Disk brakes will squeal for various reasons. The number one thing to check is if the pads are worn. Most disk brake pads have a small tab that will start rubbing on the rotor when the pad is worn down as a warning. This causes the brakes to squeal. The solution is to replace the pads. The following method will NOT work if you have worn pads!
But what if the pads are fine and the brakes squeal whenever you stop? This is a generic description on how to fix those annoying squealing disk brakes based on my Ford Ranger pickup. I've used this method successfully on my old 1990 Honda, my new at the time 1998 Subaru (the dealer couldn't stop the squealing after 3 trips for servicing!) and many other vehicles.
After checking that you have good pad thickness, remove the caliper and remove the pads. There are many methods to do this and that depends on the year, make and model of your vehicle - which is way beyond the purpose of this webpage. Once you have the pads removed you should clean the backs of them with a wire brush to remove any rust or previous anti-squeal backings.
Back of a fairly new brake pad with surface rust and the remenants of anti-squeal backing
Same pad cleaned with a wire brush
I found that quite a few car manufacturers add thin plastic or metal backing pads behind the brake pad to eliminate brake squeal - most are useless. I've not used them and thrown them away - that is your choice to do.
I use a long metal file and quickly run it across the face of the pad if there is any glazing. It doesn't take much pressure as the file will quickly cut through the pad so be GENTLE! The next step is to give the face of the pad's edges a slight contour with the metal file. I feel that the squealing is coming from the edge of the pad so I round off all edges. Again, it takes very little pressure to do this - one or two strokes all around the edge. It is very easy to gounge the pad with the file so be gentle.
Face of a fairly new brake pad looks good but the edge of the pad is very sharp
Same pad with the edge gently rounded off with a metal file
The next step is to apply brake anti-squeal to the back of the inner pad where the caliper piston makes contact. I find that it is easier to apply the brake anti-squeal to the caliper where the outer pad makes contact. I then re-install the pads into the caliper. You can purchase brake anti-squeal at any part source place - it comes in either a squeeze tube or plastic bottle. Acetone is great for removing the brake anti-squeal off of your hands, brake rotor, tools and other places where it doesn't belong.
Caliper's outer pad contact area coated in brake anti-squeal - ready to re-install the outer pad (caliper is upside down in this picture)
Since the caliper is removed and the brakes are apart, it is a good time to do some basic maintenance. I like to clean up the caliper slides of rust and dirt - these are the slides that the caliper moves on as the pads wear. They can be steel rods, long bolts or interesting half rubber/half angle metal like my Ranger has.
Ford Ranger style caliper slide - a little dirty and rusty
Same slide cleaned with a wire brush
Next is to clean the channel or guide that the slide slides in using a wire brush. On the Ranger, the channel is half formed by the caliper and the other half by the caliper mounting bracket. Once it is reasonably cleaned, I apply anti-sieze compound to the channel so that the slide will be free to move and remove in the future.
Ford Ranger style caliper side half slide channel - cleaned up with a wire brush
Ford Ranger style caliper mounting bracket side half slide channel - already cleaned up
Anti-seize compound applied to the slide channel.
Put it all back together, pump the brakes a few times and you should be ready to roll without any squealing brakes.
If this page has helped you, please consider donating $1.00 to support the cost of hosting this site, thanks.