Bicycle Mechanics - Sticky/Stuck Cantilever Caliper

Hey everyone, I've noticed that some of my old canti caliper arms don't pivot well -- like they're stuck -- after they've been bolted to the brake post. One symptom of the bad ones is a lack of forward/back play in the direction of the bolt once they've been tightened to about 60 in-lb.

Can I restore them by flushing them with penetrating oil or WD40? What part of the mechanism has gone awry? Thanks.

I just had a case with the same symptoms (although not sure if the same cause). In my case, it was just one of the front arms that was really tight - I really had to twist and wrestle it to get it off the stud. Apparently, over time the brake bosses can sort of mushroom out under the pressure of the fixing bolt compressing them. My shop had a small manual mill/cutting tool that slips over the stud like a sleeve and as you twist it and drive it down the stud it mills away a small amount of metal and brings the stud back to size. Again, I'm not sure if my problem is the same as what you are experiencing, but it sounds like it might be just based on the symptoms.

I just had a case with the same symptoms (although not sure if the same cause). In my case, it was just one of the front arms that was really tight - I really had to twist and wrestle it to get it off the stud. Apparently, over time the brake bosses can sort of mushroom out under the pressure of the fixing bolt compressing them. My shop had a small manual mill/cutting tool that slips over the stud like a sleeve and as you twist it and drive it down the stud it mills away a small amount of metal and brings the stud back to size. Again, I'm not sure if my problem is the same as what you are experiencing, but it sounds like it might be just based on the symptoms.

Thanks for the reply. I'm not having any problems with the studs/bosses since I end up just sticking on caliper after caliper until one works. I'm guessing the body/hole of the caliper where the bolt goes through can get warped from over-tightening or something else.

Thanks for the reply. I'm not having any problems with the studs/bosses since I end up just sticking on caliper after caliper until one works. I'm guessing the body/hole of the caliper where the bolt goes through can get warped from over-tightening or something else.

OK - I guess I didn't read carefully enough to understand the nature of the problem you were having. Good luck!!