Battle Magazine — March 1997

Next, clean the caliper with brake cleaner and apply the supplied grease. Fit new seals and reinstall the piston, making sure it faces the same direction as before. That describes the front caliper. The rear piston is screw-type: its face has grooves, so carefully turn it with water-pump pliers to remove it without damage. Turn it clockwise to install. Next is bleeding the brakes, which takes two people: one pumps the brake pedal while the other opens the bleeder and keeps the reservoir topped up. Start with the wheel farthest from the master cylinder: 1) left rear, 2) right rear, 3) left front (passenger side), 4) right front.

The rear brake on the more effective version uses a single-piece solid disc. As a rotor wears, grooves like those on a record appear. If the brake pads also have ridges worn into their faces, the rotor is likely worn. With a rotor in this condition, new pads or a caliper overhaul will not restore a firm brake feel; the pedal may feel soft. Metal pads wear rotors faster. Asbestos pads are no longer allowed on public roads, but compared with them, metal pads can wear a rotor about 1.5 times faster. Braking is not produced by pad wear alone: the rotor wears too, and both surfaces work together. German brakes are often praised because their setup favors performance over service life—rotors may be replaced after every two pad changes. Rotors are wear items. ● Rotor maintenance

If a rotor is worn, resurfacing is one option, but replacement with a new part is recommended. Resurfacing costs about ¥5,000 per rotor; a new AE86 rotor costs ¥6,800, so the difference is small. Resurfacing is also limited by minimum thickness. A thinner rotor—especially the rear one-piece solid disc—holds more heat and is more likely to warp. The thinner it is, the farther the caliper piston extends, which is another reason a new part is preferable. Rotors can also lose performance without being worn: a rotor that has darkened despite being clean may have been overheated. Once heat-treated this way, it becomes hard and stops wearing normally, so braking performance worsens—

and can become ineffective. If a rotor is very dark, assume it has reached the end of its useful life. Replacing it is straightforward once the caliper is removed. After installation, press the pedal 30–40 times to extend the piston fully. Rotor tuning: drilling holes in brake rotors is one way to improve cooling. With a drill press, it can be done at home. The article says durability should be acceptable if the number of holes is limited, making rows of about four holes along diagonal lines.

For brake pads, resistance to fade from friction heat is important. If temperatures exceed a pad’s range, it can fade and stop braking effectively. For example, pads rated for roughly 400–500°C may fade if they get hotter. Let’s use Endless pads as an example. The label on the box lists an “NA-” pad for about 50–350°C, designed for strong initial bite from cold; above 350°C it is outside its stated range. By contrast, the NA-R type is rated around 300–800°C and must warm to about 300°C before it performs as intended. It emphasizes fade resistance at high temperatures, providing stable braking at high speed; it is intended for racing use. Choose pads carefully according to how you drive, considering material, temperature range, bite, noise and wear…