How to replace the Clutch system on a 997.1 2006 C4S This document intends to help the do-it-yourselfer in performing the delicate, dangerous and strenuous task of replacing the clutch system on a 2006 Porsche 997.1 C4S. It is obvious that this task is not easy, requires significant knowledge, extensive tools set and that the author cannot be held liable for anything that may happen to you. Basically, you are on your own and you do everything at your own risks. The above being said, replacing the clutch is something that can be done by an amateur with access to some tools, lift, transmission jack and engine holder. I would recommend to do it with a strong partner for moral and physical support. The psychological aspect of the task should not be underestimated. It took the author about 8 hours to perform the task (two times 4 hours). This was done in ideal conditions, using the shop of a mechanic friend, with access to a lift, transmission jack, engine support and all the tools required for the work. Most tools are readily available and should be in the amateur mechanic set. I will point to the ones that are special and necessary. I will also use some drawings from the Porsche Maintenance DVD, as they are extremely well done and explain the task to be completed in a much better way than a picture. I hope Porsche will not mind this use of their intellectual property for the advancement and knowledge of their customers and the Porsche community. Since this is a daunting task to perform, it is better to plan and spend some money upfront in order to get all the parts that will need to be replaced. Below is the list of parts I purchased from my local Porsche dealer in Cary, NC who was very helpful and generous with discounts. All parts are the original Porsche parts.

- Clutch kit (#1) 997-116-913-15 - Release Bearing (#4) 997-116-080-01 - Clutch bolts (x6) (#3) 999-073-458-01 - Clutch lever (#5) 997-116-712-01 - Ball Pin (#10) 997-116-716-01 - Clutch Seal (#8) 996-116-743-00 - Clutch Guide sleeve (#6) 996-116-087-01 - Dual-Mass Flywheel 997-114-012-01 - Flywheel bolts (x8) 999-073-092-02 - Slave clutch cylinder 997-116-237-04

The total of all the parts amounts for about $2100 including taxes.

a) Lifting the car and removing the underbody panels Before lifting the car, disconnect and insulate the ground of the battery and make sure that the trunk does not close completely. Stuff some rag or piece of wood to prevent it from closing. Then, lift the car safely and remove the 5 plastic covers from underneath starting from the rear of the car. This has been documented many times and I will not give any details besides the fact that you will need an electric wrench (manual will do but it is slow) with 10mm socket and a Torx 25/27. You should remove the central panel last. Panels can be cleaned is necessary and treated with 303 or other plastic protectant chemicals before re-assembly.

b) Removing transmission

Since we are dealing with a C4S model, there is an additional step that must be performed: the removal of the cardan shaft or front axle, leading to the visco-coupler for the front wheels. The removal of the central underbody panel gives perfect access to that cardan shaft.

a) You will need to have placed the wheels in gear (or hand brake) before attempting to unlock the three bolts of the shaft. Placing the wheels in gear is easily done by shifting from underneath the car, where the shifter cables terminate. Just rock left or right, the shifting plate.

b) Remove the little transversal support that holds the cooling lines (10 mm socket).

c) Using your engine support jack, place is under the round front end of the gear box and make sure that the entire transmission is well supported, without any stress upwards. We are going to remove the transmission vessel and for that, the gearbox must be securely held. The picture below shows what I mean in term of positioning the engine jack:

d) Remove the transmission vessel. You will need a 15 mm socket. Remove all 4 vertical nuts and the two horizontal bolts.

After removing the vessel, replace the two horizontal bolts to support your gearbox. Now is a good

time to clean the vessel for later re-assembly. Store carefully all the parts in plastic bags with labels.

The trick is to use the transmission Support to hold your gearbox/Engine set, while the vessel has been

removed.

e) You now have access to the three bolts of the cardan shaft. Use a 16 mm socket to remove them. Pry

the shaft from the rubber coupling device with a flat screwdriver or lever. Once that is done, gently pull towards the rear of the car, the entire cardan shaft. The shaft should uncouple from the rubber bellow and come easily out. Porsche recommends to be gentle and not exceed 20 degrees deflection on that cardan. Make sure the tip of the shaft does not get any dirt and protect the splines with a plastic bag and a rag.

The following pictures show the front coupler for the cardan shaft and the bellow covering the splines of the shaft. The rubber coupler between shaft and gearbox, stays with the cardan shaft.

