A miserable day.

[Old Grizz]

The idea now is to have a first hand account of how it went, and need your interpretation of "soft pedal" when you're done. IF you now press on the pedal it should be reasonably firm and while holding it, not go soft. IF you can still press harder and then feel soft, there is one more step to take.... get a bungie cord and tie the pedal down to the centerstand and leave it overnight..... should be firmer in the morning as any bits of air in the plumbing around the ABS pump or rear caliper should migrate up into the reservoir.....

Try this first, I have used this method more than once and it works! In fact I bled the brakes and the clutch fluid on my S10 a couple weeks back. Damn if I didn't have a soft clutch lever when finished, that clutch fluid reservoir is really small which doesn't help the bleeding process. Anyway, strapped the clutch lever fully engaged and turned the bars to put the reservoir at the high point and the next morning all was good! A nice 300 mile ride in the hills confirmed this.

Worth a try

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[Old Grizz]

The idea now is to have a first hand account of how it went, and need your interpretation of "soft pedal" when you're done. IF you now press on the pedal it should be reasonably firm and while holding it, not go soft. IF you can still press harder and then feel soft, there is one more step to take.... get a bungie cord and tie the pedal down to the centerstand and leave it overnight..... should be firmer in the morning as any bits of air in the plumbing around the ABS pump or rear caliper should migrate up into the reservoir.....

If you pump the pedal fast 7 orv8 times it will give solid brake action. Then if you hold it in the applied position the pedal goes soft with NO brake action

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[raYzerman]

OK, so then the bungie cord trick won't work..... back to square one, do you have a new master cylinder on there or not? I'm not sure based on your not willing to pay for it....

If there's no obvious fluid dripping on the ground, then it points to the master cylinder not holding the pressure.........

[Old Grizz]

OK, so then the bungie cord trick won't work..... back to square one, do you have a new master cylinder on there or not? I'm not sure based on your not willing to pay for it....

If there's no obvious fluid dripping on the ground, then it points to the master cylinder not holding the pressure.........

Yes they installed a new master cylinder.
And Yes I did not pay for it as they could not fix the problem

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[Old Grizz]

Tou are correct, the master cyl is not holding pressure.
The master cyl is new.
There are no leaks anywhere in the system.
The bleeder screws are new.


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[wheatonFJR]

Good luck to you...

[raYzerman]

The only other thing I've got is there is excessive travel of the brake pads or pistons hanging up, then releasing.

At this point, remove front right caliper, leave the pads in, push the pedal til the pads touch.... this will expose the pistons to the "clean part" without any danger of blowing out the pistons. Do we have good pedal now? If not, repeat with rear caliper.... I say this last because it's more painful to remove than the front.

[Old Grizz]

The saga continues with what I think I will do next..
I am going to order a brake line from good old Amazon that will go from the master to the rear caliper.
I will plug the existing line at the ABS block.
This will eliminate the abs system.
Then I will see if the rear brake operates normally. If it does I may just leave it like that and say to hell with the abs system and balanced brakes.
Or I will dive deeper into the ABS system.
I have made up the jumper so I can trigger the abs pump.
I am also going to pull the rear wheel and caliper because I think it is about time for some new pads.
I will check the piston seals at that time as well.

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[mcatrophy]

... the rear master cylinder still comes up hard then goes soft.
...

Is there any chance the disc is warped? I had a saga with my front brakes, and to cut a long story short, the discs were warped. One of the things I noticed was this "pump it and it would go hard, then it would go soft" behaviour.

The reason was that the pads would go hard against the warped disc when pumped, but when released, the warpage meant that the pads were moved back until they were square, this movement would give the softness the next time they were used.

Warping could easily be caused by the brake binding on, a well known feature of the FJR if the brake pedal pivot isn't lubricated occasionally.

Just a thought.

Picture below is of one of mine, quite extreme warping, but even a small amount of warping would be enough to do this, and may not be obvious at all.
(Click on image for larger view)

[Old Grizz]

... the rear master cylinder still comes up hard then goes soft.
...

Is there any chance the disc is warped? I had a saga with my front brakes, and to cut a long story short, the discs were warped. One of the things I noticed was this "pump it and it would go hard, then it would go soft" behaviour.

The reason was that the pads would go hard against the warped disc when pumped, but when released, the warpage meant that the pads were moved back until they were square, this movement would give the softness the next time they were used.

Warping could easily be caused by the brake binding on, a well known feature of the FJR if the brake pedal pivot isn't lubricated occasionally.

Just a thought.

Picture below is of one of mine, quite extreme warping, but even a small amount of warping would be enough to do this, and may not be obvious at all.
(Click on image for larger view)

No chance of the warped disc.
The pedal goes hard and soft when the bike is parked.
The pedal will pump up hard then a minute or so later fall with little or no resistance with no brake action if the back wheel is turned

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[mcatrophy]

...
No chance of the warped disc.
The pedal goes hard and soft when the bike is parked.
The pedal will pump up hard then a minute or so later fall with little or no resistance with no brake action if the back wheel is turned
...

That's exactly the behaviour I would expect, no need for the wheel to turn. If it is warped, the pads will have been at an angle to line up with the disc, they will relax back once pressure is released.

Take a straight edge, put it across the disc. A three second test.

[raYzerman]

The front rotors should be able to float a little bit on the rivets... road crud/brake dust there... can clear them out with say brake cleaner and insert appropriate screwdriver or dowel to spin them. When clean, one can grab the rotor and rotate it back and forth a bit.

To take this out of the picture and move the pistons to a new spot, removing the caliper and pumping the brakes out with the pads still in will perhaps tell us a bit more.

I don't have a lot of answers given the new master cyl., can't think of anything spongy that would release pressure in the ABS block, fluid path is direct bypass with no ABS activation... if fluid flows freely from the bleeders, I'm not thinking there's any issue at the proportioning or metering valves.......staying tuned for next update....

[Old Grizz]

Stay tuned, further diag is going to be put on hold for a bit as I have other priorities.

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[wheatonFJR]

Stay tuned, further diag is going to be put on hold for a bit as I have other priorities.

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Hopefully all is well??

[Steel_Gin]

This is quite the mystery. Looking forward to seeing how this turns out.

[Old Grizz]

My Amazon brake line showed up so I installed the hose. I went directly from the master cyl to the caliper. It was a bit of a fight as it is longer than I need but I could not find one on line the correct length, either too long or too short. Also the banjo end is not a perfect match for Yamaha (of course) but it works well enough for now and the rear brake works. So the problem is not in the caliper it's in the wonderful abs system. I have a stock hose ordered from the mother ship as I buggered one deliberately when doing g some trouble shooting. When that comes in I will put it back to stock as I know the problem is not in the rear caliper.
I have.ade the jumper so I can pulse the abs pump and the diagnoses will continue.
At least I have rear brakes for now.

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