Bicycle Mechanics - Campy Chorus 11 rear brake. It won't stay centered.

It is a side pull single caliper type I think. It rotates clockwise counterclockwise even though I have it as tight as I can get it. I cut off some brake cable length so that it would sit more centered- even so it still swings and sits where it will.

It only has the washer that has the spokes that bite on one side of the mounting hole in the frame, and I was wondering if I should get another one? Would that take care of it?

This group is about a year old, and it has never been right. It really became a problem last night when I was trying to fit a wider profile wheel and keep it from rubbing. By cutting the brake cable down, it's working, but still one side is much closer to the rim than the other and I am not sure it won't rub a little if I am pedalling hard, as when climbing a hill.

Please advise!

Thanks!

You're just not doing the centering properly. It is a bit tricky. You have to loosen the clamping nut, then use a 15mm wrench on the flats to position the calipers and finally retighten the clamping nut. It just requires a bit of trial and error, since it's hard to keep the 15mm wrench in the exact position as the nut is tightened. Work the brakes several times to be sure that you've really centered them.

The set screw on the right side caliper arm adjusts the spring tension and may seem to have some effect on centering, but it is not a centering screw like dual calipers have.

Single pivots never center as accurately as dual pivots. The problem is that there is unequal friction at the spring anchors that causes one side to retract more than the other. It's impossible to control that friction perfectly. As long as it doesn't rub the rim it's OK. Single pivots have more pad travel, so it's OK to adjust the pads a little further from the rim. If you are still concerned about rubbing, you can open the quick release on Campy levers as well. That doesn't affect brake operation, except it adds a little reach to the levers.
FWIW I really like the single pivot caliper on the rear wheel. It's less powerful so it's much less likely to skid the rear wheel. It's also easier to adjust, although as you found, centering is sometimes a problem. It's a little lighter too.

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The set screw on the right side caliper arm adjusts the spring tension and may seem to have some effect on centering, but it is not a centering screw like dual calipers have.


Okay- that's one thing I can quit messing with.

I have the old Campag[#2040] Sidepull brake set, Tulio's Gnarly Serrated Star Washer[#2041]

grips the center bolt and the frame, and seems to hold mine centered, just fine.

You say that the caliper keeps swinging around and won't tighten down. That should certainly not be happening. You SHOULD be able to lock the mounting nut tight enough that it takes a goodly twist to shift the caliper in the mount. To me that says that the nut is bottoming or locking against the threading before it actually pinches the frame tight enough to hold the caliper locked in place. Then you mention about only having one washer. That and your description that it's a single pivot style suggests to me that your frame has the sort of brake mount bridge that is just a tube with a hole in it and that your brake requires the two saddle washers to correctly mount it to the frame. But then you say that the group is only a year old. So that doesn't make any sense either unless it's a NOS package that you got.

Frankly I think pictures are needed so we can see what you have.

That and your description that it's a single pivot style suggests to me that your frame has the sort of brake mount bridge that is just a tube with a hole in it and that your brake requires the two saddle washers to correctly mount it to the frame

It is just a tube. It is a Serotta steel frame. I will see if I can figure out how to post picture soon.

Tulio's Gnarly Serrated Star Washer[#2041]

Fietsbob- Could you direct me as to where I might find such an animal?

Once the clamp nut is tight, be sure that the 15mm wrench can't turn easily. If it does, then most certainly the nut is too long and bottoming out. That's easy to fix - grind off a little.