Pressure/vacuum/gravity bleeding

[DEATH_INC.]

Try this.Go buy a new,or get a clean,reasnoble quality oil can,fill it with brake fluid,put a rubber hose from the end to the bleed nipple,then pump away.....
I've used this method a few times when changing brake lines with much success....

[FROSTY:Me]

A couple of points here.Before bleeding the lines properly I always hold the lever back firm against the bar and then crack EVERY joint in the lines.
To avoid mess wrap the joint in a rag.
Also I use the recycle theory. I use a piece of clear tube prefilled with brake fluid and run it from the bleed nipple back up to the master cylinder
It seems to work well.

[laRIKin]

This is a very good article on brakes.
Front Brake Problems
The way he bleeds this brakes is a bit over to top, but it will work a treat.
I'm going to pick the eyes (so to speak) out of the way he does it.
Mainly because of the mess, and I have not had that big of a problem
bleeding brakes.
Any way it's a good read and will give you some good ideas.

[laRIKin]

Also I use the recycle theory. I use a piece of clear tube prefilled with brake fluid and run it from the bleed nipple back up to the master cylinder
It seems to work well.

You are joking I hope.

The very small bubbles and the water and any rust you are recycling as well.
Not a good idear mate.

[FROSTY:Me]

You are joking I hope.

The very small bubbles and the water and any rust you are recycling as well.
Not a good idear mate.

You aint replacing the fluid-I do that totally differently We are talking brake bleeding.The air bubbles go into the master cylender and dissapear.

[laRIKin]

You aint replacing the fluid-I do that totally differently We are talking brake bleeding.The air bubbles go into the master cylender and dissapear.

Brake fluid is hygroscopic, that is it attracts and holds water.
When your brakes get hot, the water boils and you get air bubbles.
That is one of the reasons, you have may have to bleed your brakes.

By not changing your fluid, the next time you brake real hard, your fluid boils
and you get more air bubbles, because of the water boils and turns to steam
that is how you can get air in your brake lines etc.
So you must/should throw out any real old unused fluid and keep your bottle
of brake fluid with it's cap on to keep the air (moisture) out.

I bleed may road bikes at least once a year and my dirt bike at least every 6
months, and the van at least every two years.
You should do this at least twice as often, but I'm a bit lazy at times.
Even if they are good at the time to get rid of any water and to
keep the insides of the brakes and line clean and free of water that can lead
to corrosion in them which can stuff and pit your brake pistons and then stuff your seals.

I have changed the brake fluid on some of my just bought dirt bikes.
And the fluid looked more like dirty oil, to was that black.

Some of the bubbles are so small that you can not see them.
That is the reason you hold your brake lever in over night.
So the bubbles may join together so you can bleed them out.
Because they are not big enough to float up wards through the brake fluid,as it is to (I guess) dense.
And as for water, you would be lucky to see it at times, unless you have alot
of it.

I have had major brake failure when racing once because of water (air) in my lines.

I had seen God then, and he waved to me.

So it's your neck, recycle away.

[marty]

here's what you should do: pay someone else to get brake fluid over them

[Motu]

Yes,you're right about the water and boiling and stuff - the water gets in through the brake hoses,that's why they are often failed in a WoF test,as the hoses deteriorate they allow more water absorbsion.A brake system with all steel pipes will hardly absorb water at all.The next thing to happen is the heating and cooling turns the water content to acids,and this corrodes the insides of the master cyl and calipers,this is why we need to flush the system.

It's electrolisis,the water has turned to an electrolite and your brake system is a battery - here's an easy way to test your brake fluid without a very expensive brake fluid tester....put your digital multimeter on the milivolt scale,put the positive lead to earth,then the negative lead into the master cyl - if you get a reading over 300 milivolts change the fluid.The cooling system reacts the same,your coolant turns into an electrolite causing corrosion - do the same test and change the coolant if you get a reading of more than 600 milivolts.

[Dr Bob]

I think the biggest problem with bleeding brakes is specific to the vehicle. I am just doing my XV at the moment and it has that high rake master cylinder that points to the Southern Cross, I'm sure that this causes air to get trapped. My ute has it's own problems because it has a junction at the rear axle, the XJ used to have an anti-dive connection (since disconnected because bleeding brakes was always a hassle. One thing I found with the XJ when I put the calipers back together last time was that when I opened them up to go back on the bike I pushed them a fraction too far and the piston was just encroaching on the exposed pitted surface that doesn't normally go in the caliper. This was enough to buggerise any attempt to bleed the brakes (and a bloody hard thing to try to pull out again).

[F5 Dave]

Lean the bike over or remount the mc on a different part of the bar.

Stuck Pistons come out with compressed air.

- At about a million miles an hour so wrap in a rag.

Ancient Yamahas the lines are so flexi they need replacement, however then they get hard & wooden. Still doesn’t change the braking efficiency. -There is none, & you might as well drag your boots on the ground.

