Sunroof Plastic Gear Replacement
Step-by-step procedure for replacing the stripped plastic lifting arm gears in the late-model 944 sunroof (February 1986 onward), including gear removal, limit switch positioning, gear marking, and reinstallation.
This procedure covers late-model 944 sunroofs (February 1986 onward). For the early-style sunroof with the gear box between the lifting arms, a different approach is needed.
Parts
| Part | Part Number |
|---|---|
| Plastic Sunroof Gear (Feb. 1986–1991) | 944-564-430-01 |
Procedure
Step 1 — Determine Which Gear Is Stripped
Before removing anything, determine whether one or both plastic gears are stripped. If only one gear is stripped, the good gear can be used as a reference position for the replacement.
Remove the sunroof from the car first. If the motor will not retract the lifting arms electrically, operate the sunroof manually (see BODY-03 for manual operation procedure).
Step 2 — Locate the Motor Assembly
The motor assembly is behind the vertical section of carpet in the rear hatch area, behind the hatch compartment light. The carpet is held by plastic push plugs — slide your fingers behind the carpet and gently pull to release the plugs.
The motor assembly may have a black plastic cover secured by four Phillips head screws. There is a black plastic cone-shaped dust cover on the drive assembly at the base of the motor. Behind the cover are three nuts; the large rear nut (21 mm) is used to manually move the cable/cam and also to check and adjust slip clutch torque.
Caution: If one gear is still good and slip clutch torque is too high, retracting the lifting arm mechanically against the roof body may strip the remaining gear. Do not over-retract.
Step 3 — Disassemble the Headliner
Remove the cover panel on the back part of the headliner (Phillips head screws behind plastic covers). It is easiest to do this lying on your back in the luggage compartment with the rear seat folded and the rear hatch raised.
Pull back the weather-stripping along the top edge of the hatch opening to expose the back edge of the headliner. Gently pull the headliner loose from the body all the way across. This exposes the two lifting arm mechanisms and the single drive cable guide tube connecting them.
Step 4 — Inspect and Remove the Damaged Gear(s)
Carefully remove the lifting arm covers one at a time. Inspect the gears; if a gear is still good, replace its cover — it will be used as a reference for setting the replacement gear.
Remove the lifting arm and plastic gear for the stripped unit(s). There is a thin metal washer behind each plastic gear; retain this washer for reinstallation. Note that grease may cause the washer to remain in the housing rather than coming out with the gear.
Step 5 — Set the Limit Switch Position
With the bad gear removed, set the sunroof motor cam so that Limit Switch I is made and Limit Switch II is not.
How to verify the cam position:
- With ignition in position 2 and the sunroof installed, press the up-arrow console switch until the motor stops.
- Press the down-arrow console switch until the motor stops.
- At the motor assembly, look through the small opening behind the two micro-switches. The white plastic cam should be touching the arm of the bottom switch (labeled I) but not yet touching the top switch (labeled II).
If uncertain, rotate the 21 mm nut counter-clockwise (opens direction) to move the cam away from both switch arms, then rotate it slowly clockwise until you hear the bottom switch click. Verify that continuing clockwise also makes the top switch click (confirms both switches work mechanically). Return the cam to where only Switch I is made — this is the locked position.
Note: If the micro-switch mounting arm has bent so the cam cannot reach the switches, the arm must be removed and bent slightly to restore contact.
Step 6 — Mark the Lifting Arms
With the sunroof installed and closed, lay one lifting arm in its track in the lifting element (without installing the gear yet). Slide the element up into the roof track until the round peg is centered in the knee (sharp bend) of the track — this is the locked position. Mark the lifting arm at the point where it aligns with the edge of the lifting element. Bright nail polish works well as a marker.
Measure and mark the second lifting arm at the same distance. You can hold them side-by-side, count teeth, or use a ruler.
Step 7 — Check Slip Clutch Torque
Before reassembling with new gears, verify the slip clutch torque (see BODY-03). Excessive torque is the root cause of gear stripping. Set the torque at the low end of specification (5–5.5 Nm) rather than the midpoint (6 Nm) for added insurance.
Step 8 — Install the New Gears
- Remove the sunroof from the car.
- Place the thin metal washer on the back of the new gear before installing.
- Lubricate the gear with a good quality, fairly heavy grease. Porsche specifies TL-VW 745 Universal Cold Grease (available from Porsche or VW dealers), though equivalent heavy grease is acceptable. Apply a moderate amount — not excessive.
- Install the gear in the lifting element housing.
- Insert the lifting arm so the mark aligns with the edge of the housing.
- Screw the cover in place.
- Repeat for the other side.
Step 9 — Test Arm Movement
With the ignition in position 1, carefully bump the up-arrow console switch and watch the lifting arms. They should retract toward the element housing (released position).
Caution: Watch carefully that both round pegs on the lifting arms reach the element housing at the same time. The peg contact acts as a mechanical stop. If the arms are uneven, the unevenly loaded gear may strip.
Once alignment is confirmed and the slip clutch torque is verified, install the sunroof.
Adjusting the Locked Position
If the sunroof does not lock down tightly enough (pegs not hitting the correct part of the knee in the track), adjust by moving the two limit switches forward or backward:
- Moving switches forward → arms stop more toward the released position.
- Moving switches backward → arms stop more toward the raised/locked position.