Brake pads fell off

It was time to steal the rear tire off the spare parts bike.
When I pulled the wheel. The drum brake pads fell out.
They'd completely delaminated from the shoes, intact, and fell
off. OK....
I'm disappointed that a perfectly good set of brakes ain't gonna
be useful.

BUT

Now I'm worried about that happening at 60 MPH on the
freeway. Kinda hard to steer when the back wheel ain't
turning and it's on fire.
Being a grease spot on the highway ain't in my long-term
plan.

What would one look for to preempt such a problem?
mike
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Buying new shoes will keep this from happening. Just how long were those
shoes sitting around?

 

Rivetted brake shoes. Of course that means that the amount of availabe
friction lining material available for wear is approximately cut in
half. You have to throw away half your lining every time.

Chemical engineers developed some kind of bonding resin to glue the
friction material to the metal shoe in the 1940's or 1950's. I dunno
perzactly what it is, but it looks dark reddish brown, like some kind
of varnish. I don't even think it was catalyzed epoxy. It might have
been a catalyzed polyester resin.

The brake engineers are relying on the peel strength of the resin to
exceed the frictional drag applied by the rotating drum and I'm sure
they did all kinds of lab tests and came up with a safety factor of two
or three times the maximum drag in order to certify their resin as safe
for bonding whatever material they used to metal.

But, polyester resin will dry out over the years from exposure to heat
and dryness. Epoxies do better than that.

If you have doubts about the strength of bonding materials, consider
this: the pressure vessel that the Apollo astronauts rode to the Moon
and back into the Earth's atmosphere, experiencing 9 g's on
acceleration, and 11 g's on deceleration, was all bonded together by
epoxy glue, and it did not come apart...

 

When I would rivet brake linings, the rule of thumb was to countersink the
holes by 2/3 to 3/4 of the total thickness of the lining. I hated that
task. It sucked rocks. The worst were the brake bands for Cranes. What
kind of cranes? Bucyrus-Erie, Link-Belt, etc. Nasty work.

pierce