Battle Magazine — March 1997

Brake caliper: watch for a seized parking-brake cam. The front and rear calipers are single-piston, sliding types. A distinctive feature of the rear caliper is a cam mechanism for the parking brake. It is not especially powerful, which can be a drawback when drifting with frequent use of the handbrake. The most common problem is a deteriorated, stretched cable that no longer works, or rust where the cable moves the cam inside the caliper, causing it to seize—

so the parking brake stops working. This cam cannot be overhauled if it fails; the caliper has to be replaced. ● Seized slide pins Do the brake pads on your AE86 wear unevenly, with one pad thicker than the other or the piston-side pad wearing unusually fast? That points to a problem with the caliper. Uneven wear is a fault: check the remaining pad thickness. The AE86 caliper is a floating type. Hydraulic pressure pushes the piston and inner pad against the rotor; the caliper slides so the outer pad clamps the opposite side, allowing both pads to press evenly against the disc.

The pins are covered by dust boots and lubricated inside. When the grease dries out or rust develops, the pins seize. If a boot tears, grease can escape and rainwater or grit can enter and damage the part. Replace a torn boot right away. If the grease is simply missing, apply plenty and make sure the pin moves freely. Brake maintenance is more than fitting new pads: the AE86 is an old car, so dried grease is no surprise. Seized slide pins also weaken the parking brake. If you do not know the cause and only keep tightening the adjuster, you may just stretch the cable. This kind of misdiagnosis is surprisingly common, so…

Take care. ● Check that the parking brake works on both sides. In a place with no traffic or pedestrians, drive at a moderate speed and apply the handbrake. If the right wheel locks but the left does not, remove the wheel on the side that failed and inspect cable and caliper movement to identify the fault. ● Caliper overhaul. An overhaul can be done with a genuine service kit. The kit includes piston dust boots, piston grease and slide-pin boots. First remove the caliper from the strut and take out the pads. Place a thick board between the piston and caliper, then press the brake pedal to push the piston out. Repeat with progressively thinner boards until the piston comes free.