How to Replace the Clutch Master Cylinder
- Difficulty: Moderate
- Avg. Time Necessary: 1-2 Hours
- Cost: $60-$80
Replaced my CMC today and would have never been able to without this DIY. All the credit goes to Reborn on CRSX for creating the DIY.
This is a picture-heavy DIY guide intended for noobs. Everything is included. Check out some other useful guides as well as this one before tackling the job.
Start underneath the driver’s cockpit. Remove the plastic cover by turning the knob 90 degrees in either direction and yanking the cover.
Now you need to disconnect the clutch master cylinder (CMC) from the clutch pedal. I am pointing at the rod of the CMC that connects to the pedal (my finger is resting on the pedal).
Here’s a shot from a different angle, showing the pin that is in the pedal pin. You want to grab the bottom part (most right part in this picture, the triangular section) with some pliers, turn 90 degrees away from you (see what I sketched in the next pic) and pull down towards the floor of the car. It’ll come right out with this technique.
Once the lock pin is out, just push the pedal pin out of the yoke. It’ll slide right out.
Now the rod of the CMC is off the pedal. It’s time to unbolt the CMC from the firewall. There are 2 nuts (14mm) that you need to remove. They are located on either side of the clutch pedal. I’ve circled 1 nut in this photo, and pointing at the other (not visible).
Now you can move over to the engine bay. First, remove the battery. Remove the 10 mm nut holding the tie down to the radiator support. Loosen the 10mm nuts on each terminal. Get the wires/leads out of the way and pull the battery out. Also remove the battery tray (below the battery) – yank the thick wire coming out of the positive lead out of the little holding groove first.
Now you need to remove the airbox. Remove the little rubber plug at the top right of the box (when viewing from the front of the car). Remove the 12 mm bolt underneath it.
There is 1 nut and 1 bolt on the left side (12 mm). Remove them as well.
Use a Phillips head to loosen this tie down
Use pliers to loosen and move this tie down. I just slide it to the left until it is off the plastic nipple of the airbox – basically move it left more than half way.
Now pull the airbox out, slipping the rubber pieces shown in the above 2 pictures off.
Now remove the snorkel. You can either remove the single nut or the 2 little ones holding the bracket to the radiator support. I removed the 2 little ones and removed the whole bracket to make sure the studs of the bracket didn’t cut up my arm while I’m working later.
Now figure out the whole clutch system by tracing the lines, starting with the reservoir (the smaller reservoir pictured here, the other one is for the brake system). From the reservoir, there is one line (I’m holding it) that goes to the CMC – this is the input line. The CMC is tucked behind the strut at the firewall.
In the picture below, the hardline I’m holding is the one coming out of the CMC – this is the output line.
Further down the output line. See that bracket holding it to the frame (circled in red)? Remove the nut holding that bracket to the frame. You will also notice that at that point, there is a half circle of soft line, before it then turns back into a hard line. This soft line provides the flexibility needed (once you remove that bracket from the frame) to easily maneuver the CMC out of the tucked away position. There are pictures of the remaining lines all the way to the clutch slave cylinder in my DIY guide for removing the clutch slave cylinder.
Here is a schematic to also help you trace the lines.
Now that you have some flexibility, pull the CMC into the visible view of the engine bay. Remove the input line (soft line) by opening the clamp with some pliers and pulling it off the nipple on the CMC. Leave the clamp on the line, plug the line with a shop towel, and hold it upward to prevent losing fluid. The less fluid you lose, the easier it will be to bleed because there will be less air in the system. I did the job alone, so my macguyver method of holding the line up is shown below.
Remove the output line (hard line) by pulling the C clip out of the bracket and pulling the line out of the CMC. Again, plug the line with a shop towel to avoid losing fluid.
Now you can remove the CMC.
New vs. old CMC. Old is the oem rsx piece, new is the 01-05 civic piece. Notice the missing triangular piece on the civic unit. This is believed to be the culprit for early failure in the rsx units.
Reverse the steps to install the new unit. If you are doing the clutch slave cylinder at the same time, then remove that. After you are finished, you need to bleed the clutch system – described in my DIY guide for removing the clutch slave cylinder.
After installing a new CMC, you will need to adjust the pedal position as well. This is straightforward, just follow the helms.
For reference, here is the helms for the CMC removal.