Originally Posted by
Kontact
I wanted to address how exactly these things work, because I think this debate about the screw has something to do with how we understand how they work:
So the question is: When the lever is pushed forward and the clutch Spring tightens, what is supposed to move? Two possibilities:
1. The Spring moves, but the Bushing does not. In this scenario, the mounting screw has been tightened to the point that the Bushing is locked to the Post. The friction then comes from the tightend spring dragging on the outside of the Bushing to counter the derailleur return spring. Upshifts force the Spring to drag on the Bushing.
2. The Spring locks on to the Bushing, and they move together. In this scenario the mounting screw has been tightened to a moderate setting that allows the bushing to swivel around the post, and the friction resistance to the derailleur return spring comes from the tension of the mounting screw pressuring the outer washers and the inner Washer between the Bushing flange and the Post. In this case the clutch Spring is completely static to the Bushing, and all movement comes from the Bushing slipping past the various washers.
I think #2 is the case, because it explains why the Bushing is smooth on the inside rather than fixed to the Post.
Sounds like you've thought this through. Tell me why I should not worry about rotational "friction" being transmitted from 4534/4535 to 3674 to 3670 to 4413, thus unscrewing 3673. I don't think you're missing something -- I am.
Originally Posted by
BertoBerg
Definitely let us know if flushing them out helps.
Well, having been told not to dismantle, I pulled the assemblies off the frame (
and I had already crimped tips on the cables so I did not want to undo that! 
Always do those last on a project!) and, at the ends of the cables, dipped into a cup of WD40 and swished. Then I figured, let technology do the work -- put the shifters and WD40 in a very small pesto jar left over from lunch, stuck that in the ultrasonic cleaner balanced on a TV table (bike is in a stand, so too high to reach the floor with the cables in place) and gave everything about 6 minutes. The WD40 discolored but not opaque black. Reassembled, they feel great. On the stand. Without riding the bike.
Originally Posted by
santa fe 2926
The clamp on Do Not interchange with the frame mounted ones, I.e. they’re French after all. Had one of the springs break, they have a little tiny catch on the end, and that can rust and finally break, releasing the pressure, and you are in the smallest cog (of it’s the rear derailleur).
Thanks for the confirmation. On eBay, plenty of Retrofrictions if it was determined that the ones on this bike are toast, mostly clamp-on but some braze on. Mostly expensive. And how would I know I am not back to square one with worn barrels unless I locate a set of NOS in the box...