Rebuilding a clutch slave cylinder is sometimes needed after the clutch petal is no longer working. First you should check the clutch fluid container to verify it is full. If not follow the line down to the slave cylinder while looking for leaks to identify the problem. The clutch slave cylinder is located behind the passenger side wheel on this vehicle, a miata. Remove the two bolts and the clutch line and the slave cylinder should come off to the right side.
Here is the slave cylinder. Rebuild kits for the slave cylinder are generally very inexpensive. This paticular kit was under twenty dollars. You will first need to disassemble the slave cylinder parts. Start by removing the rod and protective dust boot.
Next you will need to get the plunger piston to come out. There is no retaining ring but the plunger may still not want to come out easily. When the plunger comes out there will be a spring behind it also.
Before reassembling, clean out the insides and flush the cylinder out with some fresh brake fluid. Place a little fluid on the plunger before reinstalling. Now all you have to do is replace the old plunger piston with the new aluminum piece and reassemble the parts in the reverse order as they were removed. Hold the plunger in the assembly as it may want to pop out with the new plunger assembly. Place the plunger rod in it’s origional location and reinstall the two bolts that hold it in place. Reinstall the slave cylinder line then fill the clutch reserve with fluid. Then you will need to bleed the clutch the same way you would a brake system. Press the petal down and open the bleeder located close to the clutch line. Close the bleeder screw then release the clutch petal. Press the clutch petal down break open the bleeder screw and repeat this process. The petal should become stiff again as all the air is bled out.