance. Conventional off-car resurfacing, which is usually much less expensive, was likely to be unsuccessful on these cars. American Honda continues to reccommend the on-car process. Bror Jace and others, in your Honda experience, is the on-car resurfacing necessary on later model Hondas or do you find the off-car process to be satisfactory? Thanks.
  • wtd44wtd44 Posts: 1,211
    I looked over the Raybestos site and developed the understanding that SUPERSTOP is the heavy duty fleet product, and they recommend it for police cars and taxi cabs, etc. The BRUTESTOP seems to have similar characteristics, is a newer product, and I did not get the feeling that it was held out as much different from SUPERSTOP. They referred to BRUTESTOP as a racing/high performance product. A friend at NAPA recently told me that Raybestos makes NAPA pads and shoes. I recall that many long years ago I took a set of brake shoes out of an old Harley and had a local autoshop bond woven Raybestos material on them. Wow! Did they ever work! Unfortunately, they wore out quickly as well. Over many years I have never had a failure or a disappointment using Raybestos or Bendix. I'm afraid we currently have many cars and trucks out there that have "underengineered" brake systems, and choosing brake pads and shoes has become critical. I've had some bad experiences with "unknown" makes. Have you ever heard of front pads exploding under load? Uh HuH! That's what I said...
  • I drive a 98 jeep cherokee and when I am going 65 and brake to turn, my steering wheel vibrates so bad that I can hardly hold it. It doesn't seem to happen at slow speeds.
  • alcanalcan Posts: 2,550
    It sounds like you have a warped or corroded brake rotor. Cherokee rotors are fairly substantial, so if they're warped there might be enough material left to machine them. If corroded, they'll require replacement. In either case, new brake pads are required.
  • shiposhipo Posts: 9,152
    Another possibility is a "Hot-Spot" on the rotor. Have you ever had your brakes replaced after the pads has already worn down so far that the Rivets/Metal Backing was grinding on the disk rotor? If so, you probably have a hot spot, which is where a section of the rotor has a different "Temper" (softer or harder than the rest of the rotor).

    Another problem, which was brought up by Alcan, is a warped rotor. I have heard that some folks have had warping problems with Jeep Cherokees immediately after a tire rotation. Typically, the person who did the rotation failed to use a torque wrench and the proper tightening pattern, and warped the disk as a result.

    No matter how you slice it, it sounds like you need new rotors and pads on the front of you Jeep.

    Let us know how it turns out.

    Best Regards,
    Shipo
  • brorjacebrorjace Posts: 588
    Spokane, I've owned Hondas and Acuras for over 10 years and have a friend that's gone through twice as many of their cars that I have. We have NEVER had our rotors turned while on the car and neither of us has had any sort of brake systems difficulty. My front pads usually last 80-100K miles and I've never warped a rotor yet. It may be that both of us are very good drivers, do a fair amount of highway travel and drive 100% standard transmissions.

    There was a few years of Honda Accords (mid nineties?) that almost HAD to be turned while on the car it was so difficult to remove the rotors. Once in a while Honda, known for brilliant engineering, really goofs BIG TIME.

    Late model Honda Civics, especially automatics, are prone to warping their rotors. We think it's the stop and go traffic and people sitting at stoplights with their foot mashed on the pedal. This pressure on one spot of the hot rotor warps the rotor in a hurry. Another theory is that hitting puddles of water while your rotor is really hot warps them. I favor the former rather than the latter.

    Wtd44, Raybestos makes brakes for NAPA? That's not what I remember. A company called "WorldBestos" used to make theirs ... as well as another obscure company who's name escapes me. Two different suppliers for their two different grades of friction material (one of them lifetime warranty). A steel plate is a steel plate ... it's the friction "puck" that makes all the difference.

    But that was almost ten years ago ... nothing stays the same in that business. It's good to see that NAPA continues to use quality suppliers.

    "Exploding" brakes? Never heard of them but a cracking of the material is not uncommon ... with just about ANY brand. Although, the cheaper pads will crack more often.

