In reality, the sunroof is quite simple and very easy to repair.  The sunroof motor drives two cables that move the roof forwards and backwards in a track mounted to the car.  The primary problems with the sunroof involve the cables breaking or the roof leaking.   This project will go over the details associated with complete sunroof removal and renewal of the cables, the motor, and the sunroof seals.

Figure 1:
Replacement Sunroof Parts

Figure 2:
Sunroof Motor

Figure 1 shows some of the pieces that you need to effectively repair and renew most sunroofs.  The velvet/felt seal around the outer edge mounts to the inside edge of the chassis in the front and sides of the sunroof opening.  Moving inwards in the photo, is the sunroof cable and transport mechanism (left and right required).  The cable and the mechanism are integrated so that they have to be replaced at the same time.  Inside the inner circle is the rear sunroof seal (at top), the rear sunroof guide with plastic insert (left, two required), a front lifting pad (center, four required), and the small triangular plastic lift piece that helps push the sunroof into its home position when closed (right, two required).  Not shown is the rear flat rubber seal that mates the rear of the sunroof to the car.

The first step in repair is to gain access to the sunroof motor.  The coupe cars have a zipper that runs along the WIDTH of the headliner in the rear of the car.  The sunroof motor is located near the rear of the car, and can be reached by unzipping the headliner, and removing some of the sound deadening panels (shown in Figure 2).  Be careful unzipping the headliner, as the fabric can get old and may rip when you pull on it.  Also be careful with the foam insulation that is attached to the panels that cover the motor.   The spongy material has a tendency to break down and flake off after many years of aging. Remove the panels, and above them you will see the sunroof motor and transport mechanism.  Be careful removing these panels, as the foam is sometimes quite old, and can easily flake off.

Once you have the panels removed, you can clearly see the sunroof motor and its mechanism.   In order to remove and install the new cables, the motor mechanism must be disconnected.  Release the mechanism from the sunroof cables by removing the two screws that hold it to the motor bracket.  The mechanism should remain attached to the sunroof motor, and can hang by the small flexible coupler that connects it to the motor.  The edge of the cables should be clearly visible, where the gear mates to them, as shown in Figure 3.  Now that the cables are loose, the sunroof should be able to be removed.

Proceed to the front of the passenger compartment, and examine the headliner that is installed into the sunroof.  This headliner piece is simply pressed into place by spring clips, and covers all the mounting hardware for the sunroof.  Remove this sunroof headliner by pulling down on the edges of this piece.  Grab an edge and pull downward, and the metal snaps should disengage.  Figure 4 shows this procedure.  Remember to only pull down on the piece that is attached to the sunroof, and be careful not to damage the rest of your headliner.  After you get a good grip on this sunroof headliner piece, it should simply pop out of the sunroof.  The clips that hold it in place are similar in principle to the ones that hold the door panel to the door.   If you need to slide open the roof a bit to gain more leverage, you should be able to push it now that the cables are disconnected.

Once this headliner piece is loose, slide it back towards the rear of the car.  At this point, the attachment points for the sunroof should be clearly visible.  On each side, there is a guide piece attached to the sunroof towards the rear of the car, and also a guide piece that is attached to the sunroof cable.  Remove the bolts that attach the sunroof at these four points, and the sunroof should be able to be easily lifted out.  Make sure that you place the roof in a safe location. 

Figure 6:
Sunroof Channels

Figure 7:
Sunroof Seal on Body

Figure 8:
3M Super Weatherstrip 80001

Figure 9:
Sunroof Seal on Sunroof

Figure 10:
Sunroof Seal on Body

Figure 11:
Sunroof Seal on Sunroof

Figure 12:
3M Super Weatherstrip 80001

Once you have the roof removed, it should be apparent how the track assembly works.  The cable is attached to a guide that runs inside the aluminum channel.  The motor pushes this guide forwards and backwards to open and close the sunroof.  At this point, it’s advisable to completely remove all of the aluminum channels from the top of the sunroof and clean them.  The air deflector plates at the front of the sunroof should also be cleaned (Figure 5).  In order to install the new cables and travel mechanism, you need to remove the channel that holds it in place.  Simply unscrew the main aluminum channel and any others that may  block it from the sunroof top, as shown in Figure 6.  Pull out the old cable and mechanism.  Make sure that you clean the channels completely prior to their reinstallation.