[FROSTY:Me]

Brake fluid is hygroscopic, that is it attracts and holds water.
When your brakes get hot, the water boils and you get air bubbles.
That is one of the reasons, you have may have to bleed your brakes.

By not changing your fluid, the next time you brake real hard, your fluid boils
and you get more air bubbles, because of the water boils and turns to steam
that is how you can get air in your brake lines etc.
So you must/should throw out any real old unused fluid and keep your bottle
of brake fluid with it's cap on to keep the air (moisture) out.

I bleed may road bikes at least once a year and my dirt bike at least every 6
months, and the van at least every two years.
You should do this at least twice as often, but I'm a bit lazy at times.
Even if they are good at the time to get rid of any water and to
keep the insides of the brakes and line clean and free of water that can lead
to corrosion in them which can stuff and pit your brake pistons and then stuff your seals.

I have changed the brake fluid on some of my just bought dirt bikes.
And the fluid looked more like dirty oil, to was that black.

Some of the bubbles are so small that you can not see them.
That is the reason you hold your brake lever in over night.
So the bubbles may join together so you can bleed them out.
Because they are not big enough to float up wards through the brake fluid,as it is to (I guess) dense.
And as for water, you would be lucky to see it at times, unless you have alot
of it.

I have had major brake failure when racing once because of water (air) in my lines.

I had seen God then, and he waved to me.

So it's your neck, recycle away.

A very long discourse on brake BLEEDING
As I said the first time -changing brake fluid is a different story from brake bleeding. The point of brake bleeding is to remove the air from an otherwise clean system. If the fluid is dirty or in any way suspicious I would naturally change it -totally different system used.
I think we will have to agree to dissagree here dude -Um Ive bled up literally hundreds of sets of brake lines and with never had a problem.
You need to seperate the bleed from the change and see that the tube is filled with fresh fluid-In the run uphill to the master -they condense and become bigger bubbles.

[laRIKin]

This is a very good article on brakes.
Front Brake Problems
The way he bleeds this brakes is a bit over to top, but it will work a treat.
I'm going to pick the eyes (so to speak) out of the way he does it.
Mainly because of the mess, and I have not had that big of a problem
bleeding brakes.
Any way it's a good read and will give you some good ideas.

As you can see. I agree that it is a long winded way of bleeding.
But there is still some good info in this guys post.
That I thought was good for a read, thats all.

I will be drilling some extra hole in my banjo bolts next time they come out.
I have heard that some people put a mark on the bolts so they know where
the holes are.

If you are happy bleeding your brakes the way you are, great.

The point I was trying to make is, you are having to bleed because of air.

How is the air getting in to the system? leak? low fluid? bad seal? or maybe
water?

Like I said, when racing my brakes were great until in one corner, the lever went straight to the bars and would not pump back up.
I just got around the corner pull over shaking and my heart going like the
clappers. I rode quietly to the pit wall (400M) and my brakes were back again
like nothing had happen.
I did not know what had happened and because I was young and stupid I
went back out on the track (rode a bit slower) to see if it would do it again.
And they didn't but later got told I was a silly bugger and why it had happened.

Why risk it for a couple of dollars and a thundered mills of brake fluid.
I'm not trying to be a smart a$$ about it
Just trying to let you or any one else reading this to learn by my mistake.
And maybe save you a lot of pain or at least a good scare.

[Dr Bob]

Lean the bike over or remount the mc on a different part of the bar.

Thanks Dave this is the most useful tip anyone has given me for a while. I was leaning the bike before, but not enough. The Master Cylinder is on a horrendous angle and the air was getting trapped in there. I didn't want to lean it too far because the resevoir (sp) cover was a little corroded and I was worried about leakage. I left the bike last night with the bleed nipple loose a full resevoir and the bleeding kit attached. This morning I went down there and leaned the bike right over (that is wayyyy right over) and pumped a little and it got hard very quickly.

Thanks for this.

Stuck Pistons come out with compressed air.
- At about a million miles an hour so wrap in a rag.

Yeah.. not a chance on this one. This incident was some time ago. I replaced the front rota because only one caliper was working for a while (It's hard to tell with the original brakes on this bike whether they are working properly or not So I dismantled the calipers completely and removed the crud and stuck them back together, when I pushed too hard there was no way that compressed air was going to get it out. I ended up connecting it back up to the master cylinder, bleeding it and getting it out hydraulicly.

Ancient Yamahas the lines are so flexi they need replacement, however then they get hard & wooden. Still doesn’t change the braking efficiency. -There is none, & you might as well drag your boots on the ground.

Are you calling my bike ancient.....

[F5 Dave]

Another way a friend used on my stuck brakes many years ago was; he had a grease gun with the right fitting & just pumped them full of grease & kept pumping.

Are you calling my bike ancient.....

No but you should have heard what I said about your wife!

[Dr Bob]

Another way a friend used on my stuck brakes many years ago was; he had a grease gun with the right fitting & just pumped them full of grease & kept pumping.



No but you should have heard what I said about your wife!

Actually, she's 10 years younger than me