Ultegra FD pivot screw loosening
 

While prepping our tandem for a ride tomorrow, I noticed that the lower pivot screw on our Ultegra FD, the lower one that's attached to the FD housing, had backed out about 1/4". We would have been down to only 9 speeds. Oh, no! I've found this screw backed out several times on Ultegra (that all I have) FDs, but it never fell out. What to do to prevent that? I assume if it happens to me, it happens to many people. I've been nervous about adding thread locker because I don't want to gum up the working of it and am not sure how exactly to do it. Never had one apart, don't know the "do not do's."

Thanks.

Periodic maintenance is the answer i use. I've seen many of these loosen up and i just re tighten after lubng the pivot surfaces. I haven't seen any I've tightened become loose again, but then i don't track them with any real efforts. I just check each that I see. BTW there are other Shimano models with the same pivot screws that can loosen. Andy.

Here's an old mechanic's trick from the days before threadlockers.

Remove the screw, and use a pair of pliers, or blunt diagonal cutters to slightly distort a pair of threads. It's best to do this on a thread that's among the last to engage, about one turn before the end. This makes the screw need a bit of added force to turn and will usually keep it home against vibration or small torques.

Mine loosen again after I tighten them.

I suppose I should take the FD off the bike and mess with it on the bench. Take it apart and see if I can fix that screw in place one way or another.

I haven't needed to try it but a drop of hot melt glue or rubber cement where the screw enters the threaded hole should immobilize the screw but be easily broken loose if later adjustment is needed.

Francis's suggestion of putting a crimp in the threads is a good one. Just be careful not to distort too much or cut through the bolt. Andy.

Slightly damaging the thread often works, but you want to be as gentle as possible about it, particularly if the bolt screws into an aluminium thread, and it's likely to be removed more than a couple of times ever.

I think it may be a mistake to damage the threads. Instead, go back to the thread locker alternative. As you know, there are different types of "threadlockers". I like Loctite Threadlocker Blue 242. There are some similar ones on the market. As I understand it, the Blue grade is meant to prevent movement due to vibration and shock. You can easily overcome the Blue grade resistance and make required adjustments.