Broken Front Brake



Arathald

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Jul 27, 2005
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So, I was tightening a nut on my cheap GMC Denali bike, and the bolt that holds the front brake on sheared off (no, I wasn't over-torquing it, it took virtually no effort for it to shear). The bolt has essentially a cylinder built into it in the middle that looks like its only job is to hold the spring in place; I don't know if that's what a normal front brake bolt looks like, but I have no idea where to go about getting a replacement for it. I was actually considering using this as an excuse to upgrade from these single-pivot brakes that have been giving me a headache since I bought the bike to a set of dual-pivot brakes. If I bought a set of those (say from here), would I just be able to mount them as-is, or would I need to buy some special hardware or make some modifications to my frame/fork? I was doing a bit of research, and I came accross several mentions of having to drill out the mounting hole to make room for a recessed nut, but I haven't been able to get a clear and solid answer. Also, if there would be a bit of a problem mounting dual-pivot brakes, would center-pull brakes have the same problem (i.e. should I look at those as a viable alternative)?

If necessary, I can post some pictures of the old, broken brakes as well as the mounting hole on my fork.

On a related note, I noticed my front wheel was missing a nut yesterday; should i just pick up something that fits from a hardware store, or is there a place I can order one?
 

alfeng

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Jul 23, 2005
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Arathald said:
So, I was tightening a nut on my cheap GMC Denali bike, and the bolt that holds the front brake on sheared off (no, I wasn't over-torquing it, it took virtually no effort for it to shear). The bolt has essentially a cylinder built into it in the middle that looks like its only job is to hold the spring in place; I don't know if that's what a normal front brake bolt looks like, but I have no idea where to go about getting a replacement for it. I was actually considering using this as an excuse to upgrade from these single-pivot brakes that have been giving me a headache since I bought the bike to a set of dual-pivot brakes. If I bought a set of those (say from here), would I just be able to mount them as-is, or would I need to buy some special hardware or make some modifications to my frame/fork? I was doing a bit of research, and I came accross several mentions of having to drill out the mounting hole to make room for a recessed nut, but I haven't been able to get a clear and solid answer. Also, if there would be a bit of a problem mounting dual-pivot brakes, would center-pull brakes have the same problem (i.e. should I look at those as a viable alternative)?

If necessary, I can post some pictures of the old, broken brakes as well as the mounting hole on my fork.

On a related note, I noticed my front wheel was missing a nut yesterday; should i just pick up something that fits from a hardware store, or is there a place I can order one?
The CAMPAGNOLO VELOCE brakes that you are looking at are a very good brake at a discounted price (less than half of retail ... old model - NOS), even after shipping.

Center pull brakes would introduce the need for cable hangers.

In almost ALL cases, having some sort of 'star' nut to prevent the caliper from twisting really goes a long way to setting up most road brake calipers.

Post a pic of the broken brake caliper & it's sheared bolt ...

You need to measure the "reach" between the bolt & pads on your current brake(s) to ensure that the pads on the Campagnolo calipers (39-49mm) will "reach" the rims. They probably will, but that would be an unpleasant surprise if they didn't! Otherwise, you should have ZERO problems mounting different calipers ... if the current front brake's bolt extends beyond the back side of the fork & is held in place by a standard hex nut, then you may have to drill/ream the hole to accept a recessed nut.

FYI. Most of the nuts-and-bolts on most bikes are metric, so you'll probably have to go to a bike shop or an automotive store. Post a pic of where the missing nut belongs.
 

Arathald

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Jul 27, 2005
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alfeng said:
The CAMPAGNOLO VELOCE brakes that you are looking at are a very good brake at a discounted price (less than half of retail ... old model - NOS), even after shipping.

Center pull brakes would introduce the need for cable hangers.

In almost ALL cases, having some sort of 'star' nut to prevent the caliper from twisting really goes a long way to setting up most road brake calipers.

Post a pic of the broken brake caliper & it's sheared bolt ...

You need to measure the "reach" between the bolt & pads on your current brake(s) to ensure that the pads on the Campagnolo calipers (39-49mm) will "reach" the rims. They probably will, but that would be an unpleasant surprise if they didn't! Otherwise, you should have ZERO problems mounting different calipers ... if the current front brake's bolt extends beyond the back side of the fork & is held in place by a standard hex nut, then you may have to drill/ream the hole to accept a recessed nut.

FYI. Most of the nuts-and-bolts on most bikes are metric, so you'll probably have to go to a bike shop or an automotive store. Post a pic of where the missing nut belongs.
I'll post pics and take measurements as soon as I get home. I went ahead and bought the brakes, if nothing else, I can use them to fix up any of several other bikes, since they are a great deal on good brakes. Thanks for the advice.
 

