[TowerTalk] sheared bolts

Dick Green Dick Green" <dick.green@valley.net
Wed, 27 Jan 1999 12:54:43 -0500

> 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.

Indeed. Seems to me that the right approach would be to determine the proper
torque rating for the bolt/thread combination. Then you could use a torque
wrench to get the bolt tight enough but not too tight. I would imagine that
the bolt characteristics would be readily available, but probably only the
rotor manufacturer has the data for the mating holes. It always irks me that
manufacturers do not supply torque ratings as a matter of course (service
manuals for cars and motorcycles often have such information.)

A great motorcycle mechanic once taught me a way to tighten bolts that he
felt approximates the proper torque without using a torque wrench.
Basically, you have to tighten the bolt very slowly, using as little force
as possible. Relax your hand and arm so that you can feel subtle changes in
resistance as you tighten the bolt. Once the bolt begins to seat, it
gradually gets harder to turn. The change is pretty linear. Then, all of a
sudden, you can feel it getting *much* harder to turn the bolt. This is the
place to stop turning. Another 1/4 turn and you will strip the threads. The
key is to use minimal force to make sure you do not go past the point where
the bolt has snugged. It's a good idea to practice this technique with
various bolt and metal combinations until you get the feel for it.

73, Dick, WC1M

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