Gentlemen:

On the '69 Triumph I'm fixing up there is an inline front brake switch
through which the front brake cable runs (the cable has a break in the
housing to accomodate). This switch looks like a small cylindrical
object which seems as if it should work under pressure from each end.
The pressure however seems to need to be applied not by the cable but by
the cable housing which is pressing against the switch from either side.

However it doesn't work and I don't quite understand how it would work.
When the brake lever is pulled the cable moves of course but the cable
housing doesn't budge.

So am I misunderstanding completely how this switch works?

Thanks in advance,
Justin

In article <g6quin$jss$1@grapevine.wam.umd.edu>, "Justin" <no@spam.com>
wrote:

> Gentlemen:
>
> On the '69 Triumph I'm fixing up there is an inline front brake switch
> through which the front brake cable runs (the cable has a break in the
> housing to accomodate). This switch looks like a small cylindrical
> object which seems as if it should work under pressure from each end.
> The pressure however seems to need to be applied not by the cable but by
> the cable housing which is pressing against the switch from either side.
>
> However it doesn't work and I don't quite understand how it would work.
> When the brake lever is pulled the cable moves of course but the cable
> housing doesn't budge.
>
> So am I misunderstanding completely how this switch works?

When you squeeze the brake lever, the inside wire of the brake cable
gets pulled; it works against the outside sheath of the cable. The wire
is under tension; the sheath is under pressure.

Your switch works by sensing the pressure in the sheath. As you pull on
the inner cable, it wants to compress the sheath. The inner brake cable
itself doesn't have to move very much inside the sheath; indeed, if it
has to move a lot, then there's probably too much free play in the
system. (This is where my experience with cable brakes on motorcycles
ends, so I'll shut up now.)

--
Timberwoof <me at timberwoof dot com>
faq: http://www.timberwoof.com/motorcycle/faq.shtml

"Justin" <no@spam.com> wrote in message
news:g6quin$jss$1@grapevine.wam.umd.edu...
> Gentlemen:
>
> On the '69 Triumph I'm fixing up there is an inline front brake switch
> through which the front brake cable runs (the cable has a break in the
> housing to accomodate). This switch looks like a small cylindrical
> object which seems as if it should work under pressure from each end.
> The pressure however seems to need to be applied not by the cable but by
> the cable housing which is pressing against the switch from either side.
>
> However it doesn't work and I don't quite understand how it would work.
> When the brake lever is pulled the cable moves of course but the cable
> housing doesn't budge.
>
> So am I misunderstanding completely how this switch works?
>
> Thanks in advance,
> Justin
>
IIRC the cable housing should try to 'shorten' and close that gap slightly
(enough to work the switch) when the inner cable pulls on the brake. Are
your cables routed correctly. Also, could be a bad switch - Lucas no doubt.

On Jul 30, 4:47�pm, "Justin" <n...@spam.com> wrote:

> However it doesn't work and I don't quite understand how it would work. �
> When the brake lever is pulled the cable moves of course but the cable
> housing doesn't budge. �

There is probably power going to the brakelight housing and returning
to the headlight housing and going out to the brakelight switch, which
(crudely) completes the circuit to ground (or "earth" as the Brits
would say).

http://www.triumphrat.net/classic-vi...ont-brake.html

Timberwoof <timberwoof.spam@infernosoft.com> wrote:

: When you squeeze the brake lever, the inside wire of the brake cable
: gets pulled; it works against the outside sheath of the cable. The wire
: is under tension; the sheath is under pressure.

Oh, I get your point, I simply wasn't thinking about the mechanics
thoroughly and correctly.

I think the problem (as Vito hinted at) is that things mightn't be
adjusted correctly. Not enough tension in the cable to start with
perhaps. A Lucas switch of course!

I'll have a fool around with it tomorrow and see what I can do.

Many thanks indeed,
Justin

In article <g6r2uk$lqn$1@grapevine.wam.umd.edu>, "Justin" <no@spam.com>
wrote:

> Timberwoof <timberwoof.spam@infernosoft.com> wrote:
>
> : When you squeeze the brake lever, the inside wire of the brake cable
> : gets pulled; it works against the outside sheath of the cable. The wire
> : is under tension; the sheath is under pressure.
>
> Oh, I get your point, I simply wasn't thinking about the mechanics
> thoroughly and correctly.
>
> I think the problem (as Vito hinted at) is that things mightn't be
> adjusted correctly. Not enough tension in the cable to start with
> perhaps. A Lucas switch of course!
>
> I'll have a fool around with it tomorrow and see what I can do.
>
> Many thanks indeed,
> Justin

Good luck. Please post here your results: My diagnosis was really just a
shot in the dark. I've never actually seen that kind of switch; I just
took a stab at how it must work from your description. So let me know if
I was right. :-)

--
Timberwoof <me at timberwoof dot com>
faq: http://www.timberwoof.com/motorcycle/faq.shtml
Ten Steps to Fascism: http://www.guardian.co.uk/usa/story/0,,2064157,00.html