TOPIC:

I removed the front brake from my '78 kz1000 and disassembled the master cylinder for cleaning.

The piston-plunger is stuck. I've got the parts diagram
and I cannot remove the 3/4-moon-shaped 'piston stopper' washer (this piece stops the travel of the piston when the brake lever is pulled so the piston doesn't disappear into the master cyclinder innards).

But that shouldn't matter because..the piston-plunger is stuck anyways. And the plunger is stuck in the 'brake lever not squeezed' position -- the plunger's sticking way out of the master cylinder on the brake lever side of the master cylinder. And..that 3/4-moon-shaped 'piston stopper' is freed up enough to move around.

I can't move the piston-plunger because, again, it is frozen.

With the brake hose removed from the master cylinder, I can poke a metal rod or screwdriver into the master cylinder body and reach the inside end of that plunger so.....here's what I want to do to 'unfreeze' the piston-plunger:

I WANNA WAP THAT SUCKER, WITH A BIG 'OLE HAMMER, AND a big ole' metal rod or big screwdriver shoved inta the master cylinder body.

WAP WAP WAP. Damn plunger, I'll show it who the boss is. Absolutely no question about it.

So just now I've got the brake-lever side of the master cylinder pointed up skyward. The piston is sticking out on that side of the master cylinder body and touches the brake lever when the lever's in the 'fully rested' position. The parts diagram shows the plunger is pulled out of the body in the direction of the brake lever for removal.

So, with the brake lever removed, I doused the piston that's protruding out of the body on the brake-lever side with Paint Thinner. Then I switched to soaking it with penetrating oil (Liquid Wrench).

Now, what about this plan of mine.

I can't be having a small brake plunger get the best of me. Not whilst I have a big mofo hammer and a small metal rod or big screwdriver, and a scheme to use 'em. I look forward to hammering away at that plunger after it sets in the Liquid Wrench fer a bit. UNLESS you folks say 'bad idea.'

Is this a good scheme, I will be needing a front brake.
Last night I had a nightmare, I was driving my kz1000 down the road and squeezed the front brake and...nothing. So I reckon I'm in a bad way about this now.

did you take out the snap ring that holds every thing in place.

Here's the parts diagram. That 'snap' ring is freely moving back and forth on the rightmost 1" of the piston.

The piston is frozen and the rightmost 1" of the piston is sticking out the right side of the mstr cyl. and butting up against the lever with the lever in the "fully rested/lever not pulled" position.

The ring is loose enough to travel back and forth across the exposed 1" of the rightmost side of the stuck piston. The ring is playing no part whatsoever in preventing the piston from moving. The ring is freely moving on the right side of the piston shaft; you can slide the ring freely back and forth on the exposed part of the piston on the piston's right side.

You can freely slide the ring on the rightmost side of the exposed piston shaft between the mstr cyl body and the piston's right endpoint where it hits the butt end of the brake lever.

So that ring is not the problem. The piston simply will not move like it normally does.

Look here at the parts picture. Parts #9 and #10 -- I have removed them (and of course the lever too).

The ring, part #11 -- its job is to prevent the plunger from descending into the master cylinder body *when the brake lever is pulled all the way.* In my case, that doesn't even matter -- because the piston, part #12 in the diagram -- has *frozen in the fully rested/lever not pulled* position and if you look at the diagram -- the rightmost shaft section on the piston, part #12, is fully sticking out the right side of the master cylinder body. And the ring, part #11 -- is fully freely moving and can be slid back and forth on that rightmost part of the plunger. SO THE RING'S NOT THE ISSUE.

You'll also note from the diagram that the plunger is pulled out the right side of the master cylinder body -- for disassembly.

All I'm asking is, if I tap the *left* side of the piston (by sticking a screwdriver or metal rod inside the left side of the mstr cyl. body) to free it from its stuck condition -- is that a good idea?

With parts 6, 7, 8, 9, 10 and 11 removed and set aside, perhaps a shot of compressed air into the banjo bolt outlet would pop #12 out of the bore.

Point it away from yourself when shooting.

Good Luck!

I had something similar to this once, I pulled #12 out with needlenose pliers.

9am53 wrote:

I had something similar to this once, I pulled #12 out with needlenose pliers.

Right, tried that. The piston normally moves back and forth as the lever is pulled and released, but as I've mentioned it's frozen.

I have tried simply rotating the piston. No movement.
I have tried creating even a SMALL amount of back-and-forth movement of the piston. NOPE.

I think the piston just needs to sit in some penetrating oil long enough so that a hammer-tap will free it.

If anyone has solved this 'stuck piston' problem let me know a cool way to do it! Thanks.

