Welcome to Netrider ... Connecting Riders!

Interested in talking motorbikes with a terrific community of riders?
Signup (it's quick and free) to join the discussions and access the full suite of tools and information that Netrider has to offer.

spongey front brake

Discussion in 'Technical and Troubleshooting Torque' started by idontlikemondays, Aug 18, 2006.

  1. any help here would be greatly appreciated!
    so, the brake felt a little spongey, took to the honda dealer ship. they told me the seals in the master cylinder were stuffed, and replaced them. it was much firmer and more responsive. two days later, its exactly like it was before, a week later it hasnt got any worse, and the bike stops, but im starting to think there could be a problem in the caliper. when i stop really hard, i can smell what i think is brake fluid, but it could be the pads? they are new. any ideas? maybe one of cylinder seals on the caliper is stuffed?
    and while im asking newbie questions, i might as well ask a couple more but not as serious though. the rear brake sticks from time to time, when i get it first rolling, i get a recuring squicking noise that stops when i hit the brake. and is it bad to have too much oil in the motor??

  2. Front brake,

    1. Has the fluid level dropped since the service?

    2. If no, they probably just need bleeding again, it happens.

    3. If yes, find the leak, and there's your problem.

    Too much oil in the motor. Yes it's bad, you can have excessive oil pressure and blow an oil seal.
  3. Ok sounds like there is a leak somewhere else if you can smell brake fluid. Also the pads always slightly touch the discs so you will get some noise now and again. And yes too much oil is not advised.. Can put pressure on seals etc.. But also depends on how overfull it is.
  4. Sorry I didn't spot this one before. There is a trick to bleeding bike brakes. It's hard to force air downwards.

    So when you park your bike overnight, tie your brake lever back to the bar.

    This will force the air back past the master cylinder seal. do it 2 nights in a row for better results. Be carful the next morning. You may need to pump the lever a few times to get pressure back or free it up.
  5. what about after practicing emergency braking if the lever seems to be quite firm? does it mean pistons are sticking and need rebuilding? or is it fairly normal?
  6. Well you learn something new every day.

    Also if this, or bleeding them, doesn't help just have a look at your brake lines and see if they expand and contract when you pull the brake lever. If the bike is left out in the sun all year round there is a slime chance that the brake lines could deteriorate and loose some of there rigidity which would account for the spongy feel.

    This senario is less likely though.
  7. For how long? Just the next application?

    If you pump a brake a few times, they do firm up. Is this what you are experiencing?

    It may also be a heat related thing.

    I don't see how the pistons sticking would happen or feel like this. . . Anyone?
  8. If you try bleeding the brakes yourself rather than just using the bleeders alone, put a length of vaccum hose or preferabally clear tube onto the bleed valve and hold it higher than your master cylinder. Pump the fluid into that to allow air to pass through to the highest point easier and as a bonus brake fluid doesn't quite go everywhere...
  9. If the master seals were gone, I'd expect the brake lever to "creep in" as pressure is held on the brake lever, meaning the lever will "bottom-out" at a reasonably noticeable pace with pressure applied over say 15 seconds. There should be zero creep

    Brake pads still sitting to firmly on the disk after brake pressure is released would probably be the seals in the caliper a bit stuffed, it's thier job to actualy pull the pad back of the disk slightly when pressure is released.

    Bleeding, pump fast and the viscosity of the fluid should carry any air bubbles down to the calliper, yes bubbles stuck in the caliper can be a problem. Never let the brake fluid resevoir run empty when bleeding or you start again.

    Don't mix different types of brake fluids, brake lines/calipers can be cleaned out with metho, rust or corrosion on an iron disk can cause sponginess.

    After all that, chances are your problems cure aint here : (
  10. Sounds like a small amount of air in the system, which is pumped toward the calipers when you brake hard, where it has less effect on braking. If you bleed brakes in the conventional way, it pays to close the bleed nipple and pump the lever, lightly but vigorously, to 'push' the air to the nipple: then open it and pull the lever and it should be pushed out.

    Because bike brake systems are so tortuous, tiny air bubbles can get stuck in all sorts of places. The 'band around the brake lever overnight' trick is very good, blowing warm air on the lines (or putting the bike in the sun for a few hours) with the lever back/system open also helps: expands the air bubbles and makes them more likely to rise up. But they can still get to a 'high point' and be stuck. Where the hose joins the master cylinder is a prime area for this. I have seen guys pull their brake systems off completely to make a nice, straight line for the air to get out of.

    Basically, anything that moves the air bubble(s), or gives them an easier passage out, is worth trying.
  11. I got the same problem. Spongy front brakes. Found my problem quite easily tho. Fork seals are shot. Leaking fluid all over the front of my bike, brake discs and therefor the front pads. Not happy. Only just clocked up the first 1000km on the bugger too! Goes in for its first service and WARRANTY repairs on friday. My first (and hopefully last) fault on my new Hyo.
  12. It's simple, replace the sponges with brake pads. :grin:

    Arrr, leave me alone it's late. :)
  13. Too much engine oil makes it froth up causing more wear and tear than less oil. Drain it a little bit- With a little container under it, unscrew the drain bolt very very slowly till the oil slowly starts seeping out. Remove as desired; make sure u dont remove the bolt fully as it is really hard to screw it back on if the oil is in full flow...
  14. The strain of 2.00 am in the morning is obvious