Arathald

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Jul 27, 2005
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I'm not at home, these are pictures I took earlier. The focus on my camera is terrible, so it's kind of hard to see what's going on in the last two, but you an see where the bolt has sheared. And no, that's not how the parts of the brake are supposed to be arranged, I just threw everything on the bolt to hold it together when I took it off my bike.
 

alfeng

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Jul 23, 2005
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Arathald said:
I'm not at home, these are pictures I took earlier. The focus on my camera is terrible, so it's kind of hard to see what's going on in the last two, but you an see where the bolt has sheared. And no, that's not how the parts of the brake are supposed to be arranged, I just threw everything on the bolt to hold it together when I took it off my bike.
BTW. Two things to note:

1) I meant 'star' WASHER (vs. nut) ...

2) I'm hoping you simply put the parts of the brake back onto the bolt to keep them together & that is not the order the parts were assembled!

The spring is held in place by way of the notch on the 'plug' [for want of a better name] which is visible in the second & third pic -- i.e., that last piece is on in both the wrong place & pointing in the wrong direction.

While you wait for the Veloce calipers to arrive, try disassembling the caliper from the bolt ...

Install what is momentarily the back end of the bolt into the caliper arms, and continue to reassemble.

The 'plug' may be FIXED on the bolt or may be threaded in place. If it is threaded in place, then there may-or-may-not be a nut which locks the 'plug' on the bolt (it depends on the design).

There should be TWO nuts on the front of the caliper & a lot of variation exists depending on the brand & design ... one nut on the front usually snugs the calipers against that notched 'plug' & the other locks the first nut in place.

Look at the rear caliper on the bike to get a sense of which part should be next to another -- presuming it is the same "brand" then you may find that the 'white' nylon washer either goes between the caliper arms OR may be meant to be a resistance washer (in place of a star washer) that goes between the caliper & the frame-or-fork.

If the locking nut that is currently on the front of the caliper was originally on the rear, then you will probably have to enlarge the hole on the backside of the fork to accept the recessed nut (NOT a big deal ... easier to do with a drill + a bit that is the same size as the OD of the recessed nut OR by reaming it out with the "tail" end of a normal size flat, half-round, or rat tail file).

NB. If the rear brake bridge is not currently designed to accept a recessed nut, then you will undoubtdly have to enlarge the 'back' side of the brake bridge, accordingly (a little tougher since you will be working in a confined space).
 

benkoostra

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Mar 7, 2006
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Arathald said:
I'm not at home, these are pictures I took earlier. The focus on my camera is terrible, so it's kind of hard to see what's going on in the last two, but you an see where the bolt has sheared. And no, that's not how the parts of the brake are supposed to be arranged, I just threw everything on the bolt to hold it together when I took it off my bike.
What bass is that?:cool:
 

Arathald

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Jul 27, 2005
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alfeng said:
The CAMPAGNOLO VELOCE brakes that you are looking at are a very good brake at a discounted price (less than half of retail ... old model - NOS), even after shipping.

Center pull brakes would introduce the need for cable hangers.

In almost ALL cases, having some sort of 'star' nut to prevent the caliper from twisting really goes a long way to setting up most road brake calipers.

Post a pic of the broken brake caliper & it's sheared bolt ...

You need to measure the "reach" between the bolt & pads on your current brake(s) to ensure that the pads on the Campagnolo calipers (39-49mm) will "reach" the rims. They probably will, but that would be an unpleasant surprise if they didn't! Otherwise, you should have ZERO problems mounting different calipers ... if the current front brake's bolt extends beyond the back side of the fork & is held in place by a standard hex nut, then you may have to drill/ream the hole to accept a recessed nut.

FYI. Most of the nuts-and-bolts on most bikes are metric, so you'll probably have to go to a bike shop or an automotive store. Post a pic of where the missing nut belongs.


I just got around to taking the measurements. They'll reach, if just barely at 49mm. If I was to drill out the hole to accept a recessed nut, what size bit would I use? (And would a normal bit do for drilling through the aluminum? I don't have much experience working with the metal)

For some reason, it took me a while to realize you were asking me to post a picture of the missing nut on my wheel; I was wondering what you were talking about since I wasn't missing a nut on the brakes.
 

kdelong

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Dec 14, 2006
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Arathald said:
I just got around to taking the measurements. They'll reach, if just barely at 49mm. If I was to drill out the hole to accept a recessed nut, what size bit would I use? (And would a normal bit do for drilling through the aluminum? I don't have much experience working with the metal)

For some reason, it took me a while to realize you were asking me to post a picture of the missing nut on my wheel; I was wondering what you were talking about since I wasn't missing a nut on the brakes.
If you don't have much experience working with metal, you probably should have a machinist do the drilling. Because it is so soft, aluminum is very easy to mess up.

