[Franco]

Hi, I had this in my computer, can't remember where i got it, hope it can help.
Thanks to whoever did the write-up.


Boxster Clutch and Replacement
The Boxster is now in its sixth model year and proving to be one of the most
popular models Porsche has ever built. The used market is proving to be good and many
fine early examples can be found reasonably priced in comparison to other marques. I
am of the mind that a used Porsche is still a much better buy than something new and
cheaper for other manufacturers. The only caveat that I use to judge the cars is the wear
areas and there are a few that might need addressing if you purchase a higher-mileage
Boxster.
One area I have received letters about is the clutch. How long does it last? Can I
service it myself? And so on. In reality, the Boxster clutches are proving to be quite
durable and the dual-mass flywheels much more reliable than, say, the initial C4 units. I
went to a local dealer and inspected a unit being replaced. This was a 1997 Boxster with
95,000 miles (153,000 km) on the odometer.
The principle reason for the clutch replacement was a bad release bearing noise.
This is pretty rare, so don’t expect yours to fail. There was also some concern by the
owner, who in this case was the third owner of the car, about an oil drip that appeared to
be coming from inside the transaxle bellhousing. Oil leaks can damage the Dual Mass
flywheel. Wear or misuse can prematurely wear the clutch disc lining and require
replacement. Pressure plates are well designed and rarely fail, though they can become
badly damaged by a worn clutch disc. Discs can wear to the point where they will not
longer move the car. At that point they can also damage the flywheel and pressure plate.
Clutch master or slave cylinders can fail, making clutch operation and gear shifting
impossible.
The service manager of a local dealership invited me to the dealership to see the
replacement process as I had asked about what was involved. I do have a complete set of
Boxster manuals, but there is no complete removal described in the manuals for a stepby-
step process. Porsche dealers send their technicians to a training program where
instructors do a classroom project to teach the proper methods for accomplishing the job.
The manuals are for specific items that require a complex operation to be performed,
such as camshaft timing or crankcase assembly.
The operation begins by correctly lifting the car and placing the body on jack
stands (a lift at the dealership). I am assuming that you will be working at home. A lift is
much easier if you have one available. You will have to support the car on the body itself,
not the rear suspension cross member as you might for other work. You will need access
to the cross member area during the trans axle removal process, so the normal lift points
on the side sills must be used for support. You may use the cross member to support the
car while putting the jack stands in place.
Once the car is in place on the jack stands, the first operation is to remove the
under pan and stiffener assembly. These are bolted to the chassis and rear suspension
cross member on a diagonal and can be removed as a assembly if you remove the bolts at
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the chassis and cross member. Removal will give you access to the transaxle area. These
pieces only need to be disassembled to the point of removing as a unit to simplify and
shorten the process. Please note that is you choose to remove the preservative Porsche
applies to the aluminum pieces in the suspension and underframe, this is a good time to
do so.
Once the under pan is removed, the exhaust system becomes totally accessible.
This assembly must be removed to proceed further in the trans axle removal process. It
can be removed as a complete unit if you desire. Simply unplug the connectors to the
oxygen sensors, both units, both sides, and then break the connection to the exhaust
header at the point where each side bolts to the catalytic converters. Proceed to the
exhaust hangers, these are unbolted and slid back to remove the assembly. This assembly
does weigh a bit, so you might either support the assembly with a jack or have someone
assist you. Once the exhaust is removed, you can proceed to removal of the slave cylinder
and shift linkage from the transaxle. On the shifter, the easiest way is to unclip the cables
without disturbing the cable bracket. This makes reassembly much easier as very rarely
will complete alignment of the cables be required after the trans axle is replaced. (For
those people doing the shifter replacement, the same holds true in the passenger
compartment).
I usually do not break the hydraulic line to the clutch slave cylinder. I let it dangle
out of the way of the transaxle. Do not operate the clutch pedal while the slave cylinder is
in this position as it can be ruined if operated without the clutch release arm to hold it to
the operational stroke it usually operates in.
Disconnect the CV joints and pull the axles out of the way. If any of the CV
retainer bolts are damaged by the socket, replace them, do not reuse. The bolts generally
have a white “paint” applied, this is a form of Loctite that keeps the bolts from loosening.
I use Berryman’s Chem tool or similar carb cleaner as it dissolves the paint and allows
the socket to go completely into the head of the bolt. If the socket only goes part of the
way in, the bolt head will be damaged.
At this point, the engine/trans axle assembly must be supported with some tension
applied to “push” the assembly upward. This relieves the trans axle mounts of the weight
allowing removal of the trans axle mount assembly from the Boxster body first and then
the trans axle. When supporting the assembly to do this, place the jack or support under
the engine case as the engine must be supported to remove the transaxle. At this point, all
that will remain are the bolts connecting the trans axle to the engine. I would use a jack or
transmission jack to support the trans axle. Note that the trans axle must be pulled to the
rear of the car after the trans axle-to-engine bolts are removed. You will have to also pay
attention to the fact that lower suspension cross member is still in place as you do this. It
is far enough forward to allow the jack to be centered under the trans axle weight mass to
facilitate disengagement from the engine.
Pull the trans axle back slowly to make sure that you do not drop it. Once clear of
the clutch assembly and cross member, it can be lowered and inspected. The clutch
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assembly itself should be completely visible. The release bearing will remain with the
release arm in the transaxle. I recommend replacement of the release bearing during any
clutch renewal. The pivot point and the release arm should be inspected for wear,
especially the arm at the point where it moves the release bearing. If the arm has worn at
the engagement point, it will require more pedal effort to disengage the clutch. There is
usually a slight curvature on the arm at this point. Inspect to ensure that it is still present.
