What am I doing wrong here? sidepull brakes

[icecream]

The forums are always a great help for me so I figured i'd post.
I watched the video & for sidepull brakes for some reason i'm still having the same problem.

I have an older schwinn varsity.

anyway if I am working on the brakes & adjust them so they are centered up , then tighten the tension/tighten the nut on the cable and when I pull the break the left pad gos all the way to the rim, the right pad as far away as it can from the rim & the handle is loose.

what am I doing wrong?

thanks guys

[Bill]

Try squeezing the caliper together to see if it is sticking or frozen. If not is your cable new?

[trevgbb]

common problem on caliper brakes, especially cheaper end.
Some types have a centering system built into the design, but most don't;
See This:
http://techdocs.shimano.com/media/techdocs/content/cycle/SI/TIAGRA/BR-4500/SI-8E60C-001-ENG_v1_m56577569830745758.pdf
What to try?
1/ make sure the locknuts at the front are pinched up and the arms are moving and returning freely but without play, get some one to pull on the lever hard to hold blocks against rim and tighten up the rear locknuts.
2/ or, after tightening front and rear locknuts, use a blunt punch to tap on the upper part of the spring to move the appropriate arm inwards. may need repeating a few times with different torque on locknuts, but usually works in the end.

[icecream]

Thanks for the reply guys ! I have a pic to show exactly what i'm working with. this is on the back wheel.

<a href=http://img132.imageshack.us/my.php?image=brakeb.jpg><img border=0 src="http://img132.imageshack.us/img132/1451/brakeb.jpg"></a>

I know the centering system is kind've tricky and it's said to make sure that it's not too loose or tight just in the middle. I've tried holding the legs together after it's centered and tightening the cable while holding the arms.

Every time i have the same result after the cable has been tightened I will squeeze the lever up front and the shoe on the left will hug the rim and the lever is loose. If I push on the break pad on the right side to center it up again the lever has some tension to it again.

[JohnV]

In your photo, is the cable lose at this point? The reason I asked is that the end of the cable housing is sitting on the cable adjuster and not in it. If you apply the brakes and the cable end falls into the adjuster when you release them, it will cause you to have slack in the cable and may be why it keeps getting off center. I would make sure that you are not overlooking the cable housing and make sure its seated properly on each end before taking the slack out of the cable.

[icecream]

yep it's loose I actually ended up cutting the housing a little shorter so it could slide back & forth. I figured besides protecting the cable it was just more for aesthetic purposes. I will have to check the other cable attached to the lever when I get off of work. thanks

[DaveM]

The two nuts facing out in the picture are NOT the centering control. They control how tight the two arms sit on their pivot point. Too tight and they won't pop back open, too loose and the arms will have a lot of play which will hurt the braking performance.

To adjust the centering, you have to loosen up the single nut on the back (inside the rear triangle of the frame. Once this is loose you can rotate the entire assembly and then retighten. It is tricky because when you tighten the nut it tends to twist the caliper.

One trick is to put a flat head screwdriver against the spring right where the curly cue is in them on one side. Give it a firm but gentle tap with a hammer. That will twist the assembly. But ultimately, what you need to rotate is the piece that the spring passes through. That is what holds the caliper on its center. Moving any other piece won't help because it will jsut pop back once you apply and release the brake.

[RobAR]

Dave nailed it!
Here is a discontinued tool http://www.parktool.com/shop/offset-brake-wrench that I think everyone who works on old bikes should snap up before they're all gone. It makes adjusting these old calipers SO much easier.
$4 baby! I remember when Dealer cost was 2X that.

[DaveM]

Yes, those are great. If there isn't flat spots on the spring carrier, you need this type:
http://www.amazon.com/Park-Tool-OBW-3-Offset-Wrench/dp/B001B6LPA6
The left side fits into the curled part of the spring for the same effect

[RobAR]

The old Jedi OBW-3. Impressive, Dave. A formidable tool - in its day!

Did that sound like Darth Vader? LOL
Good call!

[icecream]

(04-18-2011, 05:41 PM)DaveM Wrote:  The two nuts facing out in the picture are NOT the centering control. They control how tight the two arms sit on their pivot point. Too tight and they won't pop back open, too loose and the arms will have a lot of play which will hurt the braking performance.

To adjust the centering, you have to loosen up the single nut on the back (inside the rear triangle of the frame. Once this is loose you can rotate the entire assembly and then retighten. It is tricky because when you tighten the nut it tends to twist the caliper.

One trick is to put a flat head screwdriver against the spring right where the curly cue is in them on one side. Give it a firm but gentle tap with a hammer. That will twist the assembly. But ultimately, what you need to rotate is the piece that the spring passes through. That is what holds the caliper on its center. Moving any other piece won't help because it will jsut pop back once you apply and release the brake.

thanks dave this was a great explanation however now that I have an idea of how all of these work with each other the problem is still happening. I think the centering tool would come in handy as the screwdriver is just not doing it for me. in theory couldn't i just put the spring in a vice & bring it in closer ? does the centering tool hold onto the top nut which houses the spring to keep it from shifting from side to side ?

[DaveM]

The spring itself is not off center, so bending it won't make any difference. The piece that holds the spring (the piece between the two arms of the brake and the frame) is the one that needs to be rotated in order to center the brake. It has a slot that the spring passes through and controls what angle it sits at. Simplest thing to do is just loosen the back nut, turn the whole brake assembly, and re-tighten.

One other piece of advice. Get the cable tightened first. If you try to center the brake while the cable is loose, it will be hard to get the right spot.

[Mirk]

I've been having the same problem on an early 80s Schwinn Sprint. I've done everything I could think of including what I've seen in the videos posted here. This info is great. Thanks everyone!

[cyclerUK]

If you have cut the outer cable housing too short then this could give the problem you are having.
The correct length outer housing is important for good brake operation.
Disconnect the cable and you should be able to squeeze both arms against the rim and then both arms should spring back.
To prove if the cable housing is too short then just temporarily put the piece back that you cut off. (the brake should work but you'll need to fit a new complete piece ASAP if this is the cause.)

[Rob55]

This type of brake centers itself. The outside cable is essential in getting it to work. 1. Loosen the lock nut and screw the adjusting bolt in as far as it will go. This is the hollow bolt the cable goes through at the top of the caliper arm. 2 loosen the bolt on the bottom that locks the cable so the cable pulls through it freely. 3 reach through the spokes and squeeze the brake together so it squeezes the rim. Use a wire tie or piece of solid wire and tie the caliper closed on the rim. 4. pull the inside steel cable through the lower bolt until the outside cable is firmly seated in the bolt on top. 5. tighten the lower bolt so the the cable is locked in place and can't move when you cut the wire tie holding the caliper against the rim. When you do this the spring in the caliper will try to spread the brake open. the outer cable housing pressing on the top adjusting bolt will keep the brake from spreading. spin the wheel. the spring tension should hold the brake open enough for the wheel to spin. if it drags a little do not worry the cable will stretch and the parts will settle in. if the cable was a little loose and there is more than about 1/8 inch between the wheel and the brake pad use the adjusting bolt at the top to take out the slack in the cable. To center the brakes. loosen the center bolt holding the break on the frame until it is loose then pull on the brake lever. Tighten the center bolt while the brake is fully applied and the brake will remain central when released. After you have done all of this the idea is to have the brake pads as close to the wheel as possible without dragging on the wheel. I know this is an old thread. but if anybody else reads it this should help.