snapped brake boss/pivot on fork

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lvabd
Posts: 39
Joined: 3 Mar 2018, 4:44pm

snapped brake boss/pivot on fork

Postby lvabd » 28 Oct 2018, 7:53am

hi!

I have snapped the brake boss/pivot on the fork (see pic).

Any idea how to get that out , if at all possible? I don't know if it is welded in the fork or brazed on, and can't access it from the other side of the fork tube.

Background info
It's a Surly Long Haul Trucker, 2.5 years old.
No, I really didn't use much force at all: I have changed calipers on bikes many many times, I was using a hand screw driver, and was going perfectly easy on it.

Yes I am aware I could drop it at a frame builder's, or buy a new fork: each of those solutions would cost me 70-100£, so I would much rather try before.

thanks a lot!
Image Attachments
photo (3).JPG

9494arnold
Posts: 872
Joined: 21 Jan 2007, 3:13pm

Re: snapped brake boss/pivot on fork

Postby 9494arnold » 28 Oct 2018, 8:16am

It's not good news I am afraid. The brake pivot is (usually) a one piece affair which is brazed onto the fork. Which is what you have there. And half of it is still brazed to your fork. Some forks do allow just the pivot to be replaced but not the ones you have there (I don't think). You MIGHT get away with cannibalising another brake pivot and glueing or brazing back on (which would compromise the paint) BUT do you really want to take that risk with brakes?
If you want to save money, suggest some cheap secondhand forks (Wanted ad in this forum, Local Bike Recyclers, E Bay, Local Council recycling centre)
Last edited by 9494arnold on 28 Oct 2018, 8:20am, edited 2 times in total.

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foxyrider
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Location: Sheffield, South Yorkshire

Re: snapped brake boss/pivot on fork

Postby foxyrider » 28 Oct 2018, 8:19am

Is the pivot bolt in the pic stuck?
Convention? what's that then?
Airnimal Chameleon touring, Orbit Pro hack, Orbit Photon audax, Focus Mares AX tour, Peugeot Carbon sportive, Owen Blower vintage race - all running Tulio's finest!

PH
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Joined: 21 Jan 2007, 12:31am
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Re: snapped brake boss/pivot on fork

Postby PH » 28 Oct 2018, 8:20am

I'd say probably not removable, some are but it's usually on bikes that have the option of more than one brake type. I had the same break on my tourer (Crash damage) and it had to go back to the frame builder.
My first port of call would be the dealer you bought it from, it shouldn't have broken in the way you describe.
If you have no joy with that, you might find a s/h one that fits - I just happen to have one for sale :wink: Details below, it looks like it's be a good match but I haven't checked the Surly spec.
https://yacf.co.uk/forum/index.php?topic=108331.msg2293985#msg2293985

iandusud
Posts: 198
Joined: 26 Mar 2018, 1:35pm

Re: snapped brake boss/pivot on fork

Postby iandusud » 28 Oct 2018, 8:32am

If the broken pivot is cut cut flush with the boss and the boss can be tapped with an M10 thread, then you could fit a screw in boss likes these.
https://www.amazon.co.uk/Homyl-V-Brake- ... B07BRL3MWH
The only problem is that it would sit further forward than the one on the other side, so you would probably have to do both.
However I imagine that the boss is hollow, which would preclude tapping it in which case another solution might be to weld or braze (if you have access to such kit) a screw in boss in place, which would be less fiddly than removing the existing boss and replacing it.

Ian

lvabd
Posts: 39
Joined: 3 Mar 2018, 4:44pm

Re: snapped brake boss/pivot on fork

Postby lvabd » 28 Oct 2018, 8:34am

9494arnold wrote:It's not good news I am afraid. The brake pivot is (usually) a one piece affair which is brazed onto the fork. Which is what you have there. And half of it is still brazed to your fork. Some forks do allow just the pivot to be replaced but not the ones you have there (I don't think). You MIGHT get away with cannibalising another brake pivot and glueing or brazing back on (which would compromise the paint) BUT do you really want to take that risk with brakes?
If you want to save money, suggest some cheap secondhand forks (Wanted ad in this forum, Local Bike Recyclers, E Bay, Local Council recycling centre)



Thanks a lot

I was hoping this one was removable :(

cheap secondhand forks and work-around tricks are not an option: I am leaving for a 6 Mo loaded tour in central Asia, so I don't want to try my luck

lvabd
Posts: 39
Joined: 3 Mar 2018, 4:44pm

Re: snapped brake boss/pivot on fork

Postby lvabd » 28 Oct 2018, 8:35am

foxyrider wrote:Is the pivot bolt in the pic stuck?



