Investigations
REAR BRAKE LOCKUP
NHTSA Engineering Analysis EA84026 - closed, opened 1984-08-15.
NHTSA investigation EA84026 is a Engineering Analysis opened on 1984-08-15 and currently closed. The subject is tracked inside the Office of Defects Investigation queue. Latest activity on this investigation was logged on 1988-04-08 - NHTSA updates that field whenever an Information Request goes out, a supplement is filed, or a status change is recorded in the public docket.
An Engineering Analysis like EA84026 is the deeper technical phase that follows a PE. NHTSA requests design, warranty, and field-failure data from the manufacturer, conducts its own testing when needed, and determines whether the evidence supports a safety defect finding that would compel a recall.
Investigators summarized the matter as follows: "SUMMARY: THE REAR CYLINDER DIAMETER WAS REDUCED FOR 1984 MODELS TO IMPROVEBRAKING BALANCE FOR EMPTY VEHICLES. GM CLAIMS REAR BRAKES CAN BE LOCKEDON MOST EMPTY PICKUPS ON LOW TRACTION SURFACES.ANALYSIS: PICKUP TRUCKS TRAD..." 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: THE REAR CYLINDER DIAMETER WAS REDUCED FOR 1984 MODELS TO IMPROVEBRAKING BALANCE FOR EMPTY VEHICLES. GM CLAIMS REAR BRAKES CAN BE LOCKEDON MOST EMPTY PICKUPS ON LOW TRACTION SURFACES.ANALYSIS: PICKUP TRUCKS TRADITIONALLY HAVE BEEN DESIGNED WITH BRAKINGSYSTEMS WHICH CAUSED THE REAR BRAKES TO LOCK FIRST WHEN THE CARGO BED ISEMPTY, SO THAT MAXIMUM EFFECTIVE BRAKING IS AVAILABLE WHEN A LOAD ISPRESENT. MOST MODERN LIGHT TRUCKS AND VANS UTILIZE WEIGHT SENSITIVE PROP-ORTIONING VALVES TO PROVIDE GOOD BRAKING AT ALL LOADS.STATUS: C-MEMO MAY NEED REVISION. IN FINAL BY 12/31/87.===
About This Investigation Type
An Engineering Analysis (EA) is the in-depth phase following a Preliminary Evaluation. NHTSA engineers conduct testing, collect data from manufacturers, and perform detailed technical analysis to determine whether a safety defect exists. An EA may lead to a voluntary recall by the manufacturer or, in rare cases, a mandatory recall order.
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.