The Tools That Keep Brake Service Fast & Profitable

Brake work is one area that continues to show steady growth in the aftermarket. Obviously, brakes are an essential safety item on every vehicle - you can’t stop without them! But the brakes wear every time they are applied and eventually wear out or develop problems that interfere with the safe operation of the vehicle.

Linings wear down and have to be replaced. Rotors and drums wear unevenly, warp and go out-of-round requiring them to be resurfaced or replaced. Hydraulic components such as the calipers, wheel cylinders and master cylinders can develop leaks and other problems that require these components to be rebuilt or replaced. The same goes for steel brake lines, rubber brake hoses, brake hardware, self-adjusters and parking brakes. Nor is the ABS system immune to wear and corrosion. Add it all up and it equals a tremendous service opportunity for brake repair work - provided you have the right tools and equipment.

Diagnostic Tools
On most ABS-equipped vehicles, you’ll need a scan tool to access and diagnose the ABS system if a vehicle has an ABS-related brake problem. But not just any scan tool will do. It has to have the correct software and connector to communicate with the ABS module. Some general purpose scan tools have add-on modules or memory chips that add ABS capability, while others (usually the more expensive top-of-the-line models) come with the ABS software as part of the package. Some equipment manufacturers even make dedicated scan tools that are designed just for ABS work.

In addition to diagnostics, an ABS-capable scan tool may also be needed to bleed certain ABS systems if air has gotten inside the ABS modular assembly. On General Motors vehicles equipped with Delco VI or Delphi 7 ABS systems, you need a scan tool to cycle the ABS unit. The same goes for vehicles equipped with Bosch 5 ABS and Teves Mark 20 ABS systems.

Many ABS faults are electrical and require the use of a DVOM (digital volt ohm meter) or multimeter to check circuit continuity, resistance or voltage. Measuring resistance, for example, is a good way to check a suspicious wheel speed sensor. A circuit continuity tester or logic probe also is useful for checking wiring faults. For more advanced ABS diagnostics, a digital oscilloscope (DSO) or graphing multimeter may be useful for observing wheel speed sensor outputs as a waveform.

For troubleshooting brake hydraulic problems, a set of high pressure gauges is essential. By "T"-ing gauges into brake lines, you can read pressure differentials to check brake balance, the operation of proportioning valves and load-sensing valves.

One company makes a set of hydraulic gauges with load cells that can be easily installed in place of the brake pads in each caliper. The gauges show how much pressure is being applied when the brake pedal is depressed. This can be used to check the operation of the calipers, master cylinder and brake lines for uneven pressure that can cause a brake pull condition.

Another diagnostic tool you may want to invest in is a brake fluid tester. Water-contaminated brake fluid boils at a lower temperature, increasing the risk of pedal fade under hard use. Contaminated fluid also promotes internal corrosion in the brake system. By inspecting the condition of the fluid, you can determine if a fluid change is needed. Various types of electronic testers are available for this purpose. One type measures the boiling point of a small sample of fluid to determine the amount of contamination. Other alternatives here include chemical test strips that react to either the breakdown of the corrosion inhibitors in the fluid or the fluid’s moisture content.

Another diagnostic tool that can come in handy for troubleshooting brake problems is an infrared pyrometer. These pistol-like thermometers measure infrared radiation to reveal surface temperatures. A hot brake is a good indication of brake drag. Uneven heat side-to-side may indicate a frozen or sticking caliper.

Brake Service Tools
One piece of equipment every shop needs for brake work is some type of power bleeder. Any time a brake line is opened or a hydraulic component is replaced, air gets inside the lines. Gravity bleeding is slow and may be incomplete, leaving air trapped inside the system. Air can cause a soft, spongy pedal so the system must be bled to get all of the air out.

Pressurized power bleeders use shop air to force hydraulic fluid through the lines. An adapter attaches to the master cylinder to supply fluid under pressure. To catch the fluid, you’ll need a drip pan. Other tools that will be needed include a bleeder wrench to loosen the bleeder screws on the calipers and wheel cylinders, and hoses to route the fluid into the catch pan. Some brake bleeders use vacuum to pull the fluid through the system (eliminating the need for a catch pan), while others use pressure to reverse flush the system back toward the master cylinder. A brake fluid syringe also comes in handy for removing fluid from the master cylinder.

