| This is the clutch bleed method I came up with when installing my McLeod Master Cylinder. Other than the M/C itself the tools I needed where: Your Old Slave Cylinder, Dremel tool, GM OEM Spec Brake fluid (only one bottle was needed, but much recycling took place), Mity Vac Pump, Zip Tie, Small Rubber Washer. Ok the first thing I did was to create this little helpful tool. I’ll call it a slave sim. Cause basically it’s job is to act like the slave cylinder, open up the hydraulic valve, and allow me to pull the fluid through the Master cylinder in the direction of the slave cylinder. |
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| I basically removed the female end of the Slave’s hydraulic connection by removing the pin (same pin setup as the M/C) and the connector slid right out. ***Not that you need it for this clutch bleed but if you happen to tear your M/C washer you will find the exact same sort of washer sealing the Slave’s female connector. So you might want to store it somewhere just incase.*** |
| Save yourself a half hour of frustration and Dremel out the inside of the tubing. It will make slipping the tube over the Slave's hydraulic connector so much easier. Be sure to clean out any and all loose rubber if you do Dremel the inside. I put just a little bit of grease around the tube to help slip it on. |
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| I placed a small rubber washer in the gap of the female connector. Not so much to seal the tube but just to help get the tube past that gap. The tubing came straight from the Mity Vac kit I got. I just cut one of the longer tubes in half. They are the perfect size for this job. Once the tube is on securely, zip tie it and you’ll have an airtight seal. |
| Here you’ll see the M/C setup to be bleed. Forgive me for using a stock M/C in my pictures, but the McLeod is in and working. I’m certainly not gonna rip it out to take pictures of it. :p |
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| So I’ve mounted the M/C horizontally in the vise. I’ve removed the reservoir, but left the reservoir tube and ran it into a plastic container filled with brake fluid. Be sure to keep the brake fluid level above the tube opening at ALL TIMES! Otherwise, you’ll suck air back into the system and have wasted all the time you just spent bleeding. |
| Now I have the hydraulic line running upwards to help the air get out of the system. This is probably overkill since the Mity Vac is sucking the air out, but it isn’t hurtin either. As you can see from the picture, I have my slave sim connected to the hydraulic line and running into the Mity Vac’s vacuum container. |
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| The first step is simple. Pump up the Mity Vac to 5 psi and let the pump pull out the air and fluid. Obviously when your Mity Vac’s container get near full empty it into the plastic container that feeds the reservoir tube. Continue to go through this cycle until you don’t see any more air being removed. Then, go up to 10 psi. Repeat the cycle until there are no more bubbles. Then go to 15 and then 20 psi. Every time you bump up you’ll magically see more air. At 20 psi you might notice the bubbles start to aerate a little bit (kinda looks like soap suds if you’re not familiar). Don’t worry about those; we’ll get those later. Just try and eliminate the normal air bubbles. |
| OK so now onto the second step. A little more complicated, but you’ll get all the “trapped air” with this method. The M/C should be setup exactly the same as in the first step. The only possible change would be the size of the tube inside the Mity Vac’s vacuum container. This picture doesn't quite illustrate it so well but you need to connect the tube that “almost” reaches the bottom of the container. If you were already using that one, then you’re set. If not put that tube in now. |
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| To start you’ll need to pump the Mity Vac quickly and build up 20 psi of pressure as fast as you can. The Mity Vac’s container should be filling fast. Wait till it hits about the halfway mark (the fluid level needs to be at least an inch to an inch and a half above the bottom of the tube so no air is sucked in). Once your fluid level is high enough slowly pump the M/C’s clutch pedal rod in all the way and slowly let it out. You’ll notice a ton of air released at this point. When you pump the clutch pedal rod in, the fluid flows into the container rather quickly. When you let the clutch pedal rod out it sucks whatever air and fluid are in the the Slave Sim tube back in (this is why it’s important to have the fluid level above the tube so no extra air is sucked in). The Mity Vac will not be able to suck any fluid unless the clutch pedal rod is completely released. Once the rod is back out the Mity Vac will get all those air bubbles you just shook loose. (You can use the trigger on the Mity Vac to quickly release pressure so your fluid level does not go past the top of the Mity Vac’s vacuum container) Continue to do this till you don’t see any more bubbles. |
| There is one spot left where air can still hide in the M/C unit. To get to these bubbles we have to change the setup a little bit. First off remove the Slave Sim from the Mity Vac (We’re done with the Slave Sim) and disconnect it from the hydraulic line. (The clutch pedal rod should be rock solid and you’ll not be able to push it in with the hydraulic line closed) |
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| Remove the Reservoir tube from the container and reinstall the actual reservoir. Now you need to find a way to hang it up so that it sits vertically (I mangled a couple of coat hangers for this duty) |
| On the Mity Vac attach a different tube in place of where the Slave Sim’s tube was attached. To that tube you need to find one of those little nozzle accessories. You can see from this photo that it needs to be one of the nozzles that look like a pencil tip. |
| As you can see from this picture, that nozzle has to fit “inside” the small hole at the bottom of the reservoir. |
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| With your hydraulic line disconnected and closed and your reservoir filled and vertically suspended you are ready for the Mity Vac. Before inserting the Mity Vac be sure to fill the tube holding the nozzle with brake fluid. You don’t have to fill it up all the way, but at least 4-5 inches worth of brake fluid in that tube (about the halfway mark). Snuggly insert the Mity Vac’s nozzle into the small hole at the bottom of the reservoir. Your setup should look something like this by now: |
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Pump the Mity Vac up to 20 psi and you might find a few bubbles pulled out. Be sure the nozzle is snuggly in that hole; otherwise you’ll just pull fluid out of the reservoir. I want to get any air that might be trapped in the reservoir tube or inside the M/C. Once any bubbles are pulled you can use the trigger to release the pressure and try it again. Keep doing this till no bubbles are pulled. Be sure to always keep at least 4-5 inches of brake fluid in the Mity Vac’s nozzle tube, else when you release pressure air can get sucked right back into the M/C. You’re done bench bleeding. Make sure the Reservoir is filled enough, put your moisture lock back in and recap the reservoir. You’re M/C is now ready to install back in the car. |
| The last stage of this Bleed might seem redundant, but many times air can hide in the slave and creep it's way back up. Plus this step is valuable to you when a week or two down the line you feel a little mushiness in the top travel of the pedal. Well forget pulling the M/C back out. You can just hook up the Mity Vac to the resevior and reverse pressure bleed the system while all components are installed in the car. |
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| As you can see you'll setup the Mity vac the exact same way as you did in the final stages of the bench bleed. However you can use the clutch pedal to jimmy stubborn air bubbles lose. Another trick I learned after doing this bleed method a few times is in this stage if you remove the canister from in between the Mity Vac and the Resevior you can hold 20 psi all day long. Just make sure to always have the pump elevated as you don't want fluid being sucked into the unit. When relieving presure via the trigger, do it slowly so fluid isn't sucked up. |
| After pumping the Mity Vac up to 20+ psi, you'll notice tiny bubbles are still being removed. Some of this air was freed when you banged the M/C back into place and some is coming up from the slave. After the bubbles thin out try pumping the clutch pedal in very shallow strokes(just the mushy section up top, maybe 2" of travel). Do this about ten times then one time very slowly all the way to the bottom. If the clutch pedal sticks to the ground, don't worry, sometimes the 20 psi from the Mity Vac can do that because of the reverse pressure(least, that's my guess). Continue this method till it becomes difficult to actually see the air bubbles. |
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