gjones1735

Hi All,


Like many of you, I've dealt with some clutch pedal problems on my 1995 993. The clutch pedal sticks a bit, it hangs up after some time on the track or just a hard day around town, and it always feels a bit "notchy". Not terrible and very much like other 993’s I’ve driven but no where near as light and smooth as the clutch on my wife’s new Mini Cooper or a friends Toyota.

For about three months now I've been messing with the clutch hydraulics trying to figure out what causes this. Going through various DIY's, checking every Rennlist posting I could find on the subject, and testing out some theories of my own, I feel I've now solved the problem. At least the clutch has worked perfectly now for a few weeks without any of its old problems. I think I also know why some owners still have clutch pedal problems after taking the car to a dealer or mechanic. I put this post together so everything related to clutch hydraulics would be in one place and a lot of the questions out there would be answered.

In the next few paragraphs I'll list out what seems to work, and several tips and techniques to smooth out the pedal. It's somewhat detailed and long but I wish I knew this stuff when I started out on this project. Also, this is a project that really lends itself to being a DIY as it’s mostly labor, requires lots of driving to settle everything in, and final adjustments are based on personal feel.

First off, the parts are not that expensive and the work is not that complicated. It's a PITA and time consuming but not overly difficult. Because of this, if you really want to get the hydraulics working perfectly just go ahead and do everything at the same time. By everything I mean replace the Clutch Master Cylinder, Clutch Slave Cylinder, Slave Cylinder Hose, and Clutch Kinematic Lever. Also, clean and lube the complete pedal cluster and bleed the clutch hydraulics a minimum of two times with at least a week of driving in between the first and second bleeding.

The parts you need and what I paid for them so you can get a feel for the costs…

Clutch Master Cylinder -- part # 993.423.171.00.M33 Price $78.00
Clutch Kinematic Lever -- part # 993.423.519.03 Price $86.50
Clutch Slave Cylinder -- part # 950.116.237.12.M33 Price $89.50
Clutch Slave Cylinder Hose -- part # 964.423.477.00.M33 Price $31.75
Two Liters of your favorite brake fluid Price $24.00

Total parts cost $309.75


Now that we know the total costs are around $310 plus shipping, here are links to the four excellent DIY's that lay out the work involved…

Removing the floorboard: http://p-car.com/diy/pedal/index.html

Replacing the Master Cylinder and Kinematic Lever: http://p-car.com/diy/pedal/clutchlever.html

Replacing the Clutch Slave Cylinder and hose: http://p-car.com/diy/cscr/

Bleeding the Slave Cylinder: http://p-car.com/diy/slave/index.html


The DIY’s are EXCELLENT! Here are a few very small tips to help make this whole thing go smoothly…


Removing the floorboard: http://p-car.com/diy/pedal/index.html

1. To get at the last floorboard screw that’s behind the gas pedal, spin the section of threaded height adjustment tube above the lock nut on the gas pedal counter clockwise until it separates. You may then flop the gas pedal forward onto the floor and access the last screw. This is the easy way to do it.


Replacing the Master Cylinder and Kinematic Lever: http://p-car.com/diy/pedal/clutchlever.html

1. I didn’t use a vice to hold the pedal cluster. I just screwed it down to my workbench.

2. Use a drift that fits the hole in the white plastic spring tension body pretty snugly. The white plastic is soft and you could split it if there is too much play.

3. The pressure you exert remounting the cruise control micro switch can bend the metal flange it sits on – re-bend with your fingers to line up the micro switch with the lever arm.

4. Clean and lube everything before you re-install it in the car.


Replacing the Clutch Slave Cylinder and hose: http://p-car.com/diy/cscr/

1. You MUST remove the heater vent hose to do this job – it’s just so much easier.

2. I didn’t have any problem with the slave cylinder sliding into the socket of the pressure plate but check just to make sure! Put a little grease on the tip of the slave cylinder so it’s nice and smooth in the pressure plate socket.


Bleeding the Slave Cylinder: http://p-car.com/diy/slave/index.html

1. Be very careful with the bleed screw on the slave cylinder. It can strip even using the correct 7mm 12 point wrench.

2. I used a Motive power bleeder. For the initial bleeding of the clutch hydraulics, it seemed to work better at 18 – 22 PSI rather than the 12 – 15 PSI I do the brakes at. Use lots of fluid.


Now for the important stuff!!! Repeat Important!!!

Once everything is working properly, drive the car a lot. It may still be slightly notchy and even hang up a bit. Once you’ve driven the car for a week, bleed half a pint or so of fluid through the slave cylinder. There might be a couple tiny bubbles. Also, it may have a slightly black tinge to it – I think this is from the insides of all the new parts you just added. Bleed until the fluid is clear. Important! This is the step that eliminates the final “notchiness” in the system.

Now that you’ve bled the system for the second time you can finally finish the job. Take the floorboard up again because you need to access the clutch servo spring tension adjustment bolt -- it’s the allen bolt in picture # 10 of the DIY detailing the clutch kinematic lever and master cylinder. The tension setting the bolt comes with from the factory is very high. I believe this is to overcome the poor design of the original Kinematic Lever. Now that you have the new Kinematic Lever and it’s not going to hang-up anymore you can reduce the spring tension a lot – I backed mine off a full four turns. This will dramatically lighten the clutch and give it a silky smooth feeling. Drive the car at different spring tension settings until you find one you like best. The clutch should now be light and smooth just like in any other modern car.

