Spring type thread repairs (Helicoil, Red dot etc) are
common and looking at that link are quite inexpensive.
Problem is the material they are made out of is on the soft side
and the fastener (or in this case the pedal) pulls directly against the
thread insert. During the installation you are enlarging the hole which
in this use weakens the crank arm.
Is anyone familiar with the Eldi repair ,I like the idea of
the solid bushing but is the wall thickness more than 1 mm ?
Advantage a bushing repair has is that your pedal is not pulling
against the thread and the bushing itself adds strength to the arm.
Anyone tried floating more material into the hole and just
retapping?(Aluminum brazing?)
BOB FREITAS
MILL VALLEY, CA USA
disclaimer: I sell Helicoil, Red dot ,Keensert
and Timesert