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Old 01-16-14, 09:30 PM   #1
hoyc
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Mis-Aligned Canti Brake Arm

Hi all,

On my mid-80's touring bike, I'm having some trouble getting the brakes set up. They are old-style, wide profile cantis, with post-style brake pads. One of the rear brake pads is always out of alignment, as if it has too much toe in. Since they are the post style brake pads, I don't have any adjustment to correct for this. I'm getting extremely premature wear on the one brake pad, and I can't get it set up as close as I'd like to the rim.

Is this the nature of the beast? or do I have something wrong here? Is there any way to adjust it or bend it back?

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Old 01-16-14, 10:41 PM   #2
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A few comments- First you can try a more current canti which has a pad angle adjusting design. Second the canti box looks to be a sheet metal base with a turned post shaft peened and (hopefully) brazed into this base. It is very possible that the shaft and/or the base has been bent/distorted off parallel (to the rim). If the shaft is well joined to the base (repeat IF) a bending force applied to the shaft might set it back to parallel. Third the shaft might have come loose from the base and is now loose (the worse situation IMO).

If you try to bend the shaft back and it breaks off or loose then the next step is to remove it completely from the base and use a repair canti shaft kit. This is when a pro is the best choice. Some one who has done this before. Actually I'd consult that person before any attempts to bend the shaft back.

And I'd try a cantilever with angle adjustment before any thoughts of bending. Andy.
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Old 01-16-14, 10:54 PM   #3
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Since they are the post style brake pads, I don't have any adjustment to correct for this.
You should. What brakes are these?
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Old 01-16-14, 11:15 PM   #4
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A few comments- First you can try a more current canti which has a pad angle adjusting design. Second the canti box looks to be a sheet metal base with a turned post shaft peened and (hopefully) brazed into this base. It is very possible that the shaft and/or the base has been bent/distorted off parallel (to the rim). If the shaft is well joined to the base (repeat IF) a bending force applied to the shaft might set it back to parallel. Third the shaft might have come loose from the base and is now loose (the worse situation IMO).

If you try to bend the shaft back and it breaks off or loose then the next step is to remove it completely from the base and use a repair canti shaft kit. This is when a pro is the best choice. Some one who has done this before. Actually I'd consult that person before any attempts to bend the shaft back.

And I'd try a cantilever with angle adjustment before any thoughts of bending. Andy.
Unfortunately, I don't think my canti studs are compatible with new cantilever brakes, as the spacing is only 65mm in the rear.

What would be the best approach to bend the stud? I'd imagine I only have to shift it a few degrees for it to be even.
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Old 01-16-14, 11:18 PM   #5
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You should. What brakes are these?
They look exactly like these. I don't see how I can adjust for toe-in, unless I am missing something obvious.
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Old 01-17-14, 12:00 AM   #6
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I had this exact same problem, at least in looks. I basically just loosened the bolt, and there was enough wiggle room to align it with the rim. Held it straight as I tightened the bolt, and so far so good.
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Old 01-17-14, 12:04 AM   #7
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They look exactly like these. I don't see how I can adjust for toe-in, unless I am missing something obvious.
The obvious that you may be missing is the post holder having a spherical back where it enters the brake arm. That would allow the shoe angle to be corrected.

The narrow stud separation shouldn't be an issue if the rims aren't especially wide. That's most true with post mounted shoes which offer lots of room for adjustment.

As Andrew mentioned, the box area of the stud can be bent to proper alignment with some brute force, but it takes experience to "read" how much they'll put up with before cracking.
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Old 01-17-14, 09:51 AM   #8
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Francis is possibly correct in that your canti's might be missing the spherical washer that the ball and socket angle adjusting feature is dependent on. The DC cantis shown do have this angle feature. Here are tow shots of Shimano cantis that i have found to work on narrow spaced canti shafts. The green bike's are MT60 or MT62 series and the blue bike's are an older series MC70. The MT60/62 also have one side's spring adjustable for tension, allowing some centering without back bending the spring.

The amount of off angle that your one side has is a lot. Whether an angle adjusting canti will get the pad flat w/o any shaft/base bending is yet to be discovered. But since this method is only a small cost and effort and doesn't have the consequence of frame damage it makes sense to try this first.

These cantis are offered on EBay routinely enough. I have one set of the MT62 in black that i would sell too. Andy.


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Old 01-17-14, 10:20 AM   #9
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The post-boss on the frame may be bent..
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Old 01-17-14, 10:54 AM   #10
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Francis is possibly correct in that your canti's might be missing the spherical washer that the ball and socket angle adjusting feature is dependent on. The DC cantis shown do have this angle feature. Here are tow shots of Shimano cantis that i have found to work on narrow spaced canti shafts. The green bike's are MT60 or MT62 series and the blue bike's are an older series MC70. The MT60/62 also have one side's spring adjustable for tension, allowing some centering without back bending the spring.

