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Stationary fall now rear brake jamming

Discussion in 'Technical and Troubleshooting Torque' started by solace, Apr 1, 2012.

  1. Hi all, new to biking and first post. very similar trouble here to this bloke https://netrider.net.au/forums/showthread.php?t=126580&highlight=brake+stuck#.T3gCtjEhJI0

    I had a stationary drop on a brand new Honda VTR250 600k's on the clock while at the lights - just lost balance and very embarrassing.
    Fell over to the LEFT and the only damage I could see was a scratched oggy knob, bent clutch lever and gearshift knob. Only had to replace the clutch lever as we could easily rebend the gearshift knob.

    On 3 cold start rides since, whilst riding I suddenly noticed the bike getting heavier and heavier -> the back brakes were definitely locking up mid ride, burnt my finger touching the heated disc (which is on the RIGHT side of bike - so no warping that I can see). Stopping and pumping the back brake pedal seemed to release it.
    The first time it happened, the mechanic had a quick look and said he couldn't see anything wrong with the free play of the rear lever (wasn't jammed) or rear brake assembly. Rear brake fluid level normal. This was when I went straight to the mechanic after dropping it the same day after work yesterday.

    It happened two more times subsequently today, each time when I first started riding it within the first 15min up to 60km/h speeds and had to pull over as bike got heavier. It is really strange, like when I stop initially as the bike is not cooled by moving air, it gets even harder and harder to move whilst at at standstill till I pump rear brake pedal it to "release" the stuck rear brake. However, whilst riding the next ~10km or so, using the either front or rear brake - they both worked normally, and rear didn't jam anymore once the bike had "warmed up".

    There is no obvious kinks on any of the brake lines. I have noticed though there is NO fluid visible on the front brake fluid container level on the right handlebar - there was some in there before I'm sure (is this the master cylinder?) It is in a normal upright position. I can't remember if this happened right after the fall - did not notice any leaking fluid around the front brake lever or anything. Can this be causing problems with my rear brake though??

    Any thoughts? help!
  2. Only time i have had similar , was a bit of gooey ashphalt in the rear brake pedal assembly, difficult to spot, it would drop into place jamming it ....

    popping out now and then....

    Have a look for physical problems.
  3. Thanks for the reply .. but the bike is still really new and clean - dont see any gunk in the rear brake pedal -> it doesnt get stuck in an engaged position at all and in fact is able to be pumped for me to "release" it as I say.. the pads look fine aside from the wear its had from me riding on it.. nothing obvious to my untrained eye and the mechanic did have a glance over!
  4. Only thing I can of is that air has in some way gotten into the system. I'd try giving it a bleed and see if that solves the problem.
  5. Talk to someone that's owned a 06-08 Hyo, they all had a very similar problem.
  6. Roarin I can't see how air in the brake line would cause the brakes to jam on. Could you elaborate please?

    I'd recheck carefully that it isn't anything as simple as the brake lever being slightly bent so that when used it fouls something and jams on? Or something else next to the brake lever bent and fouling it?
  7. Fill the container to the correct level first,

    Air in your line means no brake at all. You cant pull it on. let alone jam it on,

    I would go for some thing jamming your brake lever on, Some thing is stiff in there,
  8. If it's an intermittent fault they can be hard to diagnose, the best course of action is to give the mechanic as much info as possible so they can attempt to replicate your use of the bike when the fault occurs, take notes on when it happens, how long you have been riding, rough roads, smooth roads, the temp of the day-hot or cold... the smallest detail can help. Unfortunately if it ain't broke when they look at it they can't fix it so the more detail you can give them the better
  9. Sure. Air expands a lot more than fluid by volume when heated. If there is any in the caliper, it may cause the pads to drag slightly and heat the disc. Just a guess.

    Edit. It shouldn't do that though, if the pedal is returning completely. ie not bent or out of adjustment.
  10. Is this a brand new bike? Under warranty ? why not ake it back to where you bought it and ask them to fix it? Dont mention the drop tho!!
  11. Any chance you're unknowingly resting your right foot on the brake pedal?
  12. Thanks Roarin. Air does expand more but also compresses more. I am with Deadman on this one (although not on him in relation to scarves and beanies :LOL:). Air in the line is more likely to lead to no brakes than brakes locked on.

    Ned's comment is interesting. If the lever was bent maybe you are now resting on it in your natural foot position where you weren't before. Seems like a small possibility but always try to elininate the obvious.
  13. Bent axle or misalignment of the wheel? does it freespin without rubbing (ie neutral and manually turn the wheel and see if the brakes rub then?)

    Cheers Spocky
  14. hey all, thanks for the putting the thinking caps on - the dealer has had a look at it and it was due to a blocked rear brake master cylinder .. wasnt quite sure with what but they had unblocked and bled the system and replaced fluid.. will try to get mroe of the story soon

    am hoping this is more of a coincidence than not
  15. The dealer beat me to the answer. Damn.

    This was (is) common on my model of Ducati Multistradas, and other Ducatis, where people had adjusted the rear foot brake pedal up to make it easier to push the brakes on hard. They did that because early Ducati rear brakes didn't work very well, so you had to push hard to get any effect. The practice of raising the brake pedal carried forward to later model Ducatis where the brake efficiency problem was more or less corrected.

    Anyway, with the brake pedal set higher the piston in the master cylinder never moved back far enough to expose the oil return port and reduce pressure in the brake line, so each time the brake was applied the rear brake was pumped up just a little bit more, until the brake stayed on permanently.

    In the Multistrada this problem actually produced rear brake fires, at least one of which burned the bike completely. Another guy pulled into his driveway at home, hence no longer cooling the brake, and the pads burst into flame. On my bike I overheated the brakes a few times, boiling the brake fluid and spalling the disc on one occassion. That's without ever adjusting the pedal.

    Needless to say Multistrada owners learned not to adjust the rear brake lever up, and to instead swing their toe down. Who needs rear brakes anyway.

    So, I was going to suggest that the oil return port wasn't working, either because the port was blocked, which could happen on a new bike, or because the port wasn't being exposed to open it. In your case I suspect that there was some rubbish in the master cylinder, the brake lines, or in the port, slowing or preventing the oil from returning to the reservoir.

    Keep an eye on it. If they flushed the system it may be fine now, or there may be a problem with a seal breaking up, or some metal fragments still floating around. Bottom line: The bike is under warranty, so they should fix it properly.