No the bold is fine, I just leave it there so that the pivot doesn't change shape

lvabd
Posts: 39
Joined: 3 Mar 2018, 4:44pm

Re: snapped brake boss/pivot on fork

Postby lvabd » 28 Oct 2018, 8:37am

PH wrote:I'd say probably not removable, some are but it's usually on bikes that have the option of more than one brake type. I had the same break on my tourer (Crash damage) and it had to go back to the frame builder.
My first port of call would be the dealer you bought it from, it shouldn't have broken in the way you describe.
If you have no joy with that, you might find a s/h one that fits - I just happen to have one for sale :wink: Details below, it looks like it's be a good match but I haven't checked the Surly spec.
https://yacf.co.uk/forum/index.php?topic=108331.msg2293985#msg2293985



thanks for your answer

yes I think I will try with the dealer, but I have 0 hope with them

thanks for the fork link, but the LHT fork is quite specific for touring, rake is huge, braze on for front rack, and I need a long steerer.... but thanks

lvabd
Posts: 39
Joined: 3 Mar 2018, 4:44pm

Re: snapped brake boss/pivot on fork

Postby lvabd » 28 Oct 2018, 8:39am

iandusud wrote:If the broken pivot is cut cut flush with the boss and the boss can be tapped with an M10 thread, then you could fit a screw in boss likes these.
https://www.amazon.co.uk/Homyl-V-Brake- ... B07BRL3MWH
The only problem is that it would sit further forward than the one on the other side, so you would probably have to do both.
However I imagine that the boss is hollow, which would preclude tapping it in which case another solution might be to weld or braze (if you have access to such kit) a screw in boss in place, which would be less fiddly than removing the existing boss and replacing it.

Ian



thanks a lot for the suggestion

I would like to avoid work-around solutions, as the warranty might be compromised eventually, and I am soon leaving for a long loaded tour in central asia, so anything not really sturdy is not quite an option

PH
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Re: snapped brake boss/pivot on fork

Postby PH » 28 Oct 2018, 8:51am

lvabd wrote:thanks for the fork link, but the LHT fork is quite specific for touring, rake is huge, braze on for front rack, and I need a long steerer.... but thanks

You're welcome, though if it's a 700C fork you'll find the spec almost identical, same 45mm offset, mounts for low riders, same height.... I checked as your reply puzzled me (Maybe because you have the 26" version) and they came off a bike with almost identical geometry to a 700C LHT.

Brucey
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Re: snapped brake boss/pivot on fork

Postby Brucey » 28 Oct 2018, 8:52am

on some forks the boss unscrews so that everything forwards of the plate with three holes in comes off. You can identify such forks because the shoulder at the base of the boss has two flats on it. I'll be honest I don't think your forks are like that, but do check to be sure.

replacement pivot bosses look like this
Image
https://www.sjscycles.co.uk/brakes/m10-d2o-vbrake-pivot-screw-each/

and are available with different threading. M8 and M10 are common thread sizes but there are others beyond this.

There is a 'problem solvers' repair piece that can be used in some cases

https://www.sjscycles.co.uk/brakes/problem-solvers-canti-repair-kit/

but I note that this is recommended for frame bosses (i.e. rear brakes) rather than front brakes.

Breakages if the sort you have are fairly uncommon; the only ones I have seen are where the brake has an integral pivot and the mounting bolt is simply overtightened; the tension in the bolt is also imposed on the base of the boss. It is easy to generate a load of at least a tonne on the boss this way, for which it was never designed. Of course the boss could fail at a much lower load if it was flawed or already damaged in some way.

If the boss is not removable type other repair options include drilling and tapping to make the boss a removable fitting, or welding a repair piece to the boss. On the latter point I would recommend welding a solid piece onto the remains of the old boss, which is machined to have a male M6 stud at the front. The brake arm would be secured using a (threadlocked) domed nut rather than a screw.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

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foxyrider
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Location: Sheffield, South Yorkshire

Re: snapped brake boss/pivot on fork

Postby foxyrider » 28 Oct 2018, 8:57am

lvabd wrote:
foxyrider wrote:Is the pivot bolt in the pic stuck?