There is no need to remove the rubber bellow.

f) Move to the rear of the car and remove the cross member bar. Again, use a 15 mm socket.

g) Carefully open the plastic holders and move the coolant lines to the side. Attach them with wire ties (see picture) so that access all around the gear box is free. Using 10 mm socket, remove the two holders from the gearbox.

h) Carefully remove the reverse light switch. This switch is located near the engine, on the top of the gearbox. You just have to pull gently on the lug (not the wires) and it should come lose.

i) Using a 13 mm socket, undo the electrical connection between the battery and the engine. Store the battery line on the side and out of the way. Using your 10 mm socket, remove the electrical conduit holder. There is a total of four 10 mm bolts to remove.

j) Using a flat large screwdriver, pop out the two shifter cables from the shifting plate. Then prying gently

on the two tabs as shown on the drawing, pull each cable out of the cable holder.

k) Using an Allen socket (I think it was 12 mm), unscrew the six Allen bolts on each rear axle. You can have a helper hold the wheels or use the hand brake. Store aside all bolts and holders. You may want to cut two pieces of rubber hose and slit it to make some protection for the transmission shaft on each side. This way, the shafts won’t be holding on the metal parts of the suspension.

l) Using a 13 mm socket remove the two bolts that hold the clutch slave cylinder. You may need some extensions and flexible couplers to get to the two bolts. There is a small plastic tab that holds the line, before the cylinder. Gently pry the line away from the tab (#2 on the picture). Once the bolts are removed, the slave cylinder will move out of its hole.

The rubber end of the slave cylinder was damaged and the plastic end was missing. The rod inside was lose and partially bent. This may have caused a mis-alignment of the lever and certainly contributed to the hardness of the clutch pedal. In my case, there was no doubt that I had to replace that part.

m) Okay, we are now in a position to move to the tough part of the job. All the preliminary steps were just like an appetizer to warm you up. At this stage, all hoses and electrical wires have been removed from the gearbox. The gearbox is free and held by the 8 bolts to the engine and the two long bolts in the front attached to the transmission support. You must now support the engine (right above the rear torsion bar – not on the oil pan) and place a transmission jack under the gearbox. In other words, we have two devices holding the engine and the gearbox respectively and independently. You need some help to do this work safely and successfully. First, remove the two long horizontal

bolts between the transmission support and the gearbox. Make sure nothing falls. The gearbox rests now on the jack. Make sure it is attached to it. Adjust the height so that the engine is properly aligned. This phase is really delicate and you should go slowly. The transmission can be lowered by 25 or 30 mm to help you gain access to the top bolt (#1) and you will need every little space you can get. The picture below shows the gearbox, completely stripped and ready to be uncoupled from the engine. The picture below is misleading: what you see is not the transmission jack but the engine jack. The Transmission jack will be brought up later, when it is time to un-couple the gearbox from the engine.

n) Remove the transmission support nuts (15 mm socket). That support is a royal pain in the arse and you will not be able to remove it until the gearbox is almost out of the way. Really crazy design and a nightmare to handle. Make sure to not damage the large coolant line on the driver side.

o) I decided to attack bolt number 1 first. Once you do that one, then your confidence level increases dramatically and you can picture yourself driving your favorite car with its new clutch. To get to bolt #1, you need an incredibly long extension (preferably 1/2 inch) of about 33 inches long. All bolts between the engine and the gearbox can be undone with a 16 mm socket with one exception for #4 which is a triple square or ZXN (I forgot the size…maybe 12). Below is a picture of the long bar and the numbered bolts

You will need one person to hold the 16 mm socket in place while you or another person unscrew the various bolts. Again, you need help to do that job and it is folly and unsafe to pretend to do it yourself. Once you remove a bolt, place it carefully in a marked plastic bag or use a piece of cardboard as shown on the picture. Note that #5 has a nut behind the engine flange.

p) Move the transmission out downwards and towards the front of the car by lowering the transmission jack step by step. Make sure that the engine remains in its original position by controlling the height with the engine support or engine jack.

WARNING: The gearbox is extremely heavy and two to three people are necessary to hold it safely.

q) The transmission support can now be removed out of the way. Thanks God!

Get yourself some refreshments and take a break. You deserve it.

3) Removing the Clutch

To remove the clutch, Porsche suggests the use of a special tool 9538/1. You may find similar tool in specialty shops. I

did not use any special tool and instead used a bolt and a small pry bar inserted in the teeth of the flywheel to prevent the rotation of the engine (that was for the re-assembly).

I used an impact wrench to remove the clutch and therefore, there was no need to hold the flywheel. Here, since we are changing the parts, there is no special care for the old clutch. Just remove all 6 bolts (#5) and discard pressure plate and

disk.

