Automotive: Hard Parts Hunting
Adapted from Larry Carley’s articles in Brake & Front End
Loaded calipers provide a variety of benefits when doing brake jobs on customers’ vehicles. And since most brake suppliers these days have a loaded caliper program, availability is seldom an issue. Price, though, remains the main hurdle to selling loaded calipers to your customers.
One of the main advantages for the vehicle owner is that loaded caliper assemblies help restore the brakes to like-new condition. Not only do they get new friction, but also a professionally rebuilt caliper and properly matched hardware (shims, bushings, slides, etc.). This significantly reduces the risk of future leaks developing, and uneven braking or pad wear caused by calipers hanging up or dragging.
Caliper piston seals don’t last forever, and once they start to leak, it’s the end of the road for the caliper and the pads. Fluid leaks are dangerous because they can lead to a loss of hydraulic pressure in the brake circuit that may cause the brakes to fail. Brake fluid leaking from a caliper can also contaminate the brake linings and cause them to grab or pull.
A caliper may also have to be replaced if it is sticking. Internal corrosion can cause pistons to jam or freeze preventing the caliper from working normally or releasing completely. External corrosion on the caliper mounts, bushings or slides can cause problems too by preventing a floating caliper from moving normally when the brakes are applied. The result here may be uneven pad wear, uneven braking, dragging or a pull. With a loaded caliper, the caliper is replaced along with the pads.
Many technicians have learned the hard way that attempting to rebuild old calipers is often a waste of time. In many instances, the old calipers are so badly corroded or worn they can’t be rebuilt – or they leak when they are put back on the vehicle.
Disassembling a caliper to replace the piston seal and dust boot is a messy job, and may be difficult or impossible if the piston is stuck in place. Steel pistons often can’t be reused because they’re too badly corroded, and scratches or pits in the caliper bore may cause the caliper to leak even after a new piston and seal are installed. That’s why most technicians prefer to replace old calipers with new or remanufactured calipers.
Replacing the hardware is important, too, because old corroded hardware can cause braking problems. We’ve heard of shims that have worked loose and caused a rotor to fail by rubbing and cutting through the rotor hat! If a technician forgets to install an anti-rattle clip or installs one that doesn’t fit properly, the newly installed pads may be noisy. Loaded calipers reduce these risks by providing the proper hardware and replacing everything that should be replaced.
The type of friction material that’s included with a loaded caliper assembly is critical because it should be the same, or better than the original. If a vehicle was originally equipped with ceramic pads, the loaded caliper should have the same type of friction material. The same goes for semi-metallic pads.
When a loaded caliper is installed, the brake system should always be flushed and refilled with clean, fresh fluid that meets the OEM requirements for the application (DOT 3 or 4 fluid).
Caliper slides and bushings should be lubricated with a high temperature brake grease, and related brake components such as hoses, lines, rear wheel cylinders and the master cylinder should all be inspected to make sure these components are in good working condition and are leak-free.
Remanufactured replacement parts are usually less expensive than brand new parts, but are they as good? The answer to that question depends on who supplies the parts and how much expertise and effort they put into remanufacturing their products.
There are top quality remanufacturers who are QS-9000 certified and who turn out reman products that are just as good as many brand new parts. Their prices may be 20% to 40% less than a comparable new part or an OEM part, and they typically offer warranties ranging from a year up to a limited lifetime warranty.
There also are bargain-priced, low quality remanufacturers. Their prices are extremely competitive, but they may provide nothing more than a short-lived cheap fix. Warranties typically range from 30 days to 90 days at most. These kind of parts might be OK for a do-it-yourselfer who has a very limited budget, or somebody who is fixing a car or truck so he can sell it, but these “second line” reman parts may be no bargain for professional installers who take a chance on them.
The issue of quality is important because comebacks can really hurt a business, as well as your reputation. If a reman part fails, your customer will blame you – not the parts supplier. After all, you were the one who chose the part and installed it on their vehicle. These kind of comebacks not only cost you the goodwill of your customer, they can also hit you hard in the pocketbook – even if your supplier offers you a free replacement part because most warranties do not cover installation labor. On some parts like a clutch, labor is the lion’s share of the repair bill. The same goes for many steering racks. Calipers, wheel cylinders and master cylinders, on the other hand, are easier to replace. Even so, who wants to replace the same part twice, but only get paid for the job once?
Another benefit of using reman parts is that it recycles metal that would otherwise be thrown away. This may require exchanging the old part to receive a core credit with your parts supplier, or it may not if your supplier sells reman parts outright with no exchange.
