Front Brake Light Switch - What returns it to the off position?

[bgauweiler]

Hi All,

Need some help from someone who has disassembled the front brake switch on a 77-78 GS400B (With Disc Brake). I had to rebuild the master cylinder and now I'm reinstalling the front brake switch components. Looking at the switch, I see no way for the "pin" (plastic part pushed forward when the brake hand lever is squeezed) to be "retracted" into the off position. It's been several weeks since I disassembled it, so I guess I might be putting it back together incorrectly but, it looks like it can only go back together one way.

So long story short, after I put it back together, squeezing the brake lever did actuate the rear brake light but, releasing the lever did not turn the brake light off and the plastic pin is sitting in the on position.

Any help would be greatly appreciated,

Bernie

 

[cowboyup3371]

Slide the metal contacts of the switch itself (not the u-shaped contact) one way or the other so that it doesn't touch any longer. It is not an on/off but a slide

 

[bgauweiler]

I understand it's a slide and as far as I can tell, the brake lever pushes the pin/slide in to turn the brake light on. The issues I'm having is what moves the pin/slide back into the off position?

Slide the metal contacts of the switch itself (not the u-shaped contact) one way or the other so that it doesn't touch any longer. It is not an on/off but a slide

 

[cowboyup3371]

As your brake lever pulls back to the handle, it pushes on the piston that allows brake fluid to flow down to the calipers. The piston has a couple of slots in it for the U-shaped contact. That contact should be in the slot closest to the right side end of the handlebar. The switch wiring should be positioned so that the metal contacts on it touch the U-shaped contact when the handle is pulled in.

I can take a picture of my daughter's bike tomorrow night as I'm at Cincinnati Children's Hospital tonight with my other daughter.

 

[bgauweiler]

Well, I believe the mystery of the non-returning front brake light switch has been solved. The slide wasn't able to return because a previous owner must have replaced the brake lever with an incorrect one. The lever I have is missing the notch which the plastic pin rides inside (circled in red in the attached picture).



Going to order the correct lever and hopefully, that resolves my problem.

Bernie

 

[Gorminrider]

Note that the brake switch is adjustable

if you look at your switch or even your picture in post 1 you'll see that the mounting holes are a bit elongated....so when you get your new lever, this is important.

 

[Steve]

Back to the original question: "what returns the brake light switch to the OFF position?" :-k

There is a spring inside the master cylinder that pushes the piston back to its 'home' position. The brake lever rests against the other end of the piston. If the pivot point of the lever is not worn, there is usually very little clearance between the lever and the piston. You have seen the hole (notch) in the lever that surrounds the pin on the switch. There isn't much clearance between the pin and the hole, so when the spring pushes the piston back, it pushes the lever out and moves the switch. As others have noted, the housing of the switch is adjustable, so you can move it to a point where the brake light is OFF when the lever is not being pulled.

.

 

[Guest]

Hi-jacking thread; Have same issue...but confused.

So, the plastic 'u-contact retainer pin' (for lack of a better name) should be inserted within a channel at the butt end of the brake handle?
I ask because my bike came with NO switch hardware at all-just a dangling harness that at the time I had no clue what it was for. Microfische drawings really don't define how this contraption is supposed to work. Bought the switch & figured out how to build up the 'u-contact retainer pin', but popped it into the handle thinking the release butt simply pushed the 'pin'...but then, how does it retract??

 

[Gorminrider]

here, 748, from BikeCliff's. with Much sympathy for trying to find the words... second link is a pdf so right-click the mouse and choose, "save as" might download the pdf if that's your preference.
http://gsarchive.bwringer.com/
gsarchive.bwringer.com/storagecliff/images/front_brake_switch_repair.pdf

 

[Guest]

No sympathy needed. Thanks for the link!! Don't know how I missed that at Basscliff's...great stuff. Think I know what I did wrong now.

Thanks again for setting me straight.

 

[danbob]

Just a couple of quick tips that I've learned while working on tiny switch parts like these. Before and after cleaning everything, I prefer to set parts on a well anchored towel that will keep parts from blowing around in wind or otherwise getting misplaced by my activity. That, or put them in a small container like a margarine tub. I like to clean electrical parts with a small brush first and degrease. Then buff gently with a Scotchbright pad. To keep oxidation at bay, I apply dielectric grease.

Most importantly - during reassembly, I find it very helpful to liberally use dielectric grease to hold parts in place while assembling. The grease makes the tiny parts stick to anything they touch, which holds them in place for assembly and keeps the parts from going very far if they do misbehave. For example, grease holds the tiny detent spring safely in its tiny pocket and more grease on the tiny detent ball holds it in place on the end of the spring. Then the maddening job of getting the parts compressed and assembled is manageable.