Thurston Car Talk: Understanding Your Car’s Braking System

bron automotive
Brons Automotive is located in the heart of West Olympia. Photo credit: Bron's Automotive.

Submitted by Bron’s Automotive

So your car needs the front disc brakes replaced.  This is a pretty common job in a repair shop, but there are big differences between what different shops do when they perform a front disc brake job. What do you need to know?

First, the front disc brake system has three major parts: the ROTOR, which is shaped like a dinner plate and is often visible through the wheel opening.  It is attached to the same flange that the wheel and tire is, and they rotate as one piece.  Second are the friction PADS which are in a holder that bridges the rotor and sandwiches the rotor between them. Third is the hydraulic CALIPER, which, hydraulically squeezes the pads against the rotor and slows the car down when you step on the brake pedal.

The most important part that will be used in your brake job is the pads, which are available in a huge variety of prices and qualities.  You get what you pay for in this case.  High quality pads will operate quietly, last a very long time, and hold up under severe heat conditions such as when you are riding the brake pedal coming out of the mountains.  Low quality pads will likely wear out quickly and can produce bad squealing noises when braking.  Some can also damage the rotor.  Some shops offer an extremely cheap pad or even a pad that is guaranteed for life to get you in the door.  You would think that a pad that was guaranteed for life would be the best quality, but unfortunately the opposite is true.  The fine print in their contract specifies that every time you get new pads installed under the guarantee, you must again pay for labor and additional needed parts.  The higher quality pads always cost less per mile even though they cost more initially.

The rotor must have its surface machined smooth to provide a fresh surface for the new pads work against.  Rotors that are worn below a specified thickness must be discarded by law for safety reasons, namely there is not enough metal to safely dissipate the heat generated by braking. Some rotors cannot be machined because they are already too thin.  These must be replaced with new.  Not machining or replacing rotors can result in increased brake noise and other issues which may not show up immediately. The life expectancy of the brake job will be reduced if the rotors are not machined or replaced.  The rotors can be machined one of two ways. They can be removed and machined on a piece of equipment in the shop.  The other and the best way is to machine them while they are on the car with a piece of equipment designed to do this.  This insures that the rotor rotates in a perfectly vertical plane, even if the flange the rotor is bolted to has a slight wobble to it, which is not an abnormal condition.  Rotors machined in this way result in the longest lasting brake jobs, and reduce the chances that the car will later develop brake pulsation when braking.  This is called matching the rotors to the hub or flange.

The calipers and how they are treated varies greatly between different shops.  Some shops think that the calipers must be replaced with rebuilt units every time a brake job is performed.  Brons Automotive strongly disagrees with this practice.  It adds unnecessary expense to the bill, in our opinion, and often reduces quality.  At Brons Automotive, we inspect the rubber dust boots, clean and lubricate the caliper slides, and flush out all the old brake fluid and dirt that is inside. A caliper treated in this way can last the life of the car.  To be sure, there are times upon inspection that we find something wrong that requires replacement of the calipers with rebuilt units, but this only occurs about once in every 20 brake jobs or so. (My wife’s car has original calipers on it at 190,000 miles and my truck has original calipers on it at 185,000 miles, and they are just fine.)  Quality rebuilt calipers can be hard to come by in this day of having the rebuilding work done overseas.  In fact, over half of the calipers that we have to replace are not originals that have finally gone bad, but rather rebuilt units that didn’t last.  It’s always better to take care of the calipers you have on the car from the factory, as they generally are much higher quality.  At Brons Automotive, we hire only ASE certified technicians and I can trust in their ability to inspect calipers and make the proper recommendation.

If your brakes make a squealing noise that always goes away when you step on the brake, that’s the wear indicator telling you that the brake lining is getting thin, and it’s time to have a shop look at them.  If the funny noises occur when you step on the brake, that’s also an indication that it’s time to get your brakes looked at by a quality shop.  It’s important that your brakes work correctly when you really need them!  Questions? Call Bron at 36-943-5993.

Print Friendly, PDF & Email