Spacer corroded to chainplate rod

[NewToTheRoad]

Hey guys.  Rebedding chainplates and find what seems to be an aluminium spacer corroded to the bar.  It made it quite difficult to unscrew the rod.  The other side was easy and the spacer freely moved up and down the bar.  Has anyone encountered this?  Is it a reaction of dissimilar metals - steel and aluminum? 

Thanks,
Bryan

[Gregory M]

Had the same problem when rebeding mine, only in those where leaking. I guess bit of water helps corrosion. I applied visegrips on spacer, rock back and forth.... loosen ... white powder came of.

[britinusa]

Same thing here.

FYI. before putting them back, I used a felt tip pen to mark the side that was visible when they were correctly oriented, made keeping them correctly oriented while tightening the rod.

Paul

[mdidomenico]

i had the same problem on four of my six rods and it was a real pain the butt to remove them.  two of them popped with a little persuasion.  one of them required vice grips above and below to twist the wedged washer free.  the last i had to resort to a blow torch to expand the aluminum and break it free.  when i reassembled, i slathered everything in lanacote, and i mean slathered, probably too much.  i'm not sure i understand why they're alu, but i suppose it's to provide a little give in the system.  a couple of mine were slightly misshapen.