Alex Dark Posted October 14, 2008 Report Share Posted October 14, 2008 Right, got a hope mono mini with my new dmr so i decided to try it out on the trials bike...problem is i think its got sticky pistons...anyone know how to solve it? apparently wd40 works, some say silicone grease...so could someone with experience on these brakes please shed some light?Oh, and whats the best thing to clean padss? i heard it was ISA ( isopropyl alcohol ) but i vant find where to get some.... Quote Link to comment Share on other sites More sharing options...
Muel Posted October 14, 2008 Report Share Posted October 14, 2008 The best thing to clean the pads is a blowtorch, this burns off any oil residue in the pads, then bed them in with mud, which scrubs the surface and gets them bedded in properly.To sort the pistons out, take out the pads and pull the lever in, then spray some WD40 on the pistons, then let go of the lever and wipe out the caliper really thoroughly, repeat if necessary. Quote Link to comment Share on other sites More sharing options...
Alex Dark Posted October 14, 2008 Author Report Share Posted October 14, 2008 The best thing to clean the pads is a blowtorch, this burns off any oil residue in the pads, then bed them in with mud, which scrubs the surface and gets them bedded in properly.To sort the pistons out, take out the pads and pull the lever in, then spray some WD40 on the pistons, then let go of the lever and wipe out the caliper really thoroughly, repeat if necessary.sweet, thanks muel; thought you'd be the one to ask on this one if i had no replies .... ill do that tonight.Ive never had a disc brake on any of my bikes before so im totallly new to this....i think its dropped a bleed as well; when the lever's fully depressed only one piston moves, and thats only by about 1mm or so....but both pistons are sticking out by at least 2mm, so does that mean they're not returning, or i have to rebleed it as well? Quote Link to comment Share on other sites More sharing options...
Muel Posted October 14, 2008 Report Share Posted October 14, 2008 The pistons always stick out a bit, they automatically adjust for pad wear.That pads hardly move at all, each pad only moves about half a millimeter anyway. (On a Mono Trial, on a Mono Mini the leverage ratio is smaller, so the pistons should move further in theory anyway).If there is a little bubble of air trapped in the system, I've found that it doesn't matter, it moves up through the brake as you use it, just check that the diaphragm hasn't got any air under it or it can move into the hose if the bike ends up upside down.To get the sticking piston out, hold the one that's moving into the caliper with some pliers and gently pull the lever, you'll probably find it will suddenly let go and become free, apparently this is because the seal ends up drying out and sticking to the piston, in my experience it always happens on the inside piston, closest to the hub. Quote Link to comment Share on other sites More sharing options...
Alex Dark Posted October 14, 2008 Author Report Share Posted October 14, 2008 (edited) The pistons always stick out a bit, they automatically adjust for pad wear.That pads hardly move at all, each pad only moves about half a millimeter anyway. (On a Mono Trial, on a Mono Mini the leverage ratio is smaller, so the pistons should move further in theory anyway).If there is a little bubble of air trapped in the system, I've found that it doesn't matter, it moves up through the brake as you use it, just check that the diaphragm hasn't got any air under it or it can move into the hose if the bike ends up upside down.is a hope mono mini with a 180mm rotor okay for trials? has it got enough hold?To get the sticking piston out, hold the one that's moving into the caliper with some pliers and gently pull the lever, you'll probably find it will suddenly let go and become free, apparently this is because the seal ends up drying out and sticking to the piston, in my experience it always happens on the inside piston, closest to the hub.the diaphragm ? the reservoir at the top?Right; should be able to solve the sticking piston now.....right; another question ( sorry about this ) i.ve got some urban forks with a hope 180mm disk, do i need any form of adaptor or will it work okay ?( ive fitted it but it always seems to rub.....the pads dont seem to be parallel with the rotor, so i think the disc mount on the fork might be bent in some way...its definitely rubbing on the pads ; not the calliper Edited October 14, 2008 by Alex Dark Quote Link to comment Share on other sites More sharing options...
ZeroMatt Posted October 14, 2008 Report Share Posted October 14, 2008 Reset the pads and see if it still does it Quote Link to comment Share on other sites More sharing options...
Alex Dark Posted October 14, 2008 Author Report Share Posted October 14, 2008 Reset the pads and see if it still does itErm....how? push them in? Quote Link to comment Share on other sites More sharing options...
ZeroMatt Posted October 14, 2008 Report Share Posted October 14, 2008 Yeah that's it. Althought not sure exactly what the problem is to be honest if it's the alignment between pad and rotor get the mount faced. Quote Link to comment Share on other sites More sharing options...
Alex Dark Posted October 14, 2008 Author Report Share Posted October 14, 2008 Yeah that's it. Althought not sure exactly what the problem is to be honest if it's the alignment between pad and rotor get the mount faced.ohhh.....more money is it worth giving it a rebleed? it hasnt had one since new ( and they're 06s ) Quote Link to comment Share on other sites More sharing options...
Muel Posted October 14, 2008 Report Share Posted October 14, 2008 You can do if you want, but there's no real need to, my Dad's XC bike has the original Minis, bought brand new in 2002 and they still have their original bleeds. Quote Link to comment Share on other sites More sharing options...
