This article is one in a series that have been released in conjunction with Wayne's new book, 101 Performance Projects for Your Porsche Boxster. The book contains 312 pages of full color projects detailing everything from performance mods to changing your brake pads. With more than 950+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any Boxster owner's collection. The book is currently available and in stock now. See The Official Book Website for more details.
Check out some other sample projects from the book:
One of the most common repair procedures for the manual transmission Boxster is the replacement of the clutch assembly. Unfortunately, it is a rather big process involving the removal of the transmission. The good news is that it's really not a super-difficult job if you have some information, and a few hints and tips.
How do you know if your clutch is beginning to fail? There are a few ways to tell. First, you should figure out how old your current clutch is. If your car is driven with mostly highway miles, then clutches can almost last forever. However, if you often drive around town somewhat aggressively, then you will probably have to replace your clutch at about 30,000 miles or so. With a hydraulic clutch system like the one on the Boxster, it can be a bit more difficult to determine the exact problem than with an older-style cable clutch system. Spongy pedals, excessive free play, and grinding noises all indicate problems with the clutch or hydraulic system. Strange noises that change when you push in the clutch pedal can indicate a pilot bearing or throw-out bearing beginning to fail. Finally, if your clutch begins to slip when the pedal is not depressed, then chances are your clutch disc is worn, or the spring plates in your pressure plate have worn out.
The first step is to remove your transmission from the car. See Project 37 for detailed instructions on this procedure. Once the transmission has been removed, you will want to remove the pressure plate. On this particular car, I found that some of the pressure plates bolts had problems rounding out when I went to remove them. If this happens, then dig out your trusty Dremmel tool and cut them off in about 1 minute. Don't waste your time trying vice-grips or other foolish methods - you can cut them off, and you don't need to worry about damaging the pressure plate because you're going to be replacing it anyways. When you're ready to remove the last bolt, grab the pressure plate with one hand - it's easy for it to fall off when the last bolt is removed. The disc should also pop out when you remove the pressure plate.
With the pressure plate removed, you should be able to see the flywheel. The Boxster uses a dual-mass flywheel which is a two-piece component that is bonded together. This changes the natural frequency of the flywheel and reduces vibrations in the engine. Unfortunately, this flywheel can be expensive to replace. Porsche has released a Technical Service Bulletin on checking the dual-mass flywheel (TSB 911 8/02 1360), which I have placed on the 101Projects.com website for reference. Basically, the test procedure is to twist the pressure plate surface of the flywheel about 15mm to both the left and the right and check to see if it returns to approximately its original position. If the flywheel cannot be twisted at all, or if the flywheel can be twisted beyond the 15mm without a noticeable increase in the spring force, then the flywheel is likely to be faulty. Typically it's a wise idea to replace your dual mass flywheel every 100,000 miles or every other clutch replacement.
The next step here is to remove the flywheel bolts. You can use a socket and breaker bar along with your flywheel lock. With the bolts removed, your flywheel should be able to be tugged off of the crankshaft.
At this point, you'll want to turn your attention to the transmission, and refurbish the throw-out bearing and arm. Start with the throw-out bearing guide tube. This is the small tube that the throw-out bearing rides on when the clutch is disengaged. As the throw-out bearing slides back and forth on the tube, the tube has a tendency to wear out. Remove the bolts that hold the guide tube to the transmission. Remove the guide tube, and inside you will find the mainshaft seal. Using a small screwdriver, punch a small hole in one of the indents in the surface of the seal, and pick out the old seal and remove it (see Figure 5). Clean out the inside of the bore where the seal fits, and install the new one. Tap it in lightly with the end of a socket extension, taking care to make sure it doesn't go in half cocked. Install the seal so that it is flush with the flange. Now install the new throw-out bearing guide tube, using a new o-ring. Although the factory manuals state to install the guide tube without any grease, I like to apply a light coat of white lithium grease to help things along. Check the small retainer clip, the pivot pins, and the throw-out arm pivot piece (see Figure 6). Lubricate the two pivots with white lithium grease. Take the new throw-out bearing, snap it on the throw-out arm, and attach the arm to the transmission. Your throw-out arm is now ready for assembly back into the car.
