I can see that there must be air getting in somewhere, or air not getting out.I have replaced the upper brake pipe for the Cali bars. The nipple is the same as before. The brake switch has been replaced and removed from the end of the master cylinder and put back where it should be on the “splitter” between the forks. So, all joints have been undone and redone up. I have checked them all as best I can but how do I know if it’s leaking air? The master cylinder was working fine before so it should still be ok, shouldn’t it?I have never had problems bleeding brakes before on any of my vehicles and I’ve been doing it for 40 yrs.When I pump the leaver with the one way tube on, it doesn’t pump the fluid out it just sort of dribbles out and the air in the tube goes backwards and forwards with just some air coming out. Given up for today! At least it seems to be running well - touch wood!
It is annoying I have found if the front will not bleed and you are sure all the connections are good then the only thing left must be the master cyl. IF it is not pumping fluid then either some gunge has gone in there OR emtying it has disturbed it and that is where to look.
I will use ptfe tabe around any and all hydraulic threads, I have had a new hose not be sealed correctly, many yrs ago and I have had a brand new bleed nipple not seal due to some sort of crystalling of the fluid getting trapped there.
When the virago would not bleed up it was the master cyl, it had all worked well then I emptied the front to fit new caliper pistons and new pads and it just would NOT bleed, similar to what you have just moving fluid back and forth, new master cyl seals all done.
Annoying I know and frustrating BUT once you eliminate what it IS NOT what’s left must be the problem… as Spock onse quoted, from Sherlock Holmes I think!
- Pump up the lever with nipple closed, 2. hold lever pulled back then open nipple. Fluid & air should escape under pressure (because lever is still depressed) 3. close nipple, then 4. release lever, 5. go to 1 (repeat) At risk of stating the obvious but if the fluid you are trying to put in has air bubbles in it, then reservoir will have bubbles in it and you are wasting your time, that’s why it says on the bottle make sure there are no bubbles in it “do not shake bottle” etc., if so, have to let it stand for 24 hours or something like that. One has to presume therefore that this includes transporting it back from the shop, imagine it’s been bouncing about in your car boot or your pocket / shopping bag / bike’s tank bag whatever, highly likely it will have bubbles in after that shaking up. HTH
The fluid is brand new and virgin and not bounced about. I have pressurised the lever and opened the bleed nipple. That is the way I’ve always bled brakes, into a jam jar. The brakes pressurise to a certain extent - you can make the lever almost touch the bars before the resistance is too great, but it has a springy feel, ie air in the system till it gets there. You can hold it pressurised and it does not seem to lose it’s “stiffness”. When I rolled the bike back down the slope to the shed the brake lost its grip until pumped up - air again.I suppose it’s a case of change the seals, replace all the washers, re tighten everything and try again.
Then it must still have air in it. Try it my way without the one-way tube (?)
Its not just me then. In essence, my brakes were fine till I replaced the hoses and pads and flushed out all the old fluid which was thick and gungy. I have concluded that the fault rests with the master cyclinder which although ok before, with fresh new thinner fluid, gave up the ghost even with new seals. The fluid being hydroscopic will absorb water and I think the bore of the m/c was damaged by this. Judging by the state of the fluid that was in there, I wonder if the fluid had ever been changed on my 20 year old bike. New m/c on order and hopefully that will be that. Note to self; replace brake fluid annually - it’s easy enough to do when the system is working properly and will save all this grief in the future.
Yes, I will try it every which way till it works. I have just ordered a master cylinder kit from Gutsibits to rule out that being at fault. I will check the nipple seat and all the joints and string the caliper up as high as I can. I’ll dance the Fandango if it will help!I’ve then got the back and other front to do!
Best of luck! Must admit htere’s something awry somewhere, it can be a P.I.T.A. but not this awkward. Did I mention fitting new pads before bleeding would make it feel a bit spongy anyway, until they’ve bedded in and the pistons adjusted right up as far as they will go. (?)
Not changed the pads. Master cylinder kit should be here tomorrow, so I’ll see if I can sneak a bit of time to try again.
Just thought of something, I have long noticed when bleeding the rear master with the cap off, if pedal is pushed down rapidly you should get a drop of fluid leap up into the air from the exact centre, we now know this is where the very small hole is. This behaviour would therefore indicate that said hole is clear, and the drop is due to a bit of reverse flow as the piston seal rapidly approaching the hole before it can close it off. HTH
My front one does that.
Awl-righty then!
Fitted the new master cylinder, went through the usual bleeding drama and, it worked! The only thing I can conclude from this is that, provided everything is in tiptop condition, bleeding shouldn’t present any real difficulties though it helped having my better half pumping on the brake pedal while I topped up the reservoir which kept the flow going. That was the last job to do before refitting the tank and connecting up. She hadn’t been started since October last year and she fired up first prod of the button. One happy bunny off to mot.
I have said that many times bleeding should be a 5 min job for both ends reverse bleeding them IF that does NOT work then
- Look to see the nipples are fully seated…they sometimes don’t and I have had a crystal form at the bottom
- Air getting into a joint, I use PTFE tepe on connections
- Master cyl needs refurbishing