Mine was frozen too, perhaps not as bad as yours but it was stuck. Mine was stuck all the way in, so the brake lever would flop around. I took everything out like you have, and grabbed the end of the piston with needle nose pliers and started pulling. It took some work but finally it let go.

Not sure if you mentioned it, but since it is stuck in the fully "out" position could you not try to loosen it by squeezing the lever as hard as you can to break it free?

If you are planning on rebuilding the m/c and don't care about the piston so much, maybe you could take the banjo bolt out (after draining the fluid) and maybe put a nail in the hole and give it a rap with a hammer (not MC Hammer though)

9am53 wrote:

Mine was frozen too, perhaps not as bad as yours but it was stuck. Mine was stuck all the way in, so the brake lever would flop around. I took everything out like you have, and grabbed the end of the piston with needle nose pliers and started pulling. It took some work but finally it let go.

Not sure if you mentioned it, but since it is stuck in the fully "out" position could you not try to loosen it by squeezing the lever as hard as you can to break it free?

If you are planning on rebuilding the m/c and don't care about the piston so much, maybe you could take the banjo bolt out (after draining the fluid) and maybe put a nail in the hole and give it a rap with a hammer (not MC Hammer though)

I GOT THE DURNED PISTON OUT!!!!

As I said, I had already stripped off all parts from the master cylinder, the hose, the lever, etc. and was able to stick a metal rod down the hole where the hose screws on. A big-ass Philips screwdriver also fit right into that hole.

After the mstr cyldr was sitting in Liquid Wrench penetrating oil overnight, I stuck the metal rod into the hole till it touched the left side of the piston inside the mstr cylinder and WAPPED it.

That there piston shot out of the lever-end of the master cylinder like a Hedge-fund manager running from a wire-tapper. It popped out of there like a illegal alien running from the border patrol. It flew outta there like a.. well, it came right out.

So now -- what parts do I keep after I buy a master cylinder rebuild kit? Here's a photo of all the parts that come out of the master cylinder:





WHICH PARTS DO I NEED TO KEEP?

Okay, I'm shopping ebay for a mstrcyl rebuild kit, and I found one for a '77 kz1000 (my bike is a '78 'A2' standard model, and the master cylinder is different from the '77 'A' model).


And now I know where all the suggestions to 'remove the snap ring' may have come from. Here's a photo of an eBay rebuild kit for a '77 kz1000 -- notice among the parts:

1) a "C"-shaped metal ring
2) and also, a traditional 'snap' ring:



But if you look at the parts diagram I posted above, you won't find a snap ring! My parts diagram (above) only shows the "C"-shaped ring.

Notice in the picture here that "C"-shaped clip. THAT'S THE ONLY CLIP IN THE PART DIAGRAM (posted above) for my '78 kz1000.

And furthermore, there was no such snap ring when I disassembled my master cylinder parts. Only that "C"-shaped ring was there (see my photo of my disassembled parts above).

Well, that clears up the 'snap ring' mystery. There I was last night, flippin-an-a-jerkin round lookin fer a snap ring, "when I find it where'm I gonna get them long extended snap ring pliers, how much will they cost, will I be able to get it off" and other spastic and coffee-induced outburts.

The '77 kz1000 has a round master cylinder; my '78 bike's is a 4-sided polygon, not round. So apparently when Kawasaki changed the master cylinder assembly for the '78 'A2' model, they dropped the snap ring from the parts list. Mystery solved.

I can't find a rebuild kit for the '78 A2 model on ebay -- anyone know a website source for one?

THANKS ALL!!!!

everybody always recommends Z1Enterprises.com, and for good reason. I got a rebuild for my 82 1000 back brake. If you can't find it call them and ask...they likely can get you one

Thanks 9am53, z1Enterprises and all the other places/websites don't carry nor have access to the 1978 'A2' model front master cylinder rebuild kit.

Apparently the main aftermarket provider, 'K&L' doesn't make one for the '78 A2 model.

The only thing remotely close is, for $35 not including shipping, z1Entr will sell me a new mstrcyldr piston.

While that might do the trick, I'm loathe to dump big $ money like that into a repair job on a master cylinder that not even Kawasaki has rebuild kits for.

In my investigation, there's a master cylinder rebuild kit for the '77 A1, for the '78 LTD and Police kz1000s but not the single-disc brake standard '78 A2 kz1000 model.

Anyone out there got a kz1000 single disk master cylinder setup they want to sell? Heck I'll buy the entire system is that's what you need to sell.

Let me know, I've got a running kz1000 vintage and no front brake right now.

well, if you are interested I just replaced the m/c from my 82 1000 (twin disk) and I don't know what to do with it...it was working fine I just didnt have room for it on my new bars. if it fits you can have it (my bike is an LTD so it may be kind of crooked...) I think using a double disk m/c would just give you more responsive braking...but I am not sure....anyways, let me know