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 Brakes"

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by Justin Stacks, Jan 18, 2013.

  1. I'm riding an '01 VTR250. The brake pads are fairly new and the brake fluid is basically full. However, my brakes are very "spongey"' and you have to squeeze quite a bit, and it's the same for the back break as well.

    What are the reasons for this, how can I get this fixed, and will it be expensive?


     
     Top
  2. start with a bleed, there may be an air bubble in the lines
     
     Top
  3. as above bleed the brakes
     
     Top
  4. As above bleed the brakes, and you may as well replace all of the fluid in the system while you're at it (brake fluid is cheap and should be replaced every couple of years anyway). Very east to yourself, and there's plenty of guides on the internet on how to do it.

    You might also want to consider new brake lines, since if it's still on originals they're well past their intended lifespan (and braided lines will cost about as much as what you save not paying a mechanic to bleed your brakes).
     
     Top
  5. As above, bleed your brakes.


    :p
     
     Top
  6. What is the condition of your discs?
    If they are worn, then your fairly new pads may take some time before the face of the pads wear in to the same shape as the disc to get 100% contact. If for example you only have 50% contact at the moment, then there is less friction generated for the same lever pressure, so you are having to squease the lever much harder & it moves closer to the bars, for the same braking force.

    What compound pads were fitted?
    If the old pads were HH rated metallic type & you now have organic type, then this can cause & increase in lever pressure & travel required to have the same braking force.

    Have the brake calipers been stripped & cleaned with new piston seals fitted? Over time, corrosion occurs behind the caliper o'ring/seals, causing them to press harder on the pistons, increasing friction & reducing the pressure generated at the lever from being applied to the brake pads. Sometimes the seals swell from contamination. Sometimes the gunk on the outside of the piston is not cleaned off before the piston is pushed back into the caliper, causing it to stick. Jack the bike up so the wheels are off the ground and give them a spin to see how much they are dragging, which will tell you if calipers are sticking.

    Do your wheel bearings have any play?
    Worn wheel bearings allow the wheel to tilt side to side a little which can cause the discs to push the pads back into the caliper, increasing pad to disc clearance which results in increased lever travel.

    But yes, always try bleeding brakes first & perhapps throw on some new braided lines.
     
     Top
  7. Spongy brake lever could also mean that you have glazed pads, dirty hands installing new pads can cause glazing. Remove pads and clean.
     
     Top
  8. Thanks guys for the feedback. Appreciate it.

    Cheers (y)
     
     Top
  9. Got a similar prob with my 2006 GSX750F. After replacing the brake fluid and bleeding the brakes were still a little bit spongy. Spoke to a mechanic who suggested putting a cable tie on the brake lever over night, to let all the small air bubbles rise to the top of the system into the reservoir. Nothing to loos so I gave it a try and it made a noticeable difference.
     
     Top
  10. Thx for the tip!

    So effectively, it' would be like keeping the brake lever pulled in overnight?
     
     Top
  11. Good tip!
    I'll need to remember that.
     
     Top
  12. As has been said, most probably needs a bleed and given the age some new parts.

    My advice would be to take the bike to a mechanic to have the problem looked at. If your at the stage where your still asking what causes spongy brakes your probably not at the re-bleeding your own brakes stage just yet.

    There's nothing wrong with not knowing what your doing, there are however potentially serious problems with getting brake maintenance wrong.
     
     Top
  13. The other thing to check is that the pads can move freely and smoothly on the slide pins. If there is binding this can cause spongyness especially on multi pot calipers. Clean or better yet replace the slides and clean the caliper with brake cleaner to get all the dust out.

    If you bleed the brakes and it fixes the problem but then turns spongy again quickly, you'll need to look at rebuilding your mastercylinders and/or possibly calipers.

    The order I'd attack it in is;
    - bleed brakes (remember to do it at the master cyl aswell if available)
    - clean or replace slides
    - change lines
    - rebuild mc
    - rebuilt calipers
     
     Top