You tube video brake bleeding :roll:

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Mikekitts81
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You tube video brake bleeding :roll:

Post by Mikekitts81 »

So ive alawyas been taught and have always done the brake bleeding in the way ive been taught which is to get the air out the system with the spanner and tube on caliper and the pressing of the front brake till no air comes out anymore . Ive watched this video today and iam really sceptical on it seems legit like all videos online oviously :lol: but iam unsure on the matter makes senese but would you guys agree or disagree on the throey and method id like to see some replys and answers and maybe sone logic in why it would or wouldnt work ?
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zimtim
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Re: You tube video brake bleeding :roll:

Post by zimtim »

Nah I don't like that.
Can see it a very small possible solution but too actually bleed the brakes I wouldn't trust it.

I used the tube on bleed nipple into a jar with brake fluid and a lot more bubbles came through than that.
Once I have bled the brakes yes tie the lever back over night not get last micro bubbles out.

Use his method and it would take an age to get the air out the system.
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Re: You tube video brake bleeding :roll:

Post by daveuprite »

I use this. Not when I'm doing a total flush and change of fluid, but every time I do an oil level check service on the bike. Just take the reservoir lid off and tickle the lever to get rid of any bubbles. Also I 'flick-tap' all the tubes to release any bubbles, and flick the lever so that it vibrates the reservoir and the stiff bit of tube that goes into it. That often releases an extra bubble or two. Works much better on the front brake (and for the clutch) than the rear though, for the reasons he explained in the video.
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Re: You tube video brake bleeding :roll:

Post by Mikekitts81 »

daveuprite wrote: Sat Sep 21, 2019 5:11 pm I use this. Not when I'm doing a total flush and change of fluid, but every time I do an oil level check service on the bike. Just take the reservoir lid off and tickle the lever to get rid of any bubbles. Also I 'flick-tap' all the tubes to release any bubbles, and flick the lever so that it vibrates the reservoir and the stiff bit of tube that goes into it. That often releases an extra bubble or two. Works much better on the front brake (and for the clutch) than the rear though, for the reasons he explained in the video.
Have you had any problems doing this or as ut always been fine no issues ...??
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Re: You tube video brake bleeding :roll:

Post by daveuprite »

Mikekitts81 wrote: Sat Sep 21, 2019 6:34 pm
daveuprite wrote: Sat Sep 21, 2019 5:11 pm I use this. Not when I'm doing a total flush and change of fluid, but every time I do an oil level check service on the bike. Just take the reservoir lid off and tickle the lever to get rid of any bubbles. Also I 'flick-tap' all the tubes to release any bubbles, and flick the lever so that it vibrates the reservoir and the stiff bit of tube that goes into it. That often releases an extra bubble or two. Works much better on the front brake (and for the clutch) than the rear though, for the reasons he explained in the video.
Have you had any problems doing this or as ut always been fine no issues ...??
Well I've never done a complete DOT4 change using this method. I still think you need to do the bulk of the work by bleeding downwards in the usual way, to get the fluid into the system. But it makes sense that bubbles rise (that's just physics), so tapping and titillating the lever is a good way of encouraging any air upwards out through the reservoir.

Problem with bleeding downwards is you can never be absolutely sure if you have passed pure fluid (no air) through all of the tubes. Unless you bleed a whole litre through just to be sure I suppose.

As I say, I just use this method to purge a few last bubbles out. On my Beta 450 hydraulic clutch, it makes a significant difference to how the clutch works to get every last bit of air out of the system.
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Re: You tube video brake bleeding :roll:

Post by Richard Simpson Mark II »

The 'traditional' method won't work at all with some bikes...my Aprilia's underslung rear calliper for example.


KTM enduro's front brakes work better if you cabletie the lever back to the bar between rides.
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Re: You tube video brake bleeding :roll:

Post by Hugh »

Greetings,

There is no single routine that works for every manufacturer nor model so it is worth bearing this one in mind as a possible solution should you be having problems.

Personally I prefer to replace all of the fluid from the system.

