For enthusiasts of classic BMWs like the 635 Csi, maintaining its original features is paramount. One common area of maintenance, especially for models from the 1980s, is the sunroof. Whether due to age, wear and tear, or rust, sunroof replacement can seem daunting. This guide, originally crafted by a fellow BMW owner, details the process of removing and refitting a sunroof on a 1985 BMW 635 CSI. While initially time-consuming, understanding a simple trick can significantly reduce the effort and time involved in this DIY project.
Sunroof Removal Procedure
Before you begin, it’s crucial to organize your workspace and tools. Keep a note of where each screw and component is located during disassembly. This will be invaluable when you’re putting everything back together.
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Initial Sunroof Opening: Begin by opening the sunroof to approximately 10cm (4 inches). This initial opening provides access to the headlining section.
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Headlining Disconnection: Carefully unclip the headlining section that is attached to the sunroof. Once unclipped, gently push this section back into the roof cavity to keep it out of your working area.
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Full Sunroof Opening and Mechanism Access: Open the sunroof fully. This will expose the sliding mechanism and the various screws that need to be removed.
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Front Bar and Side Rail Disassembly: Locate the frontmost bar of the sliding mechanism. Unscrew the seven screws holding this bar in place. Next, identify the side guide rails. You’ll find two of these, each secured by three and two screws respectively. Unscrew and detach these side guide rail pieces.
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Tilt and Detach Sunroof: Close the sunroof completely, and then tilt it upwards into its vent position. You will now see six nuts that secure the sunroof to triangular brackets. Unscrew these six nuts.
With these steps completed, you should now be able to carefully lift and remove the sunroof from your BMW 635 CSI.
Sunroof Refitting Procedure – The Key is Temporary Guide Rails
Refitting the sunroof can be more challenging and time-intensive than removal. A critical point to remember, especially if you are installing a new sunroof, is that the alignment might differ from the original. The procedure requires fitting the sunroof, sliding it back, and then re-attaching the side guide rails. A common issue encountered is that the regulator cables (which connect to the motor and control sunroof movement) can obstruct the sunroof from opening fully during refitting because the guide rails are temporarily removed. The solution? Temporary guide rails.
Before starting the refitting process, it’s highly recommended to clean off any old grease from the sunroof mechanism and apply new Vaseline. This ensures smooth operation and prevents future sticking or stiffness.
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Fabricate Temporary Guide Rails: Create two temporary guide rails. You can repurpose materials like an old cracker tin lid. Cut two strips approximately 2cm by 10cm (or 1 by 4 inches). Precise dimensions aren’t critical. These strips will temporarily mimic the function of the guide rails.
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Attach Temporary Rails: Position these temporary strips on the sides where the actual guide rails will be reinstalled. Secure them using screws, ensuring they are long enough to cover at least two of the three screw holes for the guide rail. The primary function of these temporary rails is to keep the regulator cables in place, preventing them from lifting and blocking the sunroof’s movement.
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Initial Sunroof Attachment: Carefully position the sunroof back into the opening. Using two of the three nuts on the triangular brackets on each side, loosely attach the sunroof. Do not tighten them fully at this stage, as adjustments will likely be needed.
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Headlining Reattachment: Properly reattach the headlining piece back to the sunroof. Ensure it is correctly positioned to allow for its full range of motion without obstruction.
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Slide Sunroof to Open Position: Slide the sunroof all the way back to the fully open position. This step is crucial and should now be possible because of the temporary guide rails keeping the regulator cables in check.
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Replace Temporary with Permanent Guide Rails: With the sunroof fully open, remove the temporary guide rail strips you fabricated earlier. Replace them with the actual side guide rail pieces, screwing them securely into place.
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Sunroof Closure and Adjustment: Close the sunroof. It may not close perfectly on the first attempt. This is where adjustments come in. You might need to temporarily detach the headlining again for better access. The two rearmost screws on the side guide rails (the non-countersunk ones) are key for adjusting the closure position. Experiment with these to achieve proper alignment. For left-right adjustments, use the nuts on the triangular brackets. Up-down adjustments are controlled by the frontmost Phillips screw on each side (anodized yellow), visible when the sunroof is tilted.
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Final Checks and Tightening: Fully open the sunroof once more. Clean any fingerprints or grease from the top surfaces for a tidy finish. Thoroughly check that all screws and nuts are tightened securely.
Important Safety Tip: Exercise caution during the adjustment phase, particularly when testing the sunroof’s movement. Ensure no body parts, especially your head, are in the path of the sunroof panel when it’s being operated, especially if someone else is controlling the buttons.
Replacing a BMW 635 CSI sunroof can be a satisfying DIY task. While it might initially seem like an all-day job, the temporary guide rail technique significantly simplifies the refitting process, potentially reducing the working time to just a couple of hours. With patience and careful execution of these steps, you can successfully restore or replace your classic BMW’s sunroof.