Like Alfeng said, your wheel nut is probably metric so you will need to get the nut from a bike shop. They will probably want you to add a lock washer too.
 

garage sale GT

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Jun 6, 2006
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I don't think a hardware store will stock a 9x1 nut.


Drilling into a fork crown is definitely high-risk behavior.
 

CAMPYBOB

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Sep 12, 2005
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You would use a flat-bottom drill (preferrably with a pilot arbor) or an endmill to counterbore the backside of your fork crown...PROVIDING it would be safe to do so. That could only be determined by seeing the fork as removing material may make your fork unsafe.

The counterbore could be performed with a drill motor, but better results would be obtained using a drill press or milling machine and fixturing the fork solidly.
 

kdelong

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Dec 14, 2006
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CAMPYBOB said:
You would use a flat-bottom drill (preferrably with a pilot arbor) or an endmill to counterbore the backside of your fork crown...PROVIDING it would be safe to do so. That could only be determined by seeing the fork as removing material may make your fork unsafe.

The counterbore could be performed with a drill motor, but better results would be obtained using a drill press or milling machine and fixturing the fork solidly.
I agree with most of what you said CB, but I am a machinist and there is no way that I would try something like this with a drill motor. The only reliable way of performing this operation would be with a flat bottomed drill with a pilot arbor to ensure that you were in line with the original hole and on a vertical milling machine that would give you more precise control of the feed and depth of the drill. You would need good fixturing to ensure that the hole was plumb prior to drilling. The problem with endmills is that they tend to walk off a little, especially the small diameter ones like what would have to be used here.

Now if you could find a good flat bottomed drill with a pilot arbor and a crank operated hand drill, you might just be able to do this without the fancy equipment.
 

CAMPYBOB

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kd, I hold a Tool & Die Journeyman's card, myself!

No way in hell 'I' would do it witha Black & Decker, but it is a cheap bike and I always make allowance for the 'bubba factor'!:D

I agree, the proper way to do it (assuming the alteration will not structurally affect the fork crown) is in a drill/mill vise and clamped solidly to the table.

Don't tell anyone, but back in the day and after a few drinks, a friend persuaded me to drill a front brake mounting hole in his classic Paramount track bike's fork. Layed the fork on a carpet sample on the workbench...a tap for a centerpunch...chucked up a sharp bit in an old Rockwell drill motor...steady as she goes...turned out as good as any Italian's attempt after a three vino lunch!
 

Arathald

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Jul 27, 2005
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Sounds like this modification might turn out to be a bit more complicated than first expected? From a lot of the resources I read (I'm not saying they're right, I'm just saying what they said), it's a fairly simple matter of taking a drill to the two correct mounting holes (for the front and back brakes). The specific site I found says to use a 5/16" or 8mm drill bit (and though it doesn't give directions for mounting a back brake in the back, I read elsewhere that instead of using the bolt from a front brake, the same modification can be made in the back, it's just a bit harder to get in there). The reason I asked was that I wanted to double-check the info I got.

FYI, I meant to say that I don't have much experience with aluminum, I've done quite a bit of steel working.
 

alfeng

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Jul 23, 2005
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Arathald said:
Sounds like this modification might turn out to be a bit more complicated than first expected? From a lot of the resources I read (I'm not saying they're right, I'm just saying what they said), it's a fairly simple matter of taking a drill to the two correct mounting holes (for the front and back brakes). The specific site I found says to use a 5/16" or 8mm drill bit (and though it doesn't give directions for mounting a back brake in the back, I read elsewhere that instead of using the bolt from a front brake, the same modification can be made in the back, it's just a bit harder to get in there). The reason I asked was that I wanted to double-check the info I got.

FYI, I meant to say that I don't have much experience with aluminum, I've done quite a bit of steel working.
FWIW. Personally, I think it is a fairly easy modification UNLESS you are not handy (which IS the case with some people).

I cannot confirm the drill bit size because I have simply matched the drill bit visually with the recessed nut each time I have modified a fork or frame to accept a recessed nut. I have done this several/many times. There is actually a miniscule variation in the outer diameter of the recessed nuts, you would undoubtedly use the same drill bit, regardless ...

As Sheldon Brown noted, it is farily easy to drill out the REAR hole on a fork when using an electric hand drill.

As I noted, the rear brake bridge on the frame takes a little more effort unless you have a 90º adapter on your drill (I don't), but frames which were not designed for a recessed nuts usually have a larger space to work in.

Because aluminum is softer, there is less room for sloppy work -- the only aluminum frame I have modified was a MTB frame that I was modifying to use 700c wheels.

