NHTSA Investigation EA88006

STEERING OUTPUT SHAFT

SUMMARY OF INFORMATION FROM MANUFACTURER:BOTH CHRYSLER AND MITSUBISHIINDEPENDENTLY CONCLUDED THAT THE FAILURES WERE DUE TO SEVERE IMPACT LOADINGTRANSMITTED TO THE SHAFT BY THE STEERING LINKAGE SYSTEM -- IN OTHER WORDSSHAFT FAILURE IS THE RESULT, NOT THE CAUSE, OF THE ALLEGED COLLISIONCIRCUMSTANCES.MITSUBISHI (VEHICLE PRODUCER) DID STRENGTHEN THE SHAFTDURING THE 1984 MODEL YEAR BY INCREASING THE SPLINE AND BEARING JOURNALDIAMETERS.ANALYSIS:FAILING COMPONENT IS THE STEERING BOX CROSS SHAFT (OUTPUT SHAFT)WHICH BREAKS BETWEEN THE BOTTOM BEARING IN THE STEERING BOX AND THE PITMANARM.KNOWN FAILURES INVOLVE 4 WHEEL DRIVE UNITS WHICH ARE EQUIPPED WITHPOWER STEERING.CROSS SHAFT AND PITMAN ARM SALES ARE CONSIDERABLY HIGHERON THE 4 WD UNITS THAN THE 2 WD UNITS.CHRYSLER REPORTS THE CROSS SHAFTDIAMETER WAS INCREASED IN APRIL, 1984, FOR INCREASED SHAFT STRENGTH TOIMPROVE ITS CAPABILITY TO WITHSTAND SEVERE IMPACT LOADS.PROPOSED ACTION:IR'S TO CHRYSLER AND MITSUBISHI SENT 11/16 - 17/87.AWAITING RESPONSES.===

An investigation is a separate record from a recall and from a manufacturer communication. A manufacturer campaign to repair a safety defect or a failure to meet a federal safety standard.