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JK Write-UpsBulletin board forum regarding useful installation write-ups, budget fixes and homemade solutions for the Jeep JK Wrangler (Rubicon, Sahara, Unlimited and X).
The figures provide step-by-step on what I did to remove. If you're doing this, read all of the way through because at the end we figured out a little bit better access that would make some earlier steps easier.
The new part.
The old part.
Study the orientation of the part to help find the various connections. Note that the clutch pedal sensor electrical connection is butted against the fender well. You can disconnect it after loosening the master cylinder from the firewall.
Disconnect the brake fluid reservoir hydraulic line to the clutch master cylinder. Plug it to prevent leakage. I cut off a short piece of the old line I'd just disconnected and threaded a 1/4-20 bolt into it.
Use a screwdriver to pry out the clip that holds the hydraulic line to the slave cylinder in place.
The slave cylinder hydraulic line connection to the master cylinder is very tight. I had to pry it down, and it took a lot more pressure than I expected. Before doing it this way, note further down how I would learn later to get better access to this area through the inner fender liner.
This is what the disconnected slave cylinder hydraulic line looks like. Just ensure you aren't missing any of the specially shaped seal.
Pry the mechanical connection to the clutch pedal apart with a screwdriver.
This is what the stud that the mechanical connection goes to looks like. It's just a press fit, but does snap into place. You might want to put a little grease on it before reassembling.
In order to rotate the clutch master cylinder you'll have to make clearance for the connection to the brake fluid reservoir to rotate around--it bumps into the power brake booster. So, remove these four nuts behind the firewall. The nuts are captive--they will stay in place up there once the brake booster is loose. Because they are captive, you'll have to loosen each one a little bit, then move on to another one, keeping all within a few threads of each other on the stud. If one starts to get tight as you're unscrewing it, move on to another one and return to that one when you get the other ones about even with it. From under the hood, pull the booster forward to clear the holes for the studs, then push it to the side--only about 1/2" clearance is needed. Be careful to not put too much pressure on other hydraulic lines.
Using a pair of channel lock pliers, rotate the clutch master cylinder from under the dash in the direction shown. If you rotate it the other way, it's easy to break the stop tabs. But, the slave cylinder is keyed in place and will not be able to slide forward to remove--so turn it the correct direction.
Once the slave cylinder is rotated and pushed back, disconnect the clutch pedal position sensor electrical connector. This is actually connected to another adapter that is magnetically attached to the slave cylinder. If it comes apart there, just disconnect as shown above--your new part has that other adapter.
Partway through the job a friend came over and we were discussing how to make the task easier. I mentioned I'd considered pulling the fender, including the inner fender liner, but it was such a hassle and takes those special clips (which I have a few spares of). He said I could probably gain access without removing the entire fender, so we removed the plugs and bolt marked on this image.
That gave me this view, looking up from underneath as he pried out on the fender. From here it was easy to reconnect the hydraulic line to the slave cylinder, which is a very, VERY tight fit. You'd think if not fitted properly that the clip on the master cylinder would not slide into place, but such is not the case. It will slide into place and you'll have brake fluid squirting all over when you press the clutch pedal.
This is removal--install is basically the reverse. The torque value for the brake booster nuts is 18 ft-lbs.
After getting it all together you'll need to bleed the clutch hydraulic system. However, I inadvertently did not get the connection to the slave cylinder on there all the way, and it started squirting fluid around the engine bay. That effectively pre-bled the clutch master cylinder. And because I was careful to plug the brake fluid reservoir (where the clutch gets its fluid), I had no air in the lines up there. And the slave cylinder line was pointed up the entire time, so never drained out. Therefore, once I finally did get it all back together, I gave a few pedal pumps and almost full system pedal was restored. Enough to drive it. So I did, and the pedal is now feeling normal--bleeding from the slave cylinder was never necessary. Otherwise, you'll have to get under the Jeep and loosen the bleed valve on the slave cylinder and follow bleed procedures to remove any air from the system.
BTW, the reason I posted this on FB is because if you have a phone or tablet and get the album into the right display mode, you can just scroll up the instructions and images as you do the job. You can do the same here, but I think it's a bit neater on FB. The original album is here ...
would you recommend replacing the slave cylinder at the same time? I was told by a local mechanic that replacing both at the same time would be ideal.
The slave is external and is a very easy job. I don't know why you should replace it if it's good, but if you don't mind parting with the money for it, it will add about 10-15 minutes to the task (assuming that you'll bleed the system either way). If you do it, be particularly careful with the hydraulic line to the slave. There is a small "O-ring" on it that is highly specialized in shape. It falls off easily, and has a bounce factor somewhat higher than Flubber, LOL. Honest, be careful and be sure you don't mislay the O-ring or you'll end up buying the entire hydraulic line to get a new one (it's not sold separately anywhere that I could find).
Just curious but why exactly did you need to replace your master cylinder?
Hoped it would fix the creaky, sounds-like-plastic-breaking noise whenever my clutch pedal is pressed (engine off or on). It did not. Since the two parts in the system made of plastic are changed, I'm not worrying about that creak anymore.
Hoped it would fix the creaky, sounds-like-plastic-breaking noise whenever my clutch pedal is pressed (engine off or on). It did not. Since the two parts in the system made of plastic are changed, I'm not worrying about that creak anymore.
Didn't you say you didn't replace your slave cylinder? Pretty sure that noise your hearing is coming from the crappy plastic slave cylinder. I know because mine does the same thing
Didn't you say you didn't replace your slave cylinder? Pretty sure that noise your hearing is coming from the crappy plastic slave cylinder. I know because mine does the same thing
I had replaced the slave about six months earlier trying to stop noise. It didn't stop. Got tired of noise, which comes and goes, so tried to fix by replacing master. Since my transmission is coming out this week for an unrelated problem, I hope to fix it once and for all.
I did this last night took about 2 hours most of the time was struggling with the damn lines. Got rid of my petal squeak. Master cylinder was fine just really really loud
10-07-2014, 01:56 AM
JK Clutch Master Cylinder Replacement Procedure
