Article [13] ST1300 - Brake Maintenance - Getting all the air out of the brake system

[jfheath]

The best way of getting air bubbles removed from a tube or brake line is to make sure there are no high/low points in between.
Make sure one end is higher so the bubble will rise.

Actually, the best way is to tilt the tube so that the fluid going down and the bubble going up do not block each other's progress.
But most of the brake lines are fixed in place at certain points. It isn't possible to ensure one is higher then the other. And there are two large 'n' shaped bends in the hoses both under the headlights. You have got to flex, tap, and manipulate the tubes to encourage bubbles to move along with the flow.

But your point is well taken. The clutch and the front lever / front caliper circuits are quite easy to bleed.

 

[mjc506]

Errr... I guess boiling DOT 4 in a pan on the stove before infusing the brakes is out of the question then?

Boiling on a stove probably won't do it a huge amount of good...

...but 'boiling' it by applying vacuum... Certainly helps get air out of fluid that's been 'well shaken' in the container. Longer term application of vacuum should help remove water as well, but that's possibly a little excessive (and wouldn't, for example, undo oxidation or other chemical changes in the fluid due to moisture).

But as the brake fluid doesn't tend to go much below ambient pressure during use, it's surprising how little difference removing the entrained gas make! (A small research project while at uni...)

 

[Peto]

Errr... I guess boiling DOT 4 in a pan on the stove before infusing the brakes is out of the question then?

That's not the point I was making.
The point was trying to use logic for instance if you want to bleed the rear of the ST1100 and don't have any fancy equipment.
You could lower the calliper since the line is partially flexible, but you have to remove the tank and the wheel of course.

 

[Sadlsor]

I was making no point.
Just being my usual sarcastic self, and sarcasm is my best and only offering here, in many cases.
I am an annoyance to some, indulged by others, and ignored by the rest.
No offense intended, but you get to choose which.

 

[SMSW]

The best way of getting air bubbles removed from a tube or brake line is to make sure there are no high/low points in between.

This process can be speed up if the temperature is higher hence viscosity will be lower.

As said, the brake lines are fastened in place. However, a good bike rotisserie will make tilting, inverting, and otherwise chasing bubbles easier. @Mellow just bought one of these things, I think it's called a Sky Lift. While you are fussing with all the tilting, I'll stick with my vacuum bleeder setup.

 

[MidLife]

...but 'boiling' it by applying vacuum... Certainly helps get air out of fluid that's been 'well shaken' in the container. Longer term application of vacuum should help remove water as well, but that's possibly a little excessive (and wouldn't, for example, undo oxidation or other chemical changes in the fluid due to moisture).

On the assembly line, brake systems are filled automatically using the "evacuate and fill" method (which is the method used for industrial hydraulic systems in general, not just brake lines).

The brake fluid itself is often conditioned by being "boiled" under vacuum before filling.

Evacuation and Fill — Dominion Technologies Group, Inc.

www.dominiontec.com

.

Vehicle Manufacturing | ACCUFILL Brake Fill Equipment

The AccuFill A/C Fill System offers our premium a/c charging technology without the DatServ.NET Data Acquisition and Process Control option.

www.siqinc.com

.

 

[MidLife]

But as the brake fluid doesn't tend to go much below ambient pressure during use, it's surprising how little difference removing the entrained gas make! (A small research project while at uni...)

However....from sea level here in Houston you can be on your ST at 14000 ft the next day in Colorado (where the atmospheric pressure is getting close to half the sea level pressure) ...and it is not unusual for the brakes to feel mushier up there, specially going down passes with a fully loaded bike.

And will feel solidly firm again once back at sea level.

Not just the ST though, you can experience the same in a car.

 

[core-aggie]

The point was trying to use logic

Contrary to belief, that doesn't always work .. or may not be the most efficient (or safe?).

'll stick with my vacuum bleeder setup.

Thanks - same here, with all vehicles, bike or one with 4 wheels. I also use a pressure feeder, so I'm not constantly having to add more DOT every few minutes.

 

[Peto]

I was making no point.
Just being my usual sarcastic self, and sarcasm is my best and only offering here, in many cases.
I am an annoyance to some, indulged by others, and ignored by the rest.
No offense intended, but you get to choose which.

Sorry I didn't want to be mean. I wanted to explain my idea. so apologies

 

[jfheath]

No need to apologise for making a perfectly valid comment @Peto . You'll get used to @Sadlsor .... he never makes a comment that is aimed at a person. His quips are usually a sideways look at a thought triggered by something he has read. Great fun to read, rarely provoke a laugh, but usually manage to raise a smile.

I don't know if there is a 'like' emoji for that ! There ought to be. A half smile ?.

I had never thought about bleeding in Summer Vs Bleeding in Winter. I always do my servicing in winter because then if I cock it up, I have plenty of time to put it right before the Summer rides begin. I used to ride all year round, but now I don't have to !

 

[MidLife]

.... get used to @Sadlsor .... he never makes a comment that is aimed at a person.

Except at Sadlsor himself!

His quips are usually a sideways look at a thought triggered by something he has read. Great fun to read, rarely provoke a laugh, but usually manage to raise a smile.

Nonetheless, a thread is not a thread if it hasn't been Sadlsored!


.......

 

[Peto]

No need to apologise for making a perfectly valid comment @Peto . You'll get used to @Sadlsor .... he never makes a comment that is aimed at a person. His quips are usually a sideways look at a thought triggered by something he has read. Great fun to read, rarely provoke a laugh, but usually manage to raise a smile.

I don't know if there is a 'like' emoji for that ! There ought to be. A half smile ?.

I had never thought about bleeding in Summer Vs Bleeding in Winter. I always do my servicing in winter because then if I cock it up, I have plenty of time to put it right before the Summer rides begin. I used to ride all year round, but now I don't have to !

 

[STPaulK]

I'd l ike to thank John for his awesome PDF. Just finished bleeding after changing the SMC, man what a pain! The flow diagrams for each piston(s) were key in helping me understand why/where the bleeding is complicated.