Brake Squeal

Curing the annoying disc brake squeal

Almost everyone has experienced disc brake squeal at one time or another. What causes this? It's simply a high frequency vibration that creates a harmonic between the caliper body or piston and the back of one or more brake pads (just like vocal cords). It usually occurs often at lower speeds as the bike is slowing to a halt, very annoying and embarrassing when your high dollar hog squeals like a pig as you come to a stop at a busy intersection.

Several things can initiate the squeal. It can be caused by pads that have become glazed from extended braking, incorrect pad compound for the type of riding you do, or contamination of the surface, as from dirt, sand, or accumulated brake dust.

The surest cure is to perform a double fix on the pads themselves. First, camber the leading edges of the pads at a 45 degree Angle using a belt sander or bench grinder (see illustration). This helps the pad to glide along the rotor's surface more smoothly, sort of like the curves of a sled's rails. Second, use anti-squeal shims on the back of the pads. These usually come in the form of thing peel and stick aluminum sheets that you simply cut to fit the back of the pads. They work by actually absorbing the vibration and isolating the two harder metals from each other. Anti-squeal shims also come in other more exotic compounds (like rubber, Fiberglas, or Teflon), but I find the aluminum ones work best and cost the least. You can find them at most auto parts stores.
You may have seen or used a thick blue or red liquid anti-squeal compound that you apply to the backs of the pads. These products offer a temporary solution at best, and leave plenty of room for error (not to mention possibly fouling your pads). The can help if applied properly and allowed to cure thoroughly before reinstalling the pads, but I strongly recommend using the shim type products. While the pads are of, it never hurts to lightly sand the surface to remove any glazing, also a scuffing of the rotors with an abrasive pad or very fine sandpaper will help. And of course, always check pad wear and brake fluid level whenever you disassemble your brakes. Also be sure to grease the caliper mounting pins (if applicable on your model), as dry pins can actually contribute to brake squeal. And remember to test brakes before playing in traffic.

Let's not forget that HD came up with the service bulletin (M1192A)that swaps the two front rotors on touring bikes to eliminate the squeal also. Left to the right side and visa versa. See the link below.

Brake rotor swap

Also take a look here...

Rear Brake Noise 08-09 Touring - Harley Davidson Community

drummer · Jan 26th, 2009, 08:03 PM

Ok I had an earlier post in Nov 08....Ive replaced rotor, pads and did a partial rebuild of my front brake caliper...still squealing. My question is what could make a squeal when applying the brakes that may not actually be the brake components themselves??? Could it be wheel bearings?? I checked that there not loose..theres no vibration at any speed...this squeal brob is beyond stupid a this point...any help brothers??

glider · Jan 26th, 2009, 08:39 PM

There's a few compounds that you can get in an auto parts store that get applied to the back of the pads including some stick on pads that silence the squeal. It's actually a high pitched vibration that you are hearing.

STEVE07 · Jan 26th, 2009, 09:12 PM

Quote:

Originally Posted by drummer

Ok I had an earlier post in Nov 08....Ive replaced rotor, pads and did a partial rebuild of my front brake caliper...still squealing. My question is what could make a squeal when applying the brakes that may not actually be the brake components themselves??? Could it be wheel bearings?? I checked that there not loose..theres no vibration at any speed...this squeal brob is beyond stupid a this point...any help brothers??

drummer,did you do some of the things suggested in that thread?I would still try removing the pads,cleaning them with fine sandpaper,Emory cloth is my preference as well as a light scuff on the rotor,then re-seat them using a proper method,I would be willing to bet this gets rid of your squeal

krikket · Jan 31st, 2009, 10:34 PM

I used to work for Midas. So as you can imagine, we would get all sorts of cars with brake squeaks. Everything Glider posted in the article is spot on. The only additions I might offer is that sometimes, brake pads and rotors need to seat together...even new ones. I'm assuming the rotors are still within the discard specs. Some setups are more prone to making noise than others. So, try taking the pads off and scuff them up to take the glaze off and scuff the rotor surface with a non-directional finish (usually accomplished on a lathe with sandpaper, but not totally necessary. You can just use some fine grade sandpaper as Glider suggested). Then, what always worked for me is to use a light coating of RTV on the back of the pad, and on the back of the shim as well. This can help dampen vibrations because when RTV dries, it's essentially rubber. RTV can be purchased at any auto parts store and comes in a variety of colors. Once it's all back together, take it for a test ride but go easy. Try to avoid hard braking for about 500 miles, this will help keep the pads from glazing. Make sure all points requiring lube are lubed and all fasteners tightened to specs

drummer · Feb 2nd, 2009, 02:43 PM

Thanks bros It looks like Ill have to go back to the drawing board again....only thing I can think of is having done more of a break in of the pads. I cant remember having done that purposely before. These pads and rotor got about 1500 miles on them now. But the noise is reason enough to keep at it till I find a solution....

