Reader's contribution by Philipp Bohr
A word to all reading SAAB mechanics in advance: At the latest after completion of this project, I know what work you do, and that you are worth the sums you pay, even if that at first glance (on the bill) not always so clear. But one after anonther. At the beginning of August I drive on the road near the institute parking lot over a manhole cover (the university wants to propagate the car-free campus, and therefore delays all road construction work to the limit of bearable) - it pops metallic, it clinks, and as I sideways turn, the disc of the side window is at a crazy angle in the frame.
The visible part is intact, but still, something goes awry here. Sweats come over me: only just was a repair of the power steering (see other blog post) was due. Now put money back for a new side window? It's a vengeance that I chose the maximum excess after an accident and a change of insurance ...
But as the saying goes, the engineer has nothing to swear to. Now I'm not an engineer, but a physicist, but as an experimental physicist, you're also a kind of engineer. So first drive to the right and pull the disk straight in the frame. And the plan for the evening is clear: Remove the paneling of the door and get to the bottom of the error.
Basically, I don't shy away from such work. What scares me, however, are the large amounts of plastic fastened with clamps that make up the interior lining. It smells like scratches, cracks, unsightly discolouration, where the levering is too tight ... but there is no way around it, my decision is clear. After all, I got the Haynes repair manual shortly after buying the car, so that it should be able to do the repair armed.
First remove the paneling on the door arch. With a screwdriver with a wide blade ... As a precaution, I take that of the pocket knife, which has the widest blade. I guide it in the upper back corner of the panel between the rubber lip and plastic, feel for the clip. I find one very quickly, put some pressure on it ... and the clip is released. Lucky. I quickly move on, working first along the rear edge of the door. Then I follow the door arch, clamp after clamp, until I hold the cladding element in my hand. Fortunately, the rest of the brackets loosen quickly, once you have solved one.
The first step is done, the door arch is free. The next step is unscrewing the door inner lining, this Torx screws on the door handle and the door latch must be solved. First use a slim screwdriver to loosen the covers over the screw holes. First, I put the screwdriver too flat. An unpleasant, scraping sound is the result. Thank God for the often ugly scolded hard plastic: I was able to polish off the scratch later - soft plastic would be less tolerant. With the new knowledge of the approach angle, I can solve all three covers, open the Torx screws, and I'm ready for the next step.
This sounds difficult: Lever out the clamps on the door panel, pull the door panel upwards over the door lock, loosen the switch cables from the tank and trunk lid release and free the door lighting from its recess. The release of the clamps works very well after the exercise on the door arch, the panel can be easily pulled up over the door latch, and the cables leave me enough play for now. The plugs can also be easily removed. Unfortunately, the repair manual does not state that it would be advisable to pull the fuse for the door lighting. If you have been working on the open door for 30 minutes (like I was at this point in time), the lamp is hot and hard to grasp. With a plastic strip between the contacts you can disable it and then push it out of the recess in the door.
Under the door interior lining is an insulation film. This is glued on, but can be carefully removed from the door frame. If you are extra careful, you can even glue them back on - but you should first unscrew the speaker and loosen the adjoining screw that holds the window glass guide, otherwise the film tears at the point. So the speaker also unscrewed, and on it goes to the actual fault diagnosis.
My first guess was a broken glass. In this respect, it is reassuring to see that the disc is still fully intact. Therefore, next I take the power window, a scissor mechanism with two legs, which convert the rotational movement of a gear in an up and down movement of the disc. For this purpose, rollers are attached to one end of the legs, which run in rails at the lower edge of the disk. And it quickly becomes clear that both roles have jumped out of their tracks. At first I thought a simple re-threading would be the solution - only at second glance do I recognize the reason why the rollers jumped out of the rails: The roller in the rear rail has broken and has come loose from the thigh. Remains of her hang in the rail, a piece of fish I fish down out of the door frame.
Such a diagnosis is often annoying, as we know it all too often from modern cars: A penny part causes repair costs of several hundred euros because a screw, clamp, roller or other individual cannot be supplied. I am considering two options: ask my new acquaintances from the Muckelbauer dealership for advice, or have the role reproduced by our institute's precision engineering workshop. Made of Teflon, as a super roll. Fortunately - and just for fun - I check the Skandix website beforehand and search for "window regulator". A section opens with the related parts, some window lifters and the other "sliding bushes, window lifters". The picture next to it shows exactly the role I was looking for. Unit price: € 1,73.
The installation of the role is complicated, also because the repair manual is spongy at the crucial point - but in turn. The rolls will be delivered two days later, I ordered six: four as spare parts for both front windows, and two to try out. These are also necessary - my plan is to push the rollers first into the rails, and then fix the window arms to the rollers. This saves me from threading the window onto the windows, an undertaking that seems unnecessarily complicated to me, especially when working alone.
Again, I release the door interior, move the window lift arms into the access opening so that they can be easily grasped, gently push the window pane down so far that the rails are level with the ends of the legs. Threading the rollers into the rails is not that difficult. But then comes the critical point: connecting arms and roles. The manual states that you should press the rollers on the axes "until they audibly engage", that is, until they audibly engage. She does too. I test the power window switch as a test, without problems, the disc slides upwards. On the way down there is again a metallic bang, a clink, and disc and role are separated again.
Finding the solution to the puzzle costs me another three-quarters of an hour, and three more failed attempts, until I approach the problem from the base, and only push the roll without a disk on the axle. It is striking that after the first engagement, the role is still very loose sitting on the axis, almost free tilt in all directions and can be solved with little effort. Touching with a slender screwdriver also leads to the realization that the groove into which the clamp is to engage still remains exposed behind the shaft of the roller. Only stronger pressing - very strong pressing, I must say - leads to a second Einrastgeräusch, the role then sits firmly in the position envisaged.
With this realization it is a matter of another quarter of an hour to redeem the role, to introduce it into the rail, and to repeat the process with a disk and a pulley. Then you should definitely check whether all sealing lips sit properly outside, possibly with a narrow strip of metal - or a screwdriver with a wide blade - help. In a renewed test keep the rollers, some grease makes the rails smooth, and after another half hour and the door trim sits back where it should.
This repair is classified by the manual as medium (third of five levels). This is a realistic assessment, only someone with sufficient skill and experience with one or the other repair should dare. But if it is done, it is rewarding. My investment: 15 Euro for the rolls, including shipping, and about two and a half hours repair time. And screwing on a SAAB, where even after 13 years, the screws are still to be solved as if they have just been screwed in, can really be fun.
Incidentally, there should be SAAB workshops that also offer internships to graduate physicists - my e-mail address is available from the blog team.