Twin Leading shoe front brake not releasing

I'll go first then..

7/8 leversare highly unlikely to cause this, it's likely a coincidence.

First thing to check would be the cable because it's easy. That terrible old frayed thing with knots in it may be the priceless original, but it's crap, get a new one.

If that's cool then it's wheel out time, being a TLS there's double the amount of spindles and cams to seize and cause friction. Your glorious British weather creates quite a bit of condensation and corrosioninside the brake drum not to mention the ingress of your lovely liquid sunshine. Lots of convenient entry points for rainon those commando backplates.

While you're in there check the pull-off springs, replace if in doubt. Don't be a tightwad, they're important.

Strip it alldown, clean it all up, both spindles removed and clean,the two pivots for the brake shoes and the sliding cam surfaces, put it back together, remember to lube sparingly all moving metal to metal surfaces, I like those copper based greases on the cam surfaces, a quality heavy grease on the rotating surfaces.

Chamfer the leading edge of the shoes to stop grabby ness.

Put it all back together. Don't bother attaching the link rod on the brake arms at this stage, you need it off for adjustment. Put the wheel back in the forks, leave the spindle slack.

If working by yourself attach the cable as normal and pull the brake lever into the bars reasonably tightand tape/tie it there.

With a 5/8 spanner turn the top arm clockwise pretty hard, adjust the rod until the pin slides in, try to compensate for a slight bit of wear in the linkage, fasten everything.

Remove your means of holding the brake on, give the lever a few squeezes, feels ok?

Hold the brake on tight while doing up your spindle nut to centre the backplate.

Put your crash hat on and go and practice stoppies to impress the local oiks hanging around outside the chip shop.

What he said! Although I've always had to adjust the rod a little.

My theory (for what it's worth) is modern asbestos-free lining materials are: a) not as effective as the dangerous old stuff, and b)more unpredictable.

My 16H front brake is excellent on old linings (just like the old magazines used to say - and modern writers accuse them of telling fibs!)

I do find the TLS on the Dommie is better after a good cleaning - partly to remove dust from the chamfer on the leading edge. That chamfer should (in my experience of one observation) be generously long and shallow angled.

I confess it has snatched once or twice on the road - in a few tens of thousands of miles. But as long as I ride to the end of my street with the brake dragging (and snatching, and squealing like a stuck pig) it then sorts itself out for the day.

As for adjusting - last time I did it (many miles ago) I set it up on the bench so that the cams lifted both shoes at exactly the same instant. Then when the wheel goes on, hold the brake lever hard before tightening the spindle nut. I'm sure you know all this...maybe in the extreme a new set of shoes will improve it.

The MOT man always remarks on how its stopping power is good. And he usually tests modern bikes.

A properly arced and adjusted TLS with good shoe material, teflon cableand a 7/8 lever is a very good brake, fitted with the stiffening kit it's unstoppable..

The cable routing on the dominator with flat bars is a bugger, the levers are too flat or they're too steep. The doherty levers with no adjuster makes the cable routing slightly easier but it's not great.

i've just machined up some riser blocks to raise the centre of the bar an inch and although they're not my finest work it's function over form in this case.

My dad cannot ride a dominator with flat bars because of his damaged wrists and the lever angle, i dare say a lot of people would find their braking strength would improve if they could just get the levers in a comfortable positon.

Previously ian_cordes wrote:

With correct adjustment, the brake has worked well until recently. The cable run with the straight bars is definitely an issue, but the problem of staying on has only arisen since I replaced the old levers which were, I believe, 1 1/8" pivot centres, with 7/8" centre levers, because everyone on here says they are a must! I am not so sure....

I will sort through them thoroughly, but will reluctantly re-fit the raised bars in order to get a decent cable run.

Ian

The definitive answer to this , Ian, is to refit the 1 1/8 levers, return everything to how it wasand see if the brake stickingproblem goes away.

Thanks, that's very nice of you Ian, I've noticed this site does seem to have a rather nautical theme...

Ian - if it's worked until recently, it can't be the materials (they have not changed) and it's not likely to be the adjustment (because it will have bedded in long ago). So I suggest four things which can creep up:

1) rust on the drum if it's not been used for a while - I think that's why mine is sticky on starting

2) dust build up on the leading edge shoe chamfer - thus reducing the effectiveness of the chamfer.

3) The other possible is tightening the spindle nut last time - without holding the front brake on to make sure it's centred.

4) Worn shoes so the cams are now going more nearly over centre than they were previously

Hope the weather is better where you are (pouring down here)!

Regards

David