How to: Rebuild Clutch Master Cylinder

[97tiger885]

The kit for the clutch master cylinder rebuild should include ten (10) items:





These items are as follows:

1.  Spring,
2.  Cap w/ nipple,
3.  Piston,
4.  Piston O-ring (shown on piston),
5.  Metal washer,
6.  Circlip,
7.  Rubber boot (damaged, shown end should have small hole for #8,
8.  Piston rod(groove should have #9 in it),  NOTE: The rod is show backwards in the photo.  The rounded end goes into the cup of the piston.]
9.  Piston rod O-ring (not pictured), and
10.  Cltuch handle barrel.

Step 1:  Drain the hydraulic fluid.



Remove the banjo bolt (9/16") from the clutch slave cylinder.  The CSC is found on the left side of the mc in front of the oil filler.  Place a pan under the hose to catch the fluid.

To break the vacuum, remove the two (2) Phillip screws from the reservoir lid.  Remove the top and the dust cover found inside.



 
Finish draining the fluid and reattach the banjo bolt (9/16") to 25Nm.  There are two crush washers for each banjo bolt.  I did not replace these.




Step 2:  Remove the hand guard, clutch handle and piston rod#8



This is done by removing the clutch pivot bolt (6 Nm) which is found in front of the mirror housing.  Undo the bottom nut (10mm) and unscrew the bolt.   The hand guard, clutch handle and l piston rod, #8,  will come away. NOTE:  The straight end of the piston rod goes into the hole in the barrel in the clutch handle.  The rounded end goes into the cup on the end of the piston.
This is a good time to remove the mirror (14mm).  


Step 3.  Remove the reservoir



Undo the banjo bolt (9/16") that is attached to reservoir.  (Lower left in pic.)



Undo the two allens on the clamp on the inside of the handlebars (15Nm).
Remove the reservoir.  Finish draining the reservoir.  There is more fluid inside.

Step 4: Remove the old piston set

Looking into the piston housing you will see the boot (#7) sticking out.  Grab this with a needlenose and remove.  Next you will see the part of the piston (#3) sticking thru the circlip (#6).



Here is what it looks like from the side:



 To remove the circlip I used the following:



In my left hand, I held the housing and the screwdriver.   In my right hand, I held the pliers.  I used the screwdriver to push the piston into the housing exposing the circlip.



 I then reached in with the pliers and removed the circlip.  This last step took several tries.  



The pliers is a needlenose that I modified by grinding the ends to points small enough to fit the holes in the end of the circlip.  I put the ends in the holes, gently squeezed until the circlip came out of its groove and gently lifted.  I then grabbed the end of the piston (#3) and pulled it and the washer (#5) out.   I then used the pliers to grab the cap (#2) and the spring (#1).

Step 5: Clean the reservoir

I did not do this.

Step 6:  Install the new piston set.

Coat the new piston and the cleaned cylinder bore with hydraulic fluid.





The new set is installed in the following order.

1. Spring, large end first,
2. Cap, nipple end first,
3. Piston with seal, large end first,
4.  Washer.

At this point, you need to use the screwdrive to depress the piston, grab the circlip with the modified pliers, gently squeeze and push in until the circlip goes into its groove.  This may take a few tries to achieve.

The rubber boot (#7) is then pushed into the opening around the piston.  The large opening goes in first.  I used an allen wrench to seat the boot.  Be careful not to use anythilng sharp to avoid puncturing the boot.

Step 7:  Put the reservoir back on

Put in the two (2) allen screws in the clamp (15Nm).



Reconnect the banjo bolt to the reservoir (25Nm, 9/16").



Step 8:  Replace the piston rod, clutch handle, hand guard and mirror.

Place the new O-ring (#9) inside the groove of the small piston.  My set did not come with this O-ring and I used the old O-ring.   Place the rounded end of the piston  rod in the hole of the rubber boot.  Line up the slot of the barrel in the clutch handle with the straight end of the piston rod. REVERSING THE PISTON ROD WILL RESULT IN CLUTCH SLIP. Take the hand guard and clutch handle and line them up with the hole for the clutch pivot bolt.   Put in the bolt, screwing it tight.  Put on the nut (10mm, 6Nm).  Replace the mirror.

Step 9:  Refill the reservoir and bleed the line.



The nipple to bleed the line is on the slave cylinder (7Nm).



It took a long time to bleed.  I do it the old fashioned way by squeezing the clutch, opening the nipple, closing the nipple, squeezing...I suspect using a vacuum to pull all the air thru would be faster.

Step 9:  Replace the dust cover and the lid

[RJS]

Nice clear repair !

I recently had trouble bleeding clutch after replacing Master Cylinder (broken mirror mount) - it defied every effort to bleed it !

Eventually did it with large medical syringe & rubber tube attached to bleed nipple and 'reverse bleeding' it. Works grand now.

No idea why normal method would not work ?

[Sin_Tiger]

Good write up  , getting a link in the How To shortly.

[Mustang]

Good write up  , getting a link in the How To shortly.

it's been in there for years..........................

[Sin_Tiger]

I really need to get my eyes checked 

[ssevy]

Nice write up. Use some red rubber grease on the rubber bits during assembly, and it will help those parts work more smoothly.