Now would also be an excellent time to replace your coolant tank if you've been having problems with it. Access is very easy at this point - the removal process is very difficult when the transmission is installed in the car (see Pelican Technical Article: Coolant Tank Replacement). I also recommend that you replace your intermediate shaft bearing at this time. This bearing has been responsible for more than its share of Boxster engine failures over the years (see Pelican Technical Article: Intermediate Shaft Bearing Replacement and Upgrade (IMS)).
Now, it's time to turn our attention back to the flywheel end of the engine. Porsche Tech Bulletin 8/02 1360 says to check the dual mass flywheel by twisting it approximately 15mm to both the left and the right, checking to make sure that it returns to its approximate starting position. If the flywheel can be twisted beyond about 15mm with no noticeable increase in spring force, or if it cannot be twisted at all then it probably needs replacement. If the flywheel checks out okay, then replace the flywheel pilot bearing and the flywheel seal as shown in photo 9 and Figure 10.
Now you're ready to reinstall the flywheel onto the engine. Always use new flywheel bolts, as they are only meant to be tightened and stretched once. Install your new or reconditioned flywheel onto the engine, then install the new flywheel bolts and torque them down. You must use a torque wrench and a flywheel lock to tighten the flywheel (See Photo 11 and Figure 12).
With the flywheel mounted, now take your clutch alignment tool and place it in the center of the pilot bearing. Install the clutch disc onto the flywheel (see Figure 13). Then install the pressure plate onto the flywheel, compressing the clutch disc. Use new pressure plate bolts to keep everything fresh. When the pressure plate is tightened down to its proper torque, remove the alignment tool. The disc, pilot bearing and pressure plate should all be aligned (Figure 14).
I wish I could say this was an easy job, but it's not. It's not impossible, but there's a lot of stuff to remove and a lot of tricky spots. One of the things that you want to do is purchase a complete kit that contains everything that you need for the job: all of the nuts, bolts and bushings, as this will be a huge timesaver. The only place that currently sells such a kit is PelicanParts.com.
Lightweight Flywheel - While reducing this weight will not buy you any more horsepower, it can increase your engine's response and acceleration. The reasoning behind this is that the rotational mass of the engine takes time to spin up' when you accelerate. Decreasing the rotational mass of the engine allows for quicker response times when accelerating. This is because more energy from the engine is being used to accelerate the mass of the car, instead of accelerating the mass of the engine components. In addition, reducing the mass of rotating engine components has a two-fold result on performance: you not only make the engine quicker, but you are also reducing the total weight of the car. This is discussed further in this book under Weight Reduction' in Pelican Technical Article: Track Preparation / Rollbar extension. The flywheel and other rotational components serve to raise the rotational or angular momentum of the engine so that the engine will continue to rotate smoothly until the next compression stroke. Adding a lightweight flywheel/components allows you to adjust engine RPMs much quicker. However, it will also drop down in RPM much quicker as well when you let off of the throttle. This often makes the car difficult to drive on the street in day-to-day traffic conditions. Also be sure to only use a spring-centered clutch disc with a non-dual mass flywheel (see Figure 5).
If you are looking for an easy performance upgrade for your 1997-04 Boxster, you can install the 987 Boxster/Cayman clutch package instead of the stock setup. The later-style clutch package will give you a better disc with more clamping force from the pressure plate. Just make sure that you order the 987 Boxster/Cayman clutch that matches your transmission (5-speed 987 clutch works with the 5-speed 986 Boxster, and the 6-speed 987 S' clutch works with the 6-speed 986 Boxster S)
Figure 1
Here's what your engine will look like after you have removed your transmission. Shown here is the pressure plate (blue arrow). There is a jack stand underneath the engine supporting the weight that is normally supported by the transmission.
