Brake Pedal - Pulsation on Light Application
Group: CHASSISNumber: 94-50-004
Date: NOVEMBER, 1994
Model: '92 & '93 ELANTRA
Subject:
BRAKE PEDAL PULSATION DIAGNOSIS AND REPAIR
Some 1992 and 1993 Elantras may experience brake pedal pulsation during light brake application at speeds over 30 mph. This is caused by excessive disc thickness variation and disc run out.
Brake pedal pulsation does not affect the stopping distance of the vehicle, however, it may be annoying to the driver. To correct this condition, replace the front brake discs and pads by following the procedures stated below.
1. Remove the front wheel and tire assembly. Remove the front brake caliper assembly and suspend it with a wire. Remove the brake discs and pads and discard them.
2. Clean the surface of the hub with brake cleaner and then check the hub run out in the lateral direction. The hub run out should be measured as close to the outer edge as possible on the face of the hub and should not exceed 0.O5 mm. Replace the hub if necessary. If the run out of the new hub exceeds the limit, the bearing, hub and knuckle should be checked for proper assembly by following the procedures in the shop manual.
3. Install the new discs. Temporarily install nuts to hold the discs against the hub, with the nuts evenly torqued to specifications. DO NOT machine the new discs.
4. Measure total run out at the outer edge of the disc face. Verify that total run out is within the specification of 0.10 mm. If the total run out exceeds 0.10 mm, re-index the disc 180 degrees from its original position on the hub and recheck.
5. Apply a light coating of high-viscosity grease to these four areas:
- between the pad backing plate and each shim.
- between the shim and caliper.
- between the shim and piston.
- between the edges of the pad backing plate and the caliper bracket
6. Reinstall the caliper with new brake pads.
7. With the engine running and the transmission in gear (front wheels rotating), apply the brakes two to three times (as if you were stopping the vehicle).
8. Shut the engine off and release the brake pedal.
9. Manually rotate the brake rotors two full turns and feel the brake drag. For accurate measurement, use a spring scale attached to the wheel stud. If the drag is more than 12 kg (26 lbs.), follow the shop manual procedures to correct.
10. If the brake drag is within specification, remove the temporary nuts holding the disc onto the hub.
11. Reinstall the wheel and tire assembly, torquing the lug nuts to 65 - 80 ft.lb.
Warranty Information