I'm working on changing out my handlebars, and after removing the brake lever/master cylinder assembly, I gently lowered it down to let it hang while working on removing the throttle cables. A couple minutes later I noticed that fluid was leaking out of the top of the master cylinder while it was upside down. Is this something to be concerned about?

Thanks,
-Dave

 

Dmayer, I am not a tech but I have done a lot of work to my bike over the last year...basically tearing all down and rebuilding it.

I just wanted to tell you something that has happened to me along the same lines. When I rebuilt my front end with new folks, lower sliders etc, I also had pulled off my front brake caliber and put it aside...and yes fluid leaked out. After I got it all back together (with a new brake line)..I took FOREVER to build pressure so I had to resort to some bleeding tactics I learned here. Now that I have it all working again (including the front break) I have been chasing a leak for about 2 months now. It is either coming from where the line meets the caliper or the caliper itself.

In short, I think you should be fine, but I would get it back together and check for leaks. Perhaps someone will give you better advice, but since I had that caliper off and fluid out like you, I am still struggling with the damn thing. Good luck.

FWIW, my leak only seems to be when I apply pressure to the brake handle.

Kramer

 

I would check how tight the two screws holding the cover on are...

maybe a little light lock-tite (NOT RED) and give 'em a little love.. your bars and everything connected to them shake like the dickens , bein' that you have a rubber mount and all...

 

His leak is out of his "master cylinder" (I am just assuming it's leaking at the cover gasket)...

Your problem is MUCH more serious and you should get it fixed right away before you grab for the binders and....there aren't any.

Shouldn't be leaking at the banjo bolt/fittings or the calipers and if it happens with pressure, you could get air in your lines when you release your brakes and it "vacuums ..."

at the very least, you will continue to lose fluid 'till.. well, you know the rest...

 

Im a tech who deals with bar swaps daily this is normal. The cover was not designed to hold fluid in while upside down. make sure you remove the cover and clean the top and gasket throughly especally the part between the top cover and gasket otherwise fluid gets stuck there and you cover will begin to weep,which will cause the outside finish around the cover to bubble and peel

 

did you replace the two crush washers at the caliper fitting? they should be replaced every time that could be your issue

 

+1 and also don't over tighten the cap screws, finger tight is all that is needed or you will get a leak. Spec is 6 "inch" pounds, you can barely measure that.
CB

 

 

yeah the cover is not designed to be left upside down. whenever I do work that requires the master cyl. to come off the bars, I keep it right side up. Anyways...once you reinstall, take the cover off and clean it up then put it back on. gently tighten the screws. Watch the gasket and evenly put a little pressure (1/4 to 1/2 turn from lightly seated) on the gasket from both screws. Won't leak while upright. the gasket should compress a tiny bit if properly installed.

 

what he said