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leaking brake fluid

Discussion in 'Bling and Appearance' at netrider.net.au started by OG, Nov 20, 2007.

  1. my front break fluid thingey is leaking somewhere near the top
    saw a bit on the top fairing

    dam im going to have to drain and fill it - i cant just top it up because i dont know whats in it atm because i just got he bike

    what should i put in on the across
  2. Check your manual but is probably DOT 4.

    If it looks contaminated (dirty sludge) then change it out, if it looks clean it may just need the level adjusting. Reservoir fluid level changes with brake pad wear and putting new pads in can push the level in the reservoir up (if it was topped up as the previous pads wore down) -- if the pads have plenty of fat on them consider the possibility that the reservoir is overfilled which is causing the leak.

    If it is leaking and the level is correct then check the rubber diaphragm in the front master cylinder reservoir for damage. If its stuffed you'll need to change that out. Also check for leaks around the rubber boot where the front brake lever actuates the master cylinder piston and also the brake banjo fitting - all possible leak points.

    Another sign of leakage is if you get a firm lever if you pump it a few times and then it goes soft (oo-err missus).
  3. OK the level is on low
    the front pads were changed a month ago
    and the leak is near the handle bars where the reservoir is
    liquid looks clean
  4. ok i had a look looks like the fluid is coming out of my throttle cable, is that possible???
    they may have lubed it a week ago is that what is is or is there oil in there
    anyway there was a nut i tightened it

    i better fill up the dot4 in the across its right on the low mark
  5. If the liquid is looking good then previous owner may have changed it at the same time as the pads.

    Where exactly is the leak ? Assuming that you don't have a cracked master cylinder it has to be either:

    1. Where the brake banjo bolt (brake hose) attaches to the master cylinder
    2. The cap of the master cylinder
    3. Where the piston enters the master cylinder (on the lever side).

    Which one of them does it look like it is?

    Try wiping any leaked fluid and then pumping the lever. See if you can spot the fluid leaking out.

    If its location 1 then try releasing and re-torquing the banjo bolt (keep lever pressure on when you do this so not to suck air in) or consider removing them and fitting new crush washers - they are usually only good for one or two goes - they deform to form an air-tight seal.

    If 2 - has to be the diaphragm.

    if 3 - then its possible the piston cups/seals have worn or perished and you're leaking fluid from the piston bore. That usually means a rebuild of the master cylinder.

    If your confident with your mechanical abilities then rebuilding the front master cylinder is not too difficult as long as you have the spares. Else, if it's not 1 or 2 I reckon you should consider getting it to a garage.
  6. nah looks like it is the throttle cable , now i have no idea - the dot4 is low ill fill that up

    but how can the throttle cable leak ?
  7. Beats me. Never heard of a hydraulic throttle :)

    If you're sure its from the throttle cable then you could try opening up the throttle housing, may just be water in there or someones been a bit keen with the lube. Might be a good time to open it up, displace any water with wd40 and then lube the cables.

    You said you just got the bike so unless it was recently serviced then its good practice to give it a once over and give everything a good clean and lube.

    On the brake front - if the lever feels firm and you don't need to pump it to build pressure and the brakes are working you are *probably* ok. If you have any doubts whatsoever about your brake function and you don't know how to fix yourself then get it to a garage. Brakes are pretty important. Just keep an eye for any leaks and don't ride it if you think theres a problem with the brakes. Thats my disclaimer :grin:
  8. i think they filled the throttle with wd 40 or something