Duncy H Posted December 1, 2009 Report Share Posted December 1, 2009 Hi guysI have a hope mono trial (rear) which has been suffering a few problems lately. It is pretty much standard mono trial set up with a 160 rotor.Over a week back the brake started to stiffen up and you would pull the lever but it wouldn't really do anything. I then replaced the seals which seemed to have sorted the problem.Then after a few days started not to hold very well. I fitted new pads and rotor and have given it chance to bed in but doesn't seem to have made a lot of difference.At the lever it feels ok, perhaps a tiny bit stiff and squeaks when you pull it But I am lost for what to do next?Please give me some ideas. Quote Link to comment Share on other sites More sharing options...
Dale-Hill Posted December 1, 2009 Report Share Posted December 1, 2009 Wip the pads and brake off bike re blead and see what that does As for the squeking that just the brass barrel on the lever it's self. Just squirt a bit of WD40 that'll sort it out Quote Link to comment Share on other sites More sharing options...
Duncy H Posted December 1, 2009 Author Report Share Posted December 1, 2009 I will try a new bleed but thought it was up to scratch. Surely if I bleed with the pads out it will just pop the pistons out? Quote Link to comment Share on other sites More sharing options...
AdamR28 Posted December 1, 2009 Report Share Posted December 1, 2009 I fitted new pads and rotor and have given it chance to bed inUsually takes around 2-4 weeks to bed a Hope rotor in fully, is it 100% mirror-shiny? Quote Link to comment Share on other sites More sharing options...
Dale-Hill Posted December 1, 2009 Report Share Posted December 1, 2009 I will try a new bleed but thought it was up to scratch. Surely if I bleed with the pads out it will just pop the pistons out?Nope Or you could just put some old ones in?I all ways blead mine without the pads out, less chance of getting oil/shit on the pads. Quote Link to comment Share on other sites More sharing options...
Sam Oliver Posted December 1, 2009 Report Share Posted December 1, 2009 Take pads out, find a large flat stone or paving slab & rub gently in small circles untill you get a nice even lighter grey colour than youstarted with. Sometimes the pads seem to glaze over without beddingin properly. Then clean rotor with cellulose thinners & clean kitchen towel thouroghly!In my experience there is no alternative to thinners as it evaporates & leaves no residue.Job done Sam. Quote Link to comment Share on other sites More sharing options...
Duncy H Posted December 1, 2009 Author Report Share Posted December 1, 2009 Usually takes around 2-4 weeks to bed a Hope rotor in fully, is it 100% mirror-shiny?Oh dam it, they is a line around it that is kind of mucky but the rest is shiney.Nope Or you could just put some old ones in?I all ways blead mine without the pads out, less chance of getting oil/shit on the pads.Might give it a bleed for good measure.Take pads out, find a large flat stone or paving slab & rub gently in small circles untill you get a nice even lighter grey colour than youstarted with. Sometimes the pads seem to glaze over without beddingin properly. Then clean rotor with cellulose thinners & clean kitchen towel thouroghly!In my experience there is no alternative to thinners as it evaporates & leaves no residue.Job done Sam.I'll try that but I did only put the pads in on friday so I may have underestimated it a bit However I did run it down a very steep long hill with it on and then water on afterwards. :/ Quote Link to comment Share on other sites More sharing options...
Dale-Hill Posted December 1, 2009 Report Share Posted December 1, 2009 Oh dam it, they is a line around it that is kind of mucky but the rest is shiney.Might give it a bleed for good measure.I'll try that but I did only put the pads in on friday so I may have underestimated it a bit However I did run it down a very steep long hill with it on and then water on afterwards. :/Sure there not glazed over then? Quote Link to comment Share on other sites More sharing options...
Duncy H Posted December 1, 2009 Author Report Share Posted December 1, 2009 Nah i did it after a ride where they were poor too. Quote Link to comment Share on other sites More sharing options...
craigjames Posted December 1, 2009 Report Share Posted December 1, 2009 So the brake wasn't bedded in, you heated the pads right up by dragging them down a hill and then rapidly cooled them with water? I never understood why people do this, surely this glazes pads?! Putting water on first, drag the brake a bit. Cleans the pads surface, all the crap helps bed in the disc and then give it a good clean off after. Quote Link to comment Share on other sites More sharing options...
