New Door Lock

The driver's door locking mechanism really annoyed me. The door had to be shut very firmly (think slammed), which causes it to get out of adjustment after a time. We've been messing with for 9 months now.

This note describes replacement with the the factory recommended new design replacement part.

The door now latches with the authority one would expect.

From the factory manual

When fitting the door lock it should be noted that there are various designs of lock. If an old-type lock is locked with the push-button on the inside of the door and at the same time the lock cylinder on the exterior door handle is pressed then the lock mechanism can jam. We recommend therefore that the new model lock should be fitted.

Here the following should be noted:

1. On the new lock the pressure plate which is operated by the exterior door push-button is located on a continuous spindle. The pressure plate has a more pronounced angle and increases the distance from the pressure pin of the door exterior handle. For this reason it is necessary to change the operating peg with the longer pressure pin.

2. It should be insured that the longer pressure pin part number: 901-531-919-20 (left) and 901-531-920-20 (right) does not touch the lock pressure plate when disengaged. If this is not done there is the risk that as a result of heavy vibrations on bad roads the catch can disengage and the door spring open.

The replacement pressure pins with these part numbers are no longer available from Porsche. We will have to improvise. The problem is that later keys and the lock cylinder is longer. The pressure plate has been shifted toward the center of the door to accommodate. The old pressure pin arrangement will not work correctly - it will not have enough travel to trigger the mechanism and the pin will not be long enough to lock the door.

3. As a further safeguard again the door springing open the shape of the lock peg on the door lock and simultaneously the shape of the striker plate have been altered so that the lock peg is additionally supported in the striker plate. The hole of the lock peg should be enlarged to approximately. 33 mm.

4. A new type striker plate must always be fitted with a new type lock. Outer edge vertical - if necessary enlarge operating holes in the lock pillar.

Advice Ignored

The word from one of the local bay area mechanics is that this is a rather difficult fix. Before we are done with the job probably considerable expense and time could be saved by replacing our lock with a used one.

But, it is time for a permanent fix - and besides, "How hard can it be?".

Not that hard.

Remove the both pieces of the door upholstery panels. This is discussed here.

The door lock fits between the window frame and the rear edge of the door. The frame must be removed before the lock can be replaces.

Remove the window frame by removing the socket head screws holding the frame to the door. These are found within the door and from the edges. When all the screws are removed, the window frame can be pulled out following the same angle as the main window posts.

Remove old the door lock with the rods attached. This is easy because the socket screws holding the parts are visible and obvious.

I used a manual Phillips impact screw driver to break loose the flat head screws mounting the door lock to the door edge in order to protect the slots from damage. This proved to be unnecessary because the mounting screws for the new lock are 6 mm rather than the 5 mm of the old lock.

The method of connecting the rods to the locking mechanism has also changed. There are pins in the old design and 6 mm holes in the new. The rods also have 6 mm holes, but there are small plastic bushings that reduce the size to match the 4 mm pins on the lock.

I decided to remove the bushings and then used a 5 mm bolt, washer and elastic stop nut. The washer was treated with a dab of grease and a drop of locktite put on the end of the bolt for a bit of extra security. The rods still move freely on their pivots.

Here you can see the door lock cam on the old and new design. The new one is larger and will not fit through the hole in the door. As mentioned by the factory manual, the hole in the door must be increased to 33 mm (1.3 in.).

Enlarge hole in door. I used a paper template taped on to the door with transparent tape normally used for packages to guide the cutting operation.

I tried several cutting tools on a Dremmel tool. The grinding tools worked better than the tungsten carbide tool.

Another technique that I considered was to mount a small piece of 1/4 in. plywood in the door using the 3 mounting screw holes to secure it. Then one could use a hole saw to cut the hole. This thought was rejected because I could not find a hole saw of the correct diameter nor one that I had confidence would cut the steel.

The placement of the hole should have approximately the same center as the old one, but this is not critical. The hole is larger than the diameter of the new shaft so enlarging the hole slightly off center is not critical.

We picked up the metal filings inside the door with a magnet.

The pin which engages the locking mechanism is long enough. However, the lock tumbler case is short so the outside door release just barely pushes the release mechanism enough to open the door. I solved this by replacing the flush head mounting screw with a bolt, placing a washer under the bold head for slightly more elevation.

Here are the two lock mechanisms side by side. I did bend the tabs toward the door handle to ensure the lock pin would engage the tabs. This probably was not necessary, but seems to have done no harm.

The new striker plate is thicker than the old, but I reused the shims that were under the old one. These are a 2 mm factory shim and a piece of gasket material. 1 mm factory shims were not available when I ordered the parts.

When mounting the striker plate, the outside edge should be aligned to the vertical.
020610-1196 Here is the wrench used to remove the striker plate, a 12 point 8 mm socket head, 3/8 in drive.
Last modified: Sat, 05 May 2001


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