The complete brake job is one that should restore the brake system to like-new condition. But all too often a customer just walks up to the counter and asks for a set of brake pads, thinking that’s all he needs to fix the brakes. Or, he may ask for a pair of loaded calipers, assuming those will do the job.
The truth is, the brake parts that will need replaced depend on the age, condition and mileage of the vehicle. Some vehicles may only need a set of pads. Others may need calipers, hoses, drum hardware, maybe a master cylinder or other parts. Every brake job is unique so there is no pat answer that applies to all.
BRAKES ARE DESIGNED TO WEAR OUT
How fast the brake linings wear depend on how a vehicle is driven. Naturally, the more the brakes are used, the faster they wear. Other factors that influence brake-wear include how hard the brakes are applied, the temperature of the linings and the wear characteristics of the friction material itself.
Stop-and-go city driving obviously wears the linings down faster than highway driving. So does aggressive driving. Larger, heavier trucks and SUVs typically wear out their brakes faster than smaller, lighter cars. Consequently, a set of brake linings that might wear out in 25,000 to 30,000 miles on a large, city-driven vehicle might last 50,000 or 60,000 miles on a smaller, lighter vehicle that is driven mostly on the highway.
As a rule, most brake pads and shoes should be replaced when the thickness of the friction material is worn down to minimum specifications (typically less than 1/8 of an inch of lining thickness) or when the surface of the pads or shoes are worn down flush with the tops of the rivet heads (riveted linings). Some brake pads have built-in wear indicators that generate a metallic scraping noise when the pads are worn out and have to be replaced.
WHAT SHOULD BE REPLACED?
When it becomes obvious that the brakes need attention, the entire brake system should be closely inspected to determine the condition of its various components. Brake linings and other parts that are obviously worn out, broken or leaking need to be replaced. But what about parts that are marginal or appear to be okay? Should drum brake hardware always be replaced, or can it be reused? Should calipers or wheel cylinders always be rebuilt or replaced if they aren’t leaking, or should you leave them alone? What about replacing the master cylinder in a high-mileage vehicle? Should the brake system be flushed and refilled with fresh fluid?
Technicians often recommend replacing brake parts that are still working but are near the end of their service life. Why? Because they know many of these parts may not last until the next brake job. It’s better to replace everything at once, rather than wait for the next part to fail, and the next, and the next.
REGULATIONS AND GUIDELINES
This is a hot-button issue with consumer advocates and government regulators because some see this as an attempt to sell unnecessary parts and services. Some states (such as California) have strict regulations covering the replacement of brake components. The rules spell out when certain parts can and cannot be replaced based on wear or condition.
Additional guidance can be found in the Brake Inspection Guidelines published by the Motorist Assurance Program (MAP). The MAP guidelines cover the brake inspection process and tell when brake repairs are truly necessary, or when brake repairs should be recommended to improve braking performance or to restore the brakes to like-new condition.
One of the major issues with replacing brake parts is that the components in the brake system do not wear at the same rate. The front brakes typically wear two to three times faster than the rear brakes. Consequently, it may not be necessary to replace the rear linings until the second or third set of front pads have been replaced.
Time, mileage and the operating environment are all factors that affect the service life of parts in the brake system. Brake fluid is hygroscopic and absorbs moisture over time. As moisture accumulates in the fluid, it increases the risk of internal corrosion inside the calipers, wheel cylinders, steel brake lines, master cylinder and ABS solenoid valves. Because of this, it’s not unusual to find corrosion-related failures in these components in high-mileage vehicles that operate in wet climates. For this reason, a fluid flush is often recommended for preventive maintenance, especially if the fluid is more than three or four years old.
Many technicians recommend rebuilding or replacing calipers and wheel cylinders as part of a complete brake job and with good reason. Over time, rubber seals on caliper and wheel cylinder pistons harden and lose elasticity. This may cause the seal to leak. Corrosion inside the piston bore can also accelerate seal -wear. Pushing the caliper pistons back in their bores also causes the seals to rub against an area on the piston that may have become corroded and rough, which can also accelerate seal-wear. So even if the calipers or wheel cylinders are not leaking when the linings are replaced, there is no guarantee how much longer they will remain leak-free. That’s why many technicians recommend rebuilding or replacing the calipers and wheel cylinders when the linings are replaced, especially on higher-mileage vehicles that may have never had these parts replaced. It reduces the risk of brake-related problems down the road and restores the brake system to like-new condition.
