Originally Posted by
BluesDaddy
The only potential problem with metal caps is that they can bond to the aluminum crank arm in the same way as a stuck seatpost or stem. I had a 1984 Trek 620 given to me, and since it was missing a wheel and the Helicomatic hub was dead, I decided to part it out. One of the metal caps was absolutely welded to the crank. It took very careful cutting and grinding with a rotary tool to weaken the cap enough to peel it out without ruining the extractor threads. If you do use metal caps, put on some Permatex or grease.
POSI-LUTELY! Never ever mate steel and aluminum without something in between.
Of course if the PO failed at that, the upside here is that caps are a heck of a lot easier to remove than a galvanically-welded seat-post.