Preliminary Evaluation · INEFFECTIVE AIR BRAKES · Opened 1986-08-13 · Closed 1986-10-16
Investigation
Action number
PE86073
Type
Preliminary Evaluation
Open date
1986-08-13
Close date
1986-10-16
Manufacturer
General Motors, LLC
Affected makes
CHEVROLET; GMC
Affected components
SERVICE BRAKES, HYDRAULIC
Affected model years
1984, 1985, 1986
Affected (make, year) variants
6
Summary
SUMMARY OF INFORMATION FROM MANUFACTURER:NONE AT THIS TIME.ANALYSIS:A PNEUMATIC BALANCE TEST PERFORMED ON FOUR OF THE SUBJECT BUSESBY AFTERMARKET BRAKE SYSTEM DISTRIBUTOR INDICATED THAT DURING A 15 PSIBRAKE APPLICATION, THERE WOULD BE 15 PSI AT THE FRONT AXLE AND 0 PSI ATTHE REAR.ONE OF THE KEYS TO BRAKE BALANCE IS BRAKE ACTUATION AND RELEASE.THE REAR SHOULD APPLY BEFORE THE FRONT AND RELEASE SLIGHTLY AFTER.SINCEMOST BRAKING OCCURS BELOW 20 PSI, IT WOULD SEEM THAT HAVING THE SAME ORCLOSE PRESSURE IN ALL CHAMBERS IS IMPORTANT FOR PROPER BALANCE.PROPOSED ACTION:OPEN A PE.SEND AN IR.