At the last stop on the way home from a great weekend at Port Victoria, I noticed what appeared to be a spray of something on the front brake master cylinder. Thought it might have been a bug splatter and wiped it off, didn't really smell like brake fluid. 

Once we got on our way again, more fluid, so it had to be brake fluid leaking. Got home and examined it more thoroughly and realised the fluid was leaking slowly from the inspection window, between the grommet and the window itself. I'm not sure why, but it seems to leak faster when I depress the lever but as far as I know, there's no pressure inside the fluid chamber, is there?

I guess I could let the fluid level drop lower than the window so it didn't leak, but I should probably do the right thing and try to fix it! So if anyone has had this problem before, or has any suggestions.... I'd appreciate your input. It's an aftermarket set of controls, Custom Chrome I think, but I believe it's a clone of the OEM part.

Bummer. Don't worry about it, having brakes is only gunna slow ya down anyway.

ive had same leaking shit my 08 fatbob ,found out that rubber seal under lid will weep if overtightened also idrained my fluid with syringe down till fluid till say 5 mil over piston hole ,dont pull lever if cap off coz brake fluid will squirt strate up at you an all over ya bike yus get big syringe an suck up perhaps new rubber for cap or new cap with rubber already on it ,i bought new hd cap and rubber is already part of cap its a shithouse design someone fuked up they shouldnt leak but they do from brand new wen tightening screws jus a bit each side at a time and not tight just nip up till firm no locktite ,an if ya think ya caps ok well jus clean it up can use water then let dry in sun if its one of those rubber seal attached types u can get em off but then ya gotta get back over that window piece  ,and yes there is pressure in master cylinder wen brake applied or lever pulled ,but dont pull that lever if cap off coz could get air into system by piston sucking in if ya pull thats wat ive done over the yrs 2 all mine and no more weeping ,ive had dealers fill up master cylinder loktite screws in after ive told them not 2 and get home and hav 2 undo wat has been done ,once i forgot 2 check was in for service after week ive gone wat da fuk fukin brake fluid everywere ,had been on a run hard brakinetc only 2 spot wen get home da fukin idiots hav done it again ,i think they used impact driver on screws an loktite again an wen ya pull off cap dat shit falls into master cyl thats my 2 cents on this SHINGLES

Thanks shingles, I learnt by experience too about the seal on the lid, and the squirting thing, but my leak is from the inspection window on the side facing the rider, between the little round window itself and the rubber grommet. I'm hoping I can just replace the grommet, but I thought I'd try to benefit from the collective wisdom here....

Talking about wisdom, thanks for the tip GT! I know from experience that when riding with you, brakes become something to be scorned at, it's that twisty thing on the handlebar that gets all the attention.....

Colstah I hope you washed it down with lots of soap and water. You know what brake fluid will do to paint.... The plunger inside your cylinder provides the pressure down the brake line. So there should be no pressure inside the cylinder. if it is leaking, more than likely the rubber seal has perished. Easy fix just a bugger to bleed the brakes after.. And if you are in there you may as well replace the seals on the plunger at the same time. Cheap easy task...

The inspection window is a replaceable part and also has an "o" ring on it that does the sealing. It pushes out from the inside out. Fairly hard to do but it is doable. I have done it on a mates bike a year or so ago.
I am talking OEM here but is will prolly be the same size. Measure it up and compare with standard one. Hope this helps.

Thanks FLHuTChu, I guess I'll try to get the replacement then. I do have an old master cylinder, but I'm not sure if I'll get the glass and rubber grommet out without destroying one or both in the process. The bloke I bought the controls from said OEM seals fitted, so hopefully the glass will be the same.....we'll see.... Thinking about it now, I got some OEM controls chromed many years ago, I must have taken the grommet and glass out then....hmmmm....

As a by the way, I drained the cylinder and wondered how I would get the glass and grommet out. Well, it more or less dropped out when I tentatively pushed it with my finger. Turns out, the glass window was broken in at least two bits, might have lost a third bit somewhere when I was pulling it apart. Picture below, and I have no idea how this occurred. Didn't notice anything over the weekend but when we stopped at Lower Light I saw it when we pulled up, as I hit the kill switch, so probably started leaking between stops. There was no sign before the weekend, I pay pretty good attention cleaning it.....

The only other thought is someone is out to get me.........

 

 

And AJ, I too didn't there should be any significant pressure in the chamber. And as for the seals, the unit is only about four months old, so the seals should be OK. However, for the glass to be defective after such a short period, who knows what the seals are actually like!! I wont warranty it, unless replacing the glass turns into a hassle, should be much easier to drop in the new glass than take the unit back, re-bleed etc., etc.....

Well, I got the old glass out of an old busted master cylinder pretty easy, just eased it out with a small screwdriver blade, rubber grommet and all. Seemed to be the same size, so I used the original grommet since it was newer, put that in place, then pushed the glass window into the grommet from the inside. A little bit of tinkering to make sure it seated OK, and all is good.....so far.

Thanks for the heads-up, FLHuTChu, had the crazy thought I might have needed to buy a new master cylinder....

And just on the off chance the wifey should read this....see! I told you keeping all that old junk would pay off!!

colstah I remember seeing a seal/new window kit in one of the after market books think it was custom chrome if you still need one

Thanks, perthhog, seems OK now, but I'll keep that in mind....

Good result mate. I'm sure you only kept the good junk.