BUT, before you drill the new holes, check the 'reach' to ensure that the calipers will work with your frame & fork. Without measuring one, I think the reach on a Campy caliper is actually 39-50.

You can (I have never, yet) elongate the slot which the brake pads are mounted in by 1mm if that is needed to get the pads in the right position.

On the rear, if your 'test' fit with the FRONT caliper shows you are off by only a small amount (less than 2mm), then you can enlarge the hole on the brake bridge eccentrically so that the brake bolt is not perpendicular to the seat stays -- if I needed to make an eccentric hole then I would use something like an awl found on a Boy Scout pocket knife whose back edge is not a cutting edge ... you could "make" your own tool by rounding one edge of the tang of a regular-sized file on a grinder.

BTW. Brown's suggestion of using the 'front' caliper on the rear is a good idea AND THEN a longer recessed nut (probably, between $7-to-$10 at your local bike shop) with the 'rear' caliper on the fork IF you don't think that enlarging the backside (actually, the side facing forward) is do-able.
 

Arathald

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Jul 27, 2005
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alfeng said:
FWIW. Personally, I think it is a fairly easy modification UNLESS you are not handy (which IS the case with some people).

I cannot confirm the drill bit size because I have simply matched the drill bit visually with the recessed nut each time I have modified a fork or frame to accept a recessed nut. I have done this several/many times. There is actually a miniscule variation in the outer diameter of the recessed nuts, you would undoubtedly use the same drill bit, regardless ...

As Sheldon Brown noted, it is farily easy to drill out the REAR hole on a fork when using an electric hand drill.

As I noted, the rear brake bridge on the frame takes a little more effort unless you have a 90º adapter on your drill (I don't), but frames which were not designed for a recessed nuts usually have a larger space to work in.

Because aluminum is softer, there is less room for sloppy work -- the only aluminum frame I have modified was a MTB frame that I was modifying to use 700c wheels.

BUT, before you drill the new holes, check the 'reach' to ensure that the calipers will work with your frame & fork. Without measuring one, I think the reach on a Campy caliper is actually 39-50.

You can (I have never, yet) elongate the slot which the brake pads are mounted in by 1mm if that is needed to get the pads in the right position.

On the rear, if your 'test' fit with the FRONT caliper shows you are off by only a small amount (less than 2mm), then you can enlarge the hole on the brake bridge eccentrically so that the brake bolt is not perpendicular to the seat stays -- if I needed to make an eccentric hole then I would use something like an awl found on a Boy Scout pocket knife whose back edge is not a cutting edge ... you could "make" your own tool by rounding one edge of the tang of a regular-sized file on a grinder.

BTW. Brown's suggestion of using the 'front' caliper on the rear is a good idea AND THEN a longer recessed nut (probably, between $7-to-$10 at your local bike shop) with the 'rear' caliper on the fork IF you don't think that enlarging the backside (actually, the side facing forward) is do-able.

I took a look at what room I have to work with for the back brake (the hole in front, as you mentioned), ans I'm pretty certain that i have enough room to work with, even if I have to change up my methods a little bit.

I haven't actually gotten the brakes in yet (I just got n email that a package is waiting for me on campus, I think this is them, although I'm expecting several packages, so it could be something else entirely); I assume that the recessed nut is flared/flanged at the head, so I would be looking to drill a hole large enough for the body to fit inside the frame, while allowing the head to tighten against the frame. Correct me if I'm wrong on this (although I guess I'll see that before I make any modifications, anyways).
 

alfeng

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Jul 23, 2005
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Arathald said:
I took a look at what room I have to work with for the back brake (the hole in front, as you mentioned), ans I'm pretty certain that i have enough room to work with, even if I have to change up my methods a little bit.

... I assume that the recessed nut is flared/flanged at the head, so I would be looking to drill a hole large enough for the body to fit inside the frame, while allowing the head to tighten against the frame. Correct me if I'm wrong on this (although I guess I'll see that before I make any modifications, anyways).
Yes. If you look at the recessed nut in the brake caliper on the left, you will see that there is a 'head' at the end that is larger than the 'body' ... I match the size of the drill bit to the body/(barrel) of the recessed nut.

bolttypes500.jpg

The advantage of the recessed nut is MORE for the convenience of the mechanic, IMO -- that's a good thing! The weight & cosmetics are secondary advantages.

The recessed nut can be a disadvantage (from an-inconvenience-to-a-nuisance which must be accommodated) if you are mounting fenders & other paraphenalia from the bolt.

The rear brake bridge on some frames has a smaller diameter than the length of the shortest recessed nut ... not too often, but it happens. If that should be the case then either the nut needs to be shortened (!) or a 'washer'/spacer needs to be placed between the head of the nut & the forward facing hole of the brake bridge.