Pressure/vacuum/gravity bleeding

[kerryg]

I spent hours last night trying to bleed my brakes with a bit of tubing and a jar of fluid as per the normal way and and the **&%$ing things just won't firm up.....I've left it with the lever strapped in the fully compresed position and hope to beat the bugger tonight. But there must be a better way. Has anyone had any experience with pressure bleeding or vacuum bleeding that doesn't require a big investment in gear to do it?? I'd love to know if someone has put together an effective vacuum or pressure bleeding kit from simple and cheap items. Anyone?

[riffer]

Try "cracking" the joint on the master cylinder. Sometimes it gets trapped up there.

[kerryg]

Try "cracking" the joint on the master cylinder. Sometimes it gets trapped up there.


Yeah I've tried that, at the master cylinder and at the callipers, and tapped the lines,and checked for leaks at the junctions but no joy so far. I'm sure if I persist long enough I'll get there...I'd just like to find a quicker way, given that I had a bad experience with seized brakes recently that has educated me about the necessity for preventive maintenance (i e flushing the brake system) regularly

[sedge]

I bought a one way bleeding kit thing from Repco I think, you crack the bleeder and pump six times, do up the nipple, crank 6 times and repeat until firm, works really well for most things...

GSXR didn't get on with it too well tho ? needed to crack the nipple on the braided lines at the top a bit and it got kind of messy.

Sedge.

[F5 Dave]

You are perhaps talking about Mityvac? Rip-co are the agents some people swear by them. I considered getting one, but thought, well what are they doing?

What does it actually do I asks meself? Surely just forces fluid the other way through the system. In this case it would appear once you have the brakes bleed to the point you have then you could just prise the pads away from each other to pressurise the system forcing the fluid back to the MC. With the calliper off you could place it in another position so as to move some trapped bubbles & prise the pads apart again & pump closed. Move to another position & repeat. Do other side.

With my race bike as the MC is at a crazy angle it helps to either lean the bike over against a wall so the MC is flat (helps move any bubbles that may be trapped there & easier to add fluid).

In the bad old pre GSXR days; Suzis used to have anti-dive mechanisms that created extra lever play, they were always fun. If your system was adjusted previously with not enough lever play then it will feel sloppy now. Have you got the original lines on it? They will be well past their best by date now & be as baggy as MC Hammer’s pantaloons.

[kerryg]

I bought a one way bleeding kit thing from Repco I think, you crack the bleeder and pump six times, do up the nipple, crank 6 times and repeat until firm, works really well for most things...

GSXR didn't get on with it too well tho ? needed to crack the nipple on the braided lines at the top a bit and it got kind of messy.

Sedge.


Sedge

Thanks for that. I'll check out Repco tonight

[Motu]

I don't like vacuum bleeders,they can suck air into the system,that's the stuff you are trying to get out!They can collapse a master cyl so you just can't get it to work again.The next tool I'd like to get for bleeding is the reverse flow one,these push the fluid from caliper to master cyl,they push the air uphill,the way it wants to go and keep the system pressurised.Sometimes the best thing to do is walk away and come back when you're in a better mood,you'll find it's fixed itself while you were away - really the aireated fluid has released the bubbles which have self bleed back up to the master cyl.

[kerryg]

?

What does it actually do I asks meself? Surely just forces fluid the other way through the system. In this case it would appear once you have the brakes bleed to the point you have then you could just prise the pads away from each other to pressurise the system forcing the fluid back to the MC. With the calliper off you could place it in another position so as to move some trapped bubbles & prise the pads apart again & pump closed. Move to another position & repeat. Do other side.

With my race bike as the MC is at a crazy angle it helps to either lean the bike over against a wall so the MC is flat (helps move any bubbles that may be trapped there & easier to add fluid).

In the bad old pre GSXR days; Suzis used to have anti-dive mechanisms that created extra lever play, they were always fun. If your system was adjusted previously with not enough lever play then it will feel sloppy now. Have you got the original lines on it? They will be well past their best by date now & be as baggy as MC Hammer’s pantaloons.

Hi F5Dave. Yeessssssss buuuuttttt...some of us are lazy bastards and don't want to fgo to any more trouble than they have. I want something that I can use without having to remove the callipers etc if I can. But I hear what you're saying.

It does have anti-dive thingamabobs on it but I don't know if that is an issue or not. I hear they're worse than useless anyway so I'll probably remove them at some stage (when I service the forks...which will be sometime after I have finished bleeding the$%&*&*ing brakes). It's got brand new braided lines that run straight from the master cylinder to the callipers.

