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Clutch Slave & Master Cylinder Replacement

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Old 04-28-2012 | 09:34 PM
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Originally Posted by BobbyT
Super write-up and pictures, Alex. I always enjoy your technical posts--extremely detailed and well-written.
Thanks Bobby, but I'm sorry to say it isn't a step-by-step DIY for the novice wrench.

But the pics and brief explanations give those about to replace those items a heads up as to what to expect before swinging a wrench.

Maybe I'll get to a more detailed step-by-step DIY one day. At the moment, p-car workshop is a good resource; although I've made a couple of additions and corrections there.
Old 04-28-2012 | 11:35 PM
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nice write up. I need to do this soon. my pedal is starting to hang up in the last little bit of travel
Old 10-27-2014 | 03:04 PM
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Anyone has an approximate cost of the parts? Thanks
Old 10-27-2014 | 03:19 PM
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Originally Posted by IXLR8
I bought my 993 with the annoying and well known "grawk" sound that most of us are familiar with when activating the clutch. Worse yet was the uneven, almost stepped action when engaging the clutch making smooth starts more difficult. A simple fix which did not alter my buying decision.

This past winter I finally got around to replacing the necessary parts. I chose to go with OEM Porsche parts sourced from Sunset.

Along with a new clutch hydraulic hose and a complete pedal assembly rebuild (cleaning, new pedal bushings and re-greasing), clutch action is whisper quiet and ultra smooth. A highly recommended DIY with results that will put a smile on your face.

Brake fluid used was ATE Super Blue and flushing/bleeding was performed with the aid of a Motive Products Power Bleeder, both sourced from Pelican Parts. I modified my Power Bleeder to make using it in the "dry method" easier.

Not a DIY set of instructions, but plenty of pics with some tips.
Edited to add: I guess I never updated this. I'm sorry to say but the "whisper quiet" aspect may have been the case in the garage after the parts were replaced, but once the car was back on the road after a few kilometers, the typical "grawk" returned. So as initially thought but hoped it was not, the pressure plate and/or clutch release bearing fork bushings and shaft are the only other possibilities. Which is one of the reasons why my 993 has been on the lift for a while now.
Old 10-27-2014 | 03:27 PM
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Originally Posted by David A
Anyone has an approximate cost of the parts? Thanks
Back in 2010, the clutch slave cylinder was $98 and the clutch master cylinder was $88 from Sunset. The clutch pedal lever was $71.

In 2012: $13.62 for two clutch pedal bushings and $14.56 for two brake pedal bushings.

Check the Auto Atlanta site for current list prices.
Old 10-27-2014 | 04:16 PM
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Originally Posted by IXLR8
Edited to add: I guess I never updated this. I'm sorry to say but the "whisper quiet" aspect may have been the case in the garage after the parts were replaced, but once the car was back on the road after a few kilometers, the typical "grawk" returned. So as initially thought but hoped it was not, the pressure plate and/or clutch release bearing fork bushings and shaft are the only other possibilities. Which is one of the reasons why my 993 has been on the lift for a while now.
Yah, I know the noise - and I am not sure where exactly it comes from, or perhaps it even varies. I thought it was the pin in the clutch fork, but I lubed that up, and the same thing, quiet initially then makes noise again. The needle bearings on the clutch fork should be quiet, so lets think what moves inside the bell housing:

- the plastic bushings on the clutch fork to clutch fork shaft
- the roller bearings on the clutch fork shaft
- the metal to metal interface between the clutch fork and the throwout bearing
- the clutch tube where the throwout bearing rides along
- the pivots on the pressure plate spring

To me, the noise sounds higher up on the transmission so I am not sure where it comes from, but it sure feels like clutch fork related.

Looking at the typical wear points when doing a clutch, the plastic bushings on the clutch fork typically show little wear (likely because the clutch fork shaft is on roller bearings) so I doubt if that is it. My feeling is its either the pin on the top of the clutch fork (and when used, the pressure displaces the grease and it squeaks again) or the forks on the through bearing ...

Cheers,

Mike
Old 10-27-2014 | 05:30 PM
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Mike, my Honda CR-V was making the same noise when it got into the 12th or 13th year. I even lubed the pivot ball the release fork ran up against and the clutch master and slave cylinders were relatively new. I suspect the same issue; the pressure plate.
Old 10-27-2014 | 06:50 PM
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It could be the sliding of the pressure plate on its glide pins - or just like me, the 993's are just getting creaky!!
Old 10-27-2014 | 06:51 PM
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What about that first half inch of pedal travel where there is virtually no resistance. Anyone has a way to get rid of it?
Old 05-06-2015 | 10:14 PM
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Originally Posted by ehanauer
After my 993 passed its PPI, I was driving it back to the dealer when the clutch pedal went all the way to the floor and stayed there. Pumping it got it to work, and the dealer flushed the system. I thought maybe the master or slave cylinder needed replacing, but some 2000 miles later the clutch continues to work smoothly.
What in the world could cause that?

ChuckJ
Old 05-06-2015 | 11:48 PM
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When bleeding the clutch slave, for some reason (probably because the fluid does not circulate) it bleeds some very ugly/sludge-like fluid, and if it get too nasty, I'm thinking it could cause the slave to stick, and the pedal to stay on the floor? My theory...

Personally, I have never had my pedal go to the floor, except when I absent-mindedly introduced air into the system; and I wasn't on the road at the time. Actually, I don't see how the pedal dropping to the floor is feasible with a properly working clutch at one moment, and then BAM! Pedal to the floor. This being said, I'll stick (no pun intended) with my theory on the nasty sludge-like fluid that initially bled from the slave.

I now bleed the slave every other year when I do a brake fluid refresh on all 4 corners; with the fifth corner being the clutch slave. The logic is, if you have the car on stands and wheels off, and you're bleeding the brakes; might as well hit the clutch slave while you're up there.
Doing a slave bleed every other year does not produce the ugly fluid that I initially saw.

If you track the car, them more often I would think. Bi-annually, maybe? Beginning and again mid-season.

P.S.
Alex, am I hallucinating, or is the link to your DIY now gone?

TIA,
Paul
Old 05-06-2015 | 11:52 PM
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^ Don't forget that the boost spring preload can be adjusted.

Springs do get tired due to repeated action over 20 years.
Old 05-07-2015 | 12:07 AM
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Originally Posted by axl911
What about that first half inch of pedal travel where there is virtually no resistance. Anyone has a way to get rid of it?
If you did, then you would likely be preloading the throw out bearing too much - there is already pressure there which people who have changed out a slave cylinder can attest to. Why would you need to be rid of it other than perhaps your engagement point is too low?

Cheers,

Mike
Old 05-07-2015 | 09:58 AM
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Originally Posted by IXLR8
^ Don't forget that the boost spring preload can be adjusted.

Springs do get tired due to repeated action over 20 years.
Are you talking about the spring at the bottom of the pedal?

ChuckJ
Old 05-07-2015 | 01:48 PM
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I can understand metal fatigue and how a spring can decay with use, but I have never seen one so bad that it impacts the feel of the pedal - but then again, it might be doing that and i just never thought that could be a problem area!

Yes, its the spring assist in the pedal cluster that he is talking about.

Cheers,

Mike



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