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hydraulic disc breaks (caliper not moving)

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hydraulic disc breaks (caliper not moving)
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flag damnam
Posted: Sep 26, 2011 at 9:23 Quote
So i bought my trailstar dmr used bike 2days ago, 1 day of use in the forests, sand jumps, etc... and the next day the rear break doesnt work.
I already found out whats wrong but i dont know why and how to fix it

One side of the caliper does not push the pad against the disc, and i dont know how to fix this. anyone had this before? and how can i fix the caliper?
flag jetpilot
Posted: Sep 26, 2011 at 9:31 Quote
What brake is it? The piston is probably siezed. If so, you just need to rebuild the caliper, no big deal.
flag damnam
Posted: Sep 26, 2011 at 9:37 Quote
HOPE, do u recon i can do this myself (as in i wont break or damage the break)
flag jetpilot
Posted: Sep 26, 2011 at 9:41 Quote
I've never done a Hope so I really dont know whats involved. Check their website for a manual on how to do it.
flag damnam
Posted: Sep 26, 2011 at 9:45 Quote
i just checked and it seems to me that theres alot to do, need to get the piston out etc etc and then bleed aswell
flag damnam
Posted: Sep 26, 2011 at 9:48 Quote
when talking about piston, is it the one by the break handle?
Cause thats the only one i know exists (First time i ever had hydraulic breaks)
flag jetpilot
Posted: Sep 26, 2011 at 9:50 Quote
Yeah that sounds about right. Clean the inside of the bore really well and maybe change the seal on the piston, or even replace the piston if it's damaged in any way. If you're not comfortable with any of that, I'd just take it to your LBS or a good friend.
flag damnam
Posted: Sep 26, 2011 at 9:52 Quote
Weird how that causes the caliper not to move but thanks anyway, ill take a good look at it
flag uttanutta12
Posted: Sep 26, 2011 at 9:56 Quote
I think you've crossed wires

if one side of the caliper isn't moving, the piston there is siezed (behind the pad, after the piston on the lever there is a piston either side at the caliper behind the pads)


a quick fix would be to remove the caliper from the frame, take the pads out, and use some pliers or similar to hold the side that IS moving still, and pump the lever, forcing the piston out a little bit, once you've got the stuck piston moving put the pads back in and re-attatch to the frame Smile

May have to use some GT85 or WD40 to free it off thoughSmile
flag damnam
Posted: Sep 26, 2011 at 10:07 Quote
My dad just said if i did this, i could possibly pop the piston out which would get the air in the break = break ruined right?) is he right?
flag jetpilot
Posted: Sep 26, 2011 at 10:11 Quote
uttanutta12 wrote:
I think you've crossed wires

if one side of the caliper isn't moving, the piston there is siezed (behind the pad, after the piston on the lever there is a piston either side at the caliper behind the pads)


a quick fix would be to remove the caliper from the frame, take the pads out, and use some pliers or similar to hold the side that IS moving still, and pump the lever, forcing the piston out a little bit, once you've got the stuck piston moving put the pads back in and re-attatch to the frame Smile

May have to use some GT85 or WD40 to free it off thoughSmile

Ya, thats a good quick fix if it works. I've done that and sometime's the piston is just too dirty/damaged, but it's worth a try for sure.
flag jetpilot
Posted: Sep 26, 2011 at 10:12 Quote
damnam wrote:
My dad just said if i did this, i could possibly pop the piston out which would get the air in the break = break ruined right?) is he right?
Definatly could happen if you pump it out too far. The brake wont be ruined though....You'll just need to bleed it.
flag damnam
Posted: Sep 26, 2011 at 10:18 Quote
By the way if im using the WD40 where do i spray it? cos im guessing i dont want it going inside the caliper
flag jetpilot
Posted: Sep 26, 2011 at 10:21 Quote
On the sides of the piston itself (once its a ways out) Personally, I'd use dry lube.
flag uttanutta12
Posted: Sep 26, 2011 at 10:23 Quote
once you take the pads out, it's fine you spray it on the piston
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