I have done this conversion with a Helicoil, and consider it a decent engineering solution. The key is that the helicoil goes into new threads cut into the crank; it doesn't just cross-thread the existing ones. I suspect that it is actually stronger than the original, since the helicoil has more contact area with the crank body than the original pedal thread did. I would not hesitate to do it again, and keep helicoils and their special taps in my collection of goodies. There is one issue, though: having a drill press or equivalent to jig it up perpendicular, so you don't get a nicely tilted pedal! harvey sachs mcLean va ++++++++++++++++++++++++++
At 3/6/2005 08:50 PM -0800, Gonzalez wrote:
>>Has anyone in the group ever converted a right side crank to a left hand thread for a tandem timing crank? I have heard of using a Helicoil to do this but have never used one.
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To which Mark replied:
For years, tandem builder Terry Osell has just been running an LH thread tap through the RH threads. With the 1st set he did, he put a cheater bar on a pedal wrench and couldn't strip out the threads by overtightening. He's sold quite a few and hasn't had a failure yet.
And Greg Parker said: Ouch! As a bona fide nerd Engineer, I wouldn't recommend that. There's no "meat" left in the threads after doing that.... While it may work under some conditions for some period of time, it sounds risky to me, long term. Seems far better (to me) to get the properly threaded cranks, or reverse the pedal spindles, or use symmetrical pedals, or do just about anything but run a LH tap though a RH female aluminum thread (or vice-versa, for that matter)