    Debbi10, Sounds to me like an out-of-round or unbalanced tire ... this is especially true if the vibration is very speed-sensitive. In other words, is their a specific speed where it is REALLY bad?

    Warped rotors usually make a wobbling feel/noise at all speeds and it is especially noticeable as you apply the brakes.

    shipo, I've not really heard of that "hot spot" problem. Once the rivets are on the rotor, they can quickly gouge out a channel so deep it makes turning/cutting the rotor impossible. I'm talking 20-30 miles, depending, depending, etc ...

    The rotor can be turned down to the minimum thickness and the gouge is still apparent. So, those rotors should be junked in favor of new or good-condition used parts.

    Nowadays, some rotors are installed at the factory at the minimum thickness and so cannot be turned AT ALL. Still others can be warped merely by improper lug nut tightening. Use a torque wrench and tighten them in a star pattern a bit at a time.

    --- Bror Jace
  • It did start after I had my tires rotated. I have Michelin LTX-AT on it. I also have a high pitched squeek that only stops when I put the brake on. When I went to the dealer he said that it was probably the serpentine belt, but I already replaced that. I stop 517 times a day as I am a rural carrier. The rotors were recalled and Chrysler put new ones on 9 months ago.
  • spokanespokane Posts: 514
    Thanks for the Honda brake comments. I agree with you that it seems that a very hard stop, followed by a period during which the pads are clamped on one spot of the hot rotor, contributes to warpage. The use of "green" cast iron to manufacture the rotors can also induce warpage over a period of weeks - even if the car isn't driven at all.

    Recognizing that some rotors do warp even though you have been fortunate to avoid this problem on your own Hondas, have you seen evidence to indicate that on-car resurfacing provides any advantage over conventional off-car resurfacing for Honda rotors? Thanks.
  • leomortleomort Posts: 451
    How much better is it having rear disc brake vs rear drum brakes? I'm looking at the Subaru Forester, looking at the L and S model. The S model has rear disc brakes whereas the L has rear drum brakes.

    Leo
  • shiposhipo Posts: 9,152
    I agree that late model cars have thinner rotors out of the factory and that many of them are below minimum thickness after the first set of pads are worn out. My comment was based upon experience from older cars where it was possible to mill out surface imperfections and still exceed the minimum thickness.

    In one situation back in the late 1970's, a friend of mine who had very little money asked me to do a brake job for him. When I pulled the rotors, I could see that the piston side pads were both worn down so that the backing plates (no rivets) were rubbing on the rotor. I had both rotors turned (they were still well above the minimum thickness even after being turned), rebuilt the calipers and master cylinder and put on new pads. During my test drive I noticed severe pulsing from the front of the car that worsened in direct proportion to the amount of pressure on the brake pedal.

    I consulted an old sage and he told me that the rotor had a "Hot Spot" and was essentially worthless. I told my friend to go to a bone-yard (he claimed he could not afford new rotors) and buy some good condition rotors. When he returned, both or the new (used) rotors were slightly scored from the backing pads of the car they came off of, we had them turned and (you guessed it) the pulsing was reduced but still a problem.

    He finally asked his folks for enough money to buy new rotors, which he did, and the problem was solved.

    I suspect that this problem will soon become extinct (if it has not already) due to the thinness of modern rotors; however, it was a possible cause for Debbie10's problem.

    Best Regards,
    Shipo
  • bburton1bburton1 Posts: 395
    First Honda was an 80 accord-put 200k on that one and had several problems with warped rotors. Turns out air driven impact wrenches were the cause-even if the tire guy used Torque Sticks-warped rotor big time.

    Am on my third Accord and have 124K on this one (97)and nobody gets close to mine with an impact wrench. When I have tires replaced-I take my over priced Snap on torque wrench and watch the technician tighten to 80 foot pounds.

