Brake master cylinder woes

A little background on my bike. It has sit for 15+ years. I have cleaned the tank and all carbs apart and it is beginning to come around. The front caliper was locked up when we moved about 8 years ago and I removed it so we we could move the bike to the new garage. I got the caliper freed up and reinstalled today. However, the master cylinder was dry and when I put in some fresh brake fluid I discovered that the piston assembly was pushed all the way in and frozen up. I pulled off the dust boot but the piston is so far in that I can't get at the clip to pull it out. I hit it with PB blaster a couple of times. Any other ideas or methods to get it loose?

Come on. Somebody has to have had this issue.

I guess unless I hear otherwise, I am going to try and get ahold of it with needlenose pliers or small vice grip and pull it out enough to get the retainer clip off of it. I found a source for a rebuild kit with new piston so as long as I don't mess up the m/c itself, I should be good once I get it out.

If your banjo bolt fits opposite of the piston, why not just push the piston out that way?

Maybe a pic of what the MC looks like or what bike it's off of might help.

later, Doug

Tried air pressure? Just be sure to aim it at something soft, like a hay bail or something.

Please check "Private Message"

riverroad wrote:

Tried air pressure? Just be sure to aim it at something soft, like a hay bail or something.

Yes, I tried air pressure but to no avail. I was able to push a small punch up from the end where the bango bolt goes in and can feel the spring but it wont give. If you look down from the end that had the dusk boot on it you can see the retainer. It is very rusted.

Thanks for the PM Patton. My apologizes for the general request. I will try and narrow down the request with more specific info. My bike is a 75 Z1 900. With OKC_Kent's assistance, I located a copy of the schematic on Kaw.com and will try and post it here.

I printed out the parts diagram but unfortunately, there is no way to save it. I will have to wait until I get home and can scan the image.

Let's see if this works --




Ref # Part # Description Qty Spec #
1 43015-032
Add to pick list CYLINDER ASSY,MASTER 1 Z1
1 43015-032
Add to pick list CYLINDER ASSY,MASTER 1 Z1-A/B
1 43015-032
Add to pick list CYLINDER ASSY,MASTER 1
2 43073-001
Add to pick list REPAIR SET-MASTER CYL 1
3 43025-001
Add to pick list STOPPER-BOOTS 1
4 43024-001
Add to pick list BOOTS 1
5 481J1800
Add to pick list CIRCLIP,18MM 1
6 43022-001
Add to pick list STOPPER-PISTON 1
7 43072-001
Add to pick list PISTON ASSY 1
8 43019-001
Add to pick list CUP-PRIMARY 1
9 43018-001
Add to pick list SPRING ASSY-RETURN 1
10 43017-001
Add to pick list VALVE ASSY-CHECK 1
11 43029-003
Add to pick list LEVER,FRONT BRAKE 1
12 43033-001
Add to pick list BOLT-LEVER FITTING 1
13 312B0600
Add to pick list NUT 6MM 1
14 43031-001
Add to pick list WASHER-LOCK,8MM 1
15 43074-001
Add to pick list TUBE 1 NOT REQ'D 43015-032
16 311B0800
Add to pick list NUT,8MM 1
17 43030-002
Add to pick list BOLT-LEVER ADJUST 1 USE FOR 43015-008/012
17-1 43030-003
Add to pick list BOLT,LEVER ADJUSTING 1 USE FOR 43015-032
18 43026-003
Add to pick list CAP,OIL CUP 1
19 43027-001
Add to pick list PLATE-MASTER CYLINDER 1
20 43028-001
Add to pick list DIAPHRAGM 1
21 110N0625
Add to pick list BOLT HEX HEAD 6X25 2
22 411B0600
Add to pick list WASHER PLAIN 6MM 2
23 43034-001
Add to pick list HOLDER-MASTER CYL 1
24 43016-002
Add to pick list BODY, MASTER CYLINDER 1
25 43067-001
Add to pick list WASHER-OIL BOLT 6
26 92002-1888
Add to pick list BOLT,OIL,L=23 3
27 49006-1041
Add to pick list BOOT,DUST 1
28 43059-007
Add to pick list HOSE,FRONT BRAKE 1
29 43065-001
Add to pick list SWITCH-FRONT BRAKE 1
30 43061-002
Add to pick list JOINT,THREE WAY 1
31 110N0632
Add to pick list BOLT-HEX HEAD,6X32 1
32 110N0640
Add to pick list BOLT HEX HEAD 6X40 1
33 461F0600
Add to pick list WASHER SPRING 6MM 2
34 411B0600
Add to pick list WASHER PLAIN 6MM 2
35 43059-011
Add to pick list HOSE,FRONT BRAKE 1
36 43060-004
Add to pick list PIPE,BRIDGE 1
37 43063-001
Add to pick list BRACKET-BRAKE HOSE 1
38 43064-001
Add to pick list GROMMET-HOSE BRACKET 1

Patton - you are da man. Thanks.

I believe it is part #5 that is causing the problem. The piston is pushed so far in that I can't get pliers down to get the retainer clip off.

Starting at the left end of the master cylinder diagram ---

#3 is a semi-circular ring that presses down over the #4 rubber boot. The ring and boot should come off without drama, but the rubber boot may rip and need replacing in any event.

The #5 circlip is usually rusty, difficult to see, difficult to remove, generally not re-usable, and probably destroyed when removed. Must be removed for piston to come out of the master cylinder bore. Should be a 14mm bore (1/2 inch) used with single disc front brake. (Later model double discs versions use a larger 5/8" bore master cylinder with larger piston and cups). Might need an icepick or similar tool to force the circlip out.

The circlip is way down in there, so very long slim needle nose pliers are needed. (Kawasaki actually offered a special tool for this). Be careful not to break the tips off your needle-nose pliers attempting to remove the old crusty rusted-in-place circlip. IMO, use icepick or similar tool to remove the circlip. And use the delicate long slender needle-nose circlip pliers only to install the new circlip.

#6 is "piston stopper"

#7 is "piston assembly" on which the secondary cup" (rubber) is built in as part of the assembly.

#8 is primary cup (rubber).

#9 spring

#10 check valve assembly.

---

If the m/c bore isn't too pitted, it may be re-used after cleaning. Slight polishing of any pitted area inside the bore is okay also. Best to use a new piston and primary cup -- remember the 14mm size requirement -- a 5/8" piston and cup is too big and will NOT fit.

---

Am uncertain, but believe a slim punch could be used through the banjo bolt hole to push the piston out of the bore. Or perhaps air pressure through the same hole. (As both these already suggested). But it is of course critical that the circlip be first removed.

---

Good Luck -- and keep us posted.

Edited to conform part numbers to the posted diagram and not to numbering as shown in the factory service manual(FSM).

Post edited by: Patton, at: 2007/09/18 14:34

Post edited by: Patton, at: 2007/09/18 14:37

Here's the 1/2" m/c repair kit from Z1E:


m/c kit