A COMPLETE JOB
The brakes are the most important safety system on a vehicle, so a complete brake job should cover every aspect of the system. It should start with a thorough visual inspection of the entire brake system. This includes measuring lining thickness front and rear (which will require pulling both rear drums), the condition of the lines, hoses, calipers and wheel cylinders, the appearance and condition of the brake fluid, checking pedal feel and travel and the brake and ABS warning lights (lights should come on then go out when the ignition is turned on). Only after the inspection has been completed should any repair recommendations be made.
The ABS system is often overlooked when doing brake work on late-model cars. If the ABS warning light is on, there is a fault that needs to be investigated. This will require plugging a scan tool into the vehicle’s diagnostic connector to read out the diagnostic trouble code(s). If the light is off (and is not burned out), it’s usually safe to assume the ABS system is functioning properly unless the vehicle has been experiencing any unusual brake problems or the ABS system has been kicking in unnecessarily when braking normally on dry pavement. If those things are happening, there may be an issue that will require additional diagnosis.
WHEN REPAIRS ARE MADE
Once the entire brake system has been inspected, any or all of the following may have to be replaced depending on the condition of the parts:
Brake linings front and rear if they are worn to minimum thickness, damaged or contaminated with brake fluid or grease;
Rotors and/or drums if they are worn to discard specifications, cracked, severely corroded, warped or hard spots are found;
Drum hardware and caliper bushings/pins/sleeves;
Calipers and wheel cylinders (must be replaced if leaking or sticking);
Master cylinder if leaking internally or externally;
Brake hoses if leaking, cracked or damaged;
Steel brake lines if leaking, severely corroded or damaged;
Brake fluid if more than three or four years old, or contaminated;
Wheel bearings if worn or loose;
Parking brake cables if corroded or broken;
Brake lubricant (caliper slides and shoe pads should be lubricated with high temperature brake grease); and
Any parts that may be defective in the ABS system (wheel speed sensors, pump, pump relay, high pressure accumulator, solenoid valves, etc.).
THE PARTS LIST
When brake linings are replaced, always follow the friction supplier’s guidelines. As a rule, linings should be replaced with ones made of the same basic type of material as the original linings (or better). Replace semi-metallic with semi-metallic, ceramic with ceramic and nonasbestos organic (NAO) with NAO or upgrade NAO to ceramic. The best advice here is to recommend premium grade linings as opposed to standard or economy grade linings. Premium linings will usually give your customers the best performance, longevity and overall value.
If a loaded caliper assembly is being replaced on one side of a vehicle only, the pads should have the same approximate friction characteristics as the ones on the opposite side. If a different grade of friction material is used, it can increase the potential for a brake pull.
Unless the rotors and drums are in near perfect condition (no scoring, minimal runout, etc.), resurfacing is recommended to restore an optimum friction surface. Rotors should be resurfaced to OEM specifications.
If rotors are worn to minimum thickness, or can’t be resurfaced without exceeding the minimum or discard specs, they must be replaced. Rotors should also be replaced if they are cracked, have hard spots or are severely corroded.
It’s the same story with drums. If a drum is cracked, has hard spots, is bell-mouthed, or the inside diameter exceeds maximum specs, or a drum can’t be resurfaced without exceeding the limit, it must be replaced. Also, both drums should have about the same amount of wear. If the difference in wear is greater than about .040 inches, both drums (or rotors) should be replaced, even if only one is at or near the discard limit.
As for drum hardware (self-adjusters, return springs, shoe springs, etc.) and disc hardware (caliper slide pins, bolts, bushings, sleeves, etc.), anything that is obviously worn, damaged or badly corroded should always be replaced. And on high-mileage vehicles, a complete change is recommended to restore the brakes to like-new condition.
RELATED SALES OPPORTUNITIES
Other products that may be needed when doing brake work include aerosol brake cleaner to remove brake dust and grime from brake parts, brake grease for lubricating brake parts and special brake service tools. These include spring removal tools, a bleeder screw wrench and bleeder tools for changing the brake fluid and bleeding the brake lines, a micrometer for measuring rotor thickness, a drum gauge for measuring the inside diameter of the brake drums, wheel bearing and hub service tools and possibly a scan tool and DVOM for ABS diagnosis.
DIY customers may also need a service manual for brake diagnosis, brake assembly diagrams, brake bleeding procedures, or ABS wiring diagrams.
If your store has a brake lathe or access to a local machine shop, invite your DIY customers to bring in their rotors and drums for resurfacing.
Finally, remind your customers to also check the condition of the boots around the CV joints for splits or grease leaks. Replacing a leaky boot now can save the cost of having to replace the CV joint or entire shaft later.