Stop here! Let's talk about brakes
Do you know or suspect you've got brake trouble? Got a tip? Talk about it here.
kirstie_h
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kirstie_h
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2015 Kia Soul, 2021 Subaru Forester (kirstie_h), 2024 GMC Sierra 1500 (mr. kirstie_h)
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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_h
Roving Host
Edmunds.com
MODERATOR /ADMINISTRATOR
Find me at kirstie_h@edmunds.com - or send a private message by clicking on my name.
2015 Kia Soul, 2021 Subaru Forester (kirstie_h), 2024 GMC Sierra 1500 (mr. kirstie_h)
Review your vehicle
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 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.
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
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
My current car is running just fine... not a problem... love it!
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
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
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.
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
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
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
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
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.
Leo
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
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.
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?
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.
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
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
Regarding on car rotor machining, there are 2 advantages. First, it will compensate for any lateral runout on the hub; and second, on Accords it eliminates the 1.3 hours labour per side to remove and reinstall the rotors. My Mitchell Mechanical Labor Estimating Guide contains the following text in the Honda section:
DRUM OR ROTOR (REMOVED) - REFINISH
DOES NOT include grind hot spots:
One....................... .5
Each Additional...... .3
and:
Rotor (each) - R & I for refinishing
NOTE - If on vehicle refinishing is not possible use appropriate repair operation.
Front brake pulsation concerns usually stem from one of three areas:
- lateral runout of the rotor exceeding .003", or hub runout.
- rotor parallelism or thickness variation exceeding .0005". Usually caused by severe braking combined with deterioration of the webbing between the friction surfaces.
- a localized change in the coefficient of friction of the braking surface of the rotor. This is easy to diagnose. If a dial indicator shows rotor runout to be within spec and a micrometer check of rotor thickness at 6 points around the rotor indicates no parallelism problems, (both of which will take about 2 minutes per side to check with the vehicle hoisted and the wheels removed) the pulsation is likely caused by rotor hot spots. This is usually accompanied by discolouration of an isolated portion of the braking surface.
Leo
Best Regards,
Shipo
"combined with deterioration of the webbing between the friction
surfaces."
Master cylinder output pressure in a brisk stop = 1,000 p.s.i.
Caliper piston diameter (full size car) = 3 in.
Caliper piston surface area = about 7 sq. in. (Pi r2)
Piston output force = 7 sq. in. X 1,000 p.s.i. = 7,000 pounds or 3 1/2 tons of force
Place a brake pad, rotor, brake pad on the bed of a press, heat the whole issue to 400-500 F, bring the ram down on the upper pad, , and apply 3 1/2 tons of force. If there's any corrosion/deterioration of the heat dissipating webbing between the braking surfaces (assuming a vented rotor) you now have a rotor with a parallelism or thickness variation problem. In a panic stop without ABS, double that master cylinder pressure to 2,000 p.s.i. and double the clamp load on the rotor to 7 tons. Might not be an issue in temperate, low humidity climates, but it is where I live.
alcan, Thanks for setting the record straight about hot spots. Complete and concise!
As for turning the rotors while they're on the car, I'm glad I don't have an Accord that requires the 1.3 hours of labor (per side) for rotor removal. My Civic rotors take about 15-20 minutes for me ... 'cuz I'm in no hurry. >;^)
Since I've never had any brake 'pulsing' I can say that lateral/hub runout has not been a problem for any of the cars I've owned to date. Let's hope that remains the case.
For my next brake job (IF I keep the car another 2-3+ years) I won't even be turning them since they've already been cut once already. I'll merely clean off the loose rust with a wire wheel, detail the visible parts that look rusty and then re-install. If they squeak a tad, then so be it. By this time, the car will have well over 150,000 miles on it.
--- Bror Jace
how long do brakes usually last? has anyone else had this problem? i appreciate any information i can get. thank you.
Disc brakes are prone to occasional squealing for a variety of reasons but I find it hard to believ yours are already worn out. I'd try another shop for a second opinion on replacement ... like one of the chains that offers free inspections.
If You have to have new brakes, don't buy OEM, get a high-performance set of pads like Axxis Metalmasters, Raybestos Brute Stop or AEM. These should last longer than the factory set.
--- Bror Jace
I agree that checking with another shop to verify the wear is a good idea, and using a high performance pad as a replacement helps. Make sure the rotor condition is checked, if they aren't smooth and true (within runout specs) the pads will wear out faster.
My '00 Intrepid ate its first set of front pads at 39,000 miles, and the back ones at 50,000. I was impressed that the front pads lasted almost twice as long as the Fury's, but a bit disappointed that the rear pads didn't last longer.
Oh yeah, I also used to deliver pizzas, lots of stop-and-go driving, so I'm sure a gentler driver would've gotten a lot more out of the brakes on either car.
My '90 Acura Integra and '95 Civic's factory pads would have lasted well over 100,000 miles if I hadn't replaced them prematurely at around 90,000 miles.
--- Bror Jace
I assume the pads need replacement (my wife does right the brake a bit).
Does this sound right at that mileage and is there any way I can verify if pads need replacing and which (fron, back or both)?
Spoke to our service guy who says to do pads AND rotors - I thought you don't need the rotors done unless you overused the pads - am I getting the straight story?
Wolverine, sounds too soon for pads ... and a soft pedal is not a sign that the pads are due. They need to be inspected and the very least you'll need to do to accomplish this is remove the wheel and then peer through the window in the brake caliper if the Sienna's brakes have one.
You might have some moisture or air in your brakes so bleeding and/or flushing might be in order. As long as there is material on the pads and they are not wore out, this should be covered by warranty. Are you losing fluid? This could also be a leak. I would expect a shop to blame pads so that you will pay them instead of the service being a freebie.
Also, many shops do pads and rotors together as a matter of course. Often, this is unnecessary but it's hard to tell without inspecting them first hand. I'd say that rotors with less than 30K miles on them should be in awfully good shape ... unless the pads are worn down to metal which is very damaging to rotors. Once rotors start to corrode, they are more likely to need turning (resurfacing) in order to clean them up. Some rotors are so thin from the factory, they cannot be turned and must be replaced with brand new pieces at every brake job.
If you want a firmer-feeling brake pedal, consider having an independent shop put on an aftermarket pads from Axxis or perhaps the Raybestos Brute-Stop. If you choose an OEM pad or OEM equivalent, you'll get a similar soft pedal feel. Just know that hard, more abrasive "high-performance" pads are not for every driver. You might get some abrasion noises coming from the brakes which are not harmful but can be annoying. Also, the more severe pads will be tougher on the rotors and might require their resurfacing or replacement more often. Finding such pads in mini-van sizes might also be challenging. Still, many people such as myself find these things easy to live with knowing we have greater stopping power.
Lastly, a switch to braided stainless steel brake lines will give you a firmer pedal ... but I don't know if they are made for your van at all.
--- Bror Jace