How To Bleed A Shimano Hydraulic Disc Brake

[@gmbntech]

Are you using hydraulic brakes yet or are you still on good old-fashioned cables? Let us know in the comments below! 👇

[@LaurentiusTriarius]

On one of my road bike yes, I wish there was an inexpensive cable actuated hydraulic system for MTBs...

[@simonm1447]

On some simpler bikes and on classic mountainbikes - rim brakes. On the more modern bikes, the modern mountainbike and on the commuter - hydraulic disc brakes I have one GT Avalanche 3 with mechanical disc brakes, I kept them (Tektro IO) since they were original on this semi classic mtb but they do not nearly have the performance of a hydraulic disc brake

[@Alex-ph4iu]

I've been using mt200 for 7 years now, bled them 4-5 times during this period, but for the last 3 years i feel a big loss of power in rear brake (pads are new, rotor clean, oil is new too). Maybe it's time to change brake lever? I even thought about returning to cable type brake...

[@simonm1447]

@@Alex-ph4iuOver time the 200s can get play in the lever bolt too. However in EU you get a full set for one axle for 25 € and a caliper for under 10 €

[@GenePavlovsky]

@@Alex-ph4iu Usually you can rebuild the master cylinder (the hydraulic device inside the brake lever) by replacing the seals or the entire plunger assembly. Provided that you can find the spare parts (lever rebuild kit). There's also a possibility that the caliper pistons are not moving freely due to corrosion. Caliper rebuild kits (piston+seals or just the seals) are also available. The above is based on my experience working with cars and motorbikes. On a bicycle you have an advantage of easily being able to upgrade your brakes by replacing them with a newer and better model.

[@ThunderStruckMTB]

I'm just gonna be that guy.... 1) Before pushing the caliper pistons back into their bores you need to open the lever and install the bleed cup so that the fluid has somewhere to go, otherwise you risk tearing the delicate diaphragm in the lever and fluid WILL squirt out from the lever vent port. Shimano has updated their latest dealer manuals to say exactly this. 2) Why push all of the filthy fluid from the caliper to the lever? Do a quick gravity bleed/fluid replacement to get that filthy fluid out of the caliper first before doing any bleeding from the bottom up.

[@a8f235]

Yeah, I did find this video a bit rough around the edges. The other thing is to clean the pistons before pushing them in as well.

[@woduk]

surprised people don’t already do that. Even on my hope brakes you take the rubber diaphragm off and the reservoir top cap.

[@nathanroberts4935]

Hmm so you have to waste new oil to put in the container only to contaminate it with old oil? Seems a waste

[@OregonCrow]

that never happens

[@kevinwmitchell5773]

I appreciate all the helpful content you folks provide but I have to say this how to isn't one of your best. Most notably, you provide no comment or instruction on bleeding the syringe hose of air before attaching to the caliper. Around 5:23 you can see the hose attached, with an air void in the hose and the hose oriented in a vertical direction. Once you start injecting mineral oil into the caliper, this air is going to be pushed in first. Yes on a front caliper you probably will push this air all the way through to the collection cup. But on rear calipers where the hose routing sometimes has a number of bends, you are potentially adding air into the system that could be a bitch to bleed out. Also, after closing the bleed port on the caliper, almost all Shimano brake bleed instructions advise cycling the brake lever repeatedly, until no more bubbles exit into the bleed cup. You don't cover this.

[@hifiandmtb]

Agree. And when the pads are put back on there no mention of cycling the lever to get the pads to the correct bite point. Or rechecking pad rub on the disc. You always need to muck about a bit with caliper positioning as the pistons rarely work perfectly symmetrically.

[@BeniKenesei]

Like others said, if you press the pistons back with the bleed screw still installed in the lever, you have a pretty big chance of wrecking your shimano levers. For older shimanos and other brakes it's usually not an issue. Just install the funnel with or without oil on the lever as the first step!

[@jayvee962]

I squeezed my piston back without removing bleed screw to install new brakes. Lever is squishy even though there’s no air bubbles. Could I have screwed something up? Any way to fix it?

[@pontap90]

If you follow the steps but can't push oil through, it can be that you need to screw the lever adjustment back a bit again. I just encountered this issue.

[@kurtismckemmie4850]

The brake bleed kit I bought from dyisland the instructions say to screw the pin in to close the line before adding fluid. I was very curious about the pin next to the lever as I had a mess of mineral oil all over the cables.

[@jamesyee4143]

Nice FYI on disc system bleeding , Iam a newb on this and how often should this be done? Thanks 👌

[@JoelZieve]

Why not do a gravity bleed?

[@djhinormas959]

im a motobike guy and i only do gravity bleeds so im wondering the same thing. is there a actual reason why people dont on mtb?

