DJW997 Posted April 27, 2011 Share Posted April 27, 2011 Hi all, I'm having some trouble with my front brake and could really use some help. All was working fine until I decided to open up the front calliper to examine as it was absolutely caked in brake dust, and I planned to swap out the pads anyway so. It is one of those callipers which splits down the middle and has a 'channel' where fluid can pass from one side to the other ( has a piston either side ). Upon opening the calliper a little fluid seeped out through this channel. This is whats caused my problem I guess. I put the calliper back together etc. And I now have no pressure what so ever at the brake lever. The reservoir is full. Tried bleeding it but no fluid comes out from the bleed nipple at the calliper. So I'm pretty stumped. I've tried bleeding a few times. Sat there on the bike for at least 10 minutes just pumping the lever incase theres a big air bubble in the lines or anything. (using a one man bleeding kit). What should I do? Thanks for taking the time to read this. -DJ Link to comment Share on other sites More sharing options...
Moderator Airhead Posted April 27, 2011 Moderator Share Posted April 27, 2011 I dont think you are supposed to split the caliper in that way, I think it should have been left sealed and you have damaged the seal. Link to comment Share on other sites More sharing options...
DJW997 Posted April 27, 2011 Author Share Posted April 27, 2011 It is held together by 2 bolts, one dedicated and one that doubles as a mounting bolt. The (rubber) seal for the little 'channel' looked fine & looks to be seated nicely as well. I wiped it with a paper towel and dabbed a little brake fluid around it in hope it would seal nicely again. A slight squeeze of the brake lever does make some fluid come through the one side of the calliper yet it won't go through to the bleed nipple on the other side. I have sprayed some brake cleaner through the passages and cleaned the bleed valve and still nothing. Really struggling to think what could be stopping it since it doesn't leak from anywhere either. Link to comment Share on other sites More sharing options...
Moderator drewpy Posted April 28, 2011 Moderator Share Posted April 28, 2011 Taking into account that the caliper is ok, you need to prime the master cylinder with fluid on "the other side", my mate is having the same problems ATM and I must admit, mine took a while to bleed my brakes on the xs. It helps if you have a 3rd hand, get someone to pull the lever whilst opening the bleed screw and shutting off before the lever returns. I have also had to suck the fluid through using a clear pipe so as not to drink the stuff drewps Link to comment Share on other sites More sharing options...
FLYIN BRIAN Posted April 28, 2011 Share Posted April 28, 2011 I've heard of people strapping the brake lever t the handlebar and leaving overnight to let the air come up through. Never done myself. Link to comment Share on other sites More sharing options...
KirriePete Posted April 28, 2011 Share Posted April 28, 2011 .... I have also had to suck the fluid through using a clear pipe so as not to drink the stuff That's one way to do it - I've got 6ft of aquarium hose set aside just for this purpose. Mind you, you could always use a syringe to provide the suction, saving the possibility of getting a free drink. Having said that, you could use a syringe to push fluid through from the caliper bleed nipple - watch the master cylinder doesn't overflow if you do it this way - it's not pretty (go on, ask me how I know this!). I've heard of people strapping the brake lever t the handlebar and leaving overnight to let the air come up through. Never done myself. This is good for the little bubbles that can get trapped in the pipe, as they keep getting pushed down every time you squeeze the lever. Tying the lever back overnight gives them time to bubble up to the master cylinder and when you release the lever in the morning the bubbles pop up with the returning fluid. Link to comment Share on other sites More sharing options...
DJW997 Posted April 28, 2011 Author Share Posted April 28, 2011 Taking into account that the caliper is ok, you need to prime the master cylinder with fluid on "the other side", my mate is having the same problems ATM and I must admit, mine took a while to bleed my brakes on the xs. It helps if you have a 3rd hand, get someone to pull the lever whilst opening the bleed screw and shutting off before the lever returns. I have also had to suck the fluid through using a clear pipe so as not to drink the stuff drewps How do you mean 'prime the master cylinder'? I don't have a bleed nipple on it if that's what you mean so I can't bleed it. I can only bleed from the calliper which I've tried several times and had no luck. Link to comment Share on other sites More sharing options...
DJW997 Posted April 28, 2011 Author Share Posted April 28, 2011 I've heard of people strapping the brake lever t the handlebar and leaving overnight to let the air come up through. Never done myself. Might try this tonight! Thanks for the input. Link to comment Share on other sites More sharing options...
