DIY brake servicing

DIY brake maintenance While big savings can be made by maintaining vehicle brakes at home, mistakes can have catastrophic consequences. Rob Marshall explains how you can save money without compromising health and safety.

Everything you need to know about renewing brake pads and discs, maintaining drum brakes and troubleshooting problems.

While basic friction brake design has not changed significantly in half-acentury, it remains one of the most common areas requiring routine repairs. This was proven, when all three cars that were bought for CM’S Budget

Motoring feature in the July 2019 issue needed attention to their braking systems. While brakes undergo quick visual and performance tests during a typical MOT, a ‘pass’ is no guarantee that they are in peak condition. Closer inspection is needed at service time, with the wheels removed. If you do not have your car serviced at a garage, the responsibility falls upon you.

What goes wrong?

Traditional brakes are wasteful: they turn motion energy into heat, which is shed into the surrounding air. The resulting friction from specially-developed heat-resistant compounds being forced against a steel/cast-iron surface causes both faces to wear. As a result, periodic replacement of the brake pads and discs (disc brakes) or linings (drum brakes) is one of the most common procedures that a typical DIYER will undertake. This feature will focus on the friction side of the braking system, while other relevant elements – such as hydraulics – will be included in less depth.

Until the late 1980s, most friction pads/linings contained asbestos, meaning that brake dust posed a serious health hazard to mechanics. While asbestos has been superseded by other materials, the dust remains harmful. An aerosol, or liquid brake cleaner, should be used to clear these deposits. With cars becoming heavier and faster, braking components have tended to become larger and this, coupled with different friction materials, means that brake discs tend to require renewal at every second brake pad change, at least.

As most braking effort is performed at the front, disc brakes are more effective, because their exposed components can dissipate heat more effectively than enclosed drum brakes. Many models have disc brakes fitted to the rear hubs as well, but because they do not generate as much heat, they are more vulnerable to corrosion, causing the brakes to become noisy and/or not release/apply correctly. However, the front brakes are not immune to hydraulic piston and sliding caliper seizure. Seized brakes can cause an imbalance and excessive heat is generated, if they fail to release. This not only wears the friction components prematurely, but also total brake failure is possible. The heat can also damage other parts, such as wheel bearings.

Buying advice

The huge variety of brands in the marketplace risks confusion about which one is most appropriate for your needs. Even some motor factors and parts suppliers are introducing their own branded brake products, or gaining exclusive rights to aftermarket parts, such as Euro Car Parts with Pagid and GSF Car Parts with Bendix.

To maintain a base quality standard on such safety-critical parts, any new brake pads and discs must conform to ECE R90 specifications and be E-marked appropriately. All pads and discs that you fit must be supplied in a sealed box and bear a unique part number, date, batch number, or source code, that allows full production traceability. Should you buy through trustworthy channels, the risk of fitting non-compliant parts is low, but check any boxes carefully and reject parts that you think do not comply.

DRIV (the new name for Federalmogul) produces the Ferodo brand that is supplied to car-makers and the company confirms that R90 is only a minimum standard. It says that R90 conformity tests tend to take several hours, whereas assessments for motor manufacturers can take six months and include analyses that are not required legally, such as wet weather performance, temperature sensitivity, fade, thermal conductivity, noise and longevity.

Even though other quality brake producers might not supply direct to car-makers, they adopt a similar stance. Comline includes its own hot shear testing, durability and noise analyses for its brake pads. MEYLE-PD is another premium range of brake parts that goes

beyond R90 – for instance, one feature is reduced dust formation and the MEYLE-PD coated brake disc range contains a higher carbon content that provides superior high temperature stability, longer life and anti-vibration characteristics under heavy braking at high speeds. While fitting these enhanced OE quality parts might not require you to inform your insurance company of a modification (but it is wise to check), fitting race-oriented brake pads with compounds that favour higher temperature performance, or crossdrilled discs that can shed heat faster, will dictate that you tell your broker.

Consider ease of fitting, too. Quality friction parts will not only be easier to install, but will also include ancillaries that you might need. As much as 99% of Meyle’s brake disc range is supplied with new fixing screws, whereas its MEYLE-PD premium brake pad kits include a host of ancillary parts, depending on application and where the company recommends their renewal. Conversely, Delphi supplies fitting kits separately to limit the number of part numbers in its range, while Borg and Beck brake fitting kits include all of the components necessary to complete the task, including clips, springs, pins and bolts. It's wise to research which ancillary parts you might require before placing an order.

Brake friction parts wear out in use. They can also corrode and need replacing regardless, if unused.

Ask your parts supplier what accessories are included with your pads/discs/drum linings and consider if you need to buy fitting kits, new shims, or caliper slider kits.

On many cars, the mechanical handbrake lever has been replaced by an electric park brake (EPB). These can either have a central motor that operates cables or else each caliper might be fitted with a motor (as arrowed).

When buying new brake pads, the box should be sealed. If it isn’t, reject the parts.

Provided they are not contaminated with grease during fitting, coated brake discs can be fitted with no prior preparation, but read any instructions carefully. Coated brake discs resist corrosion for longer and enhance the look of brakes that may be visible through open-spoke alloy wheels.

Traditionally, brake discs are covered in an anti-rust wax, meaning they must be sprayed with brake cleaner before fitting.

Poor brake performance might not be due to friction components. The hydraulics might be the problem. Pictured is a handbrake cable that has succumbed to corrosion and snapped.

Some calipers come in two halves. You should avoid separating them, because there is a risk they will not seal together again afterwards, resulting in fluid leaks.

Some brake pad kits do not supply a replacement lower bolt for sliding calipers. If reusing the removed bolt, apply some thread-lock compound before refitting it.