FRONT Brake Leaking

When i last went out on my bike i noticed that the front brake went really soft, as i arrived at my destination (about 10 miles) i could smell burning, and could see the front brake resivor had leaked around the lid, in fact it must of squited out at one point as it was all down the side of the fuel tank. I then looked at my front disc which was black with burnt on oil.

My question is, i dont know where to start as im not sure what the problem is?

Do i just need to replace the oil as its to old and worn?
New pads?
New tube?
New resivor?

Any help would be great as im heading now to the ace cafe in 2 weeks and need to fix it before hand!!!

I'm not sure do I understand you properly, but let's try.
First, try to tighten reservoir cover screws. Than, check screws which are used to mount brake hose.

OK i took off the brake resivor to see what was goin on, and the rubber sack thing with oil in, has bowed both sides in the middle, the the rubber seal is therefore not sealing all the way around. Any idea where i can get a replacement?

ok i found out its called a diaghpram, ive put it back in properly so il see if it holds, as for the oil that leaked out, it didnt realise it was so aggresive till ive just looked where my plastic side panel bolts onto the bike, and its eating rite through it! the oil must of sat in the dip there. Gona need a new side panel now

Brake fluid is nasty stuff alright but water will stop it eating into your paintwork etc.

Anywhere that sells honda parts will do replacement diaphrams - try David Silver or Lings.

It would be a good idea to replace the pads & thoroughly clean the disc if they've been contaminated.

Can't see the disc becoming wet with fluid if it was just the master cylinder leaking (unless the fluid's been running down the hose), or even the banjo union at the caliper. Have you checked that the piston seals aren't leaking into the caliper?

Might explain the brakes going soft

*edited for another thought*

I wonder if the master cylinder started leaking due to the hydraulic fluid heating up and boiling?

Sounds like you'll have to bleed the brakes after a repair, no matter what the fault.

Do you have any pictures of the damage, just for reference, I think they might help people work out what's going on?

Anyway, while you are looking for a new diaphram for your brake fluid reserviour, you can do a simple test, which might help us work out what is broken (appologies if you've already done this):

1. Buy some brake fluid (DOT 4 btw)

2a. Put the bike on the centre stand.
2b. Pour some carefully into the reserviour (up to the line).

3. Pump the brake lever gently, repeatedly.
3a. If the level of the fluid falls below the line fill up back to the line.

Even if the brake system is somewhat in need of bleeding you may well be able to achieve some brake pressure - eventually (after a while pumping the lever carefully) you should feel an increased resistance as the brake fluid (hopefully) fills some of the pipe.

Also:

4. When the above hasn't worked, leave the bike overnight with the brake lever tied back against the handlebar - this may well allow some of the trapped air out of the top of the system and also allow some fluid to fill it up.


If you have access to a small spanner and a piece of small, clear rubber tubing (can be bought from halfords as a bleeder kit) you could try bleeding the system using the hexagonal bleed nipple located on the front caliper; this process is very similar to what I outlined above, except you attach the clear tubing to the bleed nipple before you unscrew it and make sure the end of the tubing is in an old jam jar (or something) to reduce the mess.

When all the air has been driven out of the system (ie. only fluid is coming out of the nipple) the nipple should be re-tightened.

I would suggest that you have a look at a haynes manual if you haven't alread got one (there is a link somwhere) - their description of brake bleeding is better than mine!

Have fun....

EDIT: found that manual - http://www.ridehard.co.uk/04/cb500/honda-cb500-service-manual-free/

I took the caliper off, and found out one of the pistions had ceased completely, the other one was leaking, so ive bought a new caliper, I have also order sum uprated brake lines , and OBC HH pads while im at it