SwEm Technical Bulletin Number 1  03/01

Attention Alternator Upgrade Owners:

This Technical Bulletin applies to all who have installed the SwEm Alternator Upgrade Kit on their B18 or B20.

A recent Bracket failure has occurred caused by a “loose mounting condition”, due to the re-use of original three 5/16NC generator bracket mounting bolts which bottomed in their holes before securely holding the new alt. bracket to the engine block.  While re-use of original bolts is OK and this situation is specifically covered in the kit instructions, failure to notice the bolts bottoming during installation and correcting for it, can (and did) lead to bracket fatigue and eventual failure.  It is recommended therefore, to double check the bracket-to-block holding bolts on your installation for secureness - NOT bottoming.  A simple way is to try to spin any of the washers.  If any are loose while the bolts seem torqued, the bolt(s) is likely bottomed in the block.  This condition must be corrected!  Remedy by using shorter bolts - cutting .25” from original bolts and re-using is acceptable.

Note - The failed bracket put up with this condition, mounted on a “daily driver”, for an entire year(!) before finally fatiguing, breaking into two pieces - see picture.  Luckily, after breaking, the front bolt still held the front part of the bracket and alternator in place enough to prevent both from being launched through the radiator, or some other equally violent event (although it must have made some gawd-awfull noises). 

Closer inspection shows evidence of galling at engine block mounting bosses behind holes #2 and #3, consistent with long-term vibration allowed by the “loose bracket condition”.  Eventually, this vibration lead to a material fatigue crack.  This crack started at the rectangular pedestal locating hole (nearest stress riser) finally extending all the way through the bracket base.  The pedestal mounting design and weld showed no evidence of weakness or having contributed to the failure.

Conclusion:  Failure was due to installation deficiency.  No bracket change or improvements are called for, however, installation instructions will be amended to further emphasize detection and prevention of the condition which lead to the failure.

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