Need help with center-pull spring
 

Please don't tell me to post this on the bicycle mechanics board. Already tried that and the request was roundly ignored. :(

Anyway, I got a bit overzealous cleaning up a set of Dia Compe and a set of Weinmann brakes. I completely disassembled them both, got them all sparkly clean and shiny. Put them back together ok, and, although they are functional, they aren't "right". The springs that tension the arms need to go round one more time. Problem is, nothing I've tried works to make them go around again. Am I lacking a tool? Am I deficient in technique? Anyone done this successfully before? If so, please share. :o

Thanks,

Z

Maybe you could post a pic? I'm having a hard time visualizing this one.

Nah -- you couldn't have unwound the coil springs. Look at the springs; one end is straight, the other has a slight dogleg bend. The dogleg points down, and goes on the caliper arm side, as opposed to the brake block side. Getting them flopped wouldn't seem like a deal-breaker, but it can be.

Keep trying, John -- there's only about four ways to put it together, and even a blind hog gets an acorn once in a while. :D

Imagine driving into a traffic circle at 6:00 on the clock face. Your exit is at 10:00. You drive all the way around the circle once and then make your exit (that's how far my springs are wound now) To be properly working, they need to go completely around the circle twice before going to the exit. This requires far more force than I can generate in any semblance of a controlled manner. Surely, there must be some way to do it.

What you've described is the way the springs are supposed to look. How did you arrive at the conclusion they've somehow unwound? Not trying to be insulting -- what did you do to them besides shine them up?

If they aren't providing enough tension to return the caliper arms you've probably got something else going on. You didn't over-tighten the bolts, or leave out any thrust washers, did you?

this is the right place to ask, I don't think they unwind but I've never paid too much attention to mine, they aren't that fussy at all, I have a broken one though somewhere in my yard that I could take apart,

next time only take one apart at a time that way you'll have a complete one for comparison.

I compared the Dia Compe's I had cleaned up, to an identical set that I hadn't. The ones that I hadn't messed with had the extra turn. I'll double check the orientation of the doglegs again.

[QUOTE=USAZorro]Please don't tell me to post this on the bicycle mechanics board. Already tried that and the request was roundly ignored. :(

Am I lacking a tool?

Ha ha what you said.

No . It can be done with one wrench. Seems to me If I remember correctly you have to put the back arm on and spin it to its proper tentioned position and hold that in place and then do the same with the other.Finger strength will do it unless you are incorrectly trying to put another 360 degrees into it.

Its kind of of a chinese puzzle/mouse trap sort of thing. You'll probably get bit a couple of times.

Oh wait a minute there. Some springs have more wraps than others. I think the dia compes might have one less than the wienmanns.

The bikes that the Dia Compe's came off were 10 years different. They looked identical though. Looking at the one with the additional turn, I thought I had lost a full turn on the other when I took it apart. There's possibly some other reason why it didn't seem to be operating at its best. The one with the three winds worked properly.

The difference between the spring off the calipers and on under tention is about a quarter turn, you won't have lost a turn. if however you tried to put in an extra one the springs might be toast. Both spring must be of the same tention.

No - I'm not enough of a gorilla to force a spring like that. I'll double-check the set-up. It must be something else that's a bit off.

Thanks for the help guys! :)

It seems that my brakes should have springs with the third turn. I can only conclude that someone changed springs on these at some point and used the wrong ones. :( Hopefully the LBS has some of the springs I need.

Thanks again.

Even a blind hog gets an acorn sometimes? wuzzupwiddat?

Well, if you can't make fun of your friends, what good are they? :D

I prefer pine nuts.

well, I'm gonna claim that phrase, and adapt it to my own ends...lessee..

even a fat hog gets a babe sometimes...
even a skinny hog gets the nuts once in a while...
even an old hog gets turned into bacon, ah, regularly...
even a fat cannondale gets the sprint if, um, ...

dunno. I don't think I can get the hang of it.

I did a survey of my bikes with centerpull calipers, it was about half and half with three and two turn springs, I never would have noticed had I not been looking for any differences.