Clutch Master Cylinder
Repair and Bleeding
by Lowell Felix Tortona
I thought I have all the necessary
tools on hand when I started the process. But I guess, I wasn't that prepared
as I thought I was. This forced me to go back and forth to a nearby hardware
shop in my vicinity to buy such tools. To help the DIY guys out there who are
planning to repair their clutch master cylinder and bleed their clutch, here
are the tools you must have.
- Master Cylinder Repair Kit
Fujiura Ltd. (FIC) [Made in Japan] or any 323/MX-5 compatible repair kit.
Serial Number: FR-3106 (for 323/MX-5)
- Socket/Rachet extension
- 12 mm. hexagon socket with at
least 1 inch of depth
- 10 mm. open wrench
- 8 mm. close wrench
- Circlip plier
- About 500ml of DOT3/DOT4 brake
- Wheel wrench
- A partner for bleeding the system
- Absorbent rags
- Clean newspaper/paper towels (to
be used on the rebuild process of master cylinder)
- Cotton buds.
- Bottle/ Plastic container to dispose
- Syringe (not necessary)
- 4-in by 4-in Glad-o-wrap plastic
seal (you can get it in your kitchen)
- Uninterrupted time
- Snacks (yum... yum...)
Let me first describe the location
of both the master and slave cylinder. For the master cylinder, it is located
inside your engine hood. Remember the two cylindrical reservoir connected on
the car's firewall in front of the steering column? Well, the master cylinder
unit is the one with the smaller cylindrical reservoir. For the slave cylinder,
it is located under the front-passenger part of our miata. It can be clearly
seen after the right-front wheel is removed. It is like a door actuator thingy
with rubber boot cover (similar to the shock absorber rubber boot cover) on
Now let me explain how to proceed
with the process.
A. Removing the Master Cylinder
- Remove the reservoir cap of the
fluid container on the master cylinder.
- Using the syringe, remove some
brake fluid from the container until it reached the minimum level. Dispose
the fluid in a bottle/plastic container.
- Put the 4-in by 4-in Glad-o-wrap
plastic seal on top of the master cylinder fluid container. Seal tightly.
(This prevent spilling of fluids when the clutch pipe line is removed from
the master cylinder.
- Put the reservoir cap and close
tight on the master cylinder fluid container.
- Put an absorbent rag under the
master cylinder body.
- Locate the clutch pipe line that
is connected on the master cylinder body. (long pipe with about 1 mm of diameter)
- Using a 10 mm open wrench, loosen
the screw connection (by unscrewing it counter-clockwise).
- After the screw is completely
removed, pull the clutch pipe lining out of the master cylinder.
- Locate the 2 screws connecting
the master cylinder onto the car's firewall.
- Spray some WD-40 on them to ease
up the removal of the nut. (Believe me... I really had a hard time removing
- Using a 12 mm. hexagon socket
connected to a socket extension and a rachet, remove the nuts (by unscrewing
- After removing the 2 nuts, you
can now remove whole clutch master cylinder. (Be careful of fluid spillage....)
B. Rebuilding/Repairing the Master
- Remove the thin woven lining
that is lying in between the master cylinder and the car's firewall. (To prevent
from fluid spillage later on our rebuild process.)
- Work on a clean paper or paper
- Look at the end of the master
cylinder (the one that is connected to the engine firewall) and locate the
circular clip that integrates the whole master cylinder. (a horseshoe like
circular object with two holes on its end)
- Press the piston using a screwdriver
and remove the circular clip with the use of the circlip plier.
- After removing the circular clip,
the piston inside the master cylinder will eventually be removed. (You can
then notice that only a cheap plastic were used as a component.)
- Shake the master cylinder until
the remaining 3 components (spring, cap, circular plastic lining) are out.
- Make sure that the repair kit
contains the the following components (piston, spring, cap).
- Clean the whole internal master
cylinder body using fresh brake fluid and wiping it with cotton bud. (Do not
use water or other solvents in cleaning this one.)
- After cleaning it, pour on some
fresh brake fluid in it.
- Soak the new spring, cap, circular
plastic lining, piston with fresh fluids.
- Put the cap on solid (flat) end
of the spring and re-insert it into the master cylinder body.
- Next, attach the circular plastic
lining and afterwards set the piston into the master cylinder. Remember that
the flat side will be used to contact with the circular plastic lining and
the side for the push rod should be exposed.
- Reinsert the circular clip by
pushing the piston with a screwdriver and clipping the circular clip (like
putting the clip on a Koni shock absorber in a reverse manner).
- Now, you have rebuilt your clutch
C. Re-installalation of the Master
- Put back the thin woven lining
that was removed in B-1.
- Set the master cylinder back onto
the engine firewall.
- Using the 12 mm socket, socket
extension and rachet, screw back and tighten the two nuts that secure the
master cylinder onto the car's firewall.
- Reconnect the clutch pipe lining.
- Using the 10 mm open wrench, screw
and tighten the connector screw between the master cylinder and the clutch
- Pour in fresh brake fluid into
- Now, the master cylinder have
been successfully re-installed.
D. Bleeding of Clutch
- Jack-up the right front side
of the car.
- Remove the wheel.
- Sit down beside the right front
side wheel-well of the car (face towards where the shock absorber is located)
- Locate the slave cylinder (You
can then see it on the left side part of shock absorber... which is directly
connected to the clutch body.)
- An air bleed valve can be seen
connected to the slave cylinder. Put the 8 mm close wrench on it and make
sure that the air bleed valve is tightly closed. (Screw clockwise.)
- Put some rags near the trajectory
path of the air bleed valve.
- Ask a friend to sit on the driver's
- Make sure that the clutch fluid
reservoir is full. Fill if necessary.
- Let him slowly push (by counting
3-5 seconds) the clutch pedal until it bottoms out.
- Let him maintain the clutch pedal
on the floor until you give a signal to release it slowly.
- Now slowly loosen (screw counter-clockwise)
the air bleed valve until a squirt of bubbly fluid emerge.
- Re-tighten the air bleed valve.
- Give a signal to your friend to
release the clutch pedal slowly.
- Repeat process D-8 to D-13 (around
5 to 7 times) until you notice that the squirt that is coming from the air
bleed valve is clear brake fluid and the clutch pedal feels tight.
- Make sure to tighten the air bleed
- Fill the clutch fluid reservoir
to the maximum level.
- Close the cap of the clutch fluid
- Clean with water all the parts
where the brake fluid spilled onto.
- Using the wheel wrench, re-install
the wheel and tighten the nuts in an X pattern.
- Jack-down the right front side
of the car.
- Completely tighten the wheels.
- Afterwhich, you can test drive
and see if everything is OK.
Finally, you can now clean-up, eat
your snacks with your friend and enjoy the rest of the day top-down driving
I hope this would serve as a reference
for you guys out there who plans to fix your cars in case such problem occurs.
Frank Reedy comments:
I recently replaced the clutch on
our 1990 Miata.It has 146,000+ miles on it and decided to do the hydraulics
also. I had done brakes before on many cars so this was not new to me. I noticed
the article on rebuilding the clutch master cylinder and noticed there was no
mention of honing the bore of the unit. This should be done because the walls
do rust. An easy fix is use at least 400 3M wet sandpaper rolled around a round
file. Use a little fluid and it will clean the bore to a new shine which will
let the plunger do a better job. I clean the cylinder with aerosol brake cleaner
that evaporates quickly. Apply dot 3 fluid to all surfaces, reassemble and your
clutch will feel like new.