On Fri, 12 Nov 2010 06:45:28 -0800, Mark Borgerson
wrote:

It looks like the right piece of equipment for the job----however,
I find the washer stack and bolt on the belt-tensioning arm a
bit troublesome. There's an inch or so of lever arm and it looks
like about half an inch of thread into the alternator front plate.
If that front plate is cast aluminum, how long will it be before
that bolt loosens with thermal cycling and vibration?


Good eye, was wondering if anyone would comment on that.

It's not just a washer stack however. At this point it is more of a
custom spacer since the SS washers are firmly stuck to each other with
JB weld.

I understand your point regarding long term stress on the adjusment
tab and bolt. It would certainly be easy enough to get a longer bolt
and put another washer/lock washer/lock nut combo on the other side of
the tab. Good idea.

For a few more boat bucks, you could replace the washer stack with
steel block of the appropriate thickness---perhaps with some filed
'tooth' on each side. Spend a few more bucks and get a bolt
a half inch longer. You might also have clearance for a thin nut
on the front to act as a lock nut.


When you're cranking out 200 amps, there's going to be substantial
load on that bracket.

TINS: Back in the 70's I drove a Chevy Vega with an aluminum
block. That never gave me problems, but I did have an alternator
problem. I was careful with belt tension and kept that bolt tight.
However, the belt kept getting looser. I finally disassembled the
system and found that the bottom of the alternator was pivoted
on a 4" long steel pin through the alternator housing. The housing
had worn away so that the 3/8" hole through the housing was now a
slot about 3/8" wide and over 1/2" long.

I had a similar issue with the alternator mount on our generator (40
hp Yanmar diesel), after about 3,000 hours. The mounting hole went
egg shaped and was virtually impossible to replace since it was part
of a casting on the front of the engine block. My local alternator
shop came up with some SS circular shim stock just the right size for
the mounting bolt. I cleaned up everything with acetone and bedded
the shim stock into the mounting bracket with JB Weld. It has been
working fine now for over 600 hours of run time.