Technical Service Bulletin Basic Cabriolet Top Adjustments

Subject: Cabriolet Top, Basic Adjustments         Models: 911 Cabrio

Bulletin Number: 87 – 08

This Bulletin is based on information found in the booklet: “Test Plan Cabriolet” order number WKD 492 620. It contains additional and updated information on basic cabriolet top adjustments.

When repairing mechanical top opening or closing malfunctions, checks and adjustments should be carried out in the following sequence:

Note: Car should be parked on level and firm surface when making repairs.

  1. Check the alignment of the centering lugs to the guide sleeves in the windshield frame. When closing the top, the lugs should contact the front rim of the guide sleeves centrally. (Picture 1)
  • If the adjustment of the centering lugs is okay, check the adjustment of the top frame microswitches left and right.

Close the top slowly step by step. Both micro switches should switch at 30mm + 3mm distance “upper roof edge to upper windshield frame edge”

(Picture 2).

If necessary, adjust micro switches using ohmmeter or beeper on disconnected wiring plug (green and white wires).

  • If the adjustment of the centering lugs is not okay, first check the synchronization of the left and right swivel gear levers. With the top closed, the marks on the gear housing and on the lever should line up. (Picture 3) This check should also be made if the swivel gears are noisy. To synchronize the swivel gears, disconnect drive cable from drive motor and turn cable until markings line up. Reconnect cable.
  • If it is still necessary to adjust the centering lugs, close the top until lugs almost make contact with guide sleeves.
    • Adjustments are made on the bearing brackets (Picture 4).

The bearing bracket slotted holes should be centerally located following basic adjustment. Adjustment of the threaded fork upward (A  in picture 5) adjusts the top forward (in driving direction).

Adjustment of the threaded fork downards (B in picture 5) adjusts the top rearward (against driving direction).

Observe location of centering lugs while making adjustments.

  • Displacment of the bearing bracket from center position in the slotted holes forward (C in picture 6) produces slight adjustment in driving direction. Displacement of the bearing bracket rearward (D in picture 6) produces slight adjustment against driving direction.

Observe location of centering lugs while making adjustments.


Both these adjustments (Steps 4A and 4B) affect the movement of the top mechanism and should therefore be carried out with appropriate care. If necessary, the opposite side will also have to be adjusted.

  • Should the adjustment of the threaded forks and bearing brackets not be sufficient, the entire top can be moved forward or backward by loosening the rear bow hinge and rear window bracket screw. (14 screws, arrows in pictures 7 and 8).
  • Important

Any tension of the top operating linkage should be eliminated after adjusting the threaded forks or bearing brackets.

To do this close the top and loosen the swivel gear mounting bolts (3 in picture 9). Pull the levers together by hand (direction of arrows in picture 9). Tighten swivel gear mounting olts in this position. Check distance (X in picture 9) between the point of attachment of swivel gear lever/thurst rod (1 in picture 9) and frame arm (2 in picture 9). Maximum difference between left and right side: 5mm.


After adjusting the top, open and close top several times. Recheck adjustment of centering lugs and top frame micro switches. Road test car, and verify proper operation of top several times.

Important Notice: Technical Bulletins are intended for use by professional technicians, not a “Do-it-yourselfer.” They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Special tools may be required to perform certain operations identified in these bulletins. Use of tools and procedures other than those recommended in these bulletins may be detrimental to the safe operation of your vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to a do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your Porsche Dealer for information on whether your vehicle may benefit from the information. Part numbers listed in these bulletins are for reference only. Always check with your authorized Porsche dealer to verify correct part numbers.


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