No the bold is fine, I just leave it there so that the pivot doesn't change shape


Not sure how it would change shape but anyway.

Personally, given what others have said about this particular fork having an integral pivot boss arrangement. I'd be beating down the door of the nearest frame builder to get it sorted out. You are going on a long trip, get it fixed properly, yes its going to cost but better spent now than on your trip.
Convention? what's that then?
Airnimal Chameleon touring, Orbit Pro hack, Orbit Photon audax, Focus Mares AX tour, Peugeot Carbon sportive, Owen Blower vintage race - all running Tulio's finest!

lvabd
Posts: 39
Joined: 3 Mar 2018, 4:44pm

Re: snapped brake boss/pivot on fork

Postby lvabd » 28 Oct 2018, 9:01am

Brucey wrote:on some forks the boss unscrews so that everything forwards of the plate with three holes in comes off. You can identify such forks because the shoulder at the base of the boss has two flats on it. I'll be honest I don't think your forks are like that, but do check to be sure.

replacement pivot bosses look like this
Image
https://www.sjscycles.co.uk/brakes/m10-d2o-vbrake-pivot-screw-each/

and are available with different threading. M8 and M10 are common thread sizes but there are others beyond this.

There is a 'problem solvers' repair piece that can be used in some cases

https://www.sjscycles.co.uk/brakes/problem-solvers-canti-repair-kit/

but I note that this is recommended for frame bosses (i.e. rear brakes) rather than front brakes.

Breakages if the sort you have are fairly uncommon; the only ones I have seen are where the brake has an integral pivot and the mounting bolt is simply overtightened; the tension in the bolt is also imposed on the base of the boss. It is easy to generate a load of at least a tonne on the boss this way, for which it was never designed. Of course the boss could fail at a much lower load if it was flawed or already damaged in some way.

If the boss is not removable type other repair options include drilling and tapping to make the boss a removable fitting, or welding a repair piece to the boss. On the latter point I would recommend welding a solid piece onto the remains of the old boss, which is machined to have a male M6 stud at the front. The brake arm would be secured using a (threadlocked) domed nut rather than a screw.

cheers



thanks a lot Brucey for the thorough information

not there are no flat bits on the boss, so from your post I conclude I have the unremovable type (question is: why does Surly fit its frameset with this old fashion type of boss???)

Now I am a little bit tempted by the drilling and taping (contrary to my previous answers), at least for the reason that if it happens again, I can fix the boss by replacing it. Do you think this is a risky procedure? don't I risk to damage the fork so that it will be "weaker" and snap in the future?

lvabd
Posts: 39
Joined: 3 Mar 2018, 4:44pm

Re: snapped brake boss/pivot on fork

Postby lvabd » 28 Oct 2018, 9:14am

foxyrider wrote:
lvabd wrote:
foxyrider wrote:Is the pivot bolt in the pic stuck?



No the bold is fine, I just leave it there so that the pivot doesn't change shape


Not sure how it would change shape but anyway.

Personally, given what others have said about this particular fork having an integral pivot boss arrangement. I'd be beating down the door of the nearest frame builder to get it sorted out. You are going on a long trip, get it fixed properly, yes its going to cost but better spent now than on your trip.


I tried to grab the boss with strong pliers in an attempt to unscrew it (my LBS suggested that...), so I put an old bolt in it so at least it wouldn't get crushed by the pliers. Didn't work anyway (seems now that it's not screwed in the fork)

Living in Scotland the nearest framebuilder is 3 hours drive. A new fork is 80 £, at this stage I'd rather get a new fork. However Brucey, below, suggested drilling and taping it: I am quite tempted, as it would be cheap and long term solution, is the fork doesn't risk to be dammaged on the way....

Eman Resu
Posts: 107
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Re: snapped brake boss/pivot on fork

Postby Eman Resu » 28 Oct 2018, 9:34am

Another option would be to use a 75mm drop nutted brake caliper such as the Dia Compe 806 .. available for a paltry 16.99 from SJS ... fixed via the central mudguard hole. I have used this on a steel touring fork and it works well.