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I installed new V-type brakes on my bike, which is the same type of brakes as it previously had. When I tighten the single bolt that holds the brake arm, the arm does not spring back. If the bolt is loose, like barely finger tight, it will spring back fine, but then starts to unthread itself when I ride around for a few minutes. That's obviously dangerous and not going to work.

This is the brake arm I am referring to:

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Another site showed putting grease on it which I did but there was no change. I don't see what else to do and it seems ridiculous that any pressure on this bolt would stop the lever from moving.

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    Can you upload a picture or 2, ideally with the bolt undone? I have an idea relating to doing up the fixing bolt deforming the body, but I could easily be wrong
    – Chris H
    Commented Sep 20, 2023 at 18:43
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    Really appreciate your help. Sorry that's a bit blurry my phone camera is damaged, but hopefully you get the idea. So when that large silver bolt in the bottom is lose it goes back and forth fine, and when you just start to make it snug it locks up. I'd think the lever would roll independently of this and tightening the bolt, especially barely tight, wouldn't influence it.
    – GeoK
    Commented Sep 20, 2023 at 21:10
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    Huge thanks to both of you, I will try this soon and let you know. I should also note the other side works fine after replacing it, and I never did anything special with it. I'll post what happens, but what was suggested makes sense.
    – GeoK
    Commented Sep 21, 2023 at 19:48

3 Answers 3

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Turns out it was the brakes themselves that were the issue. These were brand new, but after tons of playing around with them trying to get them to spring back and forth I broke one of the pins that seats into the bike itself. I ordered replacements and the new ones did the same exact thing. Finally I ordered a pair of v-brakes from Shimano, and within 30 seconds I had them installed and working perfectly without issue.

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    Nice spotting! Can you share the brand of the originals? Also, do click the small tick/check box on the left hand side to select an answer as "Accepted"
    – Criggie ♦
    Commented Sep 28, 2023 at 3:01
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    Yes these were Boao brakes. I technically had three sets and all three did the same, one for front and back, and the front that I replaced.
    – GeoK
    Commented Oct 6, 2023 at 19:58
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If the V brake arm isn't springing back on its post, it's probably not going all the way onto the post. Then the screw presses against the arm. So you need to find what's stopping it going all the way on.

Greasing or oiling that interface is good, but cleaning it up first is necessary. You may even have to sand down or take off a bit of paint if it starts to come up the post (this will be hidden inside the brake arm). I've had to do that before. Because there's normally a bushing in there, you may be able to press the arm onto the post, then release the pressure. You could use the mounting screw with a big washer under the head as a press, then remove the washer and refit the screw.

Do also check, perhaps by comparing to a known good one, that all spacers and washers are in the right place. Also adjust the spring tension to the maximum as a troubleshooting step, hopefully restoring its position later. As well as the adjustment screw, you generally have a choice of three holes to engage the spring

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I would assemble the brakes without the spring, bolt the arm in firmly, and check if it can move freely. If not, as stated above, you need to make sure the post is clean and then, carefully keeping it perpendicular, shave the end of the arm bushing, A second reason might be the large MA of a V-brake makes any friction in the cable more forceful. This needs to be countered by the arm spring. Looks like you have plenty of threads in the adjustment screw to add some spring tension.

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