For disc brake service, a set of Allen or Torx head driver bits may be necessary to remove the calipers. On some vehicles, like Ford full-size pickups, a brake pad lock pin driver comes in handy for driving out the caliper pins. You’ll also need a large C-clamp or a disc brake pad spreader to push the caliper pistons back into the calipers.

An important step when servicing disc brakes is to measure the thickness of the rotors. Measuring rotor thickness with a micrometer or brake dial indicator gauge will tell you if the rotors have enough thickness to be safely machined, or if they’re too thin and have to be replaced. Measuring rotor thickness at various places will also reveal thickness variations that can cause pedal vibrations and brake shudder.

If the rotors are serviceable, a bench lathe or on-car lathe will be needed to resurface them. On-car lathes that machine rotors in place can save valuable time (especially on vehicles that have difficult-to-remove "captured" rotors) and generally reduce runout by cutting the rotors true to the spindle. Excessive runout is a leading cause of pedal vibrations, uneven wear and comebacks. The most sophisticated on-car lathes have automatic compensating, which saves time and improves accuracy.

Most lathes, if used correctly with sharp bits, will produce a satisfactory surface finish that meets OEM requirements. For optimum tool life and a superior finish, consider using coated carbide bits or superabrasive bits. If a nondirectional surface finish is desired on rotors, grinding attachments and flexible hones are also available for this purpose.

If a vehicle is equipped with "composite" rotors, and the rotors need to be resurfaced, special adapters or oversized bell caps must be used with a bench lathe to support the rotors. If not, the rotors can flex causing finish problems and runout.

If calipers need to be rebuilt, a honing tool will be needed to clean up the piston bores. The same goes for wheel cylinders or master cylinders that are rebuildable.

For rear caliper service, some vehicles have caliper pistons that must be screwed in to replace the pads. A special disc brake piston tool with pins that fit the pistons makes this job easier.

For drum service, removing the drum is often the hardest part of the job. Some type of drum puller is essential for popping loose frozen drums.

But first you need to back off the shoes from the drums. For this, a brake-adjusting spoon works much better than a large screwdriver. The spoon has the right angle to easily fit through the slot in the brake backing plate. Once the start wheel on the self-adjuster has been backed off, the drum should be free to slide off.

On GM vehicles with single spring brakes, you need a special tool to release and hold the spring during disassembly and reassembly. Brake work on these applications is almost impossible without this tool.

When the drums are off, they must be measured to determine the amount of wear. A drum gauge will reveal the inside diameter of the drum. If the ID exceeds the discard specification, or the drum cannot be turned without exceeding the "machine to" specification, it is unsafe and must be replaced. Drum resurfacing requires a bench lathe.

Drums tend to trap a lot of dust, which may contain dangerous asbestos fibers. For your own safety and the safety of others in the shop, use an aerosol brake cleaner or portable brake bath to wash off the dust and clean the brakes. Never blow off brake dust with an air hose!

To remove the brake shoes, spring pliers work much better than ordinary pliers, especially on hold-down and stiff return springs. And to hold the wheel cylinder pistons in place, use a spring-loaded piston clamp.

Disconnecting the parking brake hardware can also be tricky on some vehicles, and may require the help of a special parking brake spring compressor or release tool.

If the wheel cylinders need to be rebuilt, a hone of some type will be needed to clean up the piston bore. If replacement is needed, some cars may require a special tool to release the wheel cylinder retainer on the brake backing plate (older GM X-cars, for example).

When the brakes go back together, you’ll need the spring pliers to get the hold-down and return springs back in place. You’ll also need an adjuster spoon to adjust the shoes once the drums have been reinstalled.

With its continued growth in the marketplace, brake work is a profitable sector. Special tools designed for various types of brake work can not only save valuable time and effort, but also may be required to perform certain diagnostic or repair tasks.