Rear brake/ABS problem

[Cortez]

Just got the bike and there's issues already.

I noticed that when I picked the bike up, the rear brake was "sticky", as in..
it would stay applied for a few milliseconds after I released the pedal.

Didn't think much of it, scheduled a brake fluid swap in a week or so, since
I don't know if it's ever been done (bike has 8k miles, 2008.).

On a ride yesterday, after 2 or 3 harder stops using the rear too, I noticed
it became stiffer and lost a bit of power. Tried "pumping" it a bit, and poof,
it became almost completely stuck, the bike could hardly move. Decided to take
it to the petrol station just a stone throw away to check it out, but riding there
(very slowly) the rear disc heated up to red glow.


Cooled it down with the tire pump, tried to move the bike, wouldn't budge.

Waited for the pads to cool down completely, and about 10 minutes later,
the brake let go completely and I was able to ride the bike, HOWEVER, the
rear brake was not working AT ALL and the pedal was almost impossible to
press.

Today I took the bike into the shop, they took the calipers down, tried
moving them manually, seemed to work fine. The "blockage" is between
the pedal and the ABS unit.

Anyone have any idea what could be wrong and what to expect?

The guy in the shop says he's seen this happen on some other ABS bikes,
mostly on BMW's, and that it's usually dirt/crap in the brake lines that gets
lodged into the valves in the ABS unit. Says all it needs is to be cleaned out.

Something tells me that up until now, it's always been the issue he described,
but I wanna be prepared for what else could be wrong and if anyone knows
how expensive it might be to fix, that is.. if it's unfixable (and I need a new
ABS unit).

Thanks everyone.

EDIT: The front brake / ABS works fine.

 

[Gelvatron]

Euro model? As my American model has no abs so I can not speak from experience but abs monitors wheel speed usually with a toothed ring around the axel and a Hall effect sensor nothin to do with the piston for the brakes

 

[Cortez]

Euro model? As my American model has no abs so I can not speak from experience but abs monitors wheel speed usually with a toothed ring around the axel and a Hall effect sensor nothin to do with the piston for the brakes

Yes, EU model.
The valves in the ABS pump can get stuck.
That's supposedly the issue.

The question was - how fixable is that, or if it can be "bypassed" since it's
the rear brake and I could live without ABS on the rear, but not on the front.

The new pump supposedly costs over $2000.

 

[TownsendsFJR1300]

Yes, EU model.
The valves in the ABS pump can get stuck.
That's supposedly the issue.

The question was - how fixable is that, or if it can be "bypassed" since it's
the rear brake and I could live without ABS on the rear, but not on the front.

The new pump supposedly costs over $2000.

You could certainly bypass the ABS but may have to bypass the front wheel too.

The US models (as noted above), don't have ABS. A caliper, a line and a master cylinder, very simple.....

IMHO, I'd order SS lines for the front and back, install them and chuck that ABS unit..

I suspect the parts are the same, if you would post a picture of the rear master cylinder and caliper, it should be easy to determine..

 

[PosterFZ6]

You could certainly bypass the ABS but may have to bypass the front wheel too.

The US models (as noted above), don't have ABS. A caliper, a line and a master cylinder, very simple.....

IMHO, I'd order SS lines for the front and back, install them and chuck that ABS unit..

I suspect the parts are the same, if you would post a picture of the rear master cylinder and caliper, it should be easy to determine..

I disagree.

Try doing first the easy fix. Maybe the mechanic is correct. When that fails starts thinking on other options.

 

[TownsendsFJR1300]

I disagree.

Try doing first the easy fix. Maybe the mechanic is correct. When that fails starts thinking on other options.

I agree, if the problem is easy, say a clog in the line right there, of course, clean it, replace a line, etc...

The Op also asked in post #3:

" Yes, EU model.
The valves in the ABS pump can get stuck.
That's supposedly the issue.

The question was - how fixable is that, or if it can be "bypassed" since it's
the rear brake and I could live without ABS on the rear, but not on the front.

The new pump supposedly costs over $2000"


I stand by my response to his question, can it be bypassed? If you put the US parts on the rear, your going to bypass that $2,000 ABS unit if it has indeed failed and the op does want to invest $2k in a new pump...

 

[PosterFZ6]

I agree, if the problem is easy, say a clog in the line right there, of course, clean it, replace a line, etc...

The Op also asked in post #3:

" Yes, EU model.
The valves in the ABS pump can get stuck.
That's supposedly the issue.