Attach your flywheel lock (see Figure 11) and constrain the flywheel in position as you remove the flywheel bolts. With the flywheel off, remove the flywheel seal underneath. Using a screwdriver, puncture and remove the seal. Be careful not to damage any of the side surfaces where the seal mates to the engine case.
The first step is to make sure that you gather all the required parts for the job before you begin. It is very frustrating to get half way through a replacement job, only to find out that you need a part or a tool that you don't have. Here is photo of the PelicanParts.com clutch SuperKit that contains a comprehensive set of clutch replacement parts for a Boxster: Pressure Plate Throw-out arm pivot piece Throw-out bearing Pivot ball pin for pivot piece (B) Dual-mass flywheel O-ring for guide tube Pilot bearing (shown already installed in flywheel E) Throw-out bearing guide tube Engine flywheel seal Pressure plate bolts Clutch disc Transmission mainshaft seal Flywheel bolts Retaining spring for pivot piece (B) Clutch release lever
Shown here is a lightened flywheel. The main advantage to using the lighter-weight flywheel is that it reduces the weight of the rotational elements in the engine. However, the installation of the lightened flywheel may make the car difficult to drive, particularly in traffic. In addition, if you install a lightened flywheel, make sure you install a spring clutch disc along with it (inset photo). Don't use the stock clutch disc. If you use the stock disc there will be nothing to absorb driveline shock and vibrations, and you might damage your engine and/or cause the engine to trigger false misfire faults.
This photo shows the steps associated with replacing the transmission mainshaft seal. Pluck the old seal out of the guide tube and tap in a new one. Replace the o-ring with a new one and then install back onto the transmission.
The throw-out fork (inset) is attached at one end with a small metal clip (yellow arrow). Remove the fork from the transmission by pulling out on the fork and unhooking the clip from its catch on the bottom. Clean the entire assembly and then lubricate everything with white lithium grease, including the throw-out bearing guide tube (green arrow). Make sure that the parts are assembled correctly, as per the photo. The throw-out bearing clips onto the throw-out arm as shown in the inset photo. Pay special attention to the orientation of the pivot piece and pin (red arrow).
If your back-up lamp switch is giving you trouble, now is the perfect time to replace it. The switch is located on the top of the transmission. Replacement is as simple as removing it from the top of the transmission case. The inset photo shows the plug for the switch.
Shown here is the infamous intermediate shaft bearing which is responsible for so many engine failures on both the Boxster and the 996. Recent advances from crafty engineers in the aftermarket have developed a solution to remove and repair this bearing while performing a clutch replacement. To ignore this bearing while performing your clutch replacement is somewhat foolhardy: the majority of engines that have blown up in recent years have been attributed to the failure of this bearing. For more information, see Pelican Technical Article: Intermediate Shaft Bearing Replacement and Upgrade (IMS).
A- The pilot bearing holds the transmission input shaft in place and aligns the transmission up with the crankshaft. B- To remove the flywheel pilot bearing, use an appropriately sized socket and gently tap with a hammer. C- The new bearing should fit easily inside the hole in the crankshaft. D- Use a deep socket to evenly tap in the bearing so it's flush with the surface of the flywheel (inset).
Take your new flywheel seal and coat it with a light touch of Curil-T. Then install it onto the engine, taping lightly around the edge. The newer-style seal is supposed to be seated about 14mm or so below the end of the crankshaft. This means that the seal will sit about 3mm or so recessed beyond the edge of the case (yellow arrow). There is a special Porsche tool designed for the installation of this seal, but I simply made my own using some plastic pipe from the local hardware store that was the same diameter of the seal. Tap lightly and carefully - make sure that the seal doesn't become cocked in its bore. Clean up any leftover sealant that squeezes out.
I use a simple flywheel lock that is basically a strip of metal with two large slots in it (arrow - right). This allows you to attach the lock to a bolt affixed to the engine case, and one affixed to the flywheel, where the pressure plate bolts normally mount. This inexpensive lock works great on almost any car. With the lock in place, torque the bolts, working in a crisscross pattern. Start by tightening all the bolts to 50% of their final value, and then go around again and tighten them to the final value. Then crank them another 90° as shown in the next photo.
