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Brake Caliper Mounting - old frame - new brakes

Old 09-11-08, 01:35 PM
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Brake Caliper Mounting Question - old frame - new brakes

I'm mounting brakes on an old Schwinn frame and I have a few questions...

For the rear brake, can I drill out the nut entry hole side to insert the nut to secure the brake this way? Nut would tighten against the inside back surface of the bridge piece?





For the front brake...would I

Drill out the back hole in the fork crown(yellow arrow) to have the nut shoulder rest against the fork crown surface?
Drill out the back hole in the fork crown(yellow arrow) and use a few washers so the nut rests against the washers inside the fork?
Shorten the nut so I would not have to drill out the back of the fork crown and instead install it inside the fork with a few washers?

I can access the nut head inside the fork without opening the back hole any further if desired.



Appreciate any input.

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Old 09-11-08, 01:45 PM
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You used "nut" everytime instead of nut and bolt, so a couple places I got confused.

Anyway, if you can drill out the back of the brake bridge to fit the nut through, yes, do that.

Also drilling out the back of the fork crown is common so yes, do that.

Don't shorten the front bolt, if you're going to do that just use the rear brake on the front and the front brake on the rear- you probably wouldn't need to drill out the back of the brake bridge that way.
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Old 09-11-08, 01:51 PM
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Originally Posted by TimJ View Post
You used "nut" everytime instead of nut and bolt, so a couple places I got confused.

Anyway, if you can drill out the back of the brake bridge to fit the nut through, yes, do that.

Also drilling out the back of the fork crown is common so yes, do that.

Don't shorten the front bolt, if you're going to do that just use the rear brake on the front and the front brake on the rear- you probably wouldn't need to drill out the back of the brake bridge that way.
Thanks for the reply.

It's my understanding that the front and back brakes are specifically designed for front and back use and should not be interchanged?
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Old 09-11-08, 04:28 PM
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Yes, but mostly because they have diffrent length mounting bolts (the long one goes in front).
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Old 09-11-08, 04:43 PM
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Originally Posted by somegeek View Post
Thanks for the reply.

It's my understanding that the front and back brakes are specifically designed for front and back use and should not be interchanged?
They can be interchanged. Just make sure to switch the pads around so they're correct.
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Old 09-11-08, 05:40 PM
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in my experience--- yes , but if you look at older bikes---there are arched spacers to better fit the round bridge--- could you incorporate them? it would help steady the brake.....my 2 pennies
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Old 09-11-08, 06:26 PM
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Originally Posted by G piny parnas View Post
in my experience--- yes , but if you look at older bikes---there are arched spacers to better fit the round bridge--- could you incorporate them? it would help steady the brake.....my 2 pennies
Can you buy those online? Is that something a LBS would have?
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Old 09-11-08, 06:41 PM
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Originally Posted by somegeek View Post
Can you buy those online? Is that something a LBS would have?
An LBS that's been around for a long time might have them. They're still in the QBP catalog, so anybody can get them for you. You want a Dia-Compe concave brake washer. They're different front to back, make sure you get the right one.
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Old 09-11-08, 09:04 PM
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On the front you can easily drill out the back hole to 5/16 or 8 mm to fit the nut. But don't drill all the way through. Leave the front hole alone so it supports the caliper best.

The rear is hard since the front hole that is inside the rear triangle is the one that needs drilling but you do NOT want to drill the rear side of the brake bridge. This makes it tough because a drill and drill bit will not fit in there by any chance at all. You need a special "pull" drill or perhaps a right angle head drill and a very stubby 5/16 inch drill bit to get in there.
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Old 09-11-08, 09:08 PM
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Originally Posted by BCRider View Post
On the front you can easily drill out the back hole to 5/16 or 8 mm to fit the nut. But don't drill all the way through. Leave the front hole alone so it supports the caliper best.

The rear is hard since the front hole that is inside the rear triangle is the one that needs drilling but you do NOT want to drill the rear side of the brake bridge. This makes it tough because a drill and drill bit will not fit in there by any chance at all. You need a special "pull" drill or perhaps a right angle head drill and a very stubby 5/16 inch drill bit to get in there.
I was only planning to drill out the back side of the fork crown. I hadn't thought of the brake bridge access yet in regards to a drill. I do have a dremel with a right angle adapter which would do the trick. Could use a conical bit to ensure my grinding stays centered.

