Clutch Master Cylinder replacement

[Av8ferg]

This past week, I went to get my Z ready to move to my new place from where it’s being stored,   I knew the clutch hydraulics was having an Issue, because the last time I went to see the car the pedal had no back pressure.  I assumed I got a either a leak or air in the system, so I bleed both the master and slave cylinder and it was totally unsuccessful.  I had replaced both the master and the slave about 18 months ago when I first started trying to get this car road worthy.  I think they are both made by Wagner? 
This will be the 3rd master I’ve installed.  The first I got from AutoZone and that one wouldn’t fit due to the rod being the wrong length.  I tried to cut it and then it was too short.  No biggie it was line $23.  Then I ordered one from RockAuto which is the one in there now (about the same price) ,  BTW, I found it to be difficult to install due to the limited space under the pedals, and having to hold the pedal, while compressing the road and holding a light all at the same time while inserting the clevis pin.  I remember saying to myself, “I hope I don’t have to do this again”.  Not the case...So, it appear the master is bad now,  it won’t transfer pressure to the slave and when I push the pedal with the cap off I can see a small boil of liquid come out of the reservoir.  
Well, this weekend, I decided I was going buy the real deal and ordered the Nabco master cylinder from a Nissan Dealership locally.   The lesson learned for me in this is, it’s almost always better to buy OEM, this isn’t a hard and fast rule but if I would have done it right the first time I would have saved time, money and a lot of inconvenience.  The new OEN master was $67 plus $4 tax and local pickup, being cheap doesn’t always pay...and sometimes it cost more,   Buy once.....cry once.  Lesson learned,  

[Zed Head]

Several of us have had new aftermarket parts fail soon after install.  The seals seem to get damaged because they don't clean the parts before they assemble them.  We recommend taking any new aftermarket part apart, cleaning the seals and bores, and reassembling before using.

I developed a trick on that clevis pin.  Tie a thread through the hole in the pin, then use a wire to thread the thread through the hole in the pedal.  Pull the wire through the hole, then the thread, and use the thread pull the pin up to the pedal.  Then you can use one finger or a screwdriver to do the final push through the pedal.  The thread is thin enough to make it through the hole beside the clevis pin.  I could not get my fingers up there even though a PO had created room with what looked a hammer and vise-grips in the past.

[Av8ferg]

Great advice. I was going to try a couple other techniques. Wish I would have gotten this advice earlier because that install wasn’t easy and I have a bum shoulder that made it extra hard. Thanks for the tip.


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[Captain Obvious]

So I don't have any additional advice to make the install any easier, but I was thinking about your clutch problem a little more since we talked.

I took a look at the exploded parts pics in the manual and I stick to the theory we discussed that there's something wrong with the valve that closes off the fluid reservoir when you push the pedal down. The valve is probably stuck open or the front seal is messed up. Either of those could occur maybe from leftover chips from the manufacturing process as ZH mentioned.

In any event, good luck with the replacement and I hope your shoulder holds up!     

Try knocking on the outside of the master a couple times with a plastic screwdriver first... Maybe (longshot) if the front valve is just stuck, you might be able to knock it into temporary working position.

[Dave WM]

Are you replacing the slave as well? a few weeks back I started having issues getting the proper feel on the clutch (and would grind if I tried to engage). I too did the lets bleed it, perhaps I goofed it last time I did a maintenance fluid replacement. I seemed better but a few weeks later started acting up. the Clutch would not disengage even when it was freshly blead until it was all the way to the floor. I bought the Nissan master and slave getting ready for the operation. about a week ago I noticed a drop of brake fluid on the bottom of the slave bellows. At that time I replaced just the slave (the master was newish but not OE from the PO). I was surprised by how much more throw the clutch fork was getting while bleeding, and now the clutch will be fully disengaged much earlier than ever before.

FYI if you order a new hose from Nissan it does NOT come with a copper washer. There was one on the slave I replaced so I assumed it was supposed to be there. the threads look to be the kind that need the washer to seal.

[Roberts280Z]

I like the thread idea.  I once managed to flip the clevis pin out of my grasp, and had it disappear behind the kick panel - twice.

[Av8ferg]

I like the thread idea.  I once managed to flip the clevis pin out of my grasp, and had it disappear behind the kick panel - twice.

That’s how all my projects work out...nut or screw somehow always finds the a wormhole the the next universe. I think it’s a curse I have but I can’t find my wallet most mornings either.


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[Av8ferg]

Dave, maybe I should replace the slave as well just to make sure I’m not stuck again or made a bad assumption with the master. I have to see if so can get an OEM one in time. I’m on a tight schedule. 4 post car lift will be ready for pickup tomorrow at the freight terminal. Then I have to build the lift.
I don’t think there is time between now and my next trip to get a new
OEM slave. Probably could get a aftermarket one by tomorrow. I think I’ll buy a cheap come-along at harbor freight I guess as a back up plan.
“Proper planning prevents wizz poor performance”


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[Dave WM]

Well its a ton easier to replace than the master that's for sure. Hardest part for me bleeding it. I tried the vacuum pump approach (no helper) that did not really work out well. With my helper it was done in just a few cycles. Again the diff in throw was what really amazed me.

I hope to be making my east coast trip in the coming months, are you going to be in NC? I need a few stops to stretch my legs, looking for some Z people to yak at.

I was hoping to make it to Mt Mitchell maybe keep going depending on how the trip goes. Looking at I think it was the 301 out of Florida, seems to be a nice non interstate way to go.

[Mark Maras]

 It's also a good idea to check the clevis and clevis pin for wear.

[Av8ferg]

Dave, yea I’ll be in and out all summer for work. Let me know.
So digging through my bins of parts that came with the car I found two old Clutch Master Cylinders. This car has gone few several over its life it seams.
I took some pics of them and I’ve come up with an idea for an easier install. You see that the shaft that connects to the pedal is easily removed with the a retaining collar. I can use the shaft in the car now and just take the new one off the new master. If there is sufficient room to get the collar on it would negate the Jiu-Jitsu maneuvering under the pedal. All I need to verify is the shaft length is correct. The Clovis pin is pretty new so that’s not going be be worn.
Option 2, would be to unscrew the shaft from the u-shaped bracket that goes around pedal. I could spin the entire assembly until it’s at the proper length and then bolt the master to the firewall. I think this was one of Captain Obvious’ idea.
See pics, bottom one is an OEM Nabco. Still have to remove one from the car.






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[Zed Head]

Another thing that I found that works on both the clutch and the brake is that you can use a pair of pliers to spin the rod without removing the clevis pin.  Just loosen the lock nut, grab the rod with the pliers and spin it a quarter turn at a time.  The end in the booster or clutch master is free to spin.  You can gauge proper tightness by how the clevis pin wiggles in the hole.  I just adjusted mine up until it was almost tight, to give maximum travel, and no pedal play.  Much simpler than taking measurements, taking the pin out, and spinning the clevis.