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I was checking the brake pads on my bicycle and I noticed one of the arms seems to be seized:

Seized arm

It's this arm (I hope that's the right technical term). It will move but it's very stiff and when I use the brakes the other arm is doing all the work.

I did a search of the site and this seems a common problem but I couldn't find a simple explanation of how to fix it. Do I just undo the hex bolt at the end, apply grease and hope I can put it all back together? If so are there any I wish I hadn't done that pitfalls to avoid?

If it's relevant this is a town bike, a hybrid, rather than a true mountain bike so it's not a performance machine.

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    Release the cable. Throw away the useless rubber boot. Unscrew the pivot bolt and work the arm off it's post. Use some fine steel wool and oil or spray lube to clean off all the rust and grime, including inside the bushing that fits over the post. Apply a tiny bit of bearing lube to the inside of the bushing and put it back onto the post. Reinstall pivot bolt. Make sure the arm now swings freely. Inspect cable and make sure it moves freely -- replace if needed. Spray some lube into the "noodle". Reconnect cable and adjust. – Daniel R Hicks Jan 4 '17 at 18:49
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    @RoboKaren When working the review queue you can't see the answers, only the comments. So its easy to comment without knowing what others have answered. – Criggie Jan 4 '17 at 20:16
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    @compton: thanks. I've been oiling the pivot for the last two days but is hasn't freed up much (it has improved a little). I think I'm going to have to tale the arm completely off. – John Rennie Jan 8 '17 at 6:04
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    @compton You can often rebraid the wire just enough using pliers. Or see the problem beforehand, and use solder+iron to tie it all together before removal. Or just fit a new inner cable - they're cheap and should be replaced periodically anyway. Bonus marks if you solder a new brake inner cable. – Criggie Jan 8 '17 at 6:42
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    All done, thanks everyone. I did have to take the arm off, but it was all pretty straightforward in the end :-) – John Rennie Jan 8 '17 at 16:34
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V-brakes aren't too complicated but there are a few things to watch out for:

  • you need quite a lot of torque to undo the bolt
  • the spring may make it fall apart sooner than you expect - hold on as you undo
  • make sure all the parts go back in the right order - take care as you dismantle. Work with a tray underneath to catch anything that falls.

Once you've taken it to bits, clean all the muck and loose rust off the parts, the grease and reassemble. The bolt should be tight. You'll probably need to do the other arm as well, and may need to adjust the return spring screws. Obviously don't get grease or greasy hands on the pads.

  • Thanks Chris. RoboKaren warns me that letting the spring come off might be one of those I wish I hadn't done that moments. What's your view on that? – John Rennie Jan 4 '17 at 20:25
  • RoboKaren has a good point, but I think you might have to -- by all means try their approach first. In between the two suggestions, you could try backing off the screw a turn or two to get some penetrating oil right in there (e.g. chain oil). – Chris H Jan 4 '17 at 20:27
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Your brake pads are worn down. As a result, you've had to cinch down on the brake cable so much that there's almost no brake movement possible.

  1. The first thing you need to do is get new brake pads.

  2. Then release the brake cable by unscrewing the hex bolt on the very top of your stuck arm.

  3. When you release the brake cable, the brake arm should rotate outwards. Use this opportunity to try to loosen it up by shooting in some WD-40 to flush the rust/grit and rotating it in and out a few dozen times until it's loose. Once it's loose, you might want a final shot of a telfon lubricant as WD-40 dries up.

  4. Then replace the pads on both sides.

  5. Then put the brake cable onto the hex nut from #1. You'll notice that you will have to give it much more cable than previously.

  6. Then look at various youtube videos for final adjustment.

I warn against trying to remove the brake arm itself from the frame. There's a spring that keeps tension against the frame and when that goes sproing, it's a bit of a pain getting it back on.

Now there's a good chance that your brake spring itself has broken/stuck and in that case, you have to replace the entire brake assembly. The good news is that you have relatively inexpensive brakes. The bad news is that it's just a bit fiddly to get the springs in properly to get the tension you want.

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    The brake pad's not that badly worn. – Daniel R Hicks Jan 4 '17 at 18:45
  • Or rather (also @DanielRHicks) it might not be that worn. I've seen some that look like that new, others would be completely shot at that point. – Chris H Jan 4 '17 at 18:49
  • Look at where his brake cable is. It's cinched up all the way - the boot is totally scrunched up. At this point he has maybe 3 mm of arm travel. – RoboKaren Jan 4 '17 at 19:10
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    Thanks. The pads aren't completely worn down, or at least there is still some pattern on them, but I was planning to replace the pads - in fact I ordered the replacements yesterday. I note that you advise me not to try and remove the arm while Chris says to go ahead and remove it. I suspect you have the better judgement of my mechanical skills :-) – John Rennie Jan 4 '17 at 20:20
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    @Paul: the pad isn't fouling on anything. It's just very stiff. – John Rennie Jan 4 '17 at 20:23
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Chris H's answer pretty much nailed it, but I'd like to add an answer to capture useful points made in the comments.

The job turned out to be really simple and the only tools needed were an allen key and a piece of old pipe. I tried getting penetrating oil into the bush without taking off the arm, but after two days it had little effect so I had to take the arm off.

As Chris said, the bolt was really, really tight. In the end I put a piece of pipe over the end of the allen key and the extra leverage did the trick. Getting the arm off the pivot was a bit hard, but I just wiggled it to and fro whilst pulling for about five minutes and it eventually came off. It didn't any great force, just a lot of patience.

On my bike the spring is secured to the back of the arm so nothing dropped off or came apart when I took the arm off.

Compton warned me to check which of the three holes the spring was attached to, but of course the spring came free before I could check. However it was obvious which hole the pin on the spring needed to go in as trying the other two holes made the spring tension obviously wrong.

And that's all there was to it. I rubbed the pivot clean with some wire wool. I didn't have a tool to get at the inside of the bush in the arm so I just pulled a cloth through it to clean it as much as I could. I put a small amount of lithium grease on the pivot, refitted them and it now works perfectly.

  • Good summary of the added information in the comments, thanks for taking the time to collate these. – gschenk Jan 10 '17 at 20:55

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