Editing Forums/Z31P/z31-performance-upgrade-forums driveline-aa/Problem with Clutch slave cylinder

{{ForumImport
|op_user=Russ84na
|op_date=2009-07-13 12:25:44
|post_count=18
|archive_url=/Z31performance_archive/forum/z31-performance-upgrade-forums/driveline-aa/7901-problem-with-clutch-slave-cylinder.html
}}

'''Russ84na:''' <small>(2009-07-13 12:25:44)</small>

Background: T-5 transmission rebuilt to WC

New Fadanza flywheel

New clutch

Problem: Piston in the slave cylinder pushes out past the bore, tilts and won't slide back in.

The first time it happened I figured it was because I had the wrong rod in the slave. I had the shorter one for the later turbo's. I replaced it with the one I had in before.

Readjusted the peddle height and put a 3/4" spacer on the firewall to keep the peddle from going to far.

Happened again this weekend. the clutch felt fine when I loaded it on the trailer. First couple of runs the clutch felt like it was harder to push. Then 5th run, took off shifted into second, the clutch peddle stuck on the floor, had to coast all the way around track and into pits. Put it back in place, bleed the clutch and it worked fine.

The peddle now engages much closer to the floor.

Any ideas why the piston keeps pushing out of the cylinder?

Thanks

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'''zmech:''' <small>(2009-07-13 13:52:38)</small>

z

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'''vagabond:''' <small>(2009-07-13 18:13:49)</small>

I have an extra MC if you need one.

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'''Russ84na:''' <small>(2009-07-13 22:17:50)</small>

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That is kind of what I was thinking as the problem is intermittent.

Thanks

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'''Russ84na:''' <small>(2009-07-13 22:19:09)</small>

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Thanks for the offer, I am going to check into a rebuild kit first. If that doesn't work I'll get back with you.

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'''Russ84na:''' <small>(2009-07-16 22:53:29)</small>

I figured it had to be either the master, damper, line or the slave. So I replaced the master, line and slave and dumped the damper.

I have a feeling that the problem was in the damper, but won't know until I take it apart.

I just needed a way to hold the line mod in place. It took longer for the paint to dry than to make it up.

[attachment=1:1x4jo07n]clutch hydrulic replacement 009 (Medium).jpg[/attachment:1x4jo07n]

[attachment=0:1x4jo07n]clutch hydrulic replacement 007 (Medium).jpg[/attachment:1x4jo07n]

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'''zmech:''' <small>(2009-07-17 06:59:54)</small>

z

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'''Russ84na:''' <small>(2009-07-24 23:14:39)</small>

No sooner did I get the problem fixed in my race Z and the same damn thing happened to my street Z…Clutch went out completely over two day period.

For $45.00, a new master, slave and 280 line, dump the damper and we should be good to go. Fortunately it died on the lift.

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'''vagabond:''' <small>(2009-07-25 01:17:14)</small>

Well, good to know the problems were concurrent. Hit us back with the final prognosis.

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'''Russ84na:''' <small>(2009-07-31 22:08:18)</small>

Just got around to doing the repairs on the 2+2. Took off the damper and took it apart to use the back plate for a bracket. This time the damper is still good. It is the original damper and was in good shape. The race Z it was the damper that the rubber back had a split in it. When I shifted fast it would force brake fluid past it and then would not let it return quickly enough so the master would refill from the reservoir. Then the next shift would have too much fluid in the system and push the piston out of the slave.

This time it looks like it is the slave and master, both of which are original have just worn out.

Should have it off the lift tomorrow.

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'''Russ84na:''' <small>(2009-08-24 16:42:37)</small>

New problem. Can not get the the transmission into any gear.

Started to see the problem on the dyno two weeks ago and then big time yesterday. It cost me my best time of the day when I couldn't get into third and had to coast the last 5 seconds of the course.

When the car is cold, no problem shifts are easy. As the car heats up it gets harder to get into gear until it won't go in at all.

If you depress the peddle all the way no go, half way and it shifts fine.

The peddle has the correct setting from the floor. Actually put a 3/4" board on the firewall under peddle to act as a stop like the carpet would.

The free play is fine.

The only thing I can figure is that the fluid is overheating and expanding, partially pushing the slave cylinder out. Then when I push the clutch down it overextends the clutch, pushing the clutch fingers in to far and locking out the shift.

Any thoughts?

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'''zmech:''' <small>(2009-08-24 18:08:42)</small>

z

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'''vagabond:''' <small>(2009-08-24 18:32:55)</small>

I apologize if I missed it, but are you using Redline MT90? When was your last Flush/Fill?

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'''Russ84na:''' <small>(2009-08-24 18:34:49)</small>

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I am using the Exedy racing clutch, nothing special with the PP. Any suggestions as to how I can prevent it from doing this? Different fluid? Shield the slave and hose from the exhaust? Build up the spacer to prevent the peddle from going down to far?

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'''Russ84na:''' <small>(2009-08-24 18:37:45)</small>

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I am using regular ATF in the tranny, DOT 3 in the clutch. Flushed the system when I changed the master,slave and hose.

Transmission is a WC T-5 that was rebuilt last winter and just put in the car a couple of event ago.

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'''zmech:''' <small>(2009-08-24 18:41:50)</small>

z

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'''Russ84na:''' <small>(2009-08-24 18:48:19)</small>

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That is interesting. I didn't have any problem with the clutch until the slave piston started popping out of the bore and jambing so it would not return. That was fixed by replacing all the hydraulic components. Now if I only press in the clutch half way when it is hot it will work. I will try it cold and see if I can shift into gear with the peddle half way in. If that is the case then I will just use a stop to keep it over doing. I'll let you know.

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'''RocknTommy:''' <small>(2009-08-24 19:03:17)</small>

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When I installed my headers, I did use a thermal sleeving

material (I forget the name, 2000 degree something or other)

to cover my wires / lines and the slave.