SUMMARY: CHEVETTE DIESELS HAVE THE SAME BRAKING SYSTEM AS GASOLINE ENGINEEQUIPPED CHEVETTES BUT CARRY MORE WEIGHT ON THE FRONT WHEELS.ALL 1983MODELS UTILIZE A DIFFERENT PROPORTIONING VALVE AND LARGER FRONT BRAKECALIPER PISTONS TO INCREASE FRONT BRAKE TORQUE.GM CLAIMS REAR BRAKEBIAS IS OF A MAGNITUDE WHICH DOES NOT CONSTITUTE A SAFETY DEFECT.ANALYSIS: TESTING AT ETF SHOWS THE SUBJECT VEHICLES HAVE SUBSTANTIALLYLESS THAN AVERAGE ADHESION UTILIZATION WHEN TESTED IN THE AS RECEIVEDCONDITION BUT THEY PERFORMED WELL WHEN NEW, PROPERLY BURNISHED LININGSWERE INSTALLED.TESTS USING NEW BURNISHED LININGS DID NOT SUPPORT THECONSUMER COMPLAINT DATA OR DESIGN CHANGE THEORY, POSSIBLY DUE TO SMALLSAMPLE SIZE.(TESTING INDICATES THE SUBJECT VEHICLES ARE BETTER THANSOME GM A BODY GROUPS BUT WORSE THAN THE AVERAGE A BODY.GM IR RESPONSE DATED 5/15/87.STATUS:BRIEFING TO BE PREPARED.===