DJW997 Posted April 28, 2011 Author Share Posted April 28, 2011 That's one way to do it - I've got 6ft of aquarium hose set aside just for this purpose. Mind you, you could always use a syringe to provide the suction, saving the possibility of getting a free drink. Having said that, you could use a syringe to push fluid through from the caliper bleed nipple - watch the master cylinder doesn't overflow if you do it this way - it's not pretty (go on, ask me how I know this!). This is good for the little bubbles that can get trapped in the pipe, as they keep getting pushed down every time you squeeze the lever. Tying the lever back overnight gives them time to bubble up to the master cylinder and when you release the lever in the morning the bubbles pop up with the returning fluid. I don't have a syringe unfortunately I did come across an idea on YouTube where someone rigged up their household vacuum cleaner to their bleeding jar to suck the fluid through. Might try this, but I don't want good old Henry sucking up any brake fluid! Link to comment Share on other sites More sharing options...
Moderator Cynic Posted April 28, 2011 Moderator Share Posted April 28, 2011 What a load of tripe, back bleed it. I used to work (still do in a way) with heavy plant and the engineers always backbleed and rarely have problems. A squeesable bottle is needed, i use an old brake fluid bottle with an old nipple fitted in the bottom. Fit hose to said nipple then other end to the caliper, Fill bottle with fluid allowing it to drain into the caliper, fit top, With a decent bit of hose you can tie it up well above the caliper, Keep checking the master cyl as you squeese the bottle, removing excess as required, if you run out of squeese just remove the top and reduce finger pressure. No air will get in to the brake system while you do this then with the top on your ready for another squeese, Once there are no bubbles in the resivoir your done, you should get a single system done in one GENTLE squeese, If its a multiple system bleed from one caliper to the other then from each to the master cyl. That method needs only one person although no harm in an extra pair of hands, needs minimal amounts of fluid and WORKS. No messing with opening and closing squeese no squeese etc,open and close the nipple just once. I even used it on those hard to bleed nissin 6 pots with excelent results. Link to comment Share on other sites More sharing options...
DJW997 Posted April 28, 2011 Author Share Posted April 28, 2011 What a load of tripe, back bleed it. I used to work (still do in a way) with heavy plant and the engineers always backbleed and rarely have problems. A squeesable bottle is needed, i use an old brake fluid bottle with an old nipple fitted in the bottom. Fit hose to said nipple then other end to the caliper, Fill bottle with fluid allowing it to drain into the caliper, fit top, With a decent bit of hose you can tie it up well above the caliper, Keep checking the master cyl as you squeese the bottle, removing excess as required, if you run out of squeese just remove the top and reduce finger pressure. No air will get in to the brake system while you do this then with the top on your ready for another squeese, Once there are no bubbles in the resivoir your done, you should get a single system done in one GENTLE squeese, If its a multiple system bleed from one caliper to the other then from each to the master cyl. That method needs only one person although no harm in an extra pair of hands, needs minimal amounts of fluid and WORKS. No messing with opening and closing squeese no squeese etc,open and close the nipple just once. I even used it on those hard to bleed nissin 6 pots with excelent results. Very interesting idea! I might try the vacuum cleaner method first, as I do not have a spare bleed nipple for your back bleeding method, but failing this, I will use your method. Thanks for your input! Link to comment Share on other sites More sharing options...
Moderator drewpy Posted April 28, 2011 Moderator Share Posted April 28, 2011 might try that meself tomorrow (on someones elses bike though) Link to comment Share on other sites More sharing options...
Moderator drewpy Posted April 28, 2011 Moderator Share Posted April 28, 2011 How do you mean 'prime the master cylinder'? I don't have a bleed nipple on it if that's what you mean so I can't bleed it. I can only bleed from the calliper which I've tried several times and had no luck. loosen the banjo connector to bleed the fluid through to prime the cyl. Link to comment Share on other sites More sharing options...
barkwindjammer Posted April 28, 2011 Share Posted April 28, 2011 Probably best to order new bleed nipples before using the 'reverse bleeding method' , and one of these kits http://cgi.ebay.co.uk/brake-bleed-kits-motorcycles-cars-vans-etc-/330552957071?pt=LH_DefaultDomain_3&hash=item4cf67dd88f Link to comment Share on other sites More sharing options...
