Cantilever spring pops out of hole on fork
sb88
Posts: 37
OK, so crown race on new fork, new fork on bike.
Re-attach old cantilever brakes, line pad up with rim, check return action and ... pop, the spring on the left hand fork has popped out of the little hole on the tab next to the brake stud that fork it goes in.
Try again, same thing. And again. Don't want to keep trying because every time it pops out the spring scratches the tab with he hole in.
The forks are Surly Big Dummies. Brakes are old Shimano Acera x (c.1997) which worked fine on the previous forks and work fine on the back. They weren't used much despite their age, before I got the bike. There is only one hole for the spring, not the traditional 3. The single hole is the 'middle' position if there were 3.
Basically, with the brake arm on the brake stud and the allen bolt fully tightened to hold it on, the bit of the spring that sticks out to go in the hole spring isn't long enough to stay in there.
The other side is fine - I notice that bits that stick out of the spring to go into the holes on the left hand arm are shorter than the spring on the right, and the springs are seemingly a different colour - the longer one on the right is more a gold colour, while the shorter left hand one is silver.
This is the same on the back brake - one shorter than the other - though that's never been a problem.
What to do!?
Tempted to buy an Avid Shorty / similar, but would like to keep re-using the old components as much as possible - that's kind of the point of this particular bike.
Cheers!
Sb
Re-attach old cantilever brakes, line pad up with rim, check return action and ... pop, the spring on the left hand fork has popped out of the little hole on the tab next to the brake stud that fork it goes in.
Try again, same thing. And again. Don't want to keep trying because every time it pops out the spring scratches the tab with he hole in.
The forks are Surly Big Dummies. Brakes are old Shimano Acera x (c.1997) which worked fine on the previous forks and work fine on the back. They weren't used much despite their age, before I got the bike. There is only one hole for the spring, not the traditional 3. The single hole is the 'middle' position if there were 3.
Basically, with the brake arm on the brake stud and the allen bolt fully tightened to hold it on, the bit of the spring that sticks out to go in the hole spring isn't long enough to stay in there.
The other side is fine - I notice that bits that stick out of the spring to go into the holes on the left hand arm are shorter than the spring on the right, and the springs are seemingly a different colour - the longer one on the right is more a gold colour, while the shorter left hand one is silver.
This is the same on the back brake - one shorter than the other - though that's never been a problem.
What to do!?
Tempted to buy an Avid Shorty / similar, but would like to keep re-using the old components as much as possible - that's kind of the point of this particular bike.
Cheers!
Sb
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Comments
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Sounds like you have an odity set with different springs.
Can you use a washer on the brake arm side behind the spring to push it back towards the fork and increase the engagement? If not you may be able to buy a used pair of normal brakes arms (Shimano) and swap out the springs.Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.0 -
Sounds like you have an odity set with different springs.
Can you use a washer on the brake arm side behind the spring to push it back towards the fork and increase the engagement? If not you may be able to buy a used pair of normal brakes arms (Shimano) and swap out the springs.
That's what I thought (washer) though not inside the brake arm behind the spring, as that could be fiddly and uneven given the contours inside the area the spring sits, but between the allen bolt and the brake arm, to push the whole thing further towards the fork. Even then, if I push the brake arm onto the fork manually as firm as I can, you can see the spring squirming to get out of the hole and nearly popping out, whereas on the other side it goes right through the hole and out the other side...0 -
Have just taken apart a similar-era Shimano Altus canti brake (slightly lower end but quite similar brake) and the springs are the same length as each other - the same length as the shorter spring on the problematic Acera brakes, but they are different colours for some reason (one silver, one gold) perhaps so mechanics don't mix them up? Though it's pretty obvious if you put them on the wrong side as it tensions the brake arm towards the rim, not away from it...
I'm stumped.0 -
Pu a washer in front of the arm and you may lock it up!Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.0
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Pu a washer in front of the arm and you may lock it up!
You're right... though I seem to remember it was possible to lock them up if the allen bolt was tightened fully on the original forks, so I used to tighten it fully, then loosen it a bit, with a bit of thread lock on it.
FWIW, someone on another forum (!) suggested measuring the canti bosses if they were post-2008 as they could be longer. They were right - they are about 1.5mm longer, so the brake arm isn't pushed in very hard. However I still think it's the shorter anchor on the spring that's the problem; the spring on the other side works fine...
Will go to the bike co-op tomorrow and have dig about in their box of bits - rang them and they didn't know what could be wrong.0 -
the brake mounts are generally removable - swap them for the shorter versions?0
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Generally not removable on steel forks.Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.0
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Generally not removable on steel forks.
Am I right in thinking a more modern brake (Avid / Tektro) might fit better then ?0 -
should do0
