How To Bleed A Shimano Hydraulic Disc Brake

are your brakes feeling inconsistent they feeling a bit spongy are they pulling to the bar maybe it's time to give your brakes a bleed we're going to show you how to bleed Shimano brakes step by step hydraulic brakes use the power of fluid dynamics we're not going to go into it too deep but essentially what happens is that well fluids aren't compressible so a force up here at the lever means that the fluid is pushed all the way through the hose and then it pushes those pads unfortunately if you've got any bit of air as you might have in a suspension system you'll know that it's springy and it can be springy in your brake we're going to bleed it and get rid of all that air before we start brief warning time uh mineral fluid a bit like some other brake fluids it's not nice stuff so be really careful with handling it so wear Nal gloves wear some protective eyewear uh make sure you keep it off paint and especially off braking surfaces the other thing to be really mindful of is how you dispose of the old oil we've got an old container here that we use to pour in the container and then we're going to take it to our local recycling center so make sure you adhere to your local rules and regulations about disposing of oil to do this bleed you're going to need a variety of different tools you'll need a four M most likely to adjust your lever you may need a range of Allen Keys Torx keys or a flathead screwdriver to remove the pin that holds your pads in obviously the big thing that you'll need is a dedicated bleed kit so the bleed kits come with a a little kind of storage container bit like a yogurt pot that sits on top of the lever comes with a syringe it's got dedicated fitting so you'll probably need to get the right one for your system so do some research the other thing that will come with is a not really a pad spacer but more a piston spacer so this once you've removed the pads will hold the Pistons in the right place so you're not going to walk those out of the caliper other thing that you'll need surprising it doesn't come with a kit but it doesn't is mineral oil so Shimano make their own there's a number of different different aftermarket Brands you can get as well but make sure that it's designed to work with Shimano there's a couple of different versions out there that might not work with shiman as you might think you'll need a pad spacing tool to push the Pistons back in and push the pads in and you'll need some disc Brak cleaner this process like many fixes on mountain bikes is much easier with a bike in the stand it's not essential but it will make it a lot easier so we've po the bike in a stand first step in bleeding the front brake is to take out the front wheel and then we're going to slowly push the Pistons back in by using a pad spreader with the pads pushing the Pistons all the way back it's now time to remove the pads so they don't get contaminated just be mindful that there's often a little retaining clip on the opposite side from where the uh the nut is on the caliper and sometimes these can ping off really quickly so just be really mindful that you keep a hold of it with the pads out we're going to install a piston spacer this is like a block of plastic which stops the Pistons pushing in when we're moving the fluid around be really mindful to use the right one so this one is about the right width but it isn't going to cover the four Pistons this one is the right one it's a little bit trickier to put in but make sure it's a really good tight interface fit I've not used the retaining pin in the past that's the same pin that's holding your pads together uh and Midway through the bleed I've had this spacer drop out it then can lead to lots of things like Pistons falling out of the caliper it's not ideal so make sure when you put this in even though it's a really tight fit that you put the retaining pin in to hold it in place with the pads out and the caliper set up ready to bleed is now time to get messy get the fluids out but the brake fluid so that means we've got to get gloves out and we've got to get protective eyewear on so as we've discussed we're trying to get rid of any air that's in the system and we're going to help gravity do its magic we're going to position the lever up sort of making the top of the lever at the highest point another advantage of using it at the stand if you're having to bleed a rear brake for example and the hose routing is a little sort of curvy and undulating make sure that you tip the bike really high at the front so the lever is at the highest point so any air that's in the system is going to migrate that way naturally through gravity which the mono brakes they recommend that you adjust the lever reach out and if you've got a freest stroke adjuster like this one that you open that up as well it all helps with a bleed process with the lever positioned kind of on the bar in the right place and lever positioned out from the from the bar as well it's time to take off this top bleed Port there should be a little rubber bung on it so sometimes that's missing