Did find those washers for $7 a bag of 10 back Dia-compe washers. Thanks for the suggestion, dscheidt!
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Old 09-11-08, 09:19 PM
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Originally Posted by BCRider View Post
On the front you can easily drill out the back hole to 5/16 or 8 mm to fit the nut. But don't drill all the way through. Leave the front hole alone so it supports the caliper best.

The rear is hard since the front hole that is inside the rear triangle is the one that needs drilling but you do NOT want to drill the rear side of the brake bridge. This makes it tough because a drill and drill bit will not fit in there by any chance at all. You need a special "pull" drill or perhaps a right angle head drill and a very stubby 5/16 inch drill bit to get in there.
I just drilled through both sides and made a bushing out of a piece of aluminum tubing you can buy at hobby shops.
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Old 09-11-08, 10:40 PM
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The rear is not hard. All you have to do is use a front and a longer nut on the back.
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Old 09-11-08, 11:27 PM
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Originally Posted by operator View Post
The rear is not hard. All you have to do is use a front and a longer nut on the back.
That'll work too and in the end could be the best option. Less fuss and muss and you can then use the old saddle washers and nut. No oddball tricky drilling really is a nice way to go.

A dremel really doesn't have the torque for drilling this sort of hole size in steel. Although your idea of a tapered bit or one of the Unibit step drills is a very interesting one.

What some have done is use a pair of pliers or vise grips to hold the drill and manually twist it in to drill out the poor access hole. If you do it this way then go with 9/32 first and then the 5/16 both to aid in good centering and to ease the work load on the twisting.

I've also seen some references to where folks mount the caliper inside the rear triangle. Of course this means the brake housing has to bend a little tighter and it'll be on the "wrong" side if that makes any difference. Other than that I don't know if there's any other issues with doing that or not.
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Old 09-12-08, 09:25 AM
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Thanks for the replies.

I believe I do have a dremel grinding bit close to the size of the recessed brake nut outer diameter and the hole in the bridge is pretty close to this size so I'll prolly give grinding the hole a go.

The rear brake on the front is a no go as I'd only have 4 threads to accomodate a washer and recessed nut.
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Old 09-12-08, 10:00 AM
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I really do not advise grinding that hole out. The problem is that you MUST keep the hole centered with the other hole and grinding will not do that for you. If it's the only way you've got then mark it out really well with a small tipped permanent marker, masking tape or some other way to act as a guide to keeping the hole as centered as you can possibly manage.

Oh, and regardless of using the real rear brake and tubular nut or getting a second front caliper you will want to use those saddle washers on the rear with one each on the caliper side and the nut side. Frames intended for these brakes have a little block that carries the pressure normally but on this frame all you've got is the tube. That tube will crush easily under the small contact area of the caliper and nut without those saddle washers.

If need be you can make your own from a couple of the thicker cup washers used on V brake pads. Just Dremel or file out the shape so it fits nicely to the tube. The center hole may need to be filed out slightly to let the tubular nut fit.
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Old 09-12-08, 10:25 AM
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Originally Posted by BCRider View Post
I really do not advise grinding that hole out. The problem is that you MUST keep the hole centered with the other hole and grinding will not do that for you. If it's the only way you've got then mark it out really well with a small tipped permanent marker, masking tape or some other way to act as a guide to keeping the hole as centered as you can possibly manage.

Oh, and regardless of using the real rear brake and tubular nut or getting a second front caliper you will want to use those saddle washers on the rear with one each on the caliper side and the nut side. Frames intended for these brakes have a little block that carries the pressure normally but on this frame all you've got is the tube. That tube will crush easily under the small contact area of the caliper and nut without those saddle washers.

If need be you can make your own from a couple of the thicker cup washers used on V brake pads. Just Dremel or file out the shape so it fits nicely to the tube. The center hole may need to be filed out slightly to let the tubular nut fit.
I found those washers by the ten pack which I will order.

I'll need then to replace my Campy Centaur caliper bolt for the rear brake with a front one. Those something a LBS would carry?
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Old 09-12-08, 08:09 PM
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So I have a question about the front brake mounting... gonna use the front brake on the back so I can mount it along with the dia-compe curved washers. Going to mount the back brake on the front... it's got a shorter mounting bolt so I I took one of the recessed nuts, beveled the tip a little and threaded it on. I got about 4.5 turns on threads. Campy suggests six threads minimal.



Will 4.5 threads work?

If not, I could purchase a 30mm recessed nut (~$10 for one), drill the back hole through and drill the front hole out about 1/2 the depth or so so I could grab a few more threads and still have some original fork hole material left to keep the caliper centered using the pivot bolt.

