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Bled Motorcycle Front Brake and now Dragging?
Hi all. The front brakes on my MC started to get really spongy so I loosened off the bleeder valve on the master cylinder and pumped the brakes a few times.
A few bubbles came out of the teet and the brakes became really stiff. So much so that it drags slightly on the rotor when pushing the bike forwards/backwards.
It feels like the lever has no dead zone or graduation at all now. The tiniest amount of pressure on the lever locks the front wheel. Feels a bit sketchy to me.
It occurred to me that I may have pumped the lever too many times when bleeding the cylinder and now there is not enough air to displace the fluid.
Question is: how do I get air back in the cylinder or is there any other trick to fixing this ?
Bike is a 2015 1290 superduke, if that matters.
@Mark- Thanks for the reply. I only bled the tiniest amount of fluid from the cylinder, which was inconsequential to the amount in the reservoir.
There are no leaks anywhere. I assumed that because the bike only has 1300km on it, that it's possible that some residual air in the system finally dislodged and made it's way to the master cylinder.
I've had absolutely no problems with the callipers or brake system at all until it got spongy. The callipers react normally if I manually press them.
I will check for any abnormal routing of the brake line as per your suggestion.
Regards the master cylinder. I read that master cylinder overfill is a thing and can cause such issues. I just have no idea how to remedy that. Admittedly when I was pumping the lever, I should have stopped earlier as it felt normal after the initial squirt of fluid/air came out of the teet.
PS. It was only the tiniest amount of fluid that got bled from the system. I'd estimate it to be about 0.5ml or less. Barely enough to wet my finger.
PPS. By "pumps" I am referring to very minimal presses on the lever. I think at most, a few mm of travel each press.
Thanks for all the info guys. I'm still a little stumped as the list of potential causes are many. Being that the initial issue was loss of pressure, I'm pretty skeptical that the problem is at the caliper. This new set of symptoms would seem to suggest a cylinder issue, as that would at least correlate with the original point of failure.
Can't really afford to have this kind of thing serviced atm. I guess I should be happy that the brakes are no longer super spongy. Beggars can't be choosers
Hmm, I'm not sure why some people are getting so triggered here, was just after some advice lol. Yes, "take it to a professional" and pay them with my imaginary money. Of course! Why didn't I think of that earlier...
Correction on the mileage, the bike has 10,300km on it not 1300. Also, 2015 model so not eligible for either warranty or recall. But thank you for bringing the recall notice to my attention.
Brakes have retained their stiff feel from yesterday.
Seems that they have relaxed ever so slightly. It's not dragging quite as much as it did initially. I think what might have happened is that I had some pressure on the lever when locking the valve nut.
I have since loosened it and let it do its thing. Got a few dribbles of fluid, but nothing too exciting. The brakes are actually functional now so I consider that a win. I'm not ruling out the possibility that the system always had some air in it and so what I feel now might be considered normal
And lol, I can't help but see the irony in people saying "you have no clue what you are doing" to someone asking how to do something on their bike. I wouldn't be here if I knew what I was doing lol.
I may be inept at the inner working of hydraulics, but I have managed to frame my motard, rebuilding it in it's entirety. I also managed to do AM air-box, SAS delete, fuel mapping, PC5 install, suspension kit, Evotech frame sliders, USB ports, rotor/pad replacements And the list goes on.
I figure if I can do all that by myself, why not attempt to fix what could easily be a simple issue, especially when I can't afford to take it to the shop anyway. The level of ignorance here is astounding.
Thank you Anon for your civil and humble answer. At this point I suspect the dragging was a result of my bleeding method. After riding the bike, it appears that everything is working normally now.
It could still be the case that I need to bleed the entire system. The fluid is very off-colour and is slightly cloudy. I will get around to that once I have the confidence and materials for it.
Also thank you to others who offered similar advice without all the belligerence and arrogance.
14 Answers
- ?Lv 61 month agoFavourite answer
"Spongy" usually means water turning to vapor when brakes hot. Sometimes, air. When U bled them, the firmness came back and the stiff O rings to calipers were apparent.
Rebuild caliper; or at least grease the O rings; flush entire brake out with fresh Synthetic DOT 4 or better, bleed..
My rear brake dragged, I didn't realize it until I went thru entire system. MC brakes are easy to rebuild/bleed.