The amount of off angle that your one side has is a lot. Whether an angle adjusting canti will get the pad flat w/o any shaft/base bending is yet to be discovered. But since this method is only a small cost and effort and doesn't have the consequence of frame damage it makes sense to try this first.

These cantis are offered on EBay routinely enough. I have one set of the MT62 in black that i would sell too. Andy.

Hi, I can't be certain, since I'm at work right now, But I'm fairly sure I do not have spherical washers. If I'm correct, they would it be located where the red arrow is in the photo below? I was under the impression that older "post-type" canti's didn't have this type of adjustment.
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Old 01-17-14, 11:02 AM   #11
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When I built my own frame , in '75, with Mafac cantilever brakes a traditional type
with out a lot of adjustment, .. precisely where I mounted the frame boss was the adjustment..


You may be ready to just buy a new set of cantilever calipers ..

since spare parts of those are not available , other than the auction gamble..

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Old 01-17-14, 11:58 AM   #12
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Hi, I can't be certain, since I'm at work right now, But I'm fairly sure I do not have spherical washers. If I'm correct, they would it be located where the red arrow is in the photo below? I was under the impression that older "post-type" canti's didn't have this type of adjustment.
IME the older brakes all had angle adjustments. You can know for sure by looking at the face where the post is laying across. I suspect you'll find it's concave, and made to accept a convex washer under the post. (see it here right next to the shoe holder bolt).

If that's the case, you might find a pair at a co-op, but I suspect you'll need to buy brakes.
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Old 01-17-14, 11:59 AM   #13
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Originally Posted by hoyc View Post
Hi, I can't be certain, since I'm at work right now, But I'm fairly sure I do not have spherical washers. If I'm correct, they would it be located where the red arrow is in the photo below? I was under the impression that older "post-type" canti's didn't have this type of adjustment.
they absolutely did have toe in adjustments

if you look at the bottom of the washer visible in the photo
there is a tab pointing straight down

that washer is inclined so when it is rotated
the toe in on the brake changes
and a curved or sperical washer is usually found on the back
so that the nut can be tightened at differnet angles

the tab on the washer gives you something to push against to rotate the washer whn the nut is loosened
and also provides a visible cue as to the orientation of the washer

the only cantis i know of that did not have a proper toe in adjustment were the two plate mafac types
and the toe in on these was adjusted with a pair of channel lock pliers
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Old 01-17-14, 01:19 PM   #14
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.....and the toe in on these was adjusted with a pair of channel lock pliers
Anyone remember the Park BT-3 brake caliper alignment tool? It was a handle with a slotted end that went over the caliper arms and bent them into alignment. It looked a bit like the Park tool currently sold to align disc brake rotors but was much stronger. I have one and still remember wincing the first time I used it on old Dia Compe brakes before concave washers were provided on brake shoes. It was a crude approach but it worked.
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Old 01-17-14, 01:34 PM   #15
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Anyone remember the Park BT-3 brake caliper alignment tool? It was a handle with a slotted end that went over the caliper arms and bent them into alignment. It looked a bit like the Park tool currently sold to align disc brake rotors but was much stronger. I have one and still remember wincing the first time I used it on old Dia Compe brakes before concave washers were provided on brake shoes. It was a crude approach but it worked.
Not suitable for this because the arm is too short and stiff. The boss itself can b corrected (if it's off) but I'm sure the brake has an adjustment built in.
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Old 01-17-14, 02:56 PM   #16
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Hi, I can't be certain, since I'm at work right now, But I'm fairly sure I do not have spherical washers. If I'm correct, they would it be located where the red arrow is in the photo below? I was under the impression that older "post-type" canti's didn't have this type of adjustment.
The arrow points to the slanted washer. If you don't have it, then those Dia-compe 960's are impossible to align. They weren't easy to begin with.

But it looks from the pictures that the brake pad comes off at a different angle than the post, so I bet you just need to loosen the nut and rotate the washer around so the pad contacts the rim correctly.
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Old 01-17-14, 03:01 PM   #17
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BT3 was OK with old , non U, centerpull brakes .. soft aluminum , not too thick ..
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Old 01-17-14, 06:10 PM   #18
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Not suitable for this because the arm is too short and stiff.
Sure, I know that but I was just reminiscing prompted by Wilfred's mentioning Channel Locks to align brake arms.
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Old 01-17-14, 08:26 PM   #19
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Thanks for everyone's help. I did indeed just have to adjust the washers. I had to loosen the nut all the way as the concave washers were a bit "stuck" in place, which may be why I never noticed them before. Phew! I'm just glad I didn't have to knacker around with bending any braze-ones.
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Old 01-19-14, 12:23 AM   #20
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Anyone remember the Park BT-3 brake caliper alignment tool? It was a handle with a slotted end that went over the caliper arms and bent them into alignment. It looked a bit like the Park tool currently sold to align disc brake rotors but was much stronger. I have one and still remember wincing the first time I used it on old Dia Compe brakes before concave washers were provided on brake shoes. It was a crude approach but it worked.
Sure do and I still use it often. We get a lot of old bikes at the shop.
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