After all my recent Hokkaido and Eastern Honshu road trip around Japan, my brakes have been run down to about a quarter remaining, so I figured one of the most important “modifications” I can do is maintenance in the form of a good brake job on my Suzuki Swift Sport.
Brakes are one of the most important safety aspects of a car. In conjunction with good tires, good brakes can literally be the difference between life and death... or a wrecked car. Almost all modern cars use disc brakes, but some economy cars, such as kei cars, use drum brakes for the rear. Their stopping methods are different and there are some minor positive reasons to use drums over discs for the rear, but suffice to say most sport-oriented cars utilize discs all around.
Disc brakes, as the name implies, use large, typically steel, disc rotors attached to the wheel and hub. One or more brake pistons push against brake pads which apply pressure to the spinning disc, slowing the car down by changing the kinetic energy state to sound, heat, and wear. Most discs also incorporate vents and spacing in the center of the disc to better dissipate heat. More advanced rotors are made of materials that better reject or give off heat like carbon-ceramic or use of mixed metals like steel in the disc and aluminum in the hub hat.
The stopping action of disc brakes is very similar to the way a typical brake system on a bicycle works, with two little pads applying pressure against a spinning disc. Well, in the case of a bike, the wheel itself.
Drum brakes are a completely different design, because they utilize brake pads that push outwards against a spinning brake drum to reduce speed. The main problem with this setup is the inability to reject or reduce heat quickly, critical for sporty applications.
The benefits of a disc brake are numerous which is why almost all manufacturers currently employ at least disc front brakes. They reject heat quickly, are durable and easily maintained, and may have better stopping power than most drums. Some economy cars utilize drum brakes for the rears simply because of manufacturing costs. However, on off-road truck applications, drum brakes can have some advantages. Drums are essentially sealed items, so in muddy, dusty, or wet applications, drums can still stop despite environmental effects. One additional benefit of drum brakes is the ease and reliability of the mechanical parking brake which does not require the hydraulic booster system to function at all, since the lever actually moves the brake pad directly.
Brakes are an oft overlooked modification for ricers (Iike me). Some car guys dump money into exterior mods or some into improving power or handling… but overlook or cut corners on the brakes. For me, many of the cars I’ve had stop well enough with their stock setup… that’s my excuse at least.
Basic upgrades to brakes mean replacing pads to a more aggressive compound. This usually means more dust and noise, since a more heat-resistant, “stronger” material means more sacrificial wear to the rotors and eventually, the pad itself, resulting in more frequent replacements.
The next level of upgrade is usually to also replace the stock rotors with slotted or cross-drilled disc rotors. Such opening slots allow worn dust and material to be “swept away,” and there are some additional cooling benefits to the increased surface area, but there are some drawbacks like the additional risk of warping or cracking under extreme duress.
The biggest upgrade is to replace the brake system with larger calipers, allowing the use of bigger pads and discs. Some larger calipers also mean there are more pistons which can put more consistent and firmer pressure on the pads, resulting in amazing stopping distances, repeatable over prolonged use. (Assuming the tires are not the weakest link.) Of course, model-specific brake upgrades can be wildly expensive.
Is it all really even necessary? It’s true stock brakes can more than handle slowing a car down quickly for normal day-to-day traffic. But repeated, quick, and harsh stoppages in extreme conditions as found on a racetrack or even on a long touge mountain run, the brakes “fade” and squeak in agony due to warping from heat and pressure, potentially leading to spongy, inconsistent braking feel, weaker pressures, or failure to stop.
It sounds strange to say brakes “fade” because they are still there. It actually just means brake pressures fade or weaken to the point of failing to stop as expected. Assuming the pads and discs are otherwise properly maintained, the most common fault of brake fade during spirited driving is fluid fade, the boiling of the brake fluid itself due to heat transfer. This increased heat in the fluid leads to air separation and loss of pressure. Typically, one can feel the fading gradually from a “spongy” brake pedal that requires more pressure than usual to slow the car.
The commonality of all modern brakes is this brake fluid. The standard OEM-supplied brake fluid is acceptable, but DOT4 or synthetic fluids allow much more heat transfer before the liquid reaches the boiling point, allowing consistent brake feel during aggressive use.
But I digress… it’s time to change the brakes on my Swift Sport!