ST1300 Front Brakes do not release

[Igofar]

Funny, I had a mechanic in the local Honda shop tell me the exact same thing, after replacing a guys master cylinder housing, front brake lever, hose(s), rebuilding the master cylinder on the handlebars, replacing the pads, replacing the seals in both front calipers, and charging the guy a small fortune etc.
What was amazing is they missed checking the most simple things.
As far as your disagreeing with me, no worries there, as we are both trying to help this guy etc.
But what your not understanding, or what I'm not explaining well enough is, once you apply pressure, and things bind up, they usually remain in that "crooked" position, until they are moved around, either by removing the pressure, hoses, or tapping things.
If the bracket or clip is damaged , bent, rusted, or dry, and pressure causes things to cant, thus binding the brakes up, then removing pressure, to allow it to be free again, don't be so sure that its a pressure issue and not a binding issue.
And yes, a damaged or failing SMC can cause the front brakes to act up as well.
Remember the brakes are linked.
If the return port is clogged up (screen/cartridge) on the back side of the SMC, it will keep building pressure in the entire system (path of least resistance) and cause binding somewhere.
Remove the SMC from the from a possible cause and see if the other brake still binds and locks up, I'm guessing it won't.
Has anyone checked the rear stopper bolt?
It could be loose, allowing the caliper to rock forward, and press down enough on the rear line to cause issues as well.
For the OP, a couple other things to check for....
Did someone over grease the guide pins, causing suction, and not allowing them to release?
They should have only a very light amount of grease on them?
So far nobody has said anything about rebuilding the rear master cylinder unit behind the right side step?
Linked system, you have to check everything.

 

[Igofar]

Hello RT,
thanks for your postings. But the thing is: Your proposal is so obvious, that we tried this when the problem started. 2 years ago. And the break opened when we did that. But it also opened, when we just knocked the calipers - and it opened, when we moved the hoses and and and .... So - what did it help us?
Greetings from Germany
Michael

That it was a binding issue, and not a pressure issue
Hang in there Michael, you'll get to the bottom of this.

 

[rwthomas1]

Hello RT,
thanks for your postings. But the thing is: Your proposal is so obvious, that we tried this when the problem started. 2 years ago. And the break opened when we did that. But it also opened, when we just knocked the calipers - and it opened, when we moved the hoses and and and .... So - what did it help us?
Greetings from Germany
Michael

The hardest problems to troubleshoot are the intermittent, or multiple factors. It sucks. Good luck.

RT

 

[rwthomas1]

Funny, I had a mechanic in the local Honda shop tell me the exact same thing, after replacing a guys master cylinder housing, front brake lever, hose(s), rebuilding the master cylinder on the handlebars, replacing the pads, replacing the seals in both front calipers, and charging the guy a small fortune etc.
What was amazing is they missed checking the most simple things.
As far as your disagreeing with me, no worries there, as we are both trying to help this guy etc.
But what your not understanding, or what I'm not explaining well enough is, once you apply pressure, and things bind up, they usually remain in that "crooked" position, until they are moved around, either by removing the pressure, hoses, or tapping things.
If the bracket or clip is damaged , bent, rusted, or dry, and pressure causes things to cant, thus binding the brakes up, then removing pressure, to allow it to be free again, don't be so sure that its a pressure issue and not a binding issue.
And yes, a damaged or failing SMC can cause the front brakes to act up as well.
Remember the brakes are linked.
If the return port is clogged up (screen/cartridge) on the back side of the SMC, it will keep building pressure in the entire system (path of least resistance) and cause binding somewhere.
Remove the SMC from the from a possible cause and see if the other brake still binds and locks up, I'm guessing it won't.
Has anyone checked the rear stopper bolt?
It could be loose, allowing the caliper to rock forward, and press down enough on the rear line to cause issues as well.
For the OP, a couple other things to check for....
Did someone over grease the guide pins, causing suction, and not allowing them to release?
They should have only a very light amount of grease on them?
So far nobody has said anything about rebuilding the rear master cylinder unit behind the right side step?
Linked system, you have to check everything.

I think we are ultimately saying the same thing. Something is causing it to bind up.

 

[XS Michael]

You all gave me a lot of things to think about - I will not give up As I love my PAN and want to drive it to Norway again this summer ...
I will write again - need some time to check things.

 

[Igofar]

Michael, another thing to check...
I believe you said the shop rebuilt the front master cylinder housing a couple times?
In my mind, that could mean that they simply pulled the piston assembly out, and put another on in etc.
If they did not make sure that the return port (Tiny pin sized hole under the deflector spoon) is clear and unobstructed, this could be plugged, causing the fluid to build up pressure behind the pistons, and keep the pressure on them against the rotors etc.
Try taking a high E guitar string, or acupuncture needle and making sure the smaller port is clear so the fluid can return to the master cylinder housing etc.
You could also use a children's aspirator (bulb) and push and suck fluid through both the holes until clear etc.
This may explain why its just the outside pistons (front brake master cylinder activated) etc.
I have found varnish hardened in these ports before causing the issues you are having.

 

[Sadlsor]

that has already been mentioned, but no harm / no foul.
it gets harder to read everything in every thread, once it gets into multiple pages.
easy to miss things, especially for those like me with attention deficit.
wait -- why did i post this...?