there it is so don't lose that you can see it just on there pop that safely to one side now it's time to install the open sort of bucket just be careful that you get the threads in correctly and also be careful not to tighten it too tight if you've got a little plug plunger like this make sure it's fully inserted and it's time to fill it with fluid in regards to how much fluid to put in you don't actually need that much because with the Shimano way bleeding you push up all the fluid from the base so this is more the storage collector than it is a siphon or or loading area for the fluid fill the syringe 2/3 full next step is we're going to attach the syringe on the bottom so first we've got to remove a little rubber guard uh hopefully yours is still there we'll need to get a 7 mil wrench uh just to open it up once the syringe is on and we'll need to prep the syringe as well so we'll attach all of that together and then once the syringe is on we'll open up the valve and then we'll start the bleed process once you've open it up you can then release the plug at the top on the reservoir so that's just pop it up you've got a little clip space where you can clip that little plugin later once you've got that all effectively open then begin pressurizing the syringe now it should flow really smoothly through the system if you've got any kind of resistance it might mean that you've got kind of some other issues so just gently tap the hose that might help accelerate the air moving through the system and um just yeah be really careful and and sort of slow if you try and force the syringe some of the Shimano brakes have got a relatively delicate sort of diaphragm assembly in here that you can break with too much force um keep checking that the fluid is Flowing from the syringe through and up into that Reservoir part that you've got on top hopefully you'll see some bubbles come through you might even see a color change now if the fluid is Flowing up and it's it's still kind of coming through quite dark close off the syringe at the bottom remove it fill it up with more fresh mineral oil reattach the hose open it up again and then force it through again obviously be really careful that you're not going to overflow your Reservoir at the top another reason why we kept it relatively low when we filled it but make sure that you're cycling all that new fluid through once you're sure that there's no more bubbles so you've kind of like pushed the syringe a couple of times and it's the fluid flows up really easily make sure again that that that fluid looks as fresh and kind of like bright pink with a Shimano uh stuff anyway is is flowing through and then it's just time to kind of like lock off the lower bleed Port uh remove the syringe reinstall the rubber grommet um if you're being really keen and probably the best practice is then to miss that area with some disc brake cleaner or some isopropyl alcohol to make sure it's clean and devoid of any of that brake fluid because if that contaminates pads well it's new pads time then up at the lever Point um you can cycle the lever a couple of times just to feel to the system and see that it's all okay it's now time to take off the upper Reservoir or yogurt pot make sure that the plug is plugged in because I've removed the OT before and then poured mineral oil everywhere especially where you don't want it so make sure it's plugged in carefully remove it store it to one side uh for safe disposal later return the O-ring and that top plug into the reservoir and screw it in make sure it's nice and tight um you can then miss that area with isopropyl alcohol we're now going to put in your brake pads now everything's nice and clean so carefully put the pads in obviously do check if they're worn cuz if you've done a brake bleed you may as well put in fresh pads at the same time but if the pads are still in good Nick replace them it's time to put the wheel back in and then you can set up your lever so you can adjust the angle of inclination that you need the the lever bite point and then if you've got a freest stroke adjuster you can also change that to your preferred setting hopefully this brake bleed has really helped and hopefully it's demystified what can be a little bit of a scary thing to do but it's not as long as you're careful with the mineral oil and you're careful with the disc brake cleaner it's quite a simple task keep it systematic go step by step and you too can have a great feeling break

Channel: GMBN Tech

Views: 83,543

Keywords: How To, learn, bike maintenance, tutorial, how, brakes, brake bleed, brake bleeds, brake bleeding, spongy mtb brakes, spongy brakes, mineral, bleed kit, shimano, gmbn tech, mtb tech, bike tech, mountain bike, Bicycle (Product Category), MTB, bicycle, gmbntech, GMBN, Global Mountain Bike Network, mountain biking, Downhill, XC, Cross Country, Enduro, MTB skills, bike skills, mountain bike skills, bike, bike riding, cycling, gmvn, Owen Coutts, Ҙ, 5360, scany15, ᐶ, 1k, 1o, 1t, Ꮖ, 𑢪‎, ፕ16, 𑣞‎, 𑫦‎, Ҫ, Ҧ, ҭ, Ҳ, Ҵ

Id: px0HFtoXNL0

Length: 8min 49sec (529 seconds)

Published: Sat Mar 09 2024