[Roadsters] Broken bolts

[Gary and Cindy Ault]

Steve,

Define "lower bracket" and "upper bracket".  If you are referring to hole 
tapped into the block, they are almost certainly metric, M10x1.5, I think. 
I recently pulled the alternator mounting bracket off my '67-1/2 2000 to 
install the correct brace which attaches to the timing case.  The PO had 
installed, I think, 5/16 x something SAE bolts, which fit ALMOST correctly. 
Two of the three bolts threaded in and out with no problems.  What tipped me 
to the issue was slight damage to the ends of the threads on one of the 
bolts.  Measured the bolts, and found they were SAE instead of metric. 
Pulled a bolt from my other car, which I know to be correct, and -- M10x1.5. 
Replaced all three bolts.

If you want to wait until out June Mississippi River Run, we can check it 
then.  Otherwise, send further information.  Photos would help.

Your issue is why I will not even consider replacing stock alternator with 
something else.  I now have a couple of spares, one working, one not.  If I 
can get the non-working one rebuilt, I will be REAL hard to convince to do 
anything different.

Gary

----- Original Message ----- 
From: "Steve Harvey" <stebharvey at ameritech.net>
To: <datsun-roadsters at autox.team.net>
Sent: Friday, May 22, 2009 7:58 AM
Subject: [Roadsters] Broken bolts


> Last year I replaced my alternator with a GM and located it in the upper
> right position on the engine. I purchased a Datsun mounting bracket (smog
> pump I think) and attached the new alternator. The lower bracket is tapped
> with 3/8-16 thread and the upper is 5/16-18.  Im using grade 8 bolts for
> both fasteners. In order to align the alternator with the engine pulley I
> made two spacers. The lower position spacer is = long and upper is 2-1/2 
> long. I since the installation last summer I have broken one upper 5/16-18
> bolt and two 3/8-16 bolts. All three broke clean two to three threads from
> the bottom of the thread. When the alternator is properly installed the
> alignment with the engine pulley looks correct and nothing looks out of
> place. Im confused as to what is causing the shearing action on the
> hardened bolts.  Has anyone seen this situation or may have a solution?
>
>
>
> Steve
>
> P.S. Remember a Vet this weekend
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