    Have seen the same story with friends Accords whom I have helped maintain. The newer Accords are supposedly less prone to warping rotors due to over torquing the lug nuts.

    Got 112k out of the OEM front pads on this one and had another 15k on the pads.

    And yeah I have heard all the song and dance about water on hot rotors and warping due to heavy pressur on a hot disk. Think about this-the pressure is applied on both sides equally-if it would do anything it would make a dent in both sides of the rotor.

    Beware of impact wrenches and people who want to turn your rotors whether you need to or not.
  • andre1969andre1969 Posts: 22,007
    Is it easy to spot a warped rotor with the naked eye? I recently bought a '79 New Yorker, and in sudden braking, it feels like the rotors are warped. Whatever the problem is, it passed inspection with it.

    To the naked eye, at least, the front pads look like they have plenty of meat on 'em, and the rotors don't look scored or damaged in any way. To pass inspection, it did need the rear drums turned, and new shoes, as the ones on the car were cracked.

    Still, the vibration is coming from the front of the car. Anybody got any ideas?
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 45,042
    No, you can't tell with the naked (am I allowed to use that word in Town Hall?) eye.

    And yes, it sounds like warped rotors, or less likely, a suspension problem of some sort. Given the aircraft carrier size of your car, a warped rotor is very possible.

    MODERATOR --Need help with anything? Click on my name!

  • brorjacebrorjace Posts: 588
    Spokane, I have no experience with the on-car rotor resurfacing ... but I cannot imagine how/why it could be better than a rotor being removed and turned on a lathe. As long as everything is straight and true, what's the difference? I always thought dealerships pushed this kind of service because they were equipped to do the job (because of those silly Accords) and few other places were. But, that's just an educated guess.

    Yep, Debbi10, I think it's a tire. 2 years ago, I rotated my tires after having left them in the same positions for 15,000 miles and a couple were so bad, at 65mph I was afraid I was gonna lose a filling from the car's vibration. I merely put them back where they started and the vibration went away. As a general rule, you'll get the longest, most even wear from tires if you rotate them regularly ... but if you put it off and the tires have spent a long time (10,000+ miles) in one position, it's often best to leave them there for the rest of their useable life.

    shipo, what you are referring to as 'hot spotting' I would just call warpage. The excessive (possibly uneven) heat caused to rotors to warp and, once warped, I don't think cutting on a lathe can fix the problem ... especially in the long run. Once a rotor is warped, figure on getting new ones regardless how it happened.

    leomort, Disc should help the car stop better (but only if the front-rear bias is tuned properly) but drums seem to last much longer. I prefer discs ... and I find them easier to work on.

    burton 1990s Hondas are just amazing when it comes to brakes ... but I hear the newer ones go through pads more frequently. Good point about the rotors getting squeezed on both sides. I hadn't thought of it that way.

    - Bror Jace
  • shiposhipo Posts: 9,152
    Hmmm, maybe we are talking about the same thing, or maybe we are just splitting hairs. Admittedly, it has been well over 20 years since I turned a serious wrench, however, as I remember it, a Warped rotor was typically caused by an overzealous impact wrench where as the Hot Spotted rotor was caused by heat. The feeling in the pedal (and the rest of the car for that matter) was much the same.

    The way it was explained to me (and until now, I have never had any reason to question this) is that while the reason that a warped rotor causes vibration is fairly obvious, the reason a hot spot on a rotor causes similar vibration is fairly subtle. Said hot spot is where the metal has been re-tempered, and as a result, some of the metal is softer than the rest (I do not remember whether the “Hot Spot” is supposed to be softer or harder than the rest of the disk). The result of this hard (or soft) spot is a slightly different coefficient of friction between the pads and the disk, hence more stopping power on one portion than the rest of the disk.

    Maybe, modern metals have better tempering and are more immune from this type of thing, that and the fact that many disks are throw-aways after a single set of pads might mean that “Hot-Spotting” is simply a thing of the past and my age is showing.

    Best Regards,
    Shipo
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