Alex Dark Posted October 14, 2008 Author Report Share Posted October 14, 2008 You can do if you want, but there's no real need to, my Dad's XC bike has the original Minis, bought brand new in 2002 and they still have their original bleeds.ah reet.....so wd40 and some tyre levers to puch the pistons back in and im good to go? Quote Link to comment Share on other sites More sharing options...
ZeroMatt Posted October 14, 2008 Report Share Posted October 14, 2008 Depends what the issue is, if it's just the sticky piston and pad(s) out too far from taking it off another bike then yeah that's it Quote Link to comment Share on other sites More sharing options...
Alex Dark Posted October 14, 2008 Author Report Share Posted October 14, 2008 Depends what the issue is, if it's just the sticky piston and pad(s) out too far from taking it off another bike then yeah that's itawesome, whats best to clean pads in your experience; is it worth sanding them as well? Quote Link to comment Share on other sites More sharing options...
ZeroMatt Posted October 14, 2008 Report Share Posted October 14, 2008 Acetone works pretty good for me, never bothered sanding them down although can see some merit in doing so Quote Link to comment Share on other sites More sharing options...
Alex Dark Posted October 14, 2008 Author Report Share Posted October 14, 2008 Acetone works pretty good for me, never bothered sanding them down although can see some merit in doing soright...is that nail varnish remover?is a hope mono mini powerful enough as a front brake? ( 180mm rotor ) Quote Link to comment Share on other sites More sharing options...
ZeroMatt Posted October 14, 2008 Report Share Posted October 14, 2008 right...is that nail varnish remover?is a hope mono mini powerful enough as a front brake? ( 180mm rotor )Yeah kind of, it's the base ingredient. Don't use nail varnish remover though as it can and most likely will have a load of shit in there that's not good on the disc. May as well just get some disk brake cleaner, don't know how well they work but can't be that bad.If it's set up well deffinately Quote Link to comment Share on other sites More sharing options...
Alex Dark Posted October 14, 2008 Author Report Share Posted October 14, 2008 (edited) Yeah kind of, it's the base ingredient. Don't use nail varnish remover though as it can and most likely will have a load of shit in there that's not good on the disc. May as well just get some disk brake cleaner, don't know how well they work but can't be that bad.If it's set up well deffinatelyright....any idea where i can get some?disk brake cleaner managed to ruin jakes disc brake ....so i wont be using that in a a hurry!Sweet..! I think plymouth is my best bet.... Edited October 14, 2008 by Alex Dark Quote Link to comment Share on other sites More sharing options...
ZeroMatt Posted October 14, 2008 Report Share Posted October 14, 2008 Well I get mine from my worplaces supplier but CFS seems allright but expensive for 5L or more.Btw gotta ride soon mate Quote Link to comment Share on other sites More sharing options...
Alex Dark Posted October 14, 2008 Author Report Share Posted October 14, 2008 we have to have a decent plymouth ride soon..... Quote Link to comment Share on other sites More sharing options...
Ross McArthur Posted October 14, 2008 Report Share Posted October 14, 2008 Hey man,I took the pads out last night in my mini and poured a whole kettles worth of boiling watter over the pads to give them a good clean them dried them with a bit of kitchen roll.I also pumped the lever so the pistons moved out because they were sticking. I knew they were sticking because I could hear them clicking as I pulled the lever, the lever got stiff before and braking force was applied then it clicked(when the pistons pushed them selves by the sticky bit then the brake bit.I personally use Dot fluid to lubricate my pistons as thats whats being used in the brake anyway. I wouldnt want wd40 somehow mixing with the fluid in my brakes if it ever met up in the caliper. Dont know if it would do anything but id rather not take the chance.I cleaned the disc with a blast of cold water and a clean cloth.I then pushed the pistons back in cleaned the caliper all up and slotted the pads back in. In the same sides as they came out.!!Disc works well now with no clicks and has a decent bite.hope that helps. Quote Link to comment Share on other sites More sharing options...
Alex Dark Posted October 14, 2008 Author Report Share Posted October 14, 2008 Hey man,I took the pads out last night in my mini and poured a whole kettles worth of boiling watter over the pads to give them a good clean them dried them with a bit of kitchen roll.I also pumped the lever so the pistons moved out because they were sticking. I knew they were sticking because I could hear them clicking as I pulled the lever, the lever got stiff before and braking force was applied then it clicked(when the pistons pushed them selves by the sticky bit then the brake bit.I personally use Dot fluid to lubricate my pistons as thats whats being used in the brake anyway. I wouldnt want wd40 somehow mixing with the fluid in my brakes if it ever met up in the caliper. Dont know if it would do anything but id rather not take the chance.I cleaned the disc with a blast of cold water and a clean cloth.I then pushed the pistons back in cleaned the caliper all up and slotted the pads back in. In the same sides as they came out.!!Disc works well now with no clicks and has a decent bite.hope that helps.ah, so thats what those clicks are..... i dont have any dot fluid at home atm....i think ill wait to do it; get the mount faced, lube the pistons, give it a fresh bleed, and source some IPA to clean the pads and rotor Quote Link to comment Share on other sites More sharing options...
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