Investigations
REAR DISC BRAKE FAILURE
NHTSA Preliminary Evaluation PE87039 - closed, opened 1987-07-14.
NHTSA investigation PE87039 is a Preliminary Evaluation opened on 1987-07-14 and currently closed. The subject is tracked inside the Office of Defects Investigation queue. Latest activity on this investigation was logged on 1987-10-13 - NHTSA updates that field whenever an Information Request goes out, a supplement is filed, or a status change is recorded in the public docket.
A Preliminary Evaluation like PE87039 is the entry point of the federal defect-investigation process. NHTSA engineers scan complaint databases, field reports, and manufacturer data to decide whether an Engineering Analysis is warranted, whether a voluntary recall is already sufficient, or whether the pattern does not rise to a defect finding.
Investigators summarized the matter as follows: "SUMMARY OF INFORMATION FROM MANUFACTURER: VEHICLES INVOLVED ARE EQUIPPEDWITH FOUR WHEEL HYDRAULIC DISC BRAKES. THE ALLEGED DEFECT PERTAINS TO THEREAR BRAKES ONLY AND INVOLVES SEPARATION (DEBONDING) OF THE BRAKE LININGPAD..." Investigations are the early-warning layer of the federal auto-safety system, sitting upstream of formal recalls and defect orders. Whether this one closes without action or escalates into an Engineering Analysis, the full history stays in the ODI archive so researchers, litigators, and buyers can pull the paper trail at any time.
Investigation Summary
SUMMARY OF INFORMATION FROM MANUFACTURER: VEHICLES INVOLVED ARE EQUIPPEDWITH FOUR WHEEL HYDRAULIC DISC BRAKES. THE ALLEGED DEFECT PERTAINS TO THEREAR BRAKES ONLY AND INVOLVES SEPARATION (DEBONDING) OF THE BRAKE LININGPAD FROM THE STEEL BACKING (SHOE). ALL FIELD REPORTS AND COMPLAINTSINVOLVE FLEETS. THE SPECIFIC NUMBER OF ACTUAL SEPARATIONS IN UNKNOWN.ANALYSIS: DEBONDING RESULTS IN DISINTEGRATION AND POSSIBLY EJECTION OF THEPAD FROM THE CALIPER. IT IS INITIATED BY A COMBINATION OF TIME AND HIGHOPERATING TEMPERATURES, WHICH CAUSE THE ORGANIC RESINS IN THE BONDINGADHESIVE TO BREAK DOWN AND LOOSE THEIR STRENGTH. WHEN THE PAD IS EJECTED,THE CALIPER PISTON WILL MOVE OUT UPON THE NEXT FOOT APPLICATION, FORCINGTHE REMAINING STEEL SHOE TO CONTACT THE ROTOR. FURTHER OPERATION MAYDAMAGE THE PISTON "O" RING, RESULTING IN BRAKE FLUID LEAKAGE AND PARTIALBRAKE LOSS. SINCE THE VEHICLES ARE EQUIPPED WITH A DUAL MASTER CYLINDERAND A SPLIT BRAKE SYSTEM, A PORTION OF THE BRAKE SYSTEM WOULD REMAINFUNCTIONAL.ALTHOUGH REPORTS ON THIS PROBLEM COMMENCED IN 1983, THERE ARE NO KNOWNACCIDENTS OR INJURIES. PRESENTLY THE MOST SIGNIFICANT AFFECT OF THEPROBLEM IS THE ECONOMIC LOSS TO THE FLEETS DUE TO THE NECESSARY INCREASEDFREQUENCY OF MAINTENANCE. PRODUCTION HAS COMMENCED ON 1988 MODEL YEARVEHICLES USING A NEW PAD WITH IMPROVED MECHANICAL LOCK WHICH ELIMINATESDEBONDING, ACCORDING TO FIELD TESTING. THE NEW PAD SUPERSEDES THE PREVIOUSPAD, WILL BE AVAILABLE THROUGH GM PARTS DISTRIBUTORS IN THE NEAR FUTURE,AND IS EXPECTED TO REDUCE MAINTENANCE FREQUENCY. THIS ISSUE BECOMES SAFETYRELATED ONLY IF IGNORED.PROPOSED ACTION: CLOSE THIS PE. NO SAFETY RELATED DEFECT TREND HAS BEENIDENTIFIED. MAINTAIN CONTACT WITH THE SCHOOLBUS INDUSTRY AND MONITORCOMPLAINT DATA ON THIS ISSUE.===
About This Investigation Type
A Preliminary Evaluation (PE) is the first phase of NHTSA's investigation process. It is opened when the agency identifies a potential safety defect pattern, usually triggered by consumer complaints, manufacturer reports, or field monitoring. During a PE, NHTSA gathers information to determine whether a formal engineering analysis is warranted.
Data from NHTSA Office of Defects Investigation. Cross-references: NHTSA recall campaign API and NHTSA FARS where fatality records overlap. PlainCars does not rate or recommend vehicles. about how PlainCars sources NHTSA data.
Read our methodology - how this data is sourced, computed, and verified.