Clutch slave cylinder adjustment

[mally002]

Hey guys,

I just replaced the clutch slave cylinder on the 71 240, I have done this before with no problems but this time I'm stumped. I but everything back on, did proper bleeding, topped off fluids and have great pedal action and resistance.........However, when I took it for a test drive, or tried to take it for a test drive I couldn't even get up the driveway. The engine would rev and the car would barely pull.

Is the slave cylinder just out of adjustment? The last one I did I just bolted back on, bleed and drove away.

Is it not letting the clutch go all the way out, how do I correct it.

Thanks,

PS......I just tried to fiddle with it some more, I did notice that I can start the car, put it in gear, let off the clutch and the car will still idle in gear.....it just starts to stall and then it's like the clutch is still depressed. I watched the slave and it goes back and forth and travels a good distance.....I have no clue.

Randy

Edited June 11, 2009 by mally002

[Arne]

Did you get the correct slave with the adjustable pushrod? If so, you need to adjust the clutch at both the pedal pushrod and the slave. (Applies to '70-72 only.) I've found that getting it just right is a bit fussy.

[Ttiger]

Did you put the return spring back on the slave (if it had one)?

Is there some play at the end of the clutch release lever, where it touches the end of the pushrod from the slave?

The early Z slave pushrod is adjustable (two 10mm open end wrenches). You need some play (about 2mm) so the the clutch can fully release when you take your foot off the pedal.

Speaking of the pedal, do you have some free play when the pedal is released?

[mally002]

That may help explain some of it, the last one I did was on a 73....no adjustment was needed.

Ok, Yes correct slave with adjustable nut and the spring is on. There is no play at all on the slave, I cant move it by hand at all forward or backward, it is very tight. But when my wife pushes in the clutch it goes back forth very well and the pedal is tight, no play.

On the slave should the nut go more toward the dust cover or the other way. I went through my haynes book and it was no help.

Any step by step instuctions would be appreaciated. Going back out to look at again, be right back.

Thanks,

Randy

[mally002]

Hellooooo, anyone..........still can't get it.....Help!

[Arne]

The nuts (use two 12mm wrenches, not 10mm) need to be closer to the slave body, effectively making the pushrod shorter. The manual says to back them way off, then tighten just to the point that all play is gone, then back off 1.5 turns. That will give the "proper" amount of free play at the clutch fork.

I've found that I prefer a bit more play at the fork than that, generally backing off 2-2.5 turns. But that is just my personal preference.

[mally002]

Thanks Arne,

Will give it a try tomorrow, I'm beat........

Thanks very much for the info, I'll post my progress....or lack of soon.

[mally002]

Ok,

I couldn't wait, I went back out there and made the adjustment. My pedal now feels like a wet rag, before it was very tight. I guess as you said Arne it's just going to take some tweeking. Maybe I went to far in, as I do have some play in the slave.........I'l do some more adjusting later.

After all this I sure wish I had bought that 4 post lift...........:stupid:

[Arne]

My pedal now feels like a wet rag....

Actually, both myself and Jim (a7dz) have commented about the crappy pedal feel we both have with currently available clutch hydraulic parts. We're not sure what part causes this, but Jim has owned his '70 for more than 30 years, and never had this limp pedal until he put on new cylinders last year. My car came to me with recently replaced cylinders, so the crappy pedal is all I've ever had since I got it.

Did you replace both cylinders, Randy? Or just the slave? What did the pedal feel like before the change? (Or before it failed, if that's what prompted the change?)

[bobc]

Tend to agree with Arne. This used to be an easy fix, but now it seems to be much more finicky. I have been advised by some knowledgeable Z mechanics and I think it even says so in the MSA catalog that you should change both the slave and master cylinder at the same time. Also, I've found what you use for fluid makes some difference in pedal feel too. Silicone tends to be the worst, especially after the car has been sitting for awhile. One mechanic told me that no matter how bad the fluid gets (black!), don't change it. He said I'd regret it if I did. And...he was right. I didn't listen and I ended up replacing the master cylinder twice and the slave once. For some reason, I never could get the first master to work right.

It's not easy to get all the air out of the clutch line either. First, I'd recommend that you bleed the line (either through vacuum, pressure, or the old have your wife pump the pedal for you and hold it down method) several times. If no improvement, then go to the master, which BTW doesn't have a bleed screw like the brake master. If you have a bleed kit, take the fitting that fits the master and after disconnecting the line from it insert the fitting and insert it in the master. Then bleed it like you would a brake cylinder. (make sure you always have fluid in the cup.) Pump it several times, and then refill the cup. Then take out the bleed fitting and reattach the clutch line quickly, before the fluid runs out. Then, bleed the whole system again at the slave. Oh, and don't forget to put a towel or absorbent cloth under the master cylinder so brake fluid does not get on your paint!

Also, if you keep backing the nut inward towards the slave cylinder (towards the front of the car), with the spring off you should reach a point where there is play in the clutch arm. Keep going in several more turns. Now with the clutch depressed, you shouldn't be able to shift gears at all. Then, put the spring back on and work the nut outward, towards the back of the car a couple of turns at a time. Have your wife push in the clutch and see if she can change gears. When she gets the gears to change, you should be able to go a couple of turns further. Take off the spring, and see if you have play in the arm. If not, back off 1 to 2 turns and see if you have play. You need to have some play or your throw out bearing will be in constant contact with your clutch plate. This will wear it out. The way you are describing the problem is that the gears shift, but the clutch is slipping. this sounds like you have too much adjustment and need to move the nut inward towards the cylinder.

One more thing. Randy don't you have two Z's? If you do, or can check out a friends. Look or measure the travel of the slave cylinder (the amount the rod moves out and in) on a working Z and then compare it to yours. You shouldn't have the same travel if you have air in your system.

Good luck!

Best,

Bob

Edited June 12, 2009 by bobc

[mally002]

Bob and Arne,

Thanks for the detailed information, I have to put in a few hours today but plan on working on the Z this afternoon.

The Master was done a few months ago, and I should have replaced the slave at the same time (but I had an extra master in the garage), anyway after it was replaced it shifted fine, the pedal was by no means "firm" but it was ok. Last week I was driving home after about a 40 mile drive, I had noticed when hitting red lights that it was getting harder to put in first gear, when I made the turn into the neighborhood I couldn't change to any gear and limped home in 2nd. There was no fluid in the master so I filled it up and re-checked. Everytime the clutch was pressed fluid was shooting out the slave. Ordered a new one and thus my story.

My 70 model is still at the shop getting the final touches.....thats another story, as we are two months behind, and of course over budget, but hey I will have a wonderful fully restored Z one day..........

I will start backing the nut toward the front of the car and re-bleed it again. Hopefully I'll have some good news before 5:00 pm.

Thanks again,

Randy

[mally002]

Arne, Bob and Tiger,

Thanks for the input, Mission Accomplished......

It just took a bit of tweeking on the slave, the pedal is still slightly spongy, but is shifting great. I really liked the feel of the pedal when the slave was adjusted more toward the rear of the car, but of course it didn't work there.

Many thanks,

Now somebody buy this car so I can finish #797.....

Randy