 

[jfheath]

I am not going to disagree with Larry's comments about linked brakes. But I am going to say something different.
@XS Michael said that the two front outer pistons were the ones that were sticking, not the centre piston.

There is no hydraulic link between the front outer pistons and the other 5 pistons (3 rear pistons and 2 front centre pistons). As far as the brake fluid is concerned, the route between front lever / reservoir and the 4 front outer pistons, is completely self contained.

IF the fault is with the front outer piston hydraulics, then that does not involve anything else, but I am not clear how Michael established that only the outer pistons were sticking and not the centre.

But the actions of one brake will affect the others whether they are linked hydraulically or not. For example, if the rear pedal is applied, it will operate the front centre pistons, and this will move the front caliper a bit. It may also pinch the pad spring if the spring isn't properly seated, and this will affect the operation of the outer pistons.

Similarly, if the front lever is applied when the brake pedal is also pressed, you can actually feel the brake pedal dip due to the movement of the caliper.

So you cannot ignore the fact that the brakes are linked mechanically - by design and also by the odd behaviour that results when one part of the system doesn't operate as intended.

I learned a long time ago that the first thing to suspect if the rear brakes are dragging is not a faulty SMC, but a dragging front left pad. Suspecting that first can save a lot of time worrying about the rear caliper or the SMC. Especially so if front pads have just been changed, or fiddled with by someone who doesn't know the system.

Bottom line is that this problem needs checking all aspects of the brake system, finding out which parts work as intended and which parts don't. Its actually very easy if done methodically, but knowing how it all works really helps.

 

[SMSW]

Hello RT,
thanks for your postings. But the thing is: Your proposal is so obvious, that we tried this when the problem started. 2 years ago. And the break opened when we did that. But it also opened, when we just knocked the calipers - and it opened, when we moved the hoses and and and .... So - what did it help us?
Greetings from Germany
Michael

When you put a wrench on the bleeder, did you apply a counter torque to the caliper? If the caliper slides freely on the pins (a necessity), there will be some play and giving a jammed caliper a twist by loosening the bleeder is going to be very similar to whacking the caliper with your piece of wood/mallet/sledge/Thor's hammer, (thumper of your choice).

A better question, when you open the bleeder on a stuck caliper, does brake fluid jet out or just dribble as if it is draining down from the reservoir on the handlebars?

 

[rwthomas1]

When you put a wrench on the bleeder, did you apply a counter torque to the caliper? If the caliper slides freely on the pins (a necessity), there will be some play and giving a jammed caliper a twist by loosening the bleeder is going to be very similar to whacking the caliper....

Well, if you are careful and paying attention you should be. I go very light on the bleeder screws on any brake system. They take very little torque to seal. People like to gorilla stuff, but a tapered seat takes about one finger of force to actually seal.

And you don't have to crack the line at the bleeder either. Move up to the next fitting in line. That way you don't disturb it.

RT

 

[XS Michael]

IF the fault is with the front outer piston hydraulics, then that does not involve anything else, but I am not clear how Michael established that only the outer pistons were sticking and not the centre.

That was easy - I just went under the pistons with a .... how is that thing called - the thin measurement-plates for checking the adjustment of the valves? It was obvious, that the middle-pistons were free - i could easily go under them.

 

[caldercay]

how is that thing called - the thin measurement-plates for checking the adjustment of the valves?

feeler gauge

 

[XS Michael]

Merci!

 

[XS Michael]

Oui, je parle francais aussi Et aussi un peu de norwegian
But not as good as english

 

[Sadlsor]

Oh these Europeans... unlike most Americans you know so many languages.

I'm bilingual.
Fluent in English; extraordinarily adept and creative in Sarcasm.

 

[XS Michael]

Yes, back to brakes I got the bike back tody - with the replaced right caliper. I will do test-drives as soon it stops raining But I am not very optimistic. I will see.

I also want to say, that I am very happy about the warm welcome in your forum. And if anyone of you will visit Germany, then we (Petra + me - she is driving a Suzuki V-Strom 650) would be happy if you would visit us and spend some days in our place! Our place = not far from Stuttgart.

Greetings, Michael

 

[caldercay]

Good luck on the test ride.

I have family in Hanover and Dresden ...

 

[jfheath]

Feeler gauge. That's how I do it.

Hope the test ride goes OK and it is all sorted now.

 

[XS Michael]

No, it was raining too much. And the other thing is, that the test needs some time - I will test it the next days.

 

[XS Michael]

Hello America ,
rain stopped, I drove and tested tody. And the brake got stuck as stuck can be If kicked both calipers and from then I used only the back-brake. So I could drive home.
I have to change the mechanic. I stayed so long with him because it is difficult, "to change the doctor during the treatment". What I decided to do: I will print out all your information. And I will go to a mechanic I know from earlier times. Not close to the place I live now - that was why I changed to the other one. I need a mechanic who uses his brain more.
I can not do too much myself with the brakes, because I do not have a good place and the pump to get out the air of the system. The PAN-brakes are too complicated to get out the air the easy (old-fashioned) way. I prefer to do that in a workshop.
Thanks a lot again - I will report the results. But that may take some time.
Greetings from Germany!
Michael