Eagle Posted August 4, 2012 Share Posted August 4, 2012 Now if I could match this for the old, Ford-style, dual chamber master cylinders on the early XJs and MJs, I'd be ecstatic. Had to replace nearly all of the hard brake lines under a 2001 XJ due to rust-out. Nobody around to help with the bleeding, and my Mighty-Vac suction bleeder wasn't getting the job done. I think it was pulling air around the threads of the bleeder screw. Dilemma. Then I noticed the neat little black circle in the center of the bright yellow cap for the master cylinder. That little hole just seemed to be crying out, "Drill hole here." I also had a set of XJ alloy rims on which two of the four had aftermarket metal valve stems. Hmmm ... Picked up a spare master cylinder cover. I removed the inner gasket and drilled out the center to a 7/16" diameter, which is the right size for the rubber gasket on the metal valve stem. Added a 7/16" flat washer on the outside and snugged it up. On the inside of the cover, there's a small channel across the top and down the side. That's for pressure equalization, but it would interfere with pressurizing the master so I filled that in with RTV sealant and struck it off flush. I cut the center out of the stock cover gasket (the center portion that expands into the reservoir if the fluid level drops). Done. I used it today, and it worked like a champ. My original plan was to connect a bicycle pump to it, but I couldn't find either of the two I should have here. So I took my spare air can and charged it to between 7 and 10 psi. (I think 10 psi is an upper limit, and I tried to not go above 7.) Once I had the air can ready, I put a length of clear tubing over the bleeder and into a bottle, cracked the bleeder about a quarter of a turn, and applied the fill nozzle to the valve stem of my new master cylinder cap. Just stood there for maybe a minute, watching the level drop, then I pulled off the air nozzle, closed the bleeder screw, and that wheel was done. Refill master and repeat for the other three wheels. "I love it when a plan comes together."* *Colonel Hannibal Smith, The A-Team Link to comment Share on other sites More sharing options...
Automan2164 Posted August 5, 2012 Share Posted August 5, 2012 That guy with all the AMC stuff we picked over had a dual reservior cap like the early XJ/MJ's with a t and a valve stem brazed inbetween the two domes of the cover... It's sitting in my shed. Haven't used it yet, but I should try it out... The Diesel could use some bleeding. Any pics of your setup? Rob Link to comment Share on other sites More sharing options...
Eagle Posted August 5, 2012 Author Share Posted August 5, 2012 Photos: That's all there is to it. I don't regard it as a "pressure bleeder," because there's no reservoir and you still have to refill the master after each wheel. It's more of a "pressure-assisted gravity bleed," but it worked very well and made my job a lot easier. I didn't know what to use for pressure. I talked to a friend who is a VW shop foreman. He said VW uses a pressure of one bar (one atmospheric pressure, or about 14.x psi) on their pressure bleeders. So we figured 10 psi should be safe for the plastic reservoir on the Jeeps, and I found that 7 psi gave me enough to move sufficient fluid to purge the air even after replacing the hard line from the master to the rear axle, AND the hard line across to the right rear wheel. Link to comment Share on other sites More sharing options...
neohic Posted August 8, 2012 Share Posted August 8, 2012 I've got a similar setup. When I changed out the MC on my '91 I took the cover from the old MC, drilled a hole, and welded an air fitting to it. Then I just ran a line from my compressor with a regulator in line. 7 psi worked for me as well. Yours looks cooler than mine though! Link to comment Share on other sites More sharing options...
Comanche County Posted August 9, 2012 Share Posted August 9, 2012 You guys are freaking smart. I learn something every time I log on. Link to comment Share on other sites More sharing options...
jpdriver1 Posted September 7, 2012 Share Posted September 7, 2012 That guy with all the AMC stuff we picked over had a dual reservior cap like the early XJ/MJ's with a t and a valve stem brazed inbetween the two domes of the cover... It's sitting in my shed. Haven't used it yet, but I should try it out... The Diesel could use some bleeding. Any pics of your setup? Rob Hey automan2164 -- how about a pic of your set up -- I've got an extra MC/cover -- would like to adapt the cover --- kevin Link to comment Share on other sites More sharing options...
HOrnbrod Posted September 7, 2012 Share Posted September 7, 2012 I have to try this Eagle, I likee. But I don't think it would bleed the load sensing lines well enough, or would it? Link to comment Share on other sites More sharing options...
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