The question was - how fixable is that, or if it can be "bypassed" since it's
the rear brake and I could live without ABS on the rear, but not on the front.

The new pump supposedly costs over $2000"



I stand by my response to his question, can it be bypassed? If you put the US parts on the rear, your going to bypass that $2,000 ABS unit if it has indeed failed and the op does want to invest $2k in a new pump...

Ohh Okay, sorry I must have missed that part. If it's easy enough and cheap to fix then do it. I wouldn't spend $2000 on the replenishment part, but does it really cost that much? That might be the one of the most expensive parts on the bike

Maybe try looking for a used part on ebay? Seems like the cost is excessive for that part.

 

[fb40dash5]

When they retracted the piston, did they just push it in, or did they crack the bleeder to push it in? You could always pray it's the hose. I've seen them (on cars anyway, would be a first on a bike) swell shut internally, either altogether, or like a check valve that holds the brakes after the pedal is released.

If they had to crack the bleeder to push the piston, it's possible it's just the hose. If not, I'm just confused, either a 'check valve' hose failure or a blocked ABS unit passage that would hold pressure on the brake, should have also resisted back-flowing the fluid.

I'm not exactly an expert on the guts of ABS units, but it's always been my understanding that the pump is somewhat passive. That it, lacking any input, brake fluid go in, brake fluid go out, and it's not until the unit is activated that it acts to relieve the line pressure to the slipping wheel. But, I could be wrong. What I do know is, for $2k plus labor, I'd have a bike with no ABS.

 

[Cortez]

I'll have a look and take a picture of the disassembled ABS unit in a couple of
hours. The guy in the shop took a few hours yesterday trying to unblock the
unit but it wouldn't budge, said it was a bit corroded inside from the moisture
from the brake fluid which obviously hasn't been changed as often as needed.

He also confirmed that the bypass of the rear would be easy and assures me
I can keep the front ABS, of which I'm not so sure.

I thought ABS compares the speeds of the front and back wheel constantly
to be able to function correctly, which worries me if that's the case since I
would be able to lock up the rear - what would the ABS computer then do
when I'd apply the front?

The guy in the shop says they're separate units and that he should be able to
make it work. We'll see.

Even with the jammed ABS/fault I had yesterday riding to the shop, the
front ABS was working fine, which gives me hope.

I tried looking for a new ABS pump on ebay and there were none that I
could find, only 2 for FZ8, both used, and no way of knowing if they're
functional. $200-$300/piece.

Any further info is appreciated, as well as all you've guys written already.
The guy in the shop is working on the ABS unit as we speak, and if he
can't unblock it, he'll bypass the rear.

I'll keep you updated.

EDIT: Still need to check the price of a new pump locally, and could use an online source for parts
if anyone knows a good one for Yamaha bikes. Thanks!

 

[TownsendsFJR1300]

The Yamaha parts stores, at least here in the states, Don't show European model parts. If you have one and can post a picture or better yet a direct link to the Yamaha ABS unit would help.

I use parts fisch' all the time if somethings not clear in the shop manual, order of parts, etc.

+1 on if the rubber brake line hose just collapsed (I've also seen it happen on a Camaro front, but never on a bike). I suspect your mechanic is way ahead of the basics, bad line, sticky caliper, etc, issues.

Good luck.

BTW, re a partial bypass, I agree, but may be wrong. The ABS measures the speed between the front and rear wheels. If one wheel stops faster (or slower) than the other, it adjusts your braking accordingly (usually lessening the pressure). You'll still have the electrical pickup for the rear as well as the ABS ring on the rear wheel. I suppose if the front wheel stops quicker than the back, ithe front pressure will lighten up accordingly. Hopefully you can get it straightened out safely..

 

[Cortez]

I was just at the shop where they were in the process of polishing the parts of
the ABS pump. One of the valves that was stuck and supposedly the main issue
they managed to get out after hours of trying. There were signs of slight
corrosion on it and that made it slide a bit harder in it's cylinder and eventually
lock up.

Everything points to this valve being the only issue, but until everything is
assembled and back in the bike, there's no way of actually knowing.

One other thing that's got me thinking about bypassing the rear ABS part
(if it's unfixable).. the manual states that the ABS can not stop the rear
wheel from skidding due to engine braking etc, which we all know, BUT,
that means that the ABS ECU can "deal" with a locked up rear wheel and
not throw fault codes, or disable the ABS - if my logic is correct.

Right?!

All in all, keep your fingers crossed that the valve they just got back to
high shine was the only issue.