This picture shows the engine jack positioned right behind the clutch housing, the two transmission shafts, the old clutch

slave cylinder hanging, and the defunct clutch with its pressure plate in plain view.

Here is a clear view of the old flywheel. Note some discolorations all around its periphery. With my finger, I could feel

some tiny grooves on the surface of it. Despite the high price ($1K), I decided at this stage to bite the bullet and get a new flywheel. It basically doubles the cost of the repair but it is a good insurance for the future of the car as I intend to keep

that 997 as long as I can afford it. The picture below shows the new flywheel and the old one (after it spent a rainy night

outside, even though it was protected from the water). That cast iron is a sucker for moisture. The new flywheel is shiny,

soft, very smooth and perfectly balanced. It is worth changing it, in that specific case.

The symptoms of my failing clutch could not be clearly identified. I believe it was a mixture of the following:

- Failing pressure plate due to thermal exhaustion and aging (I live in NC and the summer can reach 100 degrees

for many months).

- Slave cylinder rod bent and pushing slightly on the side of the clutch arm.

- Disk was used but apparently fine and there was little dust inside the clutch housing. - Ball support was shot on the other side of the lever, causing the pedal to be hard and pushing the disk slightly out

of alignment.

- Discoloration on the flywheel indicating some abuse of the clutch by the former owner of the car and perhaps by

me, too.

- Poor quality of the original parts.

It is hard to finger point to a specific component and I think it was more the sum of multiple things wearing out and

failing.

The following picture shows what is behind the flywheel. The back of the engine was very clean and after blowing most

of the clutch dust, it revealed a very clean main crankshaft seal. I had originally ordered the main seal but somehow the

dealer provided me with the wrong seal and I decided to not replace it. I do not have the tool to insert the new seal

(removing is easy) and after careful examination, my friend and I decided to not touch it. The picture also shows the starter that I have replaced as well as the famous and much talked about IMS, below the crankshaft seal.

4) Installing the Flywheel The picture below, shows the new flywheel installed and properly torqued. You must use new Flywheel bolts and blue

Loctite on the thread. There is a dowel pin on the crankshaft and that pin must be inserted into the flywheel. The flywheel

is rather heavy and positioning it is not so easy. In addition, you are holding a grand ($) with your arm, and any mistake or

mishap will mean that you need to get another flywheel from your favorite dealer. So take your time and be careful.

The recommended torque for the flywheel bolts is 19 ftlb. The eight bolts must be tightened very carefully and in a

diagonally opposed way, as you do for torqueing a wheel. Once I reached the prescribed torque, I marked each bolt at

8:00 and then turn them another 120 degrees, bringing the mark to 12:00 o’clock and stretching the aluminum bolts.

Do not forget to clean carefully the surface of the flywheel with brake cleaner or acetone to remove any grease from your

fingers. On the left of the flywheel (position of the bolt #4), you can see a stainless steel bolt inserted in the crankcase. This bolt is used to provide a rest for the little pry bar and help maintain the flywheel still, during the torqueing phase.

Again, I strongly recommend doing this job with two persons, one holding while the other focuses on the torque wrench.

5) Installing the Clutch Before installing the clutch, you need to get the centering tool. There are many options:

- The plastic tool sold by Pelican Parts for the 996 (about $10).

- The official tool sold by Porsche and coming from Germany (2 weeks - $105) - The generic tool that you can find at Snap-on or other serious tool shop.

I strongly recommend the generic tool (small size) as it fits perfectly as we will see. Below is a picture of that tool:

That generic tool fits tightly into the bearing of the flywheel and slide with no play into the clutch disk. Having a properly aligned clutch is paramount to assembling back the gearbox to the engine.

- Insert the centering tool into the flywheel.

- Clean carefully the back of the pressure plate with brake cleaner or acetone.

- Wipe gently the disk with a clean rag soaked with acetone or brake cleaner fluid.

- Insert the disk on the centering tool. - Position the pressure plate and install two diagonally opposed bolts. Do not tighten them.

- Put a drop of Loctite on the other clutch bolts and hand tight them.

- Remove the first two bolts, apply Loctite and re-insert by hand.

- Now, very carefully, very progressively, and diagonally opposed, start tightening the six pressure plate bolts one

at a time. Bring the pressure plate every time closer to the flywheel while checking that the centering tool slide

easily in and out without friction or play. This phase will take some time but is critical for the good working

condition of the clutch and for aligning the gearbox with the engine. Finally, torque the bolts at 17 ftlb. - Remove the centering tool. It must slide out as if it was coated with butter…..

