I’ve been meaning to correct the relationship between the front brake cable and the brake arm on the front hub for a while. I was reminded about this while I was away at the Guzzi Festival last month.
For the best mechanical advantage the “angle of attack” between the cable and brake arm on the hub should be as close to 90° as possible when the brake begins to “bite”. On The Fire Bike the angle is obtuse (over 90°). The following photo was taken with the lever on the handlebars pulled.
I know the brake shoes are not worn out so I decided to try and move the levers round one spline on their shafts.
To disconnect the brake cable at the lower (hub) end I had to disconnect it at the top (handlebar) end first. Then I removed the clamping screws from the two brake arms and marked their positions on their shafts. There is a casting mark across the shafts and I used this as a reference point.
I made these marks in case the levers came off with a jolt and I lost track of where they had been originally.
I removed the link rod between the two brake arms (a split pin and clevis pin at each end) without altering its length. Both levers on the hub were pulled off then replaced one further tooth clockwise on their spindles. The fixing screws went back in and were tightened.
I was pleased that I managed to do this without pushing the spindles into the hub brake plate. The alternative would have been to remove the wheel to carry out the job on the bench.
As both levers had been moved by the same amount, the link rod could be put back without losing the setting of the brake arms relative to each other. Of course, new split pins were used.
Refitting the cable was a bit of a job. It’s now just a bit too short – about 5mm at a guess – and I had to remove the support for the cable from the front mudguard to do it.
Once the cable was re-attached at both ends the cable support could go back. All that was left was to adjust the brake and take the bike for a ride. I can’t say that I noticed any improvement but am happy to have “got it right”. That front brake is not brilliant and I need all the mechanical advantage I can get. This is the right-angle between cable and lever that I was looking for. Again this is with the lever pulled till the brake is just “biting”.
A squeak from the front forks?
When talking to Dave P at the Guzzi Festival I mentioned that I would probably rebuild the front forks over the winter as they squeak. He explained that his are the same. He has found that the squeak is caused by the front brake cable rubbing on that support screwed to the front mudguard (fender for our American friends). It went away when he put some grease there. Sure enough, that’s my suspension squeak!