CalVin Rear brek light switch

[robertllr]

So our 2007 CalVin rear brake light does not work.  The in-line hydraulic switch has two wires and if I jump them I get a light.

Three questions  1) Could a small amount of air in the line prevent the switch from operating?  The rear pedal comes up about an 1/8 inch when pumped, so there is at least a little air in the line.

2) An OEM replacement switch is over 50 bucks but, there are plenty of aftermarket choices.  However, I need to verify the thread size and pitch.  Anyone know?

3) Lastly, from what I read here, linked brake bleeding is--or can be--problematic?  Looks to me like the switch is at the top of the system and, though messy, might be a good place to bleed.  Thoughts? Thanks!

[rodekyll]

1)  No.

2)  Don't know, but it's a simple pressure switch.  Any switch of the proper thread ought to work.

3)  No, not really.  There's a technique that's generally effective, and a few tricks that help move air bubbles around, but it's generally the same as any other brakes.  Look at the splitter for the brake linking -- is there also a bleeder on it?  IIRC, there should be.


The 1/8 inch is probably pad slack and lever 'feel', not air.

The switch can be replaced without the need to bleed if you have the new one all ready to install.  Just have a friend apply soft, even pressure on the brake control while you quickly unscrew the old one and install the new one.  Have a cloth around the switch spigot as there will be fluid.  But as long as you have more pressure inside the brake lines than outside, air can't get in.  If your friend is too enthusiastic, once the old switch is out, put your finger over the hole and have him stroke the pump.  Install the new switch on his second stroke.  Don't forget to top off the fluid.

[robertllr]

As so often happens, one must answer one's own questions.  I hope this  additional info will help others.

The pitch and thread of the switch is 10mm x 1.00.  There are many offers to be had on Amazon and Ebay, at a cost of about $6 to $18. I chose this one: 

http://smile.amazon.com/Tusk-Hydraulic-Switch-Brembo-Brakes/dp/B0039ZS0W8?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

It is advertised as a universal fit for Brembo systems, so it may fit many other Guzzis.  Shipping was fast and free.

There is not point in pressurizing the M/C when removing the switch as no air will be drawn into the cylinder.  The mess it makes will not be worth it.

However, since  the switch has hollow passageways, putting in a new switch will introduce some air into the system.   Some suppliers advocate filling the switch with fluid before installing--but I found this to be impracticable. 

What worked very well for me was, after installing and wiring the switch, pressurizing the pedal (I had my wife do this) and then slowly cracking the switch/banjo bolt (with a rag wrapped around the fitting) until the pedal began to go down, then tightening and releasing the pedal.  Dong this three times bled all the introduced air out, without too much fluid loss, and gave me back my firm pedal, without having to bleed the rest of the system--though I did that anyway.

The Tusk switch came without the 90 degree boot, so I just reused the old one, and spliced in the stock connector as well.  It comes with a pair of aluminum sealing washers, but I decided to anneal and reuse the stock copper ones.  (Been doing that with my old Triumphs since the first time I took a wrench to a bike--back in 1969!) No leaks.

The switch works as it is suposed to do, triggering the light just as the pucks kiss the disk.

Other reviewers on Amazon seem pleased with the  longevity of the part, so I am hopeful I won't  be doing this job again soon!

Hope this helps.

[CalVin2007]

  You bet it helps...thank you! My '07 CalVin has the same problem (although intermittent) and I will order one of these to fix it. Well done. 

  Terry