Remanufacturing typically reuses castings and other major components that can be cleaned, remachined and returned to like-new condition. Items that are subject to wear and corrosion such as seals, bushings, caliper and wheel cylinder pistons, valves, bleeder screws, springs, etc. are usually replaced with all-new components. Most quality remanufacturers then test the parts to make sure they function correctly before they are boxed and shipped for distribution.
The bottom line is this: reman parts may or may not be your first choice for the repairs you do, but they generally provide good value for the money and can lower repair costs when price is an issue. When you do choose reman parts, choose a supplier who has a good reputation and who stands behind their products. The longer the warranty, the better.
When you do start performing brake jobs at a shop, don’t forget to check the vehicle’s parking brake. Though most motorists seldom use their parking brake, it is a required safety device and must work properly when called upon to keep a vehicle stationary.
The main function of the parking brake is to prevent the vehicle from rolling when it is parked. But PARK serves the same purpose in vehicles with automatic transmissions, as does leaving a manual transmission in gear. So, to many people, the parking brake seems unnecessarily redundant. Even so, it should be used – at least occasionally.
Problems From Not Using It
When the parking brake is seldom used, one of two things can happen: it may stick and not release when applied, or it may allow brake pedal travel to increase.
Using the parking brake helps keep the cables freed up so corrosion can’t buildup and cause the cables to bind. Applying the parking brake also works the self-adjusters in the rear brakes and helps keep the linings in drum brakes properly adjusted for minimum pedal travel. On cars with four-wheel disc brakes and locking rear calipers, using the parking brake keeps the threaded self-adjusting mechanisms inside the rear caliper pistons working freely to compensate for pad wear.
The parking brake system is pretty simple. On vehicles with rear drum brakes, applying the parking brake pulls a pair of cables that are attached to arms on the secondary brake shoes. This forces both pairs of shoes outward against the drums to lock the brakes. On four-wheel disc brake applications, the disc brake pads are pushed against the rotor by the caliper pistons. This requires either a cam or screw mechanism inside the caliper piston that pushes the piston out and holds it there, or a mini-drum brake inside the rear rotor.
On rear disc brake applications with locking calipers, the adjustment of the parking brake cable is especially important. If the cable is adjusted too tight, there may not be sufficient travel to work the self-adjusters and/or the brakes may drag. If the cable is adjusted too loose, the parking brake may not hold the vehicle. As a rule, most hand levers should travel only about four or five “clicks” when properly adjusted.
On rear disc brake applications with mini-drums in the rotors, the parking brake works like a conventional duo-servo drum parking brake. Pulling the cable forces the shoes outward against the drum to lock the wheel. But unlike a full-sized drum brake, there’s no self-adjuster mechanism for the star wheel to compensate for shoe wear. The only time the parking brake is applied is when the vehicle is at rest, so the shoes should last the life of the vehicle unless the parking brake is not releasing causing the shoes to drag. The thickness of the shoe linings doesn’t really matter as long as there is enough lining left to hold the car on an incline with normal cable travel.
On most vehicles, the left and right parking brake cables come together and are attached to a lever linkage called an “equalizer” yoke under the vehicle. The equalizer yoke balances, or equalizes, the amount of force that’s applied to both cables when the parking brake is applied. The equalizer linkage, in turn, is connected to a single cable that runs to the parking brake lever or pedal. An adjustment screw may be located on the front cable where it connects to the equalizer, or where the cable attaches to the parking brake lever.
Rust Never Sleeps
Rust is the main concern with the brake cables and linkage. Rust can cause the cables to bind in their sheaths, preventing the brakes from being applied or released. If one cable freezes up, the equalizer can’t do its job and only one wheel will lock. Though this may not create a problem when the parking brake is used for parking, it could create a serious brake imbalance should the system ever be called upon for emergency braking. The imbalance would likely cause one wheel to lock up and skid, throwing the vehicle into a spin.
The equalizer linkage can also rust up, interfering with proper application and release. Also inspect the hinge pivot because it can break loose, rendering the parking brake useless.
When doing a brake job, therefore, always check the operation of both parking brake cables and the equalizer linkage. Apply the parking brake to see if the linkage is working properly and that the brakes will hold the vehicle. Then check to see that the brakes release fully. If there’s any binding and/or corrosion, clean and lubricate the cables (if possible) or replace them. Also lubricate the pivot point on the equalizer linkage.