- Remove any bolt or stopping device that was used to hold the flywheel.

At this stage, we have to prepare the other end of the transmission on the gearbox side as shown in the picture below:

Since all the parts were damaged or used, I decided to replace everything: The guide sleeve ($38), the ball ($10), the rubber grommet, the lever ($30), the clip and of course the release bearing ($25). Use high pressure grease (red) to

lubricate all the parts. Here is the detail:

- Torque the guide sleeve bolts at 18 ftlb.

- Grease the splines of the transmission input shaft with high pressure grease.

- Grease gently the ball and the inside of the grommet/clutch seal.

- Fit release lever and release bearing. They simply clip into each other.

- Clip the release lever onto the ball. Now the lever can only travel front and back.

- Verify that everything moves smoothly and linearly with no friction and in silence.

6) Replacing the Clutch Slave cylinder

At this point and before re-installing the gearbox in the car, I decided to change the Clutch slave cylinder. This is something that could be done later on, but I find it so much easier when there is space to operate, without the bulky

gearbox in the middle.

With a helper, grab the old slave cylinder while you or your buddy unscrew the hydraulic line from it. Use a special open wrench to do that operation (I cannot remember if it was 11 mm or 12 mm). Of course, fluid will drain and placing a plug

on the line will help.

Quickly reconnect the new Slave cylinder and torque it with the help of your friend or buddy mechanic. Make sure that

the cylinder has the same orientation as it had before, flat with the coils and pointing in the right direction.

Changing the cylinder at this stage, helps in many ways. First you will have to bleed the circuit no matter what. Secondly,

the cylinder being full of air will not present any resistance when you insert it into the clutch housing to bolt it back on.

Leave it on the side and out of the way for now. We’ll get back to it, after re-attaching the gearbox to the engine.

7) Installing the Transmission/Gearbox That is the crux of the mission! And the use of the generic centering tool as opposed to the plastic junk usually sold will

make the whole difference. This phase is not easy and if you can gather 2 people around you, it will help immensely.

- Lubricate slightly the splines of the shaft. Make sure splines are perfectly clean.

- If you mount the same gearbox, no need to check anything else. Otherwise, make sure that the dowels on the

crankcase match the gearbox sleeves.

- Slowly place the gearbox under the car, using the transmission jack. Hold it securely with one or two people.

- The trick is to insert the shaft/splines as much as possible along the axle of the engine and clutch mechanism.

- One person should push on the back of the gearbox, after putting it in gear and rotate slowly the front cardan shaft

output. That helps aligning the splines into the disk.

- The other teammates should try to position the gearbox and insert the dowels.

I have to say that we manage to couple the gearbox to the engine in about 10 minutes, thanks to the perfect alignment

given by the generic tool and the right orientation of the axle gearbox/engine.

A couple of times, we were short of ½ inch and this had to do with the tip of the spline/shaft not being able to get into the

bearing of the flywheel. A slight dab of grease on the tip of the shaft remedied the situation immediately. Lubrication is

paramount for this kind of penetration, as we all know so well…..

Once the gearbox clicks in place with the engine, quickly grab a bolt (I used #4) and screw it in its respective location.

The dowels are holding the gearbox and that bolt stifles the gearbox from any attempts to go away.

We then moved to Bolt #1, using the super-long bar with a 16 mm socket. Bolt #1 was torqued to 63 ftlb. Whew!!!

Finish installing the remaining bolts and torque them appropriately (see below).

Transmission/engine Connection Hexagon-head bolt no. 1 in figure, M12 x 70 Tightening Torque 85 (63 ftlb.) Nm

Transmission/engine Connection Hexagon-head bolt no. 2 in figure, M12 x 100 Tightening Torque 85 (63 ftlb.) Nm

Transmission/engine connection Hexagon-head bolt no. 3 in figure, M12 x 100 Tightening torque 85 (63 ftlb.) Nm

Transmission/engine Connection Internal screw no. 4 in figure, M10 x 50 Tightening Torque 46 (34 ftlb.) Nm

Transmission/engine Connection Hexagon-head bolt no. 5 in figure, M10 x 50 Tightening Torque 46 (34 ftlb.) Nm

Transmission/engine Connection Hexagon-head bolt no. 6 in figure, M12 x 50 Tightening Torque 85 (63 ftlb.) Nm

Transmission/engine Connection Hexagon-head bolt no. 7 in figure, M12 x 70 Tightening Torque 85 (63 ftlb.) Nm

Transmission/engine Connection Hexagon-head bolt no. 8 in figure, M12 x 70 Tightening Torque 85 (63 ftlb.) Nm

At this point the gearboxes is still pointing to the ground (slightly of course, not completely), still supported by the

transmission jack and a few things must happen:

- Clean up all cables (shifters) out of the way and make sure that they can be connected. You do not want to end up

with stuff stuck between the chassis and the gearbox.

