Click here BRAKE SQUEAL for video.
Brake Squeal! One of the most common auto repair complaints, is caused by movement of the brake pad against the rotor or disc, at a very high frequency rate. The brake pad should be located solidly in place by springs, clips or other noise dampening hardware which the manufacturer includes in the engineering design.
As the brake disc wears, the surface becomes glazed and uneven. As it rotates, the brake pad tries to move to conform to this uneven surface, or it catches on ridges and hard spots,
causing the vibration of the pad against the disc which we interpret as a high-pitched and annoying squeal.
I know what you’re probably thinking, “I don’t care what causes brake squeal…just make it stop!
This is the process, commonly called a “brake job” which eliminates squeal, returns the vehicle to normal stopping ability, and lowers the anxiety level of the driver.
Our first step in the brake job is to drive the vehicle, get a good feel for any problems, including stopping distances, noises, grinding, steering pull and pedal feel. After that, we raise the vehicle on a lift, remove all 4 wheels and brake drums, if equipped with rear drum brakes and inspect everything.
The discs are measured for thickness and runout, which causes a pulsating brake pedal. Federal DOT regulations forbid machining a brake disc below the legal engineering thickness limits stamped right on the disc.
The pads are removed from the calipers, the calipers are checked for leaking brake fluid or sticking pistons, which often causes premature wear of one or more of the four brake pads in a disc front brake system. The rear brakes are also checked…as part of the front brake job.
Although they provide only 20 percent of the stopping power, without their 20%, the front brakes rapidly overheat, squeal and wear out!
We check the brake shoes, hydraulic wheel cylinders, levers, springs and other hardware, and of course, the brake drums. They also have a legal machining limit. I’ve seen drums that were machined so far that the pistons fell out of the wheel cylinders, and brake discs cut so thin that they cracked and broke while driving! Needless to say, this is a very dangerous way to “save money”!
If the brake discs check out O.K., the next step is to the brake lathe, where they are precision-cut the least possible amount that will leave a clean, smooth surface. We want them to be as thick as possible when machined.
Some brake discs also contain the hub and wheel bearing races. These must be cleaned and repacked with new wheel bearing grease.
If the calipers are leaking or sticking, the solution is to replace them with quality, factory-remanufactured units. These units save a lot of money for the vehicle owner, and are original equipment quality or better!
Now to the brake pads, most caliper re-manufacturers supply caliper units which come with their own premium brand of pads. That solution is acceptable in most cases. Some makes and models of vehicles are known for squeal and wear problems.
For these vehicles, such as mini vans and certain import cars, we may want to use a special brake pad with a non-squeal or a long wear life compound. Experience with installation of different types of brake pads is the best judge of these special circumstances. Sometimes brand-loyalty can affect that judgment adversely, so it is best to have an experienced technician and service manager advise you.
We also use chemical compounds on the brake pad itself to ensure quiet stopping and help season the new pads for break-in.
When your car is returned to you after the brake job, it’s advisable to make a number of easy gradual stops to help with the break-in process. You may notice an odor from the front wheels as the new compounds heat up for the first time. Also, the chemical compounds applied to the pads contain graphite. When hot, the graphite has a sharp, sometimes disagreeable odor. This will fade and disappear in a day or two.
As you can see, there are a lot of possibilities to consider when we estimate the cost of a brake job. That’s why telephone shopping for the best price is seldom an accurate way to determine cost.
A physical inspection with the wheels removed is the only way to tell what is actually needed for YOUR vehicle and what it will cost. Different vehicles have vastly different prices for brake components. Trucks of ¾ ton and 1 ton ratings have much larger and more costly brake parts. Expensive imports, both sports and luxury vehicles can also have very expensive components compared to the everyday family car.
Then there are the old adages such as “You get what you pay for” and “If it sounds to good to be true…it probably is”.
I don’t want to be overly melodramatic, it doesn’t fit my technical nature, but your life and the lives of your family could depend on the quality and expertise of your next brake job.
Every system in 90’s and newer cars is very sophisticated and contains a high level of technology, such as the electronic controls for antilock brake systems and traction control systems which also operate through the use of ABS.
Best advice is to call for an appointment for a brake inspection at a shop you trust, not for a telephone estimate that is really nothing more than a guess.
Happy motoring AND braking, from our staff of ASE Certified Master Automotive Technicians at Chino Autotech!
Jim O’Neill
Chino Autotech Inc.,
Auto Club of SoCal Approved Auto Repair Facility
Auto Value Certified Service Center
NASTF Service Information/Communications Committees
ASE CMAT-L1, CA. Smog Check Technician
AMI AAM Accredited Automotive Manager
Northwood University-University of the Automotive Aftermarket-Leadership 2.0, Class of 2008-2009