Note: In going through all the clutch threads on Rennlist it’s my belief that it’s these last two items that mess everyone up. The car must be driven for awhile, the system must be re-bled, and the tension bolt must be adjusted. I think this is also why we see complaints from people who have had this done professionally and aren’t particularly happy with the way their new clutch system works. It just takes too much time to go through all this at the dealer – it doesn’t get done – and the clutch is still “notchy”.

Note: I originally started all this by just bleeding my slave cylinder. This really helped! However it still wasn’t perfect and after a month or so the pedal started acting up again. I now believe that once the system starts acting up it’s best just to go ahead and replace everything.

Some pictures…



The work area




New Slave and slave hose




Remember the dab of grease on the tip of the slave cylinder pin




Installed. New hose is easy to see, new slave is mostly hidden.




The pedal cluster. Arrow pointing out new master cylinder.


Exhale and smile -- your clutch is now perfect. Happy downshifting.

George

stace

fantastic write up! thanks. I have exactly those symptoms with mine even after a good system bleed. maybe post this to pcarworkshop.com as well. sure appreciate the detail and great photos!!

Stealth 993

On a 1-10 how would you rate the pedal lever swap? My 95 doesn't stick, but it doesn't feel as good as the 97. I really hate working on pedal boxes, not room, & the door sill just gets you right in the ribs.

gjones1735

I spread the work out over a few days so it didn't seem that bad. I did end up with a bruise on my ribs. Just like you said, the bruise was from getting the hydraulic output line detached and then re-attached when getting the pedal cluster in and out. This is the most physically difficult part of the whole operation and the door frame is right there in the ribs. Be careful to get everything lined up properly so you don't cross-thread the output line into the master cylinder when putting the pedal cluster back in the car.

I guess if you look at the entire job it really is a PITA. Maybe a 7 or an 8. It's not a difficult technical a job though. ( compared to doing really technical stuff like valve train work ) The DIY's really help and you just go step by step. Since you are doing it yourself there's no time pressure.


George

IXLR8

Very well done and all info is in one package!

The clutch on my 95 feels slightly notchy, but I also have a squeak that I thought was coming from the pedal assembly till I hung my head out the open door and heard the noise coming from the rear.

The squeak is either coming from the:

• slave cylinder rod end due to a lack of lube (lets hope)
• pressure plate
• throw-out bearing lever bearings

BTW, notchy clutch action can also be caused by a dry input shaft/clutch disc spline and corrosion of the splines.

baron95993

WOW this looks great great job

nile13

My clutch seems OK other than it hangs and is super hard to press. The question is - will adjusting out the tension help at all (slave was blead not long ago). Also, would replacing the entire pedal assembly with a newer one ('96 or 97) cure the hanging issue?

e9stibi

Nice wire-up. Thanks!

gjones1735

Hi nile13,


You can certainly try reducing the required pedal force via the spring tension bolt -- counterclockwise to loosen. You can always change it back if the pedal starts hanging up more.

There might still be some issues depending on wether or not you have the updated kinematic lever arm installed in your pedal cluster. Porsche went through 4 kinematic lever arm designs before they finally got one that worked well -- the one you want is dark olive in color and the part # ends in 03. You don't need a complete new pedal cluster, maybe just the kinematic lever arm and maybe a new clutch master cylinder.

My advice would be to first try the spring tension bolt and see if that helps. Otherwise, look over my post and the DIY's and see if this is something you want to tackle.


Good luck,

George

nile13

George, thanks!

The reason i was thinking of the newer cluster is that they are easy to find used, probably easier to install and are probably cheaper too.

As far as tension screw, is it Allen and what size? Is it on the front or side of teh cluster? Does the wood plate have to be removed? I've seen the pics on Robin's page, but could not make it out.

1pcarnut

Looking at the picture of your pedal assembly, which one is the kinematic lever?

gjones1735

Hi Guys,


It's mutch easier to see the kinematic lever arm in the pictures associated with the DIY here...

http://p-car.com/diy/pedal/clutchlever.html

Yes, you have to remove the floorboard to access the allen screw -- I believe it's properly called the "clutch servo spring tension adjustment bolt". I forget the size exactly -- it's a metric size but it's close enough to a 5/32 SAE to use that if you have to. It's highlighted in pictures 5 and 10 in the same DIY.

http://p-car.com/diy/pedal/clutchlever.html


George

1pcarnut

Got it, thanks.

ABCar

George...THANK YOU! After slave bleed my clutch is very stiff, still. Your write up really filled in the blanks for me as I was about ready to replaced the clutch. Great picts too.

nile13

George, sorry to be so dense, but could you please arrow the adjustment screw (or its approximate location) on your pedal cluster photo (#4 in your first post)?

I see the close-up pics in the DIY, but need a "zoom out" to understand where the screw is.