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royalenfield@yahoogroups.com Re: [Enfield] Help! Twin leading edge basic brake setup for Bullet 500
I didn't even know that IE has a twin-leading-shoe front brake,
but that won't stop me from pontificating. Here's some pointers
that will work for any drum brake, single or twin-shoe:
First, I'd make sure the shoes are "arced" properly to the drum.
Use a "liner" of ~100 grip sandpaper in the drum, stuck on the
inside surface somehow. Drop the backing plate into place, and
twist one of the cam arms until it's up against the sand paper.
Rotate the backing plate to show you the high spots. Do what
you have to to get the shoes arced to the drum surface. This
should preferably be done with the axle in place.
Now for the setup:
>1) How do I determine the position of the cam arms? In general, is it that I position the cable arm further down so that the cable gets more pull, or am I way off with this?
You want the cable to be perpendicular to the cam arm at the point of contact (shoe with drum.) This will give you the maximum mechanical advantage. This applies to both cam arms.
>2) Do cams lie flat in the resting position, or are they supposed to be partly turned by cable tension (because there seems to be a huge amount of travel in the arms before shoe meets drum).
Cable tension. A truly refined system would have stops against which the arms rested at no-brake time, but cable tension is good enough. Has the added advantage of being adjustable from the handlebars.
>3) How, if at all, does the link rod act to adjust the arms? (I've broken one already playing with adjustment.)
Obviously, both shoes want to make contact with the drum at the
same time. So I'd twist the the cable arm until it made contact,
then twist the other one until it made contact, then with my
third and fourth hands, I'd adjust the linkage to the length at
which the clevis pins would drop easily into the clevis'. Then
I'd let go of the whole mess, put the wheel back on the bike, and
go out and make some rubber marks on the road.
As for breaking the rod, I can't imagine how. Did you maybe leave
the locknuts tight and try to adjust the length? Always loosen
locknuts before adjusting, I'd say.
Good luck.