Stoplight switch for drum brakes on a '72

aboone · Nov 15, 2012

Anybody know how to test or troubleshoot the captured style brake switch? Mine was working until I had a new Barnett cable made and they reused my part.

Is it just a reminder to never put new parts on if not totally necessary

BillT · Nov 15, 2012

I would put an ohm meter on the two spade terminals. The switch activates when cable pressure pushes the contacts together. If you don't get continuity when the lever is pulled, either the switch is broken or the cable isn't closing the switch. You should be able to press the contacts together manually, which will tell you if the switch is bad or the way the cable was done isn't closing the switch. Also check that the power wire has power while you've got the tester out.

I had to get a Commando front drum cable for my Ranger, as there was not a replacement available at the time (Previous P11s didn't have a switch on the front cable - only the rear brake lit the light!), and cut about 6" off the cable. Everything works fine. It's even got this nice little two-piece boot to cover the switch, with a hole for the wires.

aboone · Nov 15, 2012

Thanks Billr, I should have figured that out.
Now I am wondering if I should just get a new cable and eliminate the switch. Anybody know if that helps eliminate the"mushy" feel when applying the front brake?
(I have rebuilt the front per Old Britts article with the shoes and drum arced to within .025")

cjandme · Nov 15, 2012

aboone said:
Thanks Billr, I should have figured that out.
Now I am wondering if I should just get a new cable and eliminate the switch. Anybody know if that helps eliminate the"mushy" feel when applying the front brake?

I would get a new cable without the switch......My brother replaced his and said that it improved braking dramatically. He'd just hit the foot brake for the light. Cj

DogT · Nov 16, 2012

It would be easy enough to put a micro-switch on some part of the front brake where the cable comes out and wire it into the front brake switch connectors by the headlamp. Tie the wires on the cable. Something I've been thinking about but not done yet. That original switch can be taken apart, cleaned up, put some de-ox on the contacts, but it sure does make the front brake spongy and it's a kloodge of a switch.

Dave
69S

Holmeslice · Nov 16, 2012

DogT said:
It would be easy enough to put a micro-switch on some part of the front brake where the cable comes out and wire it into the front brake switch connectors by the headlamp. Tie the wires on the cable. Something I've been thinking about but not done yet. That original switch can be taken apart, cleaned up, put some de-ox on the contacts, but it sure does make the front brake spongy and it's a kloodge of a switch.

Dave
69S

Top tip!

For a customer's bike we built, I sourced a little switch that was activated (closing the loop) by pulling a little spring. The switch is mounted on a bracket on the slider, out of sight behind the fender boss. The spring is pulled by the TLS brake arm as the brake is squeezed. This setup keeps the cable as a straight shot to the linkage - nothing inline - and eliminates a lot of that mushy feel, while keeping a front brake light that's fully adjustable as to when it is activated. I've done the same on the rear, with the linkage actually activating the switch.

I can show pictures to interested parties.

DogT · Nov 16, 2012

I'd like to see what kind of switch you're using, the micro-switches are pretty small and delicate looking.

Dave
69S

J.A.W. · Nov 16, 2012

Yamaha [RZ, & others] rear brake light switches function in exactly that way, mount out of sight, & are durable, should be easy to find/inexpensive.
Unless as a legal requirement for test, I prefer not to use the front brake light.

xbacksideslider · Nov 16, 2012

As I recall the "spring" in that switch is just a piece of compressible rubber/plastic and some contacts and it just snaps together and can be "picked" apart for cleaning.

komet · Nov 16, 2012

Holmeslice: For a customer's bike we built, I sourced a little switch that was activated (closing the loop) by pulling a little spring. The switch is mounted on a bracket on the slider, out of sight behind the fender boss. The spring is pulled by the TLS brake arm as the brake is squeezed. This setup keeps the cable as a straight shot to the linkage - nothing inline - and eliminates a lot of that mushy feel, while keeping a front brake light that's fully adjustable as to when it is activated. I've done the same on the rear, with the linkage actually activating the switch.

I can show pictures to interested parties.

Yes please!

Holmeslice · Nov 17, 2012

A couple of shots I snapped yesterday. Now when doing this I have fabbed up a trick alloy arm to fit in conjunction with the top lever, extending behind the slider, allowing the switch to be mounted behind the slider with its attached to this arm, making it even more out of the way.

http://www.accessnorton.com/gallery/album.php?album_id=38

komet · Nov 17, 2012

Hey thanks for posting the pix.

DogT · Nov 17, 2012

Yeah, thanks, have you got a part number for that switch, or is it just a universal stop light switch?

Dave
69S

Stoplight switch for drum brakes on a '72

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