TTFN

Hugh.
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Re: You tube video brake bleeding :roll:

Post by frenchy3 »

I don,t need to tell everyone that most brake fluids are hygroscopic so will attract water into the system and as water compresses at a different rate to brake fluid your brakes will feel spongy. This becomes worse when the brakes get hot and the fluid in water in the brake fluid turns to steam and you often lose the braking completely. You will also get contamination from seals breaking down etc so a fluid change at least every two years is a must. I use this system for day to day bleeding to get any air out without problems. cable tying the lever back towards the bars overnight made my lever solid again. As you say all braking systems are different and the rears can often be problematic because of the routing of the brake hoses. If you get any problems bleeding brakes the conventional method you may require a vacuum bleeder or just a syringe with a piece of tight fitting hose to the bleed nipple and back bleed the brakes.
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Re: You tube video brake bleeding :roll:

Post by sledgegreen »

I think this will work most times, but there is one important limitation which he doesn't mention in the video.

Bleed nipples are mounted at the highest point on a caliper. Calipers have two ports - the bleed nipple fits in the top one, and the hose from the master cylinder fits in the lower one. This means that air in the hose will gradually rise up the hose to the master cylinder, as the video describes. However, any air which gets into the caliper will rise and collect under the bleed nipple. This is trapped in the caliper - it can't get back into the hose, unless it first sinks through the brake fluid (unlikely), or someone detached the caliper from the bike and positions it so the hose attachment point is the highest point.

I notice that the guy in the video specifically refers to changing hoses. If he leaves the caliper full of fluid when he does this, it is possible that no air will enter the calliper, and so his bleeding method will work.

In twin disc set ups where one caliper is fed from the other, the connections should be master cylinder to lower connection on caliper one, then upper connection on caliper one to lower connection on caliper 2, with a bleed nipple on the higher connection on. caliper two. This means that any air which gets into the first caliper will rise to the upper connection point and then be pushed through to caliper 2, where it can be bled off.

I don't think this method is very useful, except when changing hoses. When I have needed to bleed brakes, it has usually been because of fitting new seals ion the calliper or because I have wanted to change the fluid. Either of those means that I want new fluid flowing through the caliper to flush out the old.

The only other situation I can think of where I might have air in a hose and not in the caliper are when I have let the master cylinder run empty. That usually means I am bleeding the brakes anyway.
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Re: You tube video brake bleeding :roll:

Post by Mad Hatter »

I think the point might be being missed with this, it's not a way of bleeding an entire brake system it's useless for that. It's for getting air out if the line directly below the master cylinder or out of the master cylinder itself.

Anyone who bleeds brakes with the tube and a jar method, and in my experience a vac pump setup, already does basically this we just call it priming the master cylinder.

Any brake system will end up with contaminates in it, normally moisture and not actual air, but under hard braking the system heats up hit enough to boil the water off and give us gases, if we're lucky they hit the line and not the caliper and they travel up to the master cylinder and are taken out of the line back up through the master cylinder under normal use that's why the fluid level drops amongst other reasons like small leaks and pad wear. Normally we don't notice because we're doing things like using the front brake getting the bike out of the garage, wheeling it around or light braking applications because then it's been sat long enough to settle and rise, this is also what tieing the lever back does but in one big go. Although there also arguments against that but that's a conversation for a different day.

If we're not lucky they get stuck in the caliper at the bleed nipple and then we actually have to do something about it properly.

Air does get in to lines from all sorts of places, normally around banjo bolts in you've changed them and they haven't seated again properly, that's fine and that's life, in practice you will never have a perfectly sealed system because then we wouldn't be able to add fluid to it or bleed the brakes off.

If you're changing hoses don't be lazy drain the whole system down and bleed it properly, if you've left the bike a few weeks after a hard day's riding with lots of water and spirited braking and it feels a little spongy then flick the lever a few times, you'll probably find it's ok afterwards, if not you've got air in the caliper.

Watch the video again, all he's actually done is use the brake lever a few times but he's taken the top off. Most of us have the habit of holding the front brake lever in a bit most of the time while we're moving a bike around, or stationery, or starting it, or getting on, or a million other things so we're actually already doing this without thinking about it.
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