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Old 02-11-09, 08:11 PM   #1
tmh657
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Dia Compe brake help

I have some late 80's Royal Compe brake calipers that are going back on a bike project.
Took everything apart, cleaned them up, put them on and the rear works as it should. Still a little loose to the rim maybe.
The front Is tightened down with minimal clearance between pad and rim as usual and rim is centered between calipers.
Pull on brake lever, pads touch rim and then right side pad remains on rim, (see pics) so the brake is not centered anymore.
I can't tighten the center nut any more or they won't pivot at all. The whole assembly is tight in the fork.

Am I a dumb ass, are they worn out or is there a fix?
I lubed the brake as well.
Thanks
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Old 02-11-09, 10:11 PM   #2
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Quote:
Originally Posted by tmh657 View Post
I have some late 80's Royal Compe brake calipers that are going back on a bike project.
Took everything apart, cleaned them up, put them on and the rear works as it should. Still a little loose to the rim maybe.
The front Is tightened down with minimal clearance between pad and rim as usual and rim is centered between calipers.
Pull on brake lever, pads touch rim and then right side pad remains on rim, (see pics) so the brake is not centered anymore.
I can't tighten the center nut any more or they won't pivot at all. The whole assembly is tight in the fork.

Am I a dumb ass, are they worn out or is there a fix?
I lubed the brake as well.
Thanks
There's nothing wrong with your brakes; the calipers just need to be centered over the rim. Look closely at the pivot bolt that attaches the caliper to the bike. You should see a flat section on the pivot bolt between the frame and the caliper spring:



You can insert a thin wrench (e.g. a cone wrench) into this slot and use it to center the calipers so each pad is the same distance from the rim:

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Old 02-11-09, 10:15 PM   #3
Gonzo Bob
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Do the brake bolts have centering flats on them? They are usually 13mm and a cone wrench can be used to center the arms (or hold the arms centered as you tighten the mounting nut) as long as you have access, i.e. no racks or anything in the way.

If you center the brakes and the mounting nut is tight but the brakes still go off center, the brake bolt is probably turning in the frame or fork. Check if the brake has a serrated washer against the frame/fork. If not, using one will improve things.

Also check that the cable housing isn't pulling or pushing on the brake causing it to go off-center. If it is, cut it shorter or lengthen it as needed.

What is this "center nut" you speak of? It sounds like you're talking about the locknut used for pivot/play adjustment. The mounting nut to tighten down if the brakes are not staying centered is the one behind the fork, not the locknut on the front of the brake calipers.
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Old 02-11-09, 10:24 PM   #4
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I've seen them in 14mm, 13mm, and 10mm. Park used to make a 13mm & 10mm Offset Brake-Wrench - OBW-1. I don't know if they are still made. The current version is 14mm and is Park OBW-3. But if your brake's flats are 13 or 14mm, just use cone-wrenches.
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Old 02-12-09, 09:52 AM   #5
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Thanks for the info.
I will check to see if I have the correct cone wrench.

I do not recall the washer being serrated so I will replace it

Gonzo Bob, the center nut I speak of is the lock nut you refer to. I have shortened the cable already as it was too long and pushing the brake off center.
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Old 02-13-09, 10:44 AM   #6
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The quickest and easiest way to fix this common problem is to just unhook the spring from the side that's too close to the rim and pull it outwards to give it more tension.
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