Again, make sure that you remove and clean all inner sections of the track and also the air deflector plates.  It’s quite common for these areas to become dirty and sticky, which then stresses the sunroof cables.   I don’t recommend using any grease in the sunroof mechanism for a couple of reasons.  The heat from the sun has a tendency to melt the grease and make it drip inside the car.  Also the grease attracts dirt and debris that will stick to it.  The sunroof channels will be open to the air and wind when you are driving along; dirt and debris will find its way in there.

On the roof itself, you will want to replace the two rear channel guides that have plastic inserts, and also the small triangular shaped plastic pieces that help to lift the roof up into its closed position (Figure 8). Also replace the small plastic lift pieces if they are worn (Figure 9)In addition, I recommend replacing the sunroof seals.

New sunroof seals help finish the job correctly.  There are a total of three seals, two that go on the sunroof and one that goes on the body.   The right side of this picture shows the seal that is mounted to the sunroof.  This seal is glued onto the roof itself and winds it’s way around three-quarters of the roof, ending where the white arrow indicates in Figure 10.  At the rear section of the roof, a similar seal is glued to the roof itself, as shown on the left by the green arrow.  This seal must line up perfectly with the one on the body when the roof is closed.  When cutting and gluing these seals, make sure that you line them up carefully.  Finally the rear sunroof seal, shown by the yellow arrow is a rubber seal that is glued on the rear flat-portion of the sunroof, as shown in Figure 11.

With the aluminum guide channels removed, carefully place the sunroof seal onto the body and glue it in place using 3M Super Weatherstrip 80001 (see Figure 12).  On the sunroof, glue the rear strip and the remainder of the sunroof seal to the roof itself.  Refer to the photo accompanying this project for a clearer understanding.

After the seals have been replaced and the guide rails installed, the roof can then be reinstalled back into the car.  Make sure that the rear guides are fed into the sunroof channel, and the front of the roof is mounted to the guides that are attached to the sunroof cables.  The HEIGHT of the sunroof can be adjusted by rotating the small nuts that are located under the front channel guides, while the fastening screws are loose.  These guides also lock in the left/right position of the roof as well.  The rear HEIGHT of the roof can be adjusted by altering the location of the screws that mount the rear guides.

A little-known fact is that Porsche is no longer supplying the original sunroof cable assemblies for the pre-1989 cars.  The only new ones available are the ones for the 964 series (1989 C4 and later cars), and need to be modified to fit into the earlier cars.  There are two modifications that need to be made.  Firstly, there is a felt strip that is wound around the cables, presumably to clean dirt out of the tracks.  This felt makes the cable stick on the early cars, and needs to be removed.  Using a small pick, carefully remove the felt from around the cable.  If it comes off in one piece – you’re lucky.   Most of the time it will require some effort to get all of the felt off.

In addition to the removal of the felt, you also need to grind down the edges of the guide piece attached to the end of the cable.  On the 964 cars, Porsche enlarged the diameter of the sunroof cable guides (the long pieces that run the length of the car).  As a result, the guide piece for the 964 cable will not fit into the guide for the pre-1989 cars.  You need to file down both the top and bottom edges of the guide piece on the cable until it fits smoothly into your sunroof guide.  An alternative would be to upgrade to the later-style 964 guide pieces, but these are rather expensive to replace.

Another curious fact worth noting is that the sunroof cables are not symmetrical.  If you look at the replacement left and right cables, you would normally think that the part was incorrectly manufactured.  However, this is not the case.  Compare the new cables to the older ones, and it should become apparent how they fit into the guides.

Once the roof is installed and properly adjusted in place, reconnect the motor to the cables.  Simply bolt together the drive mechanism – there shouldn’t be any adjustment involved.  Test the sunroof motor for proper operation.  If all goes well, then reinstall the soundproofing material, zip up your headliner, and dig out the suntan lotion.