do I need a new brake master cylinder? [update]

[gPink]

Be sure you don't tell her she's dead weight.

[VirginiaJim]

+1

[martin_14]

apparently the answer to my original question is: yes 
Bike is a '08 ABS and has 75 000 miles of tons of curves, city, and highway droning. All of it.
Small summary of what's been done:
- brakes overhauled: callipers and master cylinder disassembled, cleaned and new seals. Everything looked in very good shape, no scratches, wear, etc.
- new brake lines: I went with stainless steel
- new brake discs and pads: I got EBC.

And yet... The bike brakes 100%, that's not the issue. But the brake lever has a dead stroke when I first pull it. If I release and pull again rapidly, the dead stroke is all but gone and brakes operate like new. But if I release the lever and wait, say, 5 seconds to pull it again, it'll have the same dead stroke. As it happens, while they were looking at it at the workshop I noticed that the '16 Z1000 seems to have the same master cylinder. I pulled it, and my hand perfectly remembers the perfect feel of that brake, as it was on my GTR when I bought it.
Bad news: the dealer doesn't know what to do. I told him that he has a blank check, now go fix my brakes, but he stared at me without an answer, until he said that he doesn't know what else to do. I'm not pissed at him because everything done so far to the bike had to be done anyway, so no hard feelings and no wasted money.

Anybody has an idea? The mechanic thinks that the only thing left to try is a new hand brake assembly, master cylinder and all. Since I've been a very good customer for 7 years he offered me to take the assembly from the Z1000 that they have for rent and put it in my bike for a test, before ordering the new part (350USD).

What do you guys think? I'm starting to loose the pleasure of riding the bike. I'm really feel like I'm running out of options.

[gPink]

Might as well upgrade to a Brembo master......

http://forum.cog-online.org/index.php/topic,47664.msg399712/topicseen.html#new

Re: Brake Upgrade
« Reply #60 on: September 26, 2014, 08:41:23 am »
Quote
I've learned a little more about brakes since I posed last here with my adventure.

The stock master cylinder....its decent, but...ok, its really not, but its workable. However, if you want awesome, purchase either the Brembo rcs19 or go a little cheaper.  I matches up piston sizes, from our calipers and it matched what Ducati was using on its 1098r. A 19x18.  I used a 2011 model, but others may work. Do soem research, as oithers may be different.

Ebay has take off master cylinders that will bolt right on at around 200.00 for a nice, complete one.  Powers always been fine, really, but this offers a feel and connection to the system like you wont believe.

For me, I found this to be very important and just might avoid your having to buy expensive calipers and rotors. For me, I'd do it sooner rather thna later. Its not as sexy, for sure, and we all hate spending money on something no one notices, but its a big deal.

[VirginiaJim]

If he's willing to swap you with a known good master cylinder, I'd take him up on it.   At least it would eliminate that as a cause.

[muguvian]

Why not just a rebuild of your current m/c?  I had water ingress around the piston seal that caused corrosion on the bore and piston rod.  The p/n 43020-0010 for 49USD is the rebuild kit for both the clutch and brake m/c. It's not a complicated part.

[MAN OF BLUES]

Why not just a rebuild of your current m/c?  I had water ingress around the piston seal that caused corrosion on the bore and piston rod.  The p/n 43020-0010 for 49USD is the rebuild kit for both the clutch and brake m/c. It's not a complicated part.

That's interesting....
The parts look different from each other on the Kaw parts microfiche, the FSM also shows them looking different....

And the part numbers differ also....  at least for my 2008

Clutch piston is 43020-0013
Brake piston is  43020-0010

Rear brake piston 43020-1057

 

[muguvian]

I stand corrected, I should have scrolled down the fiche I was reading to verify the tack number on the clutch side.  Regardless, this $49 part fixed the issue I had which had similar symptoms to OP.

[MAN OF BLUES]

No problem, just didn't want to give the impression they were the same, I never took my brake mc apart, but did disassemble the clutch side once after a fluid flush,
It came to mind as recently someone was asking about the internals, and differences, so it was fresh in my mind.

[martin_14]

Why not just a rebuild of your current m/c?  I had water ingress around the piston seal that caused corrosion on the bore and piston rod.  The p/n 43020-0010 for 49USD is the rebuild kit for both the clutch and brake m/c. It's not a complicated part.

What do you mean by "rebuild"? isn't taking apart callipers and brake assy with master cylinder, cleaning everything, changing all the seals and the piston in the master cylinder qualify as "rebuild"?

[MAN OF BLUES]

What do you mean by "rebuild"? isn't taking apart callipers and brake assy with master cylinder, cleaning everything, changing all the seals and the piston in the master cylinder qualify as "rebuild"?

