Caliper brakes on kids bike - Centring problems

[cjchambers]

Today I found myself assembling a small child's bike as a favour for a family member.

Everything went together OK (I even managed to get the forks facing the right way around - go me!) but I'm having some issues getting the caliper arms centred. As you can see from the photo below, these are side pull calipers, and unlike good quality ones, they have no flats on the spring pivot. Because of this, there's no way to keep the spring assembly centred as I tighten the bolt behind the fork. The spring just bends and throws the whole thing out of centre when I let go.

I'm aware there's a tool available for keeping the springs centred, but has anybody got any ideas on how it can be done without resorting to specialist tools? Or am I doing it wrong somehow?

[PW]

Take a rubber mallet and a long screwdriver to use as a punch, then tap the top of the spring until it centres. Don't try to tap the caliper across, the spring will just pull it back out of line again. That used to be the standard shop rat bodge before dual pivot brakes became popular.

[drossall]

I usually just undo the mount nut behind the fork, turn the calliper to move the offending brake block off the wheel, and tighten the nut again. Then I test the brake and note whether it is in balance. If not, I repeat the procedure, positioning the calliper slightly differently.

If that didn't work, I'd consider bending the spring a bit on one side or the other.

[prm]

Check to see if the thread at the rear of the forks is not bottoming out.

Remove the dome nut, close the arms/pads and tighten the front pivot shaft nut fully.
Release lever, pads should remain in firm contact with the rim. Gradually release this nut until one, or both arm/s just return. Refit and lock dome nut.

With the arm that returns, clamp (mole grips) the spring to the arm. Release opposite spring and gently raise as required. Remove clamp and refit spring. Repeat for even return on both arms.

You can fine tune as PW mentioned.
This bodge, sorry - adjustment, takes many many years to perfect

You may find the pads fail to line up with the rims evenly. Another adjustment!
Using an adjustable spanner, bend the flat section just above the pad fixing bolt to give a very slight toe-in.

Hope this may help.

Regards

[dbrunner]

Err... how about another spanner on the two front nuts... always works for me.

Dave

[cjchambers]

Thanks for the help everybody - I managed to get it done with a healthy combination of the orthodox and non-orthodox methods