Hi Gerry,
Your getting good advice on removing bolts, just be gentle and DON'T break
a drill bit or easyout off in the bolt!!!! You haven't had trouble until
you have a hardened steel toll broken off and stuck in the middle of a bolt
in a soft case!
Just from my experience with race cars and towers, three things probably
caused the busted bolts:
1.) Too much torque applied to the bolt when installed, putting too much
preload on the bolt. That's unlikely because the case of the rotor should
strip before a GOOD grade bolt fails.
I used to work with a tower guy who constantly complained about weird
mechanical failures. His Harley would have parts fall off, and he would
always have connectors fail after installing them. One day he pulled up and
said his alternator just "fell off" his Camero. Turns out he was
over-tightening all the bolts, the more they would fail the tighter he
would tighten them. Endless loop. Far too many of us (i.e. "Quick Change
Oil places) over-tighten bolts as a way of life, because we are worried
about them falling out.
2.) A bolt that is underrated for the load. What marking are on the bolt
heads, or where did they come from? What grade and type are they?
3.) Too much load on SOME bolts. In other words, one or two bolts under
tension while the rest are in compression. Maybe something off center or
just too little mast between the rotor and tower-top bearing compared to
mast length between the antenna and bearing.
I think even with loose bolts, a good grade of bolt wouldn't break. They
might fall out, but I doubt they would ever shear. A good bolt would be
harder than either the rotor mounting plate or the rotor. They would
probably wallow out the hole or pull the threads out of the rotor long
before killing the bolt.
I'd bet on cheap bolts or improper installation.
73 Tom
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