Sight glass on brake fluid reservoir...
 

What does it do? I've had my Ultra for nine years, change brake fluid every two years, and every time I wonder about the sight glass in the covers of both front and rear reservoirs. I have yet to see anything in it.

I'm thinking that perhaps if you didn't change your fluid, and it darkens over time, that you may see that in the sight glass, whereas you don't see clear, fresh DOT 4 brake fluid.

Well, either I asked a really dumb question, or no one else knows the answer either. When you remove the reservoir cover, you can see the sight glass telescopes down into the fluid. Does something happen, perhaps, if the reservoir is low on fluid? I'm really wondering what this sight glass is for.....

Anyone?

In the correct light, (from overhead) if the fluid drops below that plastic pointed pintle sticking down from the underside of the cover, the button will go from dark to light.

Remove the two screws and raise up the cover. You will understand.

Thank you, ripsaw, if that is what happens. In other words, if you have a fluid leak, you will see it in the sight glass?

Incidently, I do have the service manual, and can't find any reference to it at all.

If you totally ignore maintenance, as the pads go from new to almost warn out, the pistons in the calipers will get far enough out that the button will show a low level also. I would think the indicator would be mentioned in the owners manual.
Service and my State inspection removes the cover to check.