Sure it does... but you've been here long enough to know people simply refuse to read a post before responding...
Fact of life.
Sorry to see you going thru so much agony on this man,

[martin_14]

Sure it does... but you've been here long enough to know people simply refuse to read a post before responding...
Fact of life.
Sorry to see you going thru so much agony on this man,

I thought so. I was just hoping to have missed something that he had to tell me and, lo and behold, problem solved.
Oh well...
Still, I will get that Z1000 brake assy installed the other week (Tuesday 27th) and will see. Meanwhile, I'll look into those Brembo alternatives gPink mentioned.

[martin_14]

finally came Tuesday. So I drove to the dealer and test-drove the Z1000. The brakes have a great bite but, more relevant for my problem, the feeling at the lever is constant. So the mechanic took off my brake master cylinder, lever, etc. off my bike and put the one from the Z1000. Off I went for a drive and yes, the result was wonderful. It works like day 1.
So I ordered the new part, but it's not in stock in Germany so it has to come from Kawasaki Europe, which is in Netherlands, which might or might not have to order it from Japan. This can take anywhere between 3 days and 3 weeks, according to the mechanic's past experience.
Good enough, since I'm on a trip until the end of October, so that should be enough for the part to arrive. So he reinstalled my components back in my bike and I drove home. Now this is the annoying part: the brakes feel solid, perfectly fine. It's happened before that I drove home thinking that everything was well, just to find out 2 days later that the symptoms were back. For good. I just hope I didn't order the new brake assembly and after a couple of days it'll be rubbish again.
It is very frustrating because I still don't know what's causing this. So, ok, let's say is somewhere in the front master cylinder. But: what? To my engineer-mind this is important. To my budget too. I just spent 360EUR (about 400USD) ordering the part, and I'd like to know why.

BTW: I finally came across the right terminology for the problem I'm having. Apparently it's that the free-play at the brake lever is decreasing on a second, quick pull.

[VirginiaJim]

I knew what you were talking about...   Thanks for the feedback.  I've seen that issue on cars and usually a master cylinder replacement fixes it.  You said they replaced the seals and such in yours and it didn't make any difference?  If so, the cylinder could have been the issue and seals wouldn't have fixed it.  Also, did you flush the brake fluid every few years?

[martin_14]

I hope you're right. It's becoming increasingly frustrating, first not being able to enjoy the bike as much as before (I know, it's in my mind) and second not being able to pin point the source of the issue and solve it.
Yes, the fluid has been replaced every year or so.
Yesterday I managed to get a few pictures of the piston in the master cylinder, and boy is that full of tiny channels, sealings and what not. I can imagine that the cylinder is very sensitive to little issues, but the problem is that you can't see it.
I don't know if you guys know this, but the Z1000, all the C14 (from 08 to 16 so far) and a couple other Kawasaki's have all the same part number for the master cylinder assembly: 43015. It only changes in the 4-digits suffix. All the parts can be bought individually and they are all the same, except the cylinder itself. I wonder if there are really any difference besides colour or something irrelevant like that, and they are all interchangeable.

[martin_14]

After 3 weeks in the south of Italy I finally got back to Munich and had the new brake master cylinder installed. But first, an anecdote...

I just got off the ferry in Villa San Giovanni, after crossing the strait of Messina, so, from the island of Sicily to continental Italy. I took the back roads direction north, not the Autostrada, to have the chance to use the brakes. At some point, due to this annoying free play (and more annoying yet: changing free play) on the lever, at some point I stopped at the side of the road and out of pure frustration I pulled the lever all the way up until it bottomed against the handlebar. Twice. Then I waited to cool down and drove off. To my surprise, when I used the brakes they were rock hard, and the lever didn't have any free play, plus it behaved consistent. Like new, or better, in fact, since I have now SS lines.

So, after around 3 or 4 hundred miles the free play and inconsistency started showing up again. Drats. This all happened during the weekend while making my way up to Germany.

Back to this morning, I picked up the bike from the shop and, to be honest, no change. It's working like before, meaning some free play, and inconsistent at that. I paid close to 500 USD for the parts and labour and got nothing out of it. I don't just say jazaam and money appears. I don't mind paying if I have to, but this is a witch hunt. The dealer told me that I can test it and if it doesn't help he'll reinstall the old part and give me back the money minus the labour, which I found very kind of him.

I am down. This is starting to wear off the pleasure I get from driving this bike. I have no idea what to do.

[gPink]

Just for giggles, take the bike above 8000 feet and bleed the brakes again.

[VirginiaJim]

This still sounds/feels like you have air infiltration somewhere.

[martin_14]

I keep hearing that (and it makes sense to me, too) but after thorough bleeding it still does it. And when I got the Z1000 brake master cylinder installed, the mechanic didn't bleed it, just gave me the bike to test, and it was working well. But then again, when half an hour later he took that master cylinder off and reinstalled my original one, the bike didn't present the symptoms until a few hundred miles later. Sigh.

[VirginiaJim]

I'd replace the master cylinder at this point based on what you've said thus far.  'Rebuilding' sometimes helps but if the cylinder walls have been pock marked new seals may not work.  If I had a car doing this, I'd replace the master cylinder.