Repairing Campy Brake

Before buying a set of taps (expensive) or taking it to a bike shop to
have them chase the threads (cheap), you might go to the local
hardware store and buy some metric steel bolts and use them to chase
the threads (real cheap, like < $2.00.) After all, if you're just
soft aluminum steel looks like a tap to you ...

- Don Gillies
San Diego, CA

"Donald Gillies" wrote: (clip) buy some metric steel bolts and use them to
chase

Quoted message said:

the threads (clip)

^^^^^^^^^^
I agree. Cheaper is sometimes better. A bolt will force the distorted
threads back into shape, while a tap will cut away the bent-out-of-shape
threads. If you can't get a bolt to go through the munged thread, then try
making a hack saw cut across the threads of the bolt, to make it into a
pseudo-tap, and try again.

(Donald Gillies) said:

Before buying a set of taps (expensive) or taking it to a bike shop to
have them chase the threads (cheap), you might go to the local
hardware store and buy some metric steel bolts and use them to chase
the threads (real cheap, like < $2.00.) After all, if you're just
soft aluminum steel looks like a tap to you ...

Thanks. I purchased some M6 and M7 bolts and nuts. I used the bolts
to more or less chase the threads in the nuts, however, one of the
aluminum nuts was cracked so I ended up replacing it with a steel nut.
The real problem was the bolt that clamps the brake to the frame.
It has two sets of threads, M6 on the end and M7 on the shank.
The M7 threads were mangled from the set screw (as I complained before,
that is a rather poor design, using a set screw into threads).
The brake had clearly been readjusted before because there were two
different spots where the threads were misformed from the set-screw
(the brakes came with a bike I purchased used).

Running the steel nut over these threads did not sufficiently straighten
them. Because the hardware store didn't have an M7 die, I used a
different technique. I used a hacksaw to cut a slot in one flat of
a nut, oiled its threads, added some grinding compound, inserted
the screw, slightly squeezed the nut in a vise to close it a bit,
the ran the bad part of the screw in and out through the nut.
That cleaned up the threads enough so that I could now hand tighten
the aluminum nut onto it.

When I reassembled the brake I left out the set screws and just jammed
adjacent nuts together, as is normally done. If that loosens up I'll
try some locktite.

Joe