[kerryg]

I don't like vacuum bleeders,they can suck air into the system,that's the stuff you are trying to get out!They can collapse a master cyl so you just can't get it to work again.The next tool I'd like to get for bleeding is the reverse flow one,these push the fluid from caliper to master cyl,they push the air uphill,the way it wants to go and keep the system pressurised.Sometimes the best thing to do is walk away and come back when you're in a better mood,you'll find it's fixed itself while you were away - really the aireated fluid has released the bubbles which have self bleed back up to the master cyl.


Yeah I sort of imagined something like this: a big hypodermic filled with brake fluid, with a rubber tube instead of a needle, the tube attached to the nipple and is the fluid is pushed up the lines from calliper to master cylinder...would that work, dya reckon?

[F5 Dave]

Oh yeah didn’t mention that. I have one (for a horse I think) & it was ok I guess, but the oil swells the seal in the syringe & it pops off. Need the type with the o-ring. Never seen one that big (said the actress to the bishop).

Also it was just as likely to slip off & squirt around the side of the bleed nipple.

Yeah I use the leave it over night method as Motu implies. Didn’t think taking the callipers off was that big a deal. The old suzis had a separate external line for the antidive. This compressed a piston & it was this movement that took an extra amount of fluid displacement. Despite the idea behind increasing the compression damping was bollocks & is more likely to make the front wheel lock under braknig.

[kerryg]

Yeah I use the leave it over night method as Motu implies. Didn’t think taking the callipers off was that big a deal. The old suzis had a separate external line for the antidive. This compressed a piston & it was this movement that took an extra amount of fluid displacement. Despite the idea behind increasing the compression damping was bollocks & is more likely to make the front wheel lock under braknig.


Taking the callipers off is simple, true. It's the holding-calliper-in-1-hand-while-trying-not-to-get-fluid-on-the-pads-and-rotors-while-trying-to- wedge-pads-apart-while-wielding -spanner-on-nipple-while-operating-brake-lever.....that I find unappealing. :not:

There is a line to the anti-dive. I'm going to check it out tonight. I'm pretty sure on my bike it's not hydraulic though, but electrical.

[F5 Dave]

No, you misunderwheelstand.

This procedure you are trying to force the fluid & any bubbles in the direction bubbles normal like to travel. Up. Out into the master cylinder. Thus the bleed nipples are closed.

[kerryg]

No, you misunderwheelstand.

This procedure you are trying to force the fluid & any bubbles in the direction bubbles normal like to travel. Up. Out into the master cylinder. Thus the bleed nipples are closed.


Oh...I see...Ok... hey, I knew that <_<

[Drunken Monkey]

Don't know if this will help, but I errr, had problems opening the rear brake pistons on the gixxer, so um, undid the bleed valve and inadvertently bled the mother virtually dry.
Now I did have a one-man-bleed-kit (a small bottle to catch the brake fluid, connected to a hose and a supposed one-way valve). One sore arm and 2 hours later the brakes still weren't firming up. The fluid seemed to move the same direction each pump, despite the one-way valve (probably had a leak somewhere...)
I ended up getting someone to help me with a syringe = he would stick the syringe in the far end and suck while I pumped (man that sounds sick). Anyway, to cut a long story short, that got the brakes up to pressure in about 2 minutes...After that, it was easy to use the one-man-bleed-kit to get rid of the rest of the bubbles.
Sounds like you're having the same problem.

[Jackrat]

This is what I do.
I use a long plastic hose and sit my catch jar about a meter higher than the caliper.I put a little brake fluid into the hose so when I crack the bleed nipple the first air out travels up through this fluid and because it has traveled up hill it's not coming back down.I then leave the nipple open and pump at lest two master cylinder fulls of fluid through the whole system.I don't bother with the open/close thing until I get clean air free fluid coming through.
I then leave it over night and try for proper pressure the next day.
Always works for me.

[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]

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 (http://ktmtalk.com/index.php?showtopic=77758)
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]

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. :msn-wink:

[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]

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. :msn-wink:
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 (http://ktmtalk.com/index.php?showtopic=77758)
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 :eek: 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! :Oops:

[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! :Oops:

Actually, she's 10 years younger than me :D

[Motu]

We use a lever type grease gun to remove stuck pistons as Dave says - they put out 10,000psi...no way you'll get that with air pressure,or by using the systems own hydraulic force.

[F5 Dave]

Actually, she's 10 years younger than me :D

Dirty dog.

[FROSTY]

[QUOTE=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.



Holey crap batman.--a petroleum based product near the brake lines--arggg scarey

[F5 Dave]

Well obviously the brake lines are removed to fit the greasegun & once the pistons are popped out then the whole calliper has to be totally cleaned.

It is a last resort messy proceedure & that's why I use air (carefully) if I can't just pump them out with the system.