Toyota Tercel 1984-1994 Repair Guide

Brake Disc (Rotor)

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CAUTION
Brake pads may contain asbestos, which has been determined to be a cancer causing agent. Never clean the brake surfaces with compressed air! Avoid inhaling any dust from brake surfaces! When cleaning brakes, use commercially available brake cleaning fluids.

REMOVAL & INSTALLATION




CAUTION
On models equipped with a Supplemental Restraint System (SRS) or "air bag,'' work must NOT be started until at least 90 seconds have passed from the time that both the ignition switch is turned to the LOCK position and the negative cable is disconnected from the battery.

  1. Elevate and safely support the car. If only the front end is supported, set the parking brake and block the rear wheels.
  2.  
  3. Remove the wheel.
  4.  
  5. Remove the brake caliper from its mount and suspend it out of the way. Don't disconnect the hose or let the caliper hang by the hose. Remove the brake pads with all the clips and shims.
  6.  
  7. Install all the lug nuts finger-tight to hold the rotor in place. If the nuts are open at both ends, it is helpful to install them backwards (tapered end out) to secure the disc.
  8.  
  9. Remove the two bolts holding the caliper mounting bracket to the steering knuckle. These bolts will be tight. Remove the lug nuts holding the rotor.
  10.  
  11. Remove the bracket from the knuckle. Before removing the rotor, make a mark on the rotor indexing one wheel stud to one hole in the rotor. This assures the rotor will be re-installed in its original position.
  12.  

To install:
  1. Make certain the rotor is clean and free of any particles of rust or metal from resurfacing. Observe the index mark made earlier, then fit the rotor over the wheel lugs. Install the lug nuts to hold it in place.
  2.  
  3. Install the caliper mounting bracket in position, then tighten the bolts to 65 ft. lbs. (88 Nm).
  4.  
  5. Install the brake pads and the hardware (clips/shims).
  6.  
  7. Install the caliper.
  8.  
  9. Install the wheel, then lower the car to the ground.
  10.  

INSPECTION



See Figures 1 and 2

For reasons of safety and reliability, we recommend that if one rotor requires replacement, both rotors, along with new pads, should be replaced as a set.

Run-out
  1. Elevate and safely support the car. If only the front end is supported, set the parking brake and block the rear wheels.
  2.  
  3. Remove the wheel.
  4.  
  5. Remove the brake caliper from its mount and suspend it out of the way. Don't disconnect the hose or let the caliper hang by the hose. Remove the brake pads with all the clips and shims.
  6.  
  7. Install all the lug nuts to hold the rotor in place. If the nuts are open at both ends, it is helpful to install them backwards (tapered end out) to secure the disc. Tighten the nuts a bit tighter than finger-tight, but make sure all are at approximately the same clamp load.
  8.  
  9. Mount a dial indicator with a magnetic or universal base on the strut so that the tip of the indicator contacts the rotor about 0.39 in. (10mm) from the outer edge.
  10.  
  11. Zero the dial indicator. Turn the rotor one complete revolution and observe the total indicated run-out.
  12.  
  13. If run-out exceeds 0.0059 in. (0.15mm) on 1984-1990 models or 0.0035 in. (0.09mm) on 1991-1994 models, clean the wheel hub and rotor mating surfaces and remeasure. If the run-out still exceeds maximum, remove the rotor and remount it so that the wheel studs now run through different holes. If this re-indexing does not provide correct run-out measurements, the rotor should be considered warped beyond use and should be either resurfaced or replaced.
  14.  



Click image to see an enlarged view

Fig. Fig. 1: Disc run-out can be checked with a dial indicator



Click image to see an enlarged view

Fig. Fig. 2: Checking the rotor thickness with a micrometer

Thickness

The thickness of the rotor partially determines its ability to withstand heat and provide adequate stopping force. Every rotor has a minimum thickness established by the manufacturer. This minimum measurement MUST NOT be exceeded. A rotor which is too thin may crack under braking; if this occurs the wheel can lock instantly, resulting in sudden loss of control. If any part of the rotor measures below minimum thickness, the disc must be replaced. Additionally, a rotor which needs to be resurfaced may not allow sufficient cutting before reaching minimum. Since the allowable wear from new to minimum is about 0.04 in. (1mm), it is wise to replace the rotor rather than resurface it.

  1. Thickness and thickness variation can be measured with a micrometer. All measurements must be made at the same distance in from the edge of the rotor. Measure at four equally spaced points around the disc and record the measurements. Compare each measurement to the minimum thickness specifications found in the chart in this section.
  2.  
  3. Compare the four measurements to each other and find the difference between each pair. A rotor which does not meet these specifications should be resurfaced or replaced as applicable.
  4.  

Condition

A new rotor will have a smooth even surface which rapidly changes during use. It is not uncommon for a rotor to develop very fine concentric scoring (like the grooves on a record) due to dust and grit being trapped by the brake pad. This slight irregularity is normal, but as the grooves deepen, wear and noise increase while stopping may be affected. As a general rule, any groove deep enough to snag a fingernail during inspection is cause for corrective action or replacement.

Any sign of blue spots, discoloration, heavy rusting or gouges require replacement of the rotor. If you are checking the disc on the car (such as during pad replacement or tire rotation) remember to turn the disc and check both the inner and outer faces completely. If anything looks questionable or requires consideration, choose the safer option and replace the rotors. The front brakes are a critical system and must be maintained at 100 percent reliability.

Any time rotors are replaced, the pads should also be replaced (as a set) so that the surfaces mate properly. The restored feel and accurate stopping make the extra investment worthwhile.

 
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