Duncy H Posted December 7, 2009 Author Report Share Posted December 7, 2009 The problem persists. Did what sam said to do with the pads but then it went really rather bad but needs bedding in again. Just re bled it and made no difference at all. I get the feeling that it is something wrong inside. The pads do not seem to react as quick as the front brake does and to make the brake hold well the lever has to be pulled in very hard. Starting to think it may be something I did when I changed the seals, should i have lubed them up with anything? I only used some dot brake fluid for this?Please find me some answers!!! Quote Link to comment Share on other sites More sharing options...
Matt Burrows Posted December 7, 2009 Report Share Posted December 7, 2009 Might have got air trapped behind the piston or around the seal, if you have then bleeding it won't always clear it. Did you fill the caliper bore with fluid before fitting the pistons? If the brake is spongey at the lever then it almost certainly has air in the system. The only other thing it could be is a leak somewhere or a knackered seal. Quote Link to comment Share on other sites More sharing options...
Duncy H Posted December 7, 2009 Author Report Share Posted December 7, 2009 Might have got air trapped behind the piston or around the seal, if you have then bleeding it won't always clear it. Did you fill the caliper bore with fluid before fitting the pistons? If the brake is spongey at the lever then it almost certainly has air in the system somewhere. The only other thing it could be is a leak somewhere or a knackered seal.I didn't fill the caliper when i took it apart so could be that. I doubt it would be damaged seals as i took a lot of care when fitting them. Was a bit of oil on the back of the pads but i think that is from the fluid i used to lube the seals at the calipers with and seems to have stopped. Hasn't lost any power either.If it helps it does not feel much like my front one which is quite bitey and this one is not. Quote Link to comment Share on other sites More sharing options...
Matt Burrows Posted December 7, 2009 Report Share Posted December 7, 2009 I didn't fill the caliper when i took it apart so could be that. I doubt it would be damaged seals as i took a lot of care when fitting them. Was a bit of oil on the back of the pads but i think that is from the fluid i used to lube the seals at the calipers with and seems to have stopped. Hasn't lost any power either.If it helps it does not feel much like my front one which is quite bitey and this one is not.Yeah I meant the lever seals, they are subject to wear as well but are less likely to be the issue. Does the brake feel solid? If it is spongey then it has air, if its solid then you can rule out internal issues. That is assuming the caliper is aligned perfectly, if it's wonky then it can cause the brake to feel spongey. If all that is ok then it has to be down to pad/rotor performance. Either not being fully bed in, being contaminated or simply just not quite as bitey as your previous pads... Quote Link to comment Share on other sites More sharing options...
Duncy H Posted December 7, 2009 Author Report Share Posted December 7, 2009 It is very hard to descibe how it feels. It is not what I would call very spongey but when you pull it you start to feel it bite and then it takes quite a bit of travel before it holds and generally doesn't feel perticularly nice. While pulling it I can see that the pads do not react quickly making me belive that your suggestion about air in the caliper is true. How do I go about filling it up with fluid? As for the pads and disc they are a week or so old. I am using shell dot 5.1 oil if that helps? Quote Link to comment Share on other sites More sharing options...
trialsmax04 Posted December 7, 2009 Report Share Posted December 7, 2009 (edited) It is very hard to descibe how it feels. It is not what I would call very spongey but when you pull it you start to feel it bite and then it takes quite a bit of travel before it holds and generally doesn't feel perticularly nice. While pulling it I can see that the pads do not react quickly making me belive that your suggestion about air in the caliper is true. How do I go about filling it up with fluid? As for the pads and disc they are a week or so old. I am using shell dot 5.1 oil if that helps?Try dot 4. I ran mine on it and always had compliments on how nice the lever feel was.Oh as well, try taking the pistons out, polishing with wire wool, and then re-fitting them with a TINY smear or grease on the pistons Edited December 7, 2009 by trialsmax04 Quote Link to comment Share on other sites More sharing options...