[@tsops22]

I find tapping the hoses a bit at the end to get rid of any cheeky final bubbles helps also. Great vid, thanks as always for all your efforts!

[@FOTB407]

Disconnecting the calipers from their mounts and letting them hang down vertically is best ime (particularly the rear, front is already vertical when mounted). Have a stool or something for caliper to sit on

[@buffalobilly6046]

Nope and nope. Old wives tales. Same for disconnecting calipers. I’ve done this a dozen times it takes me five minutes I don’t disconnect anything and my brakes work perfectly every time.

[@Andy-zl7ce]

Changed my front brake fluid and on the inside of the caliper there was oil - is it possible it came through the pistons?

[@camelot_avalon]

When I have good pressure and I remove the top cup, it floods over and i loose presure again. What am I doing wrong?

[@SCRAPSTrash]

@gmbntech Air in the syringe when it's filed with oil. Is this an issue? Or will the air in the syringe cycle through the system with out worry of trapping air inside the brakes?

[@mattgies]

Just stop pushing on the syringe before the air gets to the tip. Easy enough if you keep the syringe vertical.

[@antc5010]

Keep the syringe vertical with the plunger at the top and the outlet hose at the bottom.

[@GenePavlovsky]

@@antc5010 Or you can get rid of the air in the syringe/hose during filling it, and not run the risk of introducing an unnecessary bubble into the system.

[@DanWebb8080]

I use green citroen lhm mineral oil works fine bet there are a ton of reasons why i probly shouldnt

[@simonm1447]

At least it's still mineral oil. What is important not to use Dot fluid in mineral oil brakes or the other way, since the rubber of the O rings is made to withstand Dot or mineral oil, but these are different sorts of rubber

[@DanWebb8080]

@@simonm1447 exatly what i thaught, lhm is way cheap but still good quality so inclined to bleed more regular the viscostity seems very similar performance wise highly recomed it genuine total lhm+

[@Paul_1970]

I'm a newbie, doing maintenance on my bike, I'm having trouble with my brakes. After pulling my brake lever, the pistons on the caliper stays out and coursing my pads to rub on the discs . Any advice would be grateful. Thank you in advance

[@spencerimre]

look up how to clean the pistons, there should be a park tool video on it

[@simonm1447]

I used the old mineral oil the last time to clean chains. If you put it into a plastic bottle with a big lid you can put the chain in and shake it (don't do it with glass bottles since they can break - don't ask why I know this). The oil cleans the chain and lubricates it at the same time. After some time the dirt settles on the ground of the bottle and the oil can be used to clean more chains

[@muppet400]

@gmbntech. Thanks for this great vid. It’s about the only one I’ve seen that tells you to adjust the reach and bite point first. Was never sure before. Great content as always.

[@MTB_FANATIC99]

Will this method work with tektro m275 hydros??

[@BeyReaper]

Is the process the same for Sram? Actually Magura, bc thats whats on the bike I just bought. If they're not the same can you make a video on that or can someone link a good video on it?

[@199724]

My bleed nipples just leak all the fluid out when I brake after bleeding. Exact same issue in both front and rear. Very frustrating. Yes of course I tightened the nut again.

[@jonathansanchez1305]

Why leave air in you fill res?

[@Themilkmanskid.]

Seen other vids where they push fluid from bottom to top to clean the line, then draw in fresh fluid from the funnel at the top.🤷 I like this vid better and will try this way.

[@UltraBiPolar]

@@Themilkmanskid. 100% agree. We tried that other method and ended with wasted oil. We followed this video, which was much easier, and the results were perfect. As others have noted, take your time and go easy when injecting the oil to not ruin any fragile seals. If oil isn’t moving, stop and reassess.

[@Themilkmanskid.]

@@UltraBiPolar Bleeding is the easy part.

[@rolandegyed6695]

A question, maybe a dumb one (I recently upgraded from v-brakes to hydros, so I don't know everything yet): why do you need to pour mineral oil into the syphon on top? Isn't that just for collecting the old oil?

[@robertbransby]

Sometimes the syringe can drag a little back when you open the bleed nipple, saves dragging air into the system from the top

[@LaurentiusTriarius]

On pretty much all the dirtbikes I had the fluid is not that nasty when I bleed them mid or off season (about every 6 months) but when I had Shimano brakes I bled them like every 2-3 months and the fluid was ALWAYS nasty, like brown/black. Why is that?

[@LowFrequencyJim]

I though you were supposed to pull the old fluid out from the caliper side as contaminated fluid can ruin the levers?

[@gmbntech]

Shimano's have always bled this way, dirty fluid will get purged at the top so you don't have to disconnect and refill a syringe with clean fluid.

