AndreZA Posted April 11, 2011 Share Last year I made tried to fix my misalign pads 5 minutes before I had to leave for work. Results, piston and fluid all over the kitchen floor. As this was a Wednesday before a race, a fellow hubber quickly helped me getting it fixed. But because it was old pads, I could not top up the system full because if I fitted new pads, the pistons would not retract fully. It worked perfectly until I got a bee in my bonnet to fix (what that thing about do not fix until broken). So 3 weekends ago I decide to top up the fluid anyway. I did this in the reservoir. Worked fine but when I went for a short spin, it became spongy. So I decided to push fluid from the calipers side. Some bubbles came out and I thought that was it. Also replaced with new pads. Felt good in the kitchen/workshop but after the ride, it was spongy again. So I did the whole squeeze lever and open bleed valve a few time an pump again exercise. Same thing. Oh, by the way, I am using the correct synthetic Shimano fluid. So the past weekend I said stuff this. I drained the complete system bu sucking everything out the caliper using a syringe. Used the same fluid and pushed it back through. Did the squeeze lever and bleed valve exercise. Topped up and closed the reservoir. Pulled the lever and BAM, perfect felt just like the shop did rear. Got about 10mm of movement then it is solid. Went for a spin and it stayed the same. Went for a 30km ride on the spruit and it was perfect. Now my front bites earlier then the rear but that will come right if I fit new pads there. So my question, where did I go wrong in the first few attempts? Dankie, ek luister by die radio. Edited April 11, 2011 by Mampara Link to comment Share on other sites More sharing options...
patches Posted April 11, 2011 Share is the title a typo for "bleeding brakes" or for "breeding braks"... cos I know very little about either, but I don't think "breeding braks" can be that hard!? Link to comment Share on other sites More sharing options...
AndreZA Posted April 11, 2011 Share is the title a typo for "bleeding brakes" or for "breeding braks"... cos I know very little about either, but I don't think "breeding braks" can be that hard!? fixed. Link to comment Share on other sites More sharing options...
Lamber Posted April 11, 2011 Share if a 'brak' bleeds, you must take him to the vet Dis ongelukkig hoe ver my kennis strek Dankie, ek luister ook verder op die radio... Link to comment Share on other sites More sharing options...
Thumper Posted April 11, 2011 Share Whats brakes you working with?After bleeding my XTR's every week for a month I consider myself fairly clued up when it comes to Shimano. Edited April 11, 2011 by Thumper Link to comment Share on other sites More sharing options...
AndreZA Posted April 11, 2011 Share Whats brakes you working with?After bleeding my XTR's every week for a month I consider myself fairly clued up when it comes to Shimano. It is XT. My bleeding kit is home made. A few silicone tubes which fits super snug around the bleed nipple, a syringe and a plastic milkshake bottle with a piece of coathanger sticking out of it. Link to comment Share on other sites More sharing options...
SwissVan Posted April 11, 2011 Share So 3 weekends ago I decide to top up the fluid anyway. I did this in the reservoir. So my question, where did I go wrong in the first few attempts? Dankie, ek luister by die radio. In my very limited experience with bicycle hydraulic brakes.... You should not have topped up the fluid, very difficult to top up without allowing some air to get in, even in PTA there is some atmospheric pressure and it forces air in everywhere if given a gap. Moral of the story, sometimes the longer road is quicker than the short cut. Link to comment Share on other sites More sharing options...
AndreZA Posted April 11, 2011 Share In my very limited experience with bicycle hydraulic brakes.... You should not have topped up the fluid, very difficult to top up without allowing some air to get in, even in PTA there is some atmospheric pressure and it forces air in everywhere if given a gap. Moral of the story, sometimes the longer road is quicker than the short cut. The way the say you should do it is to fill it so that it almost overflows. Then if you place the diaphragm in it actually does overflow and expels any air. The if you tighten the cap it is air tight. Link to comment Share on other sites More sharing options...
