Side pull calipers, centering and star lock washers
 

Hello,

I've finally got round to putting a brake cable on my side pull calipers. This is the method i'm using to centre the brakes:

1). Loosen the centering nut on the back of the brake bolt.
2). Pull down hard on the brake lever
3). Tighten the centering nut
4). Screw in the barrel adjuster

When I look at it, the caliper looks centred.

However, after pumping the brake lever a few times, things go out of alignment. One of the calipers moves really close to the rim, and the other caliper moves far away from the rim.

I think i'm getting this problem since I have a light bracket attached to my front caliper bolt. I had to back it off from the frame using regular washers. I think this is where the brake bolt is slipping.

I googled a few things and someone came up with star washers. My impression is that they lock the brake bolt in place without overtightening.

I have a few questions:

1). Do they work?
2). What size do I need? They come in 5,6,10 and 20mm.
3). Can you put two on top of each other?

I only ask question 3 because I have 3 washers holding the light bracket away from the half moon washer on the frame. You can see that in this picture (excuse the grease):

http://bikeforums.net/attachment.php...hmentid=364510

Thanks in advance.

Yes star washers do work . 5 MM should work for you . The problem you are having with the calipers might also be there if your bake's housing is to long , if so try shorting it .

There are serrated washes made specifically for brakes, but I don't think the pivot bolt is moving. Friction alone has served to keep these in place for a century, and there's no reason it can't do so today. On simple test is to tweak the light bracket and see how easily it moves. If it does without great force, you'd want a serrated washer behind it, withn the brake depending on friction alone.

But even light brackets don't move unless moved or bumped, so you need to look elsewhere before "fixing" what ain't broke.

The most common cause of single pivot brakes going off center is friction between the spring leg and arm. As the brake opens and closes the spring moves up and down the arm slightly, and it takes very little change in friction to create an unbalance.

Put a drop of thick oil or grease (or Sun Tan oil if that's all you have) where the spring sits on the post on each arm, and work the brake a few times to see where it wants to center. Then loosen the mounting bolt, rotate the brake by hand to center (open), tighten slightly to hold and recheck. If it's right, tighten the rest of the way while holding the brake . (If you have trouble holding the brake from rotating as tightened, use a screwdriver inserted into the spring's coil as a lever to steady the brake from turning as you tighten.

Now recheck by opening and closing a few times, and it should be fine, unless bumping the light backet moves everything (that's where a serrated washer will help).

i'm not surpised. that's a LOT of stuff on there! ;) i wouldn't be surprised if it turned out to be chronic problem. i'd just fiddle with it (for instance, i'd first loosen then shove it all the way to the opposite side that it wants to be when tightened and see how that goes. if it overshoots the mark, find the optimum compromise) until i got it right or until my patience ran out. at which point i'd forget about it. IME, the brakes will work that way, you just have to make sure your wheels are true. i'm sure none of my single pivot brakes are centered. i KNOW my cantis aren't.

1. It does not appear that you need that many washers for the light bracket to clear the fork race.
2. There should not be a nylock nut back of the acorn nut - a regular (thinner) nut is fine.

Method from the "old days."
1. Adjust the acorn nut and the one underneath so they are locked against each other tightly, and the caliper moves freely but does not have any significant fore-aft play.
2. When you want to center the brake put one wrench on the nut in back of the fork. Put a second (narrow) wrench on the acorn nut if moving the caliper clockwise, the other nut if moving cclockwise.
3. Move the two wrenches in unison till the brake is centered when you pull the lever a few times.

I tried this and the light bracket wouldn't move at all. I'll see if the calipers start moving after more rides, but it's nice to know that the star washers work (thanks bikeman715!).

I greased the springs and the spring leg arm. Then I repeated what I was doing before, but everything was still out of alignment.

I ended up doing this and somehow got it to work! It was luck more than anything, but I tightened and loosed the front two nuts practically randomly. When I pumped the brake, everything fell into alignment. It felt great!

Unfortunately, my light is slightly off centre. I'm going to leave it though, practice on my rear brake then try again.

The method I explained is not random, so what you did was not the same. If you attempt to re-center the light bracket do not loosen the nut at the back of the fork, as that determines the rotation of the spring assembly and thus the caliper arms. Loosen the two front nuts, center the bracket and then tighten them down again.

Just out of interest, has anyone used one of these?

Good idea, i'll do that now.

OBW3C may work better , if you had better brakes that featured the needed flat faces on the center-bolt spring carrier .

they work on copies of Campagnolo's brakes , which that steel budget brake is Not.


Old guys kludge technique: where the return spring coils on either side loop around to be doubled ,
can be used to bang on

with a, softer than the spring itself, drift punch (bronze, maple dowel?) to rotate the brake slightly ,
tapping on the punch with a hammer ..