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Why are my
brakes making a funny noise?
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Honda disc brake pads incorporate
a
clever device that warns the driver when brake pads have worn down and
need changing. It's simply a U-shaped piece of metal that, when the
pads are new, doesn't come near the rotating disk. As the pad material
wears away however, the end of this metal strip comes closer and closer
to the rotor until when there is only a marginal amount of pad left, it
touches the rotor during braking. This generates discreet squeaks and
scratchings at first, most noticeable when backing up or maneuvering
slowly in a parking lot. As the contact becomes more intimate the wear
strip can generate the most ominous gronking noises that will be
noticed by even the most inattentive driver. The cure is simple,
replace the pads with new ones.
Why do my brakes make a "click" sound when I step on the brakes when backing up? back to top
If you have a late-model Odyssey,
Element or
Pilot, see this TSB: 04-019.pdf
(You
need Acrobat
Reader for the PDF)
If you have any other kind of
Honda, and your caliper mount bracket is very old and has been serviced
and sanded many, many times, the cause is the same as the PDF above.
However, short of replacing the mount bracket, Honda has no cure for
you, since the problem did not exist when new.
Oh screw it! Your caliper piston that is. Notice it has an X shaped groove in it? Attack this groove with a large common screwdriver or the ends of a set of heavy needle-nose pliers and turn the piston in a clockwise direction. Here's a crude 550kB WMV video showing the piston being turned in. I'm using a great big screwdriver, and since my calipers are in good shape, I only need one hand to do it.
The brake piston you see, is involved with the parking brake mechanism. Here, from 'TeGGeR' is an explanation of how it works:
"The rear caliper consists of a piston, internal screw and cam (and a bunch of other parts, but we're keeping it simple here). It's pretty complex compared with the front caliper.
The caliper's piston is much like that on the front calipers, but an internal bolt is screwed into the back of the piston. The head of this bolt touches the parking brake cam at the rear of the caliper body. When you step on the brake pedal, you are pushing the piston forwards so the pads press upon the rotor.
The internal bolt does not move forward with the piston but rotates in place, trying to back out of the piston as the piston moves forward. When you let off the pedal, the bolt does not screw back in. This is how the parking brake stays adjusted. The bolt always touches the parking brake cam behind it.
When you then pull the parking brake lever, the bolt is thrust towards the rotor by the cam, pushing the piston ahead of it and squeezing the brake pads against the rotor. The bolt does not rotate when the handbrake is applied, only when the footbrake is pushed. There is a spring that will push the bolt and piston back against the cam once the parking brake lever is released.
If the weather seal on the
parking brake
cam shaft fails, water will get in and seize the parking brake cam
shaft. The brake can also seize if the parking brake cable's
clevis-and-pin get rusty and seize on the parking brake cam lever at
the top of the caliper."
I'm
having to replace my brake pads far too often
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Is only one pad wearing out while the other shows little wear? Make sure the guide pins are well lubricated and sliding freely. And how hard was it to remove the pads from the caliper? Did you have to pry them out with a big screwdriver and a hammer? If so, some hidden rust under the thin metal shims on which the pads slide is your problem. Here's TeGGeR's advice on the subject:
"The pad mount bracket is bolted to the hub. The caliper is bolted to the pad mount bracket. These two shroud the top of the rotor. In between are the pads themselves.
As with most single-piston
OEM brakes,
both the pads and the caliper must be able to slide unimpeded as they
operate in order to function correctly. There are three places where
such brakes can corrode and cause problems:
1) The pads can seize to their mount
bracket
2) The caliper's slide pins can
seize and
lock the caliper firmly to the mount bracket
3) The piston can seize in its bore.
Number three is beyond the
scope of this
section, but usually means the need to rebuild or replace the caliper.
Items one and two are due to external corrosion, normally caused by
rain and snow.
A pictorial HOWTO can be
found here.
A
verbal summary of that HOWTO is below:
Most common on Honda brakes is seizure of the pads to the mount bracket. There are stainless steel shims that are interposed between the pad and the mount bracket (NOT the shims that are installed on the back of the pads themselves. Those are different). These are installed in order to provide a relatively slippery surface for the pads to slide on.
Unfortunately, they do nothing to prevent corrosion on the plain-steel mount bracket underneath them. To prevent this, you must remove the shims and sand the corrosion off the surfaces on which the shims sit. You want to take them back to bare shiny steel, as much as you can. It's this corrosion that builds up under the shims and clamps the pads against them so they can't slide. Rust is much less dense than steel, so it puffs up and fills in the clearance that the pads would properly have.
