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Avid 3s - Juicy problem

crazycamcrazycam Posts: 13
edited March 2009 in MTB workshop & tech
Easy all,

Having a few issues with my brakes. Went to go for a ride the other day, first one since the before the cold spell. Tried to wheel the bike out of the garage (unheated) and both discs were locked up. Had never come across this before and squeezed both levers to try and free them up causing fluid to escape from between the seals on the oil sump. This freed up the jam but is obviously not right.

The oil has expanded for some reason, which I can only imagine was caused by the bike being stored outside in the cold. The seals seem to have been permanently effected as they now leak when the levers are fully compressed even though the temperature has dropped.

The brakes themselves are still working fine. I risked it and took it out for a decent x c ride but am concerned about the leak.

Any suggestions as to what the problem could be and how to prevent it happening in the future? I am supposing the seals have gone and will need to be replaced? The amount of oil lost is not great but will this need to be replaced too? Is this a job a novice could carry out?!

Any help would be appreciated.

Cheers.

Posts

  • Any suggestions as to what the problem could be and how to prevent it happening in the future?
    Don't leave it out in the cold? Not much you can do if they're freezing in this weather!
    do you put a cover over your bikes when you store them? Tucking them in could keep the frost away?
  • The bike has not been exposed to frost. It has been kept in a brick garage. I haven't put a cover on it but it did have its favourite teddy for company.
  • I need some helpful suggestions as to what can be done to fix the problem if anything. Has anyone come across this before?
  • supersonicsupersonic Posts: 82,708 Lives Here
    Yes, it has been reported here before. I think a reason could be that you have some water in the lines. When it freezes, it expands, or turns the fluid into a thicker substance of less density. Just a guess, but I'd be tempted to do a full bleed of the sytem ie change the fluid.
  • Tech manual for you if you want to give the brakes an overhaul yourself (hopefully a bit more helpful than the 1st post).
    http://sram.com/_media/techdocs/2008%20 ... %20web.pdf
  • Ok, I was hoping that would be a last resort. I suppose there is a possibility that water could have got in but as said previously the temperature in the garage would not have been below zero. I imagine the oil becomes more viscous at lower temperatures anyway. What I'm concerned about is the fact that it is escaping in the first place.

    The brakes do not feel spongey or as if performance is effected (yet).

    I am not familiar with the seal system on these reservoirs as I am fairly new to this. But seeing that the hydraulics are escaping every time the levers are compressed, this suggests that either the top cap or the seals (or both) are buggered.

    The oil lost each time is minimal but I suppose I should not ride it till its sorted. Wanna try and do it myself as my LBS is a bit of a rip off.
  • supersonicsupersonic Posts: 82,708 Lives Here
    The viscosity does change, but DOT fluids operate well down to about -230, unless water is in the line. If anything the fluid should contract! The open system reservoir should counter small increases in volume ie the method when it becomes hot.

    Also cold can contract the brake lines and casue seals to become less flexible.

    Sounds like a good service is needed.
  • Cheers bigbenj will check that out.
  • Yeah will probably put it in for a service anyway. Might give the brakes a go myself first.

    Thanks for the advice.
  • BenS999BenS999 Posts: 202
    Definitely sounds like water has got in there to me - i haven't experienced this first hand but Supersonic is right - the brake fluid should contract when cooled and I doubt your garage hits 230 below freezing...

    I suggest investing in an Avid bleed kit (see link below), they go for around £35, maybe cheaper if you shop around, and will pay itself off in a few bleeds. And some new seals to be sure. Avid also have a video on youtube for bleeding using their kit, just do a search and it walks you through the process...

    I prefer to do most things myself as im a firm believer that nobody looks after my stuff better than me!
    2011 Orange Five Pro
    On-One Pompetamine Alfine Comp
  • crazycamcrazycam Posts: 13
    Sounds like a plan. Cheers.
  • CumbrianManCumbrianMan Posts: 240
    Crazycam, have a look at mtb-bitz.co.uk. I got a bleed kit for £27 instead of the £35 to £40 that most places are asking. :D
    "There are no hills, there is no wind, I feel no pain !"

    "A bad day on the bike is always better than a good day in the office !"
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