roadking72 · Jul 12th, 2009, 01:38 PM

How much drag or free play on the front wheel is there supposed to be ? Just got it back from a 20k from the hd dealer and the front tire seems to be a little on the tight side. I can honestly say it was not like that before. Also the rotors are kind of blueing or darkening since I got it back. Again, it was not like that.

glider · Jul 12th, 2009, 02:24 PM

Light drag is normal, bluing is not, take it back to the dealer.

Jan 26th, 2009, 08:03 PM	#1
drummer New Family Ride: 2003 Heritage Join Date: Nov 19th, 2008 Posts: 6	Re: Brake Squeal Ok I had an earlier post in Nov 08....Ive replaced rotor, pads and did a partial rebuild of my front brake caliper...still squealing. My question is what could make a squeal when applying the brakes that may not actually be the brake components themselves??? Could it be wheel bearings?? I checked that there not loose..theres no vibration at any speed...this squeal brob is beyond stupid a this point...any help brothers??

Jan 26th, 2009, 08:39 PM	#2
glider Community Liaison Ride: 07 Road King Classic Join Date: Jun 21st, 2007 Posts: 20,467 My Mood:	Re: Brake Squeal There's a few compounds that you can get in an auto parts store that get applied to the back of the pads including some stick on pads that silence the squeal. It's actually a high pitched vibration that you are hearing.

Jan 31st, 2009, 10:34 PM	#4
krikket Contributor$ Ride: 2008 Night Train Join Date: Aug 17th, 2008 Location: Illinois Posts: 341 My Mood:	Re: Brake Squeal I used to work for Midas. So as you can imagine, we would get all sorts of cars with brake squeaks. Everything Glider posted in the article is spot on. The only additions I might offer is that sometimes, brake pads and rotors need to seat together...even new ones. I'm assuming the rotors are still within the discard specs. Some setups are more prone to making noise than others. So, try taking the pads off and scuff them up to take the glaze off and scuff the rotor surface with a non-directional finish (usually accomplished on a lathe with sandpaper, but not totally necessary. You can just use some fine grade sandpaper as Glider suggested). Then, what always worked for me is to use a light coating of RTV on the back of the pad, and on the back of the shim as well. This can help dampen vibrations because when RTV dries, it's essentially rubber. RTV can be purchased at any auto parts store and comes in a variety of colors. Once it's all back together, take it for a test ride but go easy. Try to avoid hard braking for about 500 miles, this will help keep the pads from glazing. Make sure all points requiring lube are lubed and all fasteners tightened to specs

Feb 2nd, 2009, 02:43 PM	#5
drummer New Family Ride: 2003 Heritage Join Date: Nov 19th, 2008 Posts: 6	Re: Brake Squeal Thanks bros It looks like Ill have to go back to the drawing board again....only thing I can think of is having done more of a break in of the pads. I cant remember having done that purposely before. These pads and rotor got about 1500 miles on them now. But the noise is reason enough to keep at it till I find a solution....

Jul 12th, 2009, 01:38 PM	#6
roadking72 New Family Ride: 06 FLHRSI Join Date: Jul 12th, 2009 Posts: 4	Re: Brake Squeal How much drag or free play on the front wheel is there supposed to be ? Just got it back from a 20k from the hd dealer and the front tire seems to be a little on the tight side. I can honestly say it was not like that before. Also the rotors are kind of blueing or darkening since I got it back. Again, it was not like that.

Jul 12th, 2009, 02:24 PM	#7
glider Community Liaison Ride: 07 Road King Classic Join Date: Jun 21st, 2007 Posts: 20,467 My Mood:	Re: Brake Squeal Light drag is normal, bluing is not, take it back to the dealer.

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Brake Squeal

Brakes, Tires and Wheels