Troubleshooting failing clutch in 29176 280Z

[PhilbertZ]

A friend at work has a 76 280Z that he got from his dad last year (Original owner) and the car's been in great mechanical shape but is now showing its age. Recently, he asked me about this condisiton in his clutch; I dropped by after work to check it out (thought it was the master cyclinder leaking or slave cylinder, since mine went on the 280ZX I have a couple years ago). After checking out the car in person, I'm stumped.

 

Here are the symptoms:

(no leaks at master, slave cylinders, and the fluid level is within normal operating levels)

- the clutch pedal has very little resistance when pressed. Resistance is constant but very light (think Honda clutch but even lighter!)

- The slave cylinder is moving the clutch fork when depressed (I confirmed this lying on the ground while he depressed the clutch); it moved the piston about half an inch in/out when operating.

- He tells me that, when driving, he'll put the clutch all the way in, shift, and then the gear engages pretty much as SOON as he starts releasing the clutch (before, it would release an inch or so, then start to engage). He says this dleta between release and engagement has gotten smaller (worse) in recent attempts to drive it.

 

 

This all happened within short time frame. I feel like it's not a fluid/pressure/cylinder issue, since those things are not leaking and the slave is doing it's job (but is 1/2" travel normal?).

 

Does this mean the clutch is going? Do the fail this quickly? I had one die on me years ago in my Corolla, but it would start slipping in the high gears, then "zzzzing" and the gear no longer works. This is different and that's why I'm stumped.

 

Any ideas/troubleshooting he/I can try before he has this thing towed to his mechanic?

 

Thanks in advance!

 

Phil

[fastzcars]

It sounds like the master cylinder has developed an internal leak. Here's a link that well help explain the functions of the hydraulics of the clutch. http://www.google.com/imgres?imgurl=http://www.4g63turbo.com/tech/images/clutch-adjustment/clutch-01.jpg&imgrefurl=http://www.4g63turbo.com/tech/eclipse-clutch-adjustment.html&usg=__T06O_FADpu4aKNDx7m-bnzHGdWA=&h=480&w=640&sz=50&hl=en&start=44&itbs=1&tbnid=UAUulX_mkiKSVM:&tbnh=103&tbnw=137&prev=/images%3Fq%3Dclutch%2Bmaster%2Bcylinder%26start%3D40%26hl%3Den%26client%3Dfirefox-a%26sa%3DN%26rls%3Dorg.mozilla:en-US:official%26gbv%3D2%26ndsp%3D20%26tbs%3Disch:1

Edited June 7, 2010 by fastzcars

[FlatBlack]

I'd replace the slave cylinder. It takes about 5 minutes to change, and they are only $17 at AutoZone.

 

I had to replace the slave on both my S30 and Z31.

[PhilbertZ]

Thanks guys for chiming in so soon.

 

So, the travel on the slave cylinder - is that shorter than normal - is that why you guys think it's still the hydraulics and not the clutch itself?

 

I remember when my clutch went out, the cluthc pedal feel never changed - it was all isolated to the transmission.

[Flexicoker]

I had a similar thing happen on my 240Z. Turns out the slave cylinder was leaking, it was all perfectly contained by the boot, so I couldn't see the leak. When I pulled the boot back, and bunch of fluid came squirting out. Its possible that he added fluid to the reservoir lately and thats why its at the normal level.

 

Other things to check:

The little pin where the clutch master attaches to the pedal

clutch fork might be cracked or broken

 

If its none of those its got to be the clutch itself or the throwout bearing. good luck!

[NewZed]

I had a similar thing happen on my 240Z. Turns out the slave cylinder was leaking, it was all perfectly contained by the boot, so I couldn't see the leak. When I pulled the boot back, and bunch of fluid came squirting out. Its possible that he added fluid to the reservoir lately and thats why its at the normal level.

 

Other things to check:

The little pin where the clutch master attaches to the pedal

clutch fork might be cracked or broken

 

If its none of those its got to be the clutch itself or the throwout bearing. good luck!

 

I also had this happen, just this weekend. All of the leaking fluid, quite a bit, from the slave was contained in the rubber boot, just a light film on the outside to give a clue that there was a leak. Mine had the same symptoms, the clutch engaged right off the floor, but the clutch fork moved as soon as the pedal was moved, making it hard to figure out what was wrong.

 

My cylinder was only 9 months old though. But I put it on a car that had sat for a while and there was, apparently, lots of old crud in the lines (the fluid had turned almost black since I put it on). I think that after a few fast runs through the gears in the days before, some of the debris had lodged under the rubber seal, letting it leak. It had been working fine up until then. I took mine apart, buffed the inside of the cylinder with some Scothbrite (the rubber seal on the piston looked in good shape but there were some corrosion marks in the cylinder), put it back together and it worked fine again. Took it for a long drive Sunday and it still works. It may leak out again, but I know the symptoms now.

 

Pop the rubber boot off and see what's in there. Watch your eyes though, it will spray.

[PhilbertZ]

I also had this happen, just this weekend. All of the leaking fluid, quite a bit, from the slave was contained in the rubber boot, just a light film on the outside to give a clue that there was a leak. Mine had the same symptoms, the clutch engaged right off the floor, but the clutch fork moved as soon as the pedal was moved, making it hard to figure out what was wrong.

 

My cylinder was only 9 months old though. But I put it on a car that had sat for a while and there was, apparently, lots of old crud in the lines (the fluid had turned almost black since I put it on). I think that after a few fast runs through the gears in the days before, some of the debris had lodged under the rubber seal, letting it leak. It had been working fine up until then. I took mine apart, buffed the inside of the cylinder with some Scothbrite (the rubber seal on the piston looked in good shape but there were some corrosion marks in the cylinder), put it back together and it worked fine again. Took it for a long drive Sunday and it still works. It may leak out again, but I know the symptoms now.

 

Pop the rubber boot off and see what's in there. Watch your eyes though, it will spray.

 

 

Thanks everyone!

 

Looks like he's going to replace both cylinders, and I'll do the work for him, since I've done the master before on my Z. I'll let you know how it turns out.

 

Cheers,

 

Phil

[PhilbertZ]

Thanks everyone for chiming in here on this.

 

He bought a master and slave cylinder and I did the job in a couple hours today at his place. When we took the rubber booth off the slave, black fluid went everywhere, as was stated here....so it seems like that was the culprit.

 

Replaced both cylinders, flushed the system and bled it (lots of dark crap came out!), and it now shifts just fine and dandy.

 

The only issue now is that there is pedal play in the clutch - it seems that there is a lot of play within the hole in the clutch pedal where the master cylinder shaft attaches with the bolt and cotter pin. The pedal just goes in about an inch before the master cylinder starts to engage. I adjusted the stopper stud/nut on the opposite side of the clutch pedal, but I maxed it out and there's still some play. Not a terrible thing - just not "perfect"

 

I really like this car. He's going to give it to his 16 year old soon...need to convince him to trade me for my S130

 

 

Thanks again guys!