So I've had something happen on my R3 that I haven't seen before in 9 years of motorcycle ownership. Lost all brake pressure over winter. Last time I used the bike was October at Daytona, and everything was fine. Since then it sat in the garage untouched. Now I realized I have zero brake pressure. I can squeeze the lever all the way to the bar with no resistance. I've tried to bleed the brakes but it's not getting any better at all. Clearly there's gotta be a leak somewhere in the system, but I've just never had this happen before so I'm not sure what it could be. I imagine it would have to either be the bleed nipple, or the line itself, or the master cylinder. I needed an excuse to get speed bleeders anyway, so I'm starting with that. Any advice on what it could be?
Well shit. Yeah there's no fluid leaking from anywhere as far as I could tell. Would've seen a spot on the garage floor if that was the case. How can a master cylinder go bad though from just sitting in a garage? Never had this happen on any bike I've ever owned, and they've all just for 6 months untouched during the winter. Maybe this is the excuse I needed to get a Brembo MC! lol
It probably didn’t go bad. I’d imagine there was an air bubble that floated up to the master cylinder. When you applied and released the brakes, it may have sucked it into the master cylinder and it’s airlocked, now. One way to get it out is try and apply pressure through the bleed nipple, via syringe or baster. Force fluid up through the master cylinder. Otherwise, you’re going to have to bench-bleed the master cylinder, hook the line back up, apply vacuum at the bleed nipple, squeeze the lever, open and close the nipple, release, squeeze the lever, etc. You DO NOT want to pump the lever, while bleeding. Just one squeeze, so you’re not pulling air back into the master cylinder.
I tried the syringe method to push fluid in from the caliper up, but still no brakes. What's weird is when I bleed the brakes by the traditional pumping method, there are no air bubbles coming through in the tube. I did it several times and it all looks good, but yet the brakes are still very mushy and I can pull the lever to the bar.
It’s just like bleeding an automotive master cylinder, if there are no hoses going back into fluid so everything moving is fluid, you’ll never get it bled and there won’t ever be any air bubbles, because it’s airlocked. That’s why they have to be bench-bled, before installation. Motorcycles can do the same. As TLR67 mentioned, the master cylinder could be bad. However, I’ve seen people replace the master cylinder, only to have the same issue, because of not properly bleeding. You may disconnect the hose at the caliper, put the end into the master cylinder reservoir, and try pumping the air through. With the hose looping above the master cylinder, any air should move upward.
I feel for ya’. I have a VFR and those still running the linked brakes just fight those things. I delinked mine, partly to avoid the mess of bleeding them. I’ve done linked brakes once and got lucky with not having problems.
Ok thanks, I will try that next. Would it just be easier to take the MC and reservoir off the bar and set it down so that the caliper is at a higher level and bleed it that way?
The bleeders can be damaged if you over tighten them. The hole going through the tapered bit at end can collapse. Almost every bleeder I’ve pulled has been collapsed (car, truck or motorcycle) but none have leaked or sucked air. It just makes it more difficult for fluid to pass through the drilling while bleeding air out of the system. On my Ninja 300 I installed a banjo fitting with a bleeder at the master cyclinder. Really speeds up the bleeding process.
I've had success getting air out of the master by pushing the pistons back into the calipers, with the cap off the master. Be careful of making a mess as brake fluid can remove paint.
Every time I bleed brakes it ends up being a mess, but at least it's always worked up until now lol That's why I got speed bleeders on order, along with the little plastic bag and tube they sell. Should reduce the mess by a lot.
I've seen your problem before, mostly on the rear brakes of a few older bike that don't get ridden. Re-bleed it, brake works just fine. But let it sit for months on end (over winter), and it'll just lose the pressure. Not the bleeders, it's the M/C like others said. Only real way for a bleeder to go bad is by tightening it too much and crushing the conical shape on the bottom. Stalhbus bleeders are legit...and totally worth the price of admission. The cheap $3 speed bleeders...you'll never see those on my bikes.
I had the bleeder fail on brembo RCS. The pressure would hold for some time but when I left it overnight the brakes would get soft. I've tried everything and then noticed a tiny smudge of fluid around the bleeder. There was also air bubbles floating up in the reservoir no matter how many times it was bleed. After replacing the bleeder the issue went away. Caused by initial over-tightening of the bleeder.
Why is there no “love” for Speed bleeders? If the bleeder is screwed in so the conical seat is sealed, the ball bearing and spring that makes them work isn’t even seeing any hydraulic pressure? They are no different than a stock bleeder nipple when screwed in .... have people seen stock bleeder nipples fail catastrophically on a regular basis?
+1 to bubble stuck in master. If there’s no bleed port on the master, u can bleed with the banjo fitting. Wrap it in a rag, hold pressure on the lever, loosen banjo 1/4 turn and tighten. I’ve removed some pesky bubbles that way, and u don’t need to worry about the crush washers.
I didn't see the last few replies until now. Some updates on this. I ended up putting a zip-tie around the brake lever and left it for a few days while I was out of town. Trick I learned from someone a few years ago. When I came back and took it off, the brake felt MUCH better, pretty close to good, although maybe still felt a bit mushy for my liking. My Speed Bleeders came in so I figured might as well replace it while I'm messing with this anyway. Those things are awesome! Why didn't I get them before?! Anyway, I re-bled the brakes while also having the MC down on the ground below the caliper. As I was bleeding I saw a few tiny bubbles coming through. Zip-tied the lever to the bar again, so hopefully it should be all good tomorrow.
Last time I had a problem like this I had to replace the master cylinder. Idk what to call it but the gaskets and seals and whatnot had little rips you couldn’t see. It was much better but still squishy. And yes bleeder nipples can go bad, if I remember correclty they are aluminum? If closed and opened too much they’ll let air in slowly cause they get worn out. At least that happened on my old 2005 zx6. When I got my new r6 I put on a brembo master and it took 5 mins to bleed it to stiffness. If it takes longer than 30 mins there’s a physical fault somewhere. Air will be quick to come out if everything’s nice and sealed and in working condition.
A bleeder is nothing but a metal on metal seated angle valve. If the seat(s) were over torqued and scored they will leak. It will be obvious. If damaged replace the nipple (cheap)....if the caliper seat is boogered up, good luck. The caliper manufacturers must have a tool for cutting these seats but I've never seen one. The angles are slightly different between the two seat faces. This way when closed all the contact pressure is concentrated on a very fine line of contact allowing for the seat to withstand the very high pressures.