DJW997 Posted April 28, 2011 Author Share Posted April 28, 2011 Ok, I've been working on this all day. I've tried the 'vacuum cleaner method' and that failed, tried sucking the fluid down using my mouth and that also failed. So I tore apart the master cylinder. Everything looked ok in there, didn't notice any cracked seals or anything. Squirted some brake cleaner and wiped around with a paper towel and rubbed some new fluid around. Put it all back together (without new seals mind). Tried bleeding again and still no luck. I tried pumping the lever with the banjo disconnected from the master, and no fluid comes out what so ever. I tried blocking the hole with my finger as I released the lever and I could feel it trying to suck my finger back in. I think I've found my problem!! Off to eBay to order a new master I think! Thank you all for your suggestions, they are greatly appreciated! I will keep you posted. Probably best to order new bleed nipples before using the 'reverse bleeding method' , and one of these kits http://cgi.ebay.co.uk/brake-bleed-kits-motorcycles-cars-vans-etc-/330552957071?pt=LH_DefaultDomain_3&hash=item4cf67dd88f Looks good! Might order one of these as well while I'm at it. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted April 28, 2011 Moderator Share Posted April 28, 2011 Probably best to order new bleed nipples before using the 'reverse bleeding method' , and one of these kits http://cgi.ebay.co.uk/brake-bleed-kits-motorcycles-cars-vans-etc-/330552957071?pt=LH_DefaultDomain_3&hash=item4cf67dd88f Suppose its an improvement on my old brake fluid bottle Link to comment Share on other sites More sharing options...
barkwindjammer Posted April 28, 2011 Share Posted April 28, 2011 Yeah Jason, its re-assuringly expensive Link to comment Share on other sites More sharing options...
Moderator drewpy Posted April 28, 2011 Moderator Share Posted April 28, 2011 Ok, I've been working on this all day. I've tried the 'vacuum cleaner method' and that failed, tried sucking the fluid down using my mouth and that also failed. So I tore apart the master cylinder. Everything looked ok in there, didn't notice any cracked seals or anything. Squirted some brake cleaner and wiped around with a paper towel and rubbed some new fluid around. Put it all back together (without new seals mind). Tried bleeding again and still no luck. I tried pumping the lever with the banjo disconnected from the master, and no fluid comes out what so ever. I tried blocking the hole with my finger as I released the lever and I could feel it trying to suck my finger back in. I think I've found my problem!! Off to eBay to order a new master I think! as a last resort, try putting some brake fluid in the other end of the master cylinder the pressure you are experiencing seems to indicate that the seals are sealing. It might just need some fluid on the other side for it to work, same as back flushing it! Link to comment Share on other sites More sharing options...
DJW997 Posted April 28, 2011 Author Share Posted April 28, 2011 as a last resort, try putting some brake fluid in the other end of the master cylinder the pressure you are experiencing seems to indicate that the seals are sealing. It might just need some fluid on the other side for it to work, same as back flushing it! Good thought, might try this tomorrow before I go about ordering things. I'm suspecting one of the two tiny holes at the bottom of the res is blocked. One of them did let tiny tiny air bubbles up if I pumped the lever rapidly before I took the master apart, but the other did not. I sprayed some brake cleaner at the holes and I could see some dripping out from inside the cylinder, but it could have just been flowing through the supposedly clear hole. I may try poke the end of a guitar string or something through it or get some compressed air on it when I get a chance, otherwise £30 for a new master on eBay, I doubt I'd bother with a rebuild kit because as you said - the seals seem to be sealing. I will try putting some fluid the other side of the master first anyway. Thanks for the advice! Link to comment Share on other sites More sharing options...
Moderator Cynic Posted April 29, 2011 Moderator Share Posted April 29, 2011 Good thought, might try this tomorrow before I go about ordering things. I'm suspecting one of the two tiny holes at the bottom of the res is blocked. One of them did let tiny tiny air bubbles up if I pumped the lever rapidly before I took the master apart, but the other did not. I sprayed some brake cleaner at the holes and I could see some dripping out from inside the cylinder, but it could have just been flowing through the supposedly clear hole. I may try poke the end of a guitar string or something through it or get some compressed air on it when I get a chance, otherwise £30 for a new master on eBay, I doubt I'd bother with a rebuild kit because as you said - the seals seem to be sealing. I will try putting some fluid the other side of the master first anyway. Thanks for the advice! If you get desparate i have a complete working brake system, it aint mint but it works fine. Certainly well enough for you to swap the guts out. At a price Thing is i can't see it being the master cyl, not unless you have done megga milage or really screwed up taking it apart. I still think your bleeding it wrong. Just think for a moment how much fluid that master cyl actually displaces, 15 maybe 20ml tops, an air bubble a quarter of that volume will render the brake useless. Have the pistons in the caliper moved yet, are they in contact with the disc? It will all have an effect. Link to comment Share on other sites More sharing options...
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