Squeaky Brakes

Not enough info!

What pads are you using, are spacers on the pads and was an anti-squeal adhesive used when installed?

 

I originally used semi-metallic pads (Lucas/Axxis MetalMax) purchased from the local Ferrari dealer, but they developed a bad squeal after aggressive driving. VERY annoying.

I changed to Porterfield R4-S carbon/kevlar pads -- never a problem, great pads on street and track, no squeal. I *still* use them after changing to a Brembo GT big brake setup. FChat Girodisc (www.************) recommends and sells them.

 

I don't believe that the pad material has anything to do with the squeel. It is caused by the friction generated between the brake pad backing plate and the caliper piston. Where the brake pad "floats" a bit it starts to squeel as you apply pressure on the caliper. There are a few ways to fix this. 1. is with an insulating backer plate that is non metal and fits between the brake pad and the piston. 2. is using anti-squeel compound which goes on like toothpaste and sets up and bonds the brake pad to the piston. 3. is an anti-squeel grease that is a high temp grease that you put on the back of the brake pad so when it goes against the piston it acts like an insulator. I think that's how it works so when your mechanic removed the pads he just cleand them up and it would make them worse. Enjoy the ride.

 

I don't think that's correct. The type of compound certainly *would* potentially affect the amount of vibration transmitted to the components to set up that squeal (or not). I can tell you with certainty the only change I made to get rid of the squeal was pad change. I'm not the only one here on FChat who has used Porterfield R4-S pads to get rid of that problem...

 

Getting rid of an annoying brake squeal and other brake noise is like trying to cure a bad case of herpes. You can treat the symptoms and improve the patient's condition. But it is virtually impossible to eliminate the underlying cause. Fortunately, brake noise is not caused by a virus. It is caused by a combination of factors that sometimes add up to create noise.

Brake squeal is really a high frequency vibration. In disc brakes, it can be caused by vibrations between the pads and rotors, the pads and calipers, or the calipers and their mounts. In drum brakes, the vibrations can originate between the shoes and drums, or between the shoes and backing plates.

Dampen the pads
Lubricate the calipers Click Here for info about Brake Lubricants
Replace the caliper hardware (slides, pins or bushings)
Replace the pads
Resurface the rotors

SHAKY PADS

One way to quiet noisy pads is to make sure the pads fit tightly in the calipers. If the pads on a single piston caliper have mounting ears or tabs that need to be bent or hammered to hold the pad in position, make sure the pad can't be wiggled by hand. If the pads have clips, shims or antirattle springs, make sure the necessary hardware is in place and properly installed. If you see no such items when you inspect the brakes, do not assume that none are needed. The last guy who worked on the brakes may have left them off. It is always a good idea to look up an illustration or parts list for the brake system to make sure all the required parts are there.

If the pads are installed correctly but are still noisy, one of the least expensive and most effective ways to quiet them is to remove the pads and install insulator shims on the backs of the pads. The shims, which are usually self-adhesive, act like little seat cushions to dampen vibrations between the pad and caliper.

Another option is to apply a noise suppressing compound to the backs of the pads. Some compounds harden to a rubber-like consistency to cushion the pads. Another good choice is to apply a moly-based dry brake lubricant to the backs of the pads. This type of lubricant is long lasting and won't burn or wash off like brake grease can. If applying a lubricant to the backs of the pads, be careful not to get any on the front side of the pads or rotor!

QUIETING THE CALIPERS

The same approach can be used on the calipers. Cleaning and lubricating the caliper mounts can also help dampen vibrations to quiet the brakes. Vibrations here can be caused by worn or loose mounts or mounting hardware.

If the calipers are badly rusted or worn, they may have to be replaced. But in most instances, you can probably clean them up, lubricate the mounting points and return them to service. You may have to replace the caliper slides, pins, clips and/or bushings, though, if there is too much play or looseness between the caliper and knuckle. Be sure to use a high temperature brake grease so the grease stays where it belongs.

NOISY BRAKE PADS

Some pads are noisy than others. Semimetallic pads are typically the ones that cause the most noise problems because they are harder than nonasbestos organic (NAO) pads. Their high metallic content often makes them squeal when metal rubs against metal.

The amount and type of fillers and binders in a friction material can make a big difference in the amount of noise a given set of pads or shoes produce. Ingredients such as graphite, carbon and "rubber modifieds" may be added to reduce noise. Brass is another ingredient that helps dampen noise (it also has a cleaning effect on drums and rotors). Many of the newest pads designed for quiet operation use a nonmetallic "ceramic-enhanced" formula to eliminate noise.

The design of the pads themselves can also affect the amount of noise produced. A chamfered leading edge on the pads eliminates the sharp edge so the pads will slide across the rotor without grabbing and vibrating. Slotting the pads changes the frequency at which the pads oscillate so noise can be tuned out of the brake system.

Some pads also have a special coating that transfers to the rotor surface when the pads are first used. The coating material leaves a film on the rotor that reduces noise, vibration and also rotor wear. The transfer film also makes the pads less sensitive to variations in the surface finish on the rotors.

If the original pads are too noisy and can't be quieted by insulator shims, noise compound or grease, therefore, replacing them may be the only way to get rid of the noise.

BRAKE PAD REPLACEMENT

Some brands and grades of aftermarket brake linings are quieter than others. So you may have to experiment with several different ones to find the quietest set for a given application. But whatever you do, do not substitute asbestos or nonasbestos organic (NAO) pads for semimetallic pads unless the friction material supplier says it is okay to do so. Asbestos and NAO do tend to be quieter than semimetallics but can't withstand the heat that semimetallics can. Consequently, if you swap asbestos or NAO for semimetallics in a front-wheel drive car or minivan where the brakes run hot, it can reduce the life of the linings significantly (up to half or more!) and increase the risk of overheating and brake fade.

After you have installed the new pads, it is a good idea to break them in (unless the pads are the "fully cured" type that do not require an initial break-in period). Not breaking in a new set of pads increases your risk of pad glazing and brake noise. A driver can glaze and ruin a new set of pads if he fails to go easy on the brakes for the first 200 miles. If he overheats the brakes by mashing down on the brake pedal at every stop light, he can cook the resin in the pads before it can cure and glaze the pads.

Pads that require an initial break-in can usually be seated by making 20 to 30 easy stops from about 30 mph with at least 30 seconds between brake applications so the brake pads have enough time to cool.

Whether a new set of brake pads need to be broken-in or not, you should still test drive the vehicle to make sure the brakes are operating properly and that your efforts to eliminate the noise problem have been successful.

To reduce the risk of brake noise during pad break-in, there are aerosol "brake silencing treatments" that can be applied to rotors to help suppress noise. These are spray-on coatings that are applied to the rotors after they have been resurfaced. Some contain microfine aluminum particles, graphite and moly that fill in the valleys on the surface of the rotors and act as a temporary lubricant to help the new pads burnish in more gradually. This not only reduces brake noise but also helps the pads develop a better cure which actually increases the coefficient of friction slightly.

 

Easy fix.
Remove the pads and chamfer the leading edge of the pad.
Then get a tube of black silicone adheasive and smear the back side of the pad let the adheasive set up and reinstall the pads.

CK