If excessive wear on the arm is present, replace the arm
Removal of the pressure plate and clutch disc are very straight forward. Be sure to
avoid stripping the retainer bolts. If you damage a head, replace it. Many shops will not
reuse pressure plate bolts, preferring to use new.
Inspect all of the pieces of the clutch system. Note that the clutch disc does not
have shock springs. These are not used on the Boxster as the flywheel performs this
springing to absorb the release and application of the clutch. This is called a Dual-Mass
flywheel and has proven to be much more robust than the first applications in the 911
C2/C4 models. If your reason for this operation is failure of the flywheel, then only a
complete replacement will cure the problem. If the disc and pressure plate have worn to
the point of non-operation, then just clutch components need replacement. Do inspect the
flywheel for grooving and bad burn marks. Some refinishing can be performed, but the
elastomer that provides the cushioning can be damaged. The usual method is to replace
the flywheel.
If the reason for disassembly is for a rear main seal leak, then the flywheel must
be removed. In removing the flywheel, again be careful with the flywheel retainer bolts.
Most mechanics will replace these bolts if the flywheel must be removed. Also be aware
that if there was a significant amount of oil leaked into the clutch area, the oil may have
attacked the elastomer. If it has, it may cause a later failure. This is your call to replace,
but be advised that if the flywheel has been immersed in a large amount of oil, that
replacement is prudent.
If the rear main seal has been leaking, note the depth that the seal has been
installed to. If it is about 1/8 inch into the engine case, then set the replacement seal in to
about 5/16”. This usually will cure most leaks providing the seal is not damaged on
installation. There are tools to install seals without cutting the lip and making another
leak. A generic installation tool may be used on the seal to drive it in but you must ensure
that you have driven the seal in parallel and evenly around the crankshaft end. Be aware
that there is no way other than to run the engine to check for leaks after a seal change.
The best way to do a clutch renewal is with all new components. This would
include the clutch pressure plate, clutch disc, release bearing, pilot bearing and, if
necessary, release arm. While the Boxster is much easier to service the clutch in, it is still
not a task you want to do more often than you have to. Replacement is the opposite of
removal, but I would inspect the CV joints fro grease condition and service the axles if
the car has over 50,000 miles (80,000km) on it. I would also take the time to clean the
exterior of the trans axle and inside of the trans axle bell housing before reassembly.
When installing the new clutch components, you will need a pilot shaft to align
the clutch disc and pilot bearing so that the trans axle input shaft will align and easily go
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into the clutch assembly. There is an inexpensive tool to do this job, it can be found at
many parts stores and is the equivalent of VW tool 3176. If you have never used a pilot
shaft alignment tool, the normal use is to put the disc on the flywheel before the pressure
plate is installed. The smaller pin that goes into the pilot bearing will center the disc. I
advise you to partially torque the pressure plate and wiggle the pilot shaft alignment tool
to ensure that the clutch disc is still centered. Then torque the pressure plate to factory
specifications in several steps to assure even torquing. I usually do this in a cross pattern
Pressure plate bolts are torqued to 25 ft lbs. Flywheel bolts to 90 ft lbs and trans axle to
bell housing at 30 ft lbs.
The pilot bearing on the Boxster engine resides in the center of the flywheel. It is
a needle bearing and can be driven out with the flywheel removed from the crankshaft. If
the flywheel is not removed, then a puller may be used to remove the pilot bearing. The
pilot bearing comes pre-lubed, so additional lubrication should never be required.
The release bearing comes pre-lubricated. Avoid handling the release bearing any
more than you have to. Do not wash the bearing if any dirt gets on it. Wipe the material
off, trying not to remove the grease.
Clutch slave bleeding. I usually recommend that the hydraulic system be bled and
the fluid renewed every two years in a fairly dry climate like California. Annually in
other climatic areas and if you use your car on the track This bleeding and renewal also
includes the clutch slave cylinder. On the Boxster, the cylinder is placed at the top of the
trans axle. This can be hard to reach and requires that the lower shield be removed for
access. The reservoir is located in the front trunk area and shared by the brake system.
Porsche recommends DOT 4 brake fluid for the Boxster system. A pressure
bleeder may be used instead of pumping manually. If you elect to use a pressure bleeder,
use no more than 22 pounds of pressure (1.5 Bar) or so. The usual method is to push the
clutch pedal to the fully depressed position and hold it there. Open the bleeder valve and,
using a clear tube into a catch container, wait until the fluid being evacuated becomes
clear and bubble-free. Turn the bleeder to the closed position and turn off the pressure
unit. Remove the device used to hold the pedal depressed. Operate the clutch pedal
manually and check for feel. If the feel seems correct, then reassemble the car and drive.
Clutch throw cannot be adjusted, so the only culprits to inspect are the master and slave
cylinder if clutch operation is not correct during shifting and gears grind.
If you have a situation where the master or slave cylinders fail, gear grinding will
occur. Park the car if this happens. It is much cheaper, though inconvenient, to park it and
have the car transported to where repairs can be accomplished. The gear synchronizers
and sliding collars will be ruined if jammed into one another without use of the clutch,
especially at rest.
The clutch master cylinder is located in the front trunk near the Brake booster. It
is a fairly easy replacement. I will warn that you should have shop rags and perhaps a
container to keep brake fluid from going any place in the trunk. Brake fluid will damage
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paint, so be extremely careful in handling it and clean it as quickly as possible if you do
spill some.
The clutch pedal assembly is very reliable and will require little if any
maintenance. The only item that seems to be of any concern is the safety switch. Porsche
and many other manufacturers have installed a safety interlock switch to help prevent
starting the car in gear. The clutch must be fully depressed to make contact to allow
starting of the engine. The dealer has seen only a pair of these switches fail since their
introduction. If you have a situation where the car will not start, but the battery is fully
charged, then this part should be checked.