Need Advice: Down Tube Shifter Alignment Issue

[Classtime]

My left shifter stop is sitting rotated a bit counter clockwise leaving the lever hiding behind the DT and hard to reach. I can deal with it but it would be nice to drop the chain onto the small ring and not be careful to leave the lever within easy reach of my right hand. I’m afraid to remove the shifters from the threaded rod to investigate which may break an irreplaceable part. My current plan is to add a little epoxy putty to build Up the stop and leave the shifter assembly alone. What do you think?

Edit: On my ride to work this morning, I thought that maybe I should modify a fender washer to replace this piece.

 

[black lightning 1987]

My best guess is that "nut" (for lack of a better term) of the boss assembly has somehow backed off, allowing for some side to side slop on the down tube, which has allowed the shifter boss to rotate. The cast bosses can also corrode and break due to corrosion from sweat. I'd recommend taking the whole assembly apart and seeing exactly what the problem is.

 

[Classtime]

My best guess is that "nut" (for lack of a better term) of the boss assembly has somehow backed off, allowing for some side to side slop on the down tube, which has allowed the shifter boss to rotate. The cast bosses can also corrode and break due to corrosion from sweat. I'd recommend taking the whole assembly apart and seeing exactly what the problem is.

This black piece seems to fit nicely against the DT. Is there a pin on the back side that may have broken off? Do I pry it off? Or do I grab the flats of the metal part and back it out? Is there a schematic somewhere?

thanks.
jeff

 

[black lightning 1987]

Your photo shows the side with the "nut". You can use the flats or the hex to remove it. It may just need to be tightened but it's a good idea to check for damage to the other end.

There is a pin on the back side of black piece but it's not very long. So if the nut somehow got loose or the threaded rod broke out of the opposite side, the black plate can be loose enough to rotate.

 

[Classtime]

Thanks for giving me the needed confidence. I backed off the nut enough to rotate the back plate. There was some play and I rotated it to make the square parallel with the DT and tightened everything back up. I'll have a look inside if this doesn't hold for me.

 

[black lightning 1987]

It's the boss on the other side that fails. The part that the steel rod threads into isn't very strong and can break off. Hoping yours is in good shape.