Brake Adjusters

[David Morris]

Hi All, with the emergence of ( finally! ) some sunny weather, I expect owners are starting to venture into their garages, and begin waking up our Javelins and Jupiters? One situation that I have experienced concerned the fitting fresh brake shoes to a full hydraulic braked Javelin. In this case it was the rear shoes, but I suspect it would also affect the front shoes on a hydro-mechanical Javelin? In reconditioning the rear brakes, we completely stripped the back plates, stripping all components off the back plate and repainting. The same would probably apply to a Jupiter.

Reassembly followed, followed by a big disappointment! The drums wouldn’t go back over the new shoes! Had we been supplied with new shoes that were too large? Much head scratching followed, with no clear solution. Suspicions were levelled on the suppliers of the new shoes!

Finally, and I do mean many hours later, we stumbled on the solution. The adjuster consists of two black iron wedges that fit against the feet of the shoes, operated on by an adjusting bolt, that had four sloping faces, two of which in turn pressed on the chamfers on the ends of the wedges. Rotating the adjusting bolt pushed the wedges in or out, hence making the adjustment of the shoes. The black iron wedges look identical. But they are not! Finally, we discovered that these steel wedges that constitute the adjusters are handed! In place, they look fine, but actually if you get them muddled, they stick out fractionally too far. The solution, if you find this problem, is to pull out the adjusters, and put the one facing forward in the facing backwards position and vice versa. Then the drum will slide nicely over the new shoes, which were the right size after all!

So, if your new shoes don’t allow the drum to fit back into place, even with the adjuster fully backed-off, check the black iron wedges! You have probably got them muddled up, even though they look perfectly ok!

And, on a postnote, don't be tempted to tighten up the nuts holding the rear hydraulic cylinders to the back plate too far. They are meant to be a sliding fit, allowing them to find their own position on the backplate, and you need some careful greasing here to make sure they do indeed slide. I have seen original nuts on these cylinders that were castellated, with a tiny split pin, so that they could be tightened enough, but not so tight that they would prevent the cylinder from being able to slide backwards and forwards. Also, in service, you need to apply some oil to the backplate here, to keep a degree of free movement, as the whole backplate gets wet in the rain and rust will prevent the cylinders moving freely.

Let's look forward to a super spring and summer!

All the best,

David