SwissVan Posted April 11, 2011 Share The way the say you should do it is to fill it so that it almost overflows. Then if you place the diaphragm in it actually does overflow and expels any air. The if you tighten the cap it is air tight. Somewhere they probably also mention that bleeding the brakes is a simple task that can be done with one hand whilst the other hand holds the instruction sheet. Think about it, until tightened down air tight how do u stop air from getting in when the atmosphere is "pushing" air in with +/- 12 pounds per square inch if u live in Gauteng or 14.7 psi at sea level? Link to comment Share on other sites More sharing options...
Thumper Posted April 12, 2011 Share It is XT. My bleeding kit is home made. A few silicone tubes which fits super snug around the bleed nipple, a syringe and a plastic milkshake bottle with a piece of coathanger sticking out of it.My home made step by step guide:- Ensure the bike is standing flat on the ground- Rotate the brake level parallel to the ground- Open the hydraulic reservoir on the brake lever- Drain all fluid out of the brakes. (this can done via the bleed nipple and reservoir using your syringe)- Fill a syringe with the appropriate brake fluid. Ensure there are no bubbles in the fluid.- Attached the syringe to the bleed nipple and pump the fuild through the system until the reservoir is full- Close reservoir Did this on a set of XT brakes before the SS champs and had no problems. Link to comment Share on other sites More sharing options...
Johan Bornman Posted April 12, 2011 Share Somewhere they probably also mention that bleeding the brakes is a simple task that can be done with one hand whilst the other hand holds the instruction sheet. Think about it, until tightened down air tight how do u stop air from getting in when the atmosphere is "pushing" air in with +/- 12 pounds per square inch if u live in Gauteng or 14.7 psi at sea level? It doesn't quite work like that. Atmospheric pressure doesn't push air into a system like that. Link to comment Share on other sites More sharing options...
SwissVan Posted April 13, 2011 Share It doesn't quite work like that. Atmospheric pressure doesn't push air into a system like that. I oversimplified, thats why I placed inverted commas around the word pushing. My point was that its difficult to open and close a brake hydraulic system without getting some air in, unless you follow a more effective but seemingly longer process i.e. as described by Thumper. I wonder what it would be like to fix Mamparas problem in a vacuum? Link to comment Share on other sites More sharing options...
AndreZA Posted April 13, 2011 Share My home made step by step guide:- Ensure the bike is standing flat on the ground- Rotate the brake level parallel to the ground- Open the hydraulic reservoir on the brake lever- Drain all fluid out of the brakes. (this can done via the bleed nipple and reservoir using your syringe)- Fill a syringe with the appropriate brake fluid. Ensure there are no bubbles in the fluid.- Attached the syringe to the bleed nipple and pump the fuild through the system until the reservoir is full- Close reservoir Did this on a set of XT brakes before the SS champs and had no problems. Yip, that is how I ended up doing it in the end. But I included a lever squeeze and nipple release in there before closing up again. But I want to know why did the simple fluid top up from the top or the bottom not work. Link to comment Share on other sites More sharing options...
AndreZA Posted April 13, 2011 Share I wonder what it would be like to fix Mamparas problem in a vacuum? I've got a Verimark Shark Stick. Will never get my whole bike in there. Link to comment Share on other sites More sharing options...
NotSoBigBen Posted April 13, 2011 Share I wonder what it would be like to fix Mamparas problem in a vacuum? You'd frikkin struggle in our Hoover Link to comment Share on other sites More sharing options...
Thumper Posted April 13, 2011 Share Yip, that is how I ended up doing it in the end. But I included a lever squeeze and nipple release in there before closing up again. But I want to know why did the simple fluid top up from the top or the bottom not work.Maybe it has something to do with the age of the fluid? I assume air could be pulled into the system when the new oil interacts with the old. Link to comment Share on other sites More sharing options...
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