Matt Burrows Posted December 7, 2009 Report Share Posted December 7, 2009 Try dot 4. I ran mine on it and always had compliments on how nice the lever feel was.Oh as well, try taking the pistons out, polishing with wire wool, and then re-fitting them with a TINY smear or grease on the pistons Don't bother, DOT 5.1 is a better fluid. And greasing the pistons is a really bad idea lol.Yeah air behind the caliper could be the issue. You have to strip the caliper, remove the pistons and hose. Put the caliper on a flat surface and fill the bore with fluid, make sure there are no air bubbles trapped around the seal. Dip the piston in some DOT and slowly fit it, fluid will be pushed through and out the caliper as you do so. Don't push the piston all the way in, leave it sticking out 2 or 3mm. With the mono caliper the other side is a bit different, you have to fit the piston in first, then fill the bore behind it with fluid, remove air bubbles then refit the cap. Now you can refit the hose and bleed it through from the bottom up, making sure the lever is the highest point of the system. Keep pushing fluid through with the syringe until no more bubbles come into the lever. Give the lever blade a few flicks as they tend to trap air, this should release some tiny bubbles into the reservoir. Be careful the pistons don't come out any further when you do that, it's worth sticking something inbetween to keep them in place. When the lever's free from air, tighten the caliper bleed nipple and remove syringe. Now you can push the pistons fully back into the caliper, before a final top up of the reservoir and fit the cap. Hope that helps Quote Link to comment Share on other sites More sharing options...
psycholist Posted December 7, 2009 Report Share Posted December 7, 2009 If you use copper grease on the back of the brake pads that's ok (And may help the brake work better or stop it squealing). Any other grease will get too hot as you use the brake, run out from behind the pad and contaminate the disk. Quote Link to comment Share on other sites More sharing options...
Duncy H Posted December 8, 2009 Author Report Share Posted December 8, 2009 Thanks for the help but I usually bleed from the top to bottom, similar to the quide on the hope website and i don't have a syringe ets to bleed opposite way.Also how do I go about filling up the opposite side to the bore cap if I have to put the piston in first? Quote Link to comment Share on other sites More sharing options...
trialsmax04 Posted December 8, 2009 Report Share Posted December 8, 2009 I have put a thin smear of grease on all my brakes, and moto bike brakes. And have never had a problem. Each to your own . . . . . . . Quote Link to comment Share on other sites More sharing options...
Matt Burrows Posted December 8, 2009 Report Share Posted December 8, 2009 Thanks for the help but I usually bleed from the top to bottom, similar to the quide on the hope website and i don't have a syringe ets to bleed opposite way.Also how do I go about filling up the opposite side to the bore cap if I have to put the piston in first?Well its certainly cheaper and simpler if you have no syringe. Although funnily enough Hope bleed a lot of their brakes from the caliper up at the factory as its more reliable and quicker. Which piston do you mean, the inner one closest to the wheel or the outer one with the bore cap?I have put a thin smear of grease on all my brakes, and moto bike brakes. And have never had a problem. Each to your own . . . . . . .Yeah it could be perfect for moto gear, but push bike brakes are not the same. What grease do you recommend? You can use silicon lube, but if you have a sticky piston that won't return this can often have the opposite effect to what is wanted. If the piston is too well lubed then the seals don't grip it, and the pistons won't return. Which leads to a dragging brake and a lever that barely moves before it bites. Quote Link to comment Share on other sites More sharing options...
Duncy H Posted December 8, 2009 Author Report Share Posted December 8, 2009 I mean the one nearest the wheel Quote Link to comment Share on other sites More sharing options...
Matt Burrows Posted December 8, 2009 Report Share Posted December 8, 2009 You just poor fluid in to fill the bore before fitting the piston. Its a bit awkward being a 1 piece caliper but shouldn't be too hard, just might be messy Quote Link to comment Share on other sites More sharing options...
Duncy H Posted December 10, 2009 Author Report Share Posted December 10, 2009 For anyone interested that seems to have done the job. I took the pistons out then filled each bore with fluid then rebuilt and rebled the brake. Made for a much nicer brake feel and holds better, need to wait for the pads to bed in then it will be super dooper!!! Quote Link to comment Share on other sites More sharing options...
Matt Vandart Posted December 10, 2009 Report Share Posted December 10, 2009 I'm interested, as I had similar problems. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.