CONVERTING TO A HYDRAULIC CLUTCH

    The first step in converting my clutch to hydraulic was to locate a suitable donor vehicle.  I chose an 84 Mazda pickup. Some things to consider in your conversion are the stroke length on the slave cylinder, and the size and shape of the master cylinder.  My slave cylinder just barely has enough stroke length to operate the clutch, one of the things that I miscalculated in my conversion. I hope to find a cylinder with a longer stroke, and put it in at a later date.

     After finding donor parts I decided on the mounting location for the master cylinder.  I located my clutch pedal inside and measured its location using a hole in the firewall that I could locate from the other side also. My clutch pedal had a hole already in it for the push rod to connect to. I don't know if this is common to all castings or if this was unique to mine. Make sure that where you mount your master cylinder will give the right amount of throw for the push rod. If you have to much throw you will probably ruin master cylinders, and if you don't have enough throw you will not get the full travel from your slave cylinder, and the clutch may not operate correctly.

    Once I decided on the location I measured from the engine side of the firewall and marked the spot.  I drilled through the firewall with a drill bit the size of the master cylinder.  I also drilled a hole above and below the main hole for the mounting studs.  If your master cylinder mounts in an area that is just sheet metal you may want to build a mounting plate to spread out the pressure that the cylinder is going to take from the pedal. After drilling the holes, I mounted the master cylinder.  I then measured the push rod length using the push rod from the Mazda pickup. I found that the original push rod and end could be used if the push rod had some threads cut off.

    With the master cylinder done, I started work on the slave cylinder. I had several ideas on how to mount the slave cylinder, but due to time constraints I chose the quick and dirty method. I mounted the slave cylinder so it operated the cross shaft. This mounting method leaves one short connecting cable in the mechanism, but I have never had to replace this cable anyway. I located the mounting point for the slave cylinder, and manufactured a spacer to hold the cylinder out from the frame so it would line up with the lever on the cross shaft. I mounted the spacer to the frame, and bolted the slave cylinder to the spacer. Then I measured the length of the push rod I would need.  I manufactured the push rod from oil hardening tool steel. I threaded one end to take the original clevis from the cable and put a radius on the other end to match the original push rod. I then hardened the rod, and cleaned the burnt oil residue from the threads. I then used a buffing wheel and polished the radius to a high polish to limit friction. I assembled the clevis and push rod and connected them to the cross shaft.

    The final item to connect is the hydraulic line between the master cylinder and the slave cylinder.  My slave cylinder had a small length of flexible hose that allowed for movement in it's original application. I left this in because if I took it out I would have had to produce an adapter for the steel line to connect. I picked up a length of line from my local auto parts store, make sure you get the right line, as there are metric and American sizes. Try and get the line as close to the right length as possible because you do not want to cut it. If you have to cut it you will have to get the end reflared. The line has to be double flared to match up. The flaring tools you buy at the auto parts stores cannot put a double flare on the tube, so you will have to go to a brake shop to get the flare redone.

    Once you have the line connected fill the master cylinder with fluid (whatever fluid was recommended for the donor vehicle).  Have someone help you bleed the system. The correct procedure for bleeding is having one person in the cab and one under the vehicle (make sure to chock the wheels). Run a clear vinyl tube from the bleeder screw on the slave cylinder to a jar half full of clean fluid. Have the person in the cab depress the clutch pedal completely and hold it. After the pedal is depressed, open the bleeder screw until the pressure is gone from the line. Close the bleeder screw, and then have the person release the clutch pedal. Repeat this process until no more bubbles are seen coming through the vinyl tube. Check the fluid level about every 4th or 5th time to make sure you don't run out. If you run out it will suck more air into the system and you will be starting over. Caution: never reuse any fluid that you have bled out of the system. Dispose of the old fluid in an appropriate manner.