[@ChrisRufus76]

Where is the video for Tekro Hydraulic Brakes, the most common brake on budget bikes sold?

[@tomekborucki1120]

The most common ones are shimano mt200.

[@plainuser48596]

Any reason why this is better or more preferable than gravity bleed?

[@aftondanforth7387]

bc air goes up but it sometimes helps to do a gravity bleed first, then push new fluid up and do a lever bleed.

[@thisone-o6o]

Is there a machine that could add the hydraulic fluid and remove any trapped air?

[@Theiliteritesbian]

Yup - ur hands

[@mlowe1000]

Thank you!!! Great video.

[@andyrogers747]

“…but the brake fluid” - lmao 👏

[@my50bike]

Thanks - Easy Az with this great video...

[@flyingdumbo76]

you are the best guys

[@hsmythi]

Pro tip: before removing the funnel, put the wheel back and push the brake lever few times.

[@johndef5075]

Can I use an old rotor as a pad spreader?

[@simonm1447]

yes, of course

[@dannyk3718]

great explanation and walk through thanks

[@byeboy00]

It’s not I’ve bled my brakes this way and the proper way and my brakes are still spongy it’s starting to piss me off 😅 nothing works

[@peacebyjesus2388]

I use cable brakes myself: much simpler and cheaper. But why can't hydraulic bike brakes be as easy to bleed out air as motor vehicle brakes? Just 1. open the reservoir (with an attached cap, and add cup), + fill with fluid as needed (which maybe could be the same kind as typical MV's)"; 2. pump the handle and hold; 3.crack open the bleeder screw (not a bolt) on the caliper till the handle goes down (+ look for air bubbles) + keep it down; 4. close the bleed screw; 5. release handle; 6. add more fluid if needed,; 7. repeat steps 1-6 sequence till fluid is just that (clean + no bubbles), and close it all up. Also stick with Allen/hex screws, and keep all caps attached.

[@paulv22]

Shimano specifically states their mineral oil hydraulic fluid isn't corrosive.

[@lewisjacksonv]

What a great tutorial! Easy to follow and understand. Asset to gmbn!

[@minethegap]

Why would you pour fresh mineral oil into the reservoir and contaminate it with the flush from the bottom up. This video has a few fundamental errors that need revised. You can’t force pistons back if the reservoir is shut. The o rings on The piston will fail. Great video but do it again. This technique really only eradicates air bubbles not contaminants and moisture.

[@mano8033]

Let's do a TRP after this one

[@eliascly2366]

Cheers!

[@bhe915]

It is not fluid dynamics it is fluid mechanics.

[@2sweetpaul]

Baby oil 😂

[@spikeymike267]

Marshy gravity bleed every time

[@dominiqued.2307]

This is a really bad instruction video. At 5:25 they don't show properly how to connect the syringe. This other GMBN video explains it way better and in real time, they don't skip the difficult steps: kzbin.info/www/bejne/fpjKh2h4e7mFrZosi=gjCSM4lpcno18QJX They explain way better how to connect the syringe and avoid air bubbles in the other GMBN video.

[@gunstargizmo]

This isn’t for someone who hasn’t done this before. Lacks steps.

[@tollav]

I would say this is very complete and easy to follow???

[@kona0197]

What is with GMBN always mispronouncing the word "Lever" ?

[@adrianrogers6976]

Because we are English and pronounce it the correct way

[@ColoradoE470]

fuckingham palace

[@stokedonearth5097]

just pour your old oil into the ocean. the sea animals love it.

[@satchmotionrc8202]

Should make a video how to bleed mechanical disc brakes 😉

[@RoyalKyleBarker]

So much of this is wrong / not recommended. These clowns are getting view-hungry in my opinion.

[@AA-dp1iy]

Please don't read it, it's that simple

[@MrSupermugen]

How many times is this channel going to rinse and repeat videos? every new tech host has done it.... GMBN is such crap now

[@ArkUSAbikerchick]

I thought this one was a little more detailed and each step had close up pictures. A little easier for me since I have not done this before, but I feel like I can do it now. And the brakes look to be the same model as mine too! I thought it was improved! 👍

[@MrSupermugen]

@@ArkUSAbikerchick pick any of the previous 10 videos.

[@Justin-ny6un]

@@ArkUSAbikerchickIt’s missing about 3/4 of the bleed process steps. From what I remember Henry’s video is the correct process

[@dc2927]

I am a newbie, but why do you need to take the wheel off and pads out (I understand why the spacer is needed after tha)

[@lunarstorm27]

@@dc2927 it is just to avoid the risk of spilling the brake fluid on the brake pads. With care it is unnecessary.

[@John3-16Clothing]

First

[@gmbntech]

🥇

[@mattgies]

You've contributed nothing and patted yourself on the back for it. Great work!