Correctly-floating pads will literally fall off the mount bracket once the caliper is removed. If the pads are seized, or even beginning to seize due to rust under the shims, you will need to lever the pads off the mount bracket. In bad cases, a hammer and drift will be necessary to knock the pads off. The rear brakes are more susceptible to this than the front ones, as they do less work and never quite get hot enough to burn off the water that coats them.
Once the mount bracket has been sanded off, apply enough aluminum-based anti-seize grease, such as Permatex 133H, to the mount bracket, them put the shims back. Reassemble.
Seized pins are a secondary--but only slightly less common--problem. Once the caliper is removed, you need to make sure the pins will move in and out smoothly and easily. The only resistance you should feel is from the grease itself. If they are very sticky and do not free up with a pull or two, then rust has invaded and caused them to stick inside their sleeves. This, like seized pads, will cause uneven and rapid pad wear, as well as brakes that pull to one side, and warped rotors.
Treating these involves pulling the pins out of their bores and removing the rubber boots. The grooves in the pin and caliper where the rubber boots sit must be sanded smooth and as free of rust as you can get them. A small rat-tail file is used to file smooth the inside of the pin bore. Blow out the dust.
After cleaning, apply generous amounts of Sil-Glyde rubber grease to the rubber parts and the pins, and reassemble.
If you live in a snow-belt area,
you
MUST service your brakes twice a year for optimum pad life. If the
sliding surfaces are properly sanded and lubed with copper-based
anti-seize, the pads will literally fall off when the caliper is
removed, even after a winter.
What
kind of pads should I
use and how should I break them in?
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Unless you plan to go racing, stick with OEM (Original Equipment Mananufacturer) pads.
I used to have a link to an excellent page that described the break-in process and why you do it. That page is now down and I did not keep a local copy of it. Paraphrased, it went something like this:
When new pads mate
to new rotors, there occurs a certain amount of pad material transfer
to the rotors. Too heavy a transfer, and you get glaze. Too light a
transfer, and you cause some other problem, which I can't remember. In
general, normal use of the brakes after installation is sufficient to
eventually effect material transfer and break-in, so long as you avoid
heavy braking for the first 50 miles or so.
By breaking in the
pads, you also force the pad surface to conform 100% to the rotor
surface. If you've ever studied new pads that have only been on the car
for a few miles, you'll see pad/rotor contact is not perfect. Some
spots on the pads will touch the rotor before others.
So how to break
them in? There are several techniques I've heard of. Probably the
simplest is this one, from Car Talk,
specifically the June 2003 issue of "Dear Tom and Ray":
How can I
tell if my brakes are dragging?
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Troubleshooting
Brakes
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by TeGGeR
Troubleshooting symptoms:
INNER pad worn, outer pad
not:
1) Caliper pins seized and caliper
not
floating
2) Outer pad seized on mount bracket
and
not floating
OUTER pad worn, inner pad
not:
1) Inner pad seized on mount bracket
and
not floating
Brakes dragging:
1) Piston seized in caliper bore
2) Flexible hose becoming internally blocked
Parking brake ineffective:
1) Aftermarket pads
2) Parking brake clevis seized and
not
pivoting
3) Parking brake cam shaft weather
seal
failed
Brakes pull to one side:
1) Sticky caliper piston on one side
2) Seized pad or caliper on one side
Sqealing noises
1) Aftermarket pads
2) Dust buildup
3) Missing anti-squeal shims from back of pads
Brakes dive to one side
momentarily when
pedal pushed, then straighten out again:
1) It's NOT the brakes! You
have a lower
ball joint seizing! Don't wait, get it replaced!
Why do
brake rotors warp? Is it caused by overtightening lugnuts?
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Some say yes, some say no,
and you'll
see debates about it in the newsgroups.
A good article on the reason for rotors warping can be found here.
Do I have
to turn the rotors of my disk brakes when I fit new pads?
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Honda themselves highly recommend
that you turn the rotors every time
the brakes are serviced. This may be in order to prevent comebacks on
account of vibration. They even have a TSB on this:
http://www.tegger.com/hondafaq/tsb/misc/x00-088e.pdf
Most dealer's service centers and repair shops will assure you that you should, but there are those who disagree. Some say you should never turn a rotor, but always fit new ones. Others argue for and against removing the rotors to turn them or turn them on the car. Turning a rotor makes it thinner and more susceptible to warping, and most rotors warp too easily anyway.
Personally I have replaced
many a brake
pad without turning or replacing rotors that are quite deeply grooved.
As long as the grooves in the rotor aren't more than an eighth of an
inch deep, and the disk is running true, (not warped or wobbling) you
shouldn't have any problems. There is less contact area for a few miles
until the pads wear to conform to the grooves, but after that you
actually get more contact area with a grooved rotor.