Edit: On some bikes, , you need to "reverse bleed", that is, get a 50 ml syringe, suck it fulla fresh fluid, , attach it to nipple with hose, open nip, hold plunger UP so bubbles aren't reintroduced, push to fill system and force air out. Dont overflow the reservoir. Close nip, pump lever a few times until no bubbles. Check brake's feel.
Edit: SpaceJ, yes, I know. I had an innocent query similar to yours; I was treated like a 12 year old. I am 64; I've fixed my 'sickles and cages since 1978. One said: "don't grease the rotors".....like, I Would? I have been maintaining my own since before that Kid was born...
- fuzzyLv 71 month ago
if bike only has 1300 km on it it is a warrantee issue - take it back to the dealer
- garryLv 61 month ago
you screwed up , something as simple as bleeding the brakes , what a fool , not telling you what is wronge , rather you take it to a bike shop and pay to have it fixed ..lol
he put air in the system and hasnt bled it properly .. lol .. thinks thats the funniest thing i heard in 40 years of motorcyling ..
- Anonymous1 month ago
What part of Screwed It Up do you not understand? You should understand you don't know what the hell you are doing. Then you should understand you need to take it to someone who does know what the hell they're doing.
- Anonymous1 month ago
Calipers drag a bit. It should not be noticeable when pushing the bike. If the wheel is up in the air you can hear the scuffing because the pads are that close to the disc. That is normal. That is why you can stop with just using your middle finger on the brake lever.
This is confusing you. It should go down to the bike shop and let the real mechanics work on it when you don't know what the "eff" you are doing. 1300km is squat for the bike. Sorry, but sometimes it is harder than you think. You seem not knowledgeable about this thing.
- 1 month ago
When servicing brakes you should leave it to the professionals if you're not competent. Your calipers need a rebuild, pistons greased, and copper grease on the BACK or the pads to prevent squealing.
It purpose of bleeding braked is to extract the air, not put it back!
- ?Lv 71 month ago
Betcha ain't never rebuilt dem calipers. Gitcha a rebuild kit, which is the piston seals, take it apart, clean it, check for scuffed pistons, and LUBRICATE the new seals and pistons with the lubricant whut comes with the rebuild kit. Helps to put a SMALL amount of disk brake lube on the back (caliper) sides of the pads. Didja know them seals is whut RETRACTS dem pistons, 'cuz thar ain't no springs thar whut kin do it? Hydraulics 101, dude.
- CBLv 71 month ago
Check this out - maybe the dealer will service the MC and sort it out if your bike is affected by the recall.
https://oemdtc.com/219/front-brake-master-cylinder... do full bleed, pump up the brakes hold pressure and bleed the caliper - close it before the brake handle bottoms. Repeat on other side caliper until no bubbles come out. IF that doesn't fix the problem the residual check valve in the MC is likely faulty.
- Anonymous1 month ago
You do not want any air in the fluid. There is a membrane in the master cylinder that expands and contracts as you apply the brakes, that is what gives you "feel" at the lever and that relies on an amount of air but it is not air in the fluid.
I suspect your problems are more likely to be at the pistons and guide rods in the caliper, it probably needs a good clean or, better, a strip and service.
Failing that it could be a piston in the master cylinder.
Did you know that there has been a recall on Superdukes because of the brake master cylinder?
- Anonymous1 month ago
Caliper is likely shot. Check if pistons are retracting completely when brake lever is released. If they are not, clean pistons or replace them, clean piston cavity and install new seals. Or just replace the caliper.
You can try bleeding the master cylinder on the bench, reinstall master cylinder and bleed the whole system again. When bleeding, press brake lever and hold, open bleeder valve and close bleeder valve. Do NOT pump brakes when bleeder valve is open.
- MarkLv 61 month ago
You do not want air back in the cylinder. Did you make sure to top off your reservoir when you bled them? If they are full, it sounds like a caliper issue. The first question you should ask though is how you got air in the system to being with. That should not be possible if the reservoir is topped off unless the system is leaking somewhere.
I once thought that I had a bad caliper because it was slow to release. It ended up being a bad brake line flex hose. It looked good on the outside, but a rubber flap formed on the inside of the hose acting like a flap valve.
It could also be a bad master cylinder or brake caliper too.