I also picked up a grade 10.8 nut which I could install instead but the nut itself only has about 4 threads but they can all engage the pivot bolt. Thinking the recessed nut is a softer material so they advise you grab more threads?

Thoughts?
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Old 09-12-08, 08:25 PM
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You're resourceful, good on ya!

I'd be a little worried about only 4.5 turns on as well.

The 30mm tube nut sounds like an option. And as long as it fits at least a couple of mm's into the front part of the fork you could get away with drilling out the front as well. The whole point of good fitting holes is to act as seats for the lever formed by the bolt and the tubular nut so the caliper can't dance around. But if you get a nut that is long enough to fit all the way through then you can drill all the way through and as long as the tubular nut doesn't bottom out before things get tight you're laughin'! I'd want to know that at least 1 and preferably 2 mm's of the nut will stick into the front portion of the fork before I drilled all the way.
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Old 09-12-08, 08:48 PM
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On that note... do you think I'd be fine to drill the front hole only to the outer diameter of this recessed nut and then put some washers on the recessed nut inside the fork to ensure tension on the bolt? I'd be set threadswise this way.
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Old 09-15-08, 11:40 AM
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ok---- I havnt read all the previous posts--- because im a little tipsy---
but---- i see the picture--- and I've done this before--- this is a rear brake--
too short--- cut the head off the nut( this must be a long nut) make an indentation for (two slots for a flathead) screw the now cut nut onto the brake bolt(through the hole )--- use a sufficient metric bolt to finish and cinch the brake----- use your arched washers for the rear......
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Old 09-15-08, 01:27 PM
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Originally Posted by somegeek View Post
So I have a question about the front brake mounting... gonna use the front brake on the back so I can mount it along with the dia-compe curved washers. Going to mount the back brake on the front... it's got a shorter mounting bolt so I I took one of the recessed nuts, beveled the tip a little and threaded it on. I got about 4.5 turns on threads. Campy suggests six threads minimal.



Will 4.5 threads work?


If not, I could purchase a 30mm recessed nut (~$10 for one), drill the back hole through and drill the front hole out about 1/2 the depth or so so I could grab a few more threads and still have some original fork hole material left to keep the caliper centered using the pivot bolt.

I also picked up a grade 10.8 nut which I could install instead but the nut itself only has about 4 threads but they can all engage the pivot bolt. Thinking the recessed nut is a softer material so they advise you grab more threads?

Thoughts?
Rule of thumb is engagement should be at least as much as the diameter of the fastener. I don't think 4.5 threads will cut it (I wouldn't do it).

Put that brake back on the rear where it belongs.
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Old 09-15-08, 03:43 PM
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Originally Posted by rmfnla View Post
Rule of thumb is engagement should be at least as much as the diameter of the fastener. I don't think 4.5 threads will cut it (I wouldn't do it).

Put that brake back on the rear where it belongs.
I'm using my front brake on the rear so I can use the curved washers with the longer bolt. Brakes are the same here - only diff is the pivot bolt length.

Rear brake will be installed on the front. Pondering drilling out the front hole in the fork so I can insert this nut so it almost rests on the caliper when secure. Will install a few washers to take up the slack in the crown. About 10 threads will engage this way.
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Old 09-17-08, 11:45 AM
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I personally would not drill the fork--- you need that threaded long sleeve nut---- to make the jump.
bolt/sleeve/"pivot bolt" --- catch all the threads and you'll be ok... my 2$. take your time and think this through...... less cutting, less labor, less material loss...
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Old 09-17-08, 12:12 PM
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Originally Posted by somegeek View Post
I'm using my front brake on the rear so I can use the curved washers with the longer bolt. Brakes are the same here - only diff is the pivot bolt length.

Rear brake will be installed on the front. Pondering drilling out the front hole in the fork so I can insert this nut so it almost rests on the caliper when secure. Will install a few washers to take up the slack in the crown. About 10 threads will engage this way.
You're really doing this wrong.

You can drill out the back of the brake bridge to use the correct nut; you will need only one curved washer between the bridge and the brake.

For the fork do the same thing; drill out the rear hole to allow the nut to enter (but not fall through) and attach the front brake the way it was designed for.

This should not be this difficult; if it is causing you this much friction you might want to get some local professional help.
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Old 09-17-08, 12:15 PM
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Uh... I was discussing different options. Just blows to drop $10 on a bolt.
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