V-brake not moving freely on their pivots
10-22-19, 02:23 PM
#1
Junior Member
Thread Starter
V-brake not moving freely on their pivots
For better or worse, I've used some thread locking compound on the v-brake pivot screws (the ones on the bosses) before mounting them. In fact, maybe I've put a little to much in and they were binding a lot, but it was just about a couple of days. They're quite normal after that and I'd just forget about it.
That happened about 6 months ago. Fast forward to two weekends ago: I was disassembling the bike for a thorough cleaning and maintenance. I do this every 6 months, just in case, as I use it on a daily basis and need it to be as reliable as possible. The v-brake screws in question where hard to remove, as it was expected due to the thread lock, but the brake arms begin binding as soon as I removed the screws. They weren't before and that makes me worry.
I didn't noticed any warping on the bosses. It was only the ones on the left, non drive side of the bike, but I don't know why. I've decided to do some light sanding with 320 grit dry/wet sandpaper, then with 600, then finally with 1200 (a nice smooth surface seems to be better than a rough one, thus the 1200 grit). The situation got a lot better, but they're still binding somewhat and not centering as well as they did before.
For fear of worsening the situation, I didn't put thread lock this time, as it looks like was the initial cause to it. As usual, I've cleaned thoroughly and put some grease around the boss and inner surfaces of the v-brake arms. The bosses are not removable, as this is and old-school steel bike.
My doubts are:
* How can I improve the brake performance?
* Can I sand the bosses without make them weak or prone to vibrations?
* Are thread locking compound on the v-brake pivot screws a bad idea?
Thanks for helping!
That happened about 6 months ago. Fast forward to two weekends ago: I was disassembling the bike for a thorough cleaning and maintenance. I do this every 6 months, just in case, as I use it on a daily basis and need it to be as reliable as possible. The v-brake screws in question where hard to remove, as it was expected due to the thread lock, but the brake arms begin binding as soon as I removed the screws. They weren't before and that makes me worry.
I didn't noticed any warping on the bosses. It was only the ones on the left, non drive side of the bike, but I don't know why. I've decided to do some light sanding with 320 grit dry/wet sandpaper, then with 600, then finally with 1200 (a nice smooth surface seems to be better than a rough one, thus the 1200 grit). The situation got a lot better, but they're still binding somewhat and not centering as well as they did before.
For fear of worsening the situation, I didn't put thread lock this time, as it looks like was the initial cause to it. As usual, I've cleaned thoroughly and put some grease around the boss and inner surfaces of the v-brake arms. The bosses are not removable, as this is and old-school steel bike.
My doubts are:
* How can I improve the brake performance?
* Can I sand the bosses without make them weak or prone to vibrations?
* Are thread locking compound on the v-brake pivot screws a bad idea?
Thanks for helping!
10-22-19, 05:04 PM
#2
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Join Date: Sep 2010
Location: Roswell, GA
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Bikes: '93 Trek 750, '92 Schwinn Crisscross, '93 Mongoose Alta
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I would use/get a digital caliper or micrometer and see whether the ends of the bosses have expanded to a larger diameter than the rest of the boss, or if the very end is "mushroomed" out. I have seen the mushrooming occur and a little work with a fine file has fixed the problem. Otherwise, sand where needed to obtain a uniform diameter and free movement. I doubt that you will remove enough material to weaken them. Then reassemble and leave the cap on the threadlocker; a properly-designed and torqued joint does not normally need it and there are no appreciable forces tending to loosen the screws.