And this, people, is what happens when you don't change your brake
fluid often enough.

I'd love to have a chat with the moron who was the first owner of my bike.
:spank:

 

[KingY]

i am normally the person to not change anything and wait for it to break but i changed my fluid on my bike recently i also believe it was the first time it has been done. mine being an 05, it didn't look to bad. didn't smell pleasant lol

I would never buy a bike off me!

 

[Cortez]

i am normally the person to not change anything and wait for it to break but i changed my fluid on my bike recently i also believe it was the first time it has been done. mine being an 05, it didn't look to bad. didn't smell pleasant lol

I would never buy a bike off me!

My Kawasaki's rear brake failed after about 3 years (a bit less) because
of humidity in the braking fluid. Service manual stated it should be changed
every 2 years.

For the FZ6 with ABS, it's _ONCE a YEAR_.
Don't do it - this is what happens.

 

[KingY]

good job i don't have ABS lol Would prob result in my opening my second bag of zip ties to fix up the beater lol

 

[FinalImpact]

You are correct in that rear wheel locking and/or bypassing it should not impair the front. ASSUMING the front does not fail for the same corrosion issue.

My question is this: it seems like the ABS unit was activated in order to cause this. Is there any chance on that day you slid the rear tire in the gravel or something similar?

Also - I hope you replaced the rear rotor, pads, and caliper seals. That was allot of temp applied back there.

 

[Cortez]

You are correct in that rear wheel locking and/or bypassing it should not impair the front. ASSUMING the front does not fail for the same corrosion issue.

Parts of the front ABS circuit were like new, and the rear has been restored
to 98% of new and works fine now.

My question is this: it seems like the ABS unit was activated in order to cause this. Is there any chance on that day you slid the rear tire in the gravel or something similar?

Nope, and it didn't happen when the ABS was activated either.
I'm not sure how this little valve works, but it takes very little to plug it up,
and one-two hard braking with the rear was all it took for the valve to
become stuck in it's lowest position (it's more like a piston in the cylinder
head then a valve actually).

Also - I hope you replaced the rear rotor, pads, and caliper seals. That was allot of temp applied back there.

The rotor and pads are fine. I was assured by the guys in the shop that
there was no need for that, and I can say from a test ride that it works
better then before it got stuck.

They took everything apart, replaced what needed replacing, and cleaned
everything back to showroom shine.

They've put DOT 5.1 fluid (motul) inside now instead of 4.0 and I've noticed
that the brakes need more effort (lever travel) to engage, but they've left
room for expansion and told me to come back in a month to get any air
out of the system that might be there, and they'll probably top-off the
braking fluid too.

I got confirmation from a local dealer that the new ABS pump would cost
me $2530.

 

[romanovski]

Hello.
I have the same problem with the ABS unit.
I think the both valves have been stuck with corrosion.

The ABS light is off. The both ABS test passes OK, but with gentle responses to the brake pedal and brake lever.

It is necessary to replace the entire ABS unit or repair an existing one.

Is the problem to disassemble the ABS pump?
Do you have any pictures or a list of procedures?
How do you bleed the ABS unit?


Hvala, Roman

[email protected]
Slovenija

 

[romanovski]

Thank you for reply.

Roman, Slovenia

 

[romanovski]

I was just at the shop where they were in the process of polishing the parts of
the ABS pump. One of the valves that was stuck and supposedly the main issue
they managed to get out after hours of trying. There were signs of slight
corrosion on it and that made it slide a bit harder in it's cylinder and eventually
lock up.

Everything points to this valve being the only issue, but until everything is
assembled and back in the bike, there's no way of actually knowing.

One other thing that's got me thinking about bypassing the rear ABS part
(if it's unfixable).. the manual states that the ABS can not stop the rear
wheel from skidding due to engine braking etc, which we all know, BUT,
that means that the ABS ECU can "deal" with a locked up rear wheel and
not throw fault codes, or disable the ABS - if my logic is correct.

Right?!

All in all, keep your fingers crossed that the valve they just got back to
high shine was the only issue.

And this, people, is what happens when you don't change your brake
fluid often enough.

I'd love to have a chat with the moron who was the first owner of my bike.
:spank:

Hello.

I have the same problem on my FZ6. I think both valves have been stuck for corrosion.

How difficult is it to disassemble the ABS unit?
Do you have any procedure, pictures, ...
How to bleed the ABS unit after installation?

Thank you for reply.

Roman, Slovenia