Replacing sight glass in front brake master

[Troyskie]

I've a leak in a nice, recently rebuild master.

A couple of years ago I found a mob in Dublin VA, USA, called New River cycle Salvage. I probably got the info from here.

They do glass replacement sight glasses.

You pull out the old plastic sight glass, give everything a clean.

Their glass is just a simple disk.

You're best to do a few test fits first. Mine were very promising

I salvaged the o-ring, but it is not necessary. When I set the glass into the silicone o-ring the silicone spread out more than I expected.

I'll let it cure and fill it with fluid to see if it leaks.

I did a messy job this first time. If it leaks I'll pop it out and not use the o-ring. I used clear RTV silicone. Without the o-ring i'd use black.

New River have both glass and plastic. I'm using the glass. It feels pretty strong, and I'm quietly confident I can save it, give it a clean and re-use it, but I did buy spares just in case....

[Tuned forks]

That is remarkably clear.  I can barely see thru the plastic sights for the master and the engine oil.

I see from the bottle caps that replacement is a two beer job.

[ZOA NOM]

Is there no concern about contaminating the brake fluid with silicone?

[Troyskie]

I did wonder about that Rick.

The instructions said to use clear RTV silicone, and the one i chose an automotive brand.

[Troyskie]

That is remarkably clear.  I can barely see thru the plastic sights for the master and the engine oil.

I see from the bottle caps that replacement is a two beer job.

He he he, I have to down tools after 3. My confidence increases, but the workmanship decreases