SUMMARY OF INFORMATION FROM MANUFACTURER:EXPERIMENTAL MODIFICATIONSPERFORMED BY ROCKWELL ON THREE VEHICLES INVOLVED INCREASING FRONT CHAMBERSIZE FROM 24 TO 30 INCHES, DECREASING REAR CHAMBERS FROM 36 TO 30 INCHES,CHANGING THE FRONT DISC BRAKE LININGS AND REAR BRAKES SHOES.IN SERVICEEVALUATION OF THE MODIFICATION REVEALS THAT THE PROBLEM IS APPARENTLYCORRECTED.PIERCE AND ROCKWELL WILL INSPECT THE REMAINING VEHICLES ANDPERFORM THE ABOVE MODIFICATIONS AS DEEMED NECESSARY.ANALYSIS:PROBLEM APPEARS TO HAVE BEEN A BRAKE IMBALANCE BETWEEN THE FRONTAND REAR AXLES.FIELD TESTS REVEAL THAT THE ABOVE MODIFICATIONS HAVESOLVED THE PROBLEM BY BETTER BALANCING THE BRAKING ACTION BETWEEN THE TWOAXLES.AFTER THREE MONTHS OF EVALUATION DURING ROUTINE SERVICE OPERATIONS,NO FURTHER FAILURES HAVE OCCURRED ON THE THREE MODIFIED VEHICLES.PROPOSED ACTION:CLOSE THIS PE.PIERCE HAS IMPLEMENTED A RECALL (87V-117)CONCERNING THIS PROBLEM.===