- Re-attach the clutch slave cylinder. Since the cylinder is full of air, it is easy to compress it and install the two

bolts (13 mm). Put a dab of grease between the plastic pusher and the clutch lever. Use a pin to align the first hole

in place and hold the cylinder while you tighten the first 13 mm bolt (17 ftlb.). Then do the other bolt. Do not

forget to clip the line in place. Bleeding will be done later.

- Insert above the gearbox, the infamous transmission support bracket. This part is insane and you need to twist in

all directions until you can find a way to line up the holes with the bolts on the chassis. Very important: make sure

that the shifter cables are routed correctly above that support.

- Torque the transmission support bolts to the chassis to 48 ftlb.

- Slowly raise the gearbox so that the horizontal 15mm long bolts can be used to hold the gearbox to the

transmission support. Install the two bolts and tighten the nuts by hand. You will want to check that nothing got

crushed between the tunnel of the chassis and the gearbox, during that process.

- Now, you can lower the car, after making sure that transmission jack, and engine support jack have been removed

from underneath.

8) Bleeding the clutch cylinder

With your car still on the lift but lowered enough, prepare what is necessary to bleed the clutch cylinder. I use the pressure

tank filled with blue fluid and lots of rags around the tank, to protect the paint. One helper will go inside and seat in the

driver seat while the second mechanic will go under the car to bleed the system.

Raise the vehicle again, so that you can work comfortably from underneath. Make sure that transmission shafts are out of

the way and shifter cables are out of the way. We have not re-attached any of these yet, and this is intentional.

Bleeding is done with the pressure tank under pressure and the action of the clutch pedal. The pedal will refuse to go up

because of the lack of pressure in the circuit and because of this silly device installed by Porsche that helps you depress

the pedal. With your hand, you will have to grab and lift the pedal many times until enough pressure is regained in the

clutch circuit. The person in the driver seat follows the order of the mechanic underneath and pushes all the way the pedal

multiple times giving feedback on the foot position. Hopefully, you all know how to do this….. It took a long time for the

pedal to regain its stiffness and we flushed a good quantity of Blue liquid through the new cylinder.

The final feel on the pedal is so smooth that you wonder if it is actually actuating the pressure plate. With all these new

components, properly lubricated and greased, a baby could depress that clutch and the Porsche helper spring is useless.

Lower the car, get rid of the driver, and raise it back up again for the final assembly.

Re-install your engine support jack under the round/front part of the transmission !!!!!

9) Install Cardan shaft (for C4S only)

- Slightly grease the splines and insert in the bellow as far as it will go. Re-insert the shaft into the rear coupler.

- Tighten the three cardan bolts to the flange. Torque at 33 ftlb.

10) Install transmission vessel and miscellaneous

- With your car lifted, and the gearbox held by the jack, remove the two long horizontal 15 mm bolts from the

Transmission Support.

- Re-install the vessel without forgetting to insert the foam pads on each side, between support and vessel.

- Torque all four bolts at 48 ftlb.

- Re-install the two long bolts coupling the support and the vessel. Torque in the same way.

- Remove transmission jack and engine jack and whatever is under the car.

- Re-attach the transmission shafts to the gearbox. Torque at 60 ftlb. A helper to hold the wheels can be a blessing.

- Re-attach the shifter cables. Make sure that the cables are clipped correctly and inserted snuggly.

- Re-install the coolant line holders (10 mm sockets).

- Re-install the electrical cable to the engine. Do not forget the separate lug coming from the cockpit. Use 13 mm

and 10 mm sockets.

- Re-insert the reverse switch on top of the gearbox.

- Re-install cross member and torque at 48 ftlb.

- Re-install all five underbody panels (10 mm socket and Torx 25/27)

- Lower the car.

- Take it for a test drive. Check your brakes….. Enjoy the new clutch!

This is not an easy job as you can tell. I would not recommend it unless you have some experiences in mechanics, access

to a decently equipped garage, lift and various jacks. If in doubt, simply take your car to your dealer or Indy. Good luck.