Shown here is a simply degree wheel that I made for tightening flywheel bolts. Download and print out the wheel on a thick piece of paper. Then, get some 3M tack adhesive and spray the back, so it sticks to the flywheel like a Post-It note. Then, crank each bolt 120° clockwise to achieve the proper tightness / stretch of the flywheel bolts. You can download and print out the template of the degree wheel from the 101Projects.com website.
Without the alignment tool (blue arrow), it would be nearly impossible to insert the transmission input shaft into the pilot bearing when mating the engine and the transmission back together. When the pressure plate bolts are all tightened down, you should be able to easily pull out the alignment tool, and the pressure plate and clutch disc should be centered with respect to the pilot bearing (photo inset). I recommend using new pressure plate bolts when performing a clutch replacement project.
Comments: Just finished this job on my 2006 Cayman. Great write-up! Oh, and all the parts delivered to my door from Cali to N.C. in 36 hours for $3!
April 22, 2012
Jeroen986
Comments: Is the flywheel the same for the 986 and 987? In other words, if I order a 987 kit for my 986 5-speed I would have the upgraded clutch and PP, but would it fit?
April 15, 2012
paradigm
Comments: The guide tube is slightly different in the 6 spd getrag, but in any case, is it ok to lubricate the OD of the transmission seal before inserting it into the guide tube? Without it it just seems like too much friction to push the seal into the bore.
February 18, 2012
damon
Comments: i was thinking about getting a lightweight flyweel for my boxster but some friends of mine told me it might make some excess noises and also might cause damage to the crank?
what do you think?
also, my clutch is still ok, so do you think it will be foolish to do such a thing when the clutch is still good?
October 24, 2011
Followup from the Pelican Staff: I don't typically recommend lightweight flywheels for street cars. Track / race cars for sure, but a lot of people who install these in street cars have issues with the fuel injection and also with driveability. The BOSCH Motronic system monitors the flywheel sensor for erratic idle and throws up a misfire code if it doesn't like what it sees from the sensors. Lightweight flywheels tend to trigger codes like these as they don't react the same way as the standard flywheels. You can get a new set of coding for your BOSCH ecu unit, but that costs big bucks. In the end, I don't really think the lightweight options are worth the hassle. - Wayne at Pelican Parts
dghii
Comments: Great write up but need a clarification.
Figure 11 write up notes to tighten flywheel bolts and addtional 90 degrees from final value.
Figure 12 write up notes to tighten flywheel bolts and addtional 120 degrees from final value.
Which is correct? Thank you
September 8, 2011
Followup from the Pelican Staff: Typically it's 90-degrees, but I see in the Bentley manual that they state it should be 120 degrees additional. - Wayne at Pelican Parts
suprauno
Comments: after full installation including new master and slave cylinders clutch peddal is hard and cant go into gear while car is running.
June 29, 2011
Followup from the Pelican Staff: Hmm, it sounds like something is stuck. I would check to make sure that the slave cylinder rod is properly inserted into the throw-out bearing arm, inside the transmission. That is really the only thing I can really think of off the top of my head. - Wayne at Pelican Parts
Aahighfly
Comments: In your text for torquing the flywheel bolts, you instruct to turn the bolts an addition 90 degrees after reaching proper torque. Won't this over torque the bolts?
June 6, 2011
Followup from the Pelican Staff: This is the newer way of tightening bolts. You tighten to a low torque value and then you go 90 or 120 degrees. The final torque value is not the value that you initially tighten to, so doing this doesn't over tighten the bolts. This is the factory procedure. - Wayne at Pelican Parts
ChrisC
Comments: I can't find a link to download the degree wheel template. Is this contained in a special section?
Comments: In this write up you mention a Pelican Parts - Clutch "SuperKit". It would be great if this was an actual product I could buy. Can't find it on the site....
Sure would save some time and I'm guessing money for buying it as a kit.
