Inspecting the Single-Pane Panel Before Fitting
Checking the replacement panel before it touches the roof opening is essential on this model because the design relies on an integrated perimeter seal rather than a standard direct-bond bead. Unlike the split panoramic layouts found on the larger X351 XJ, every trim of this saloon—from the Luxury and Portfolio editions through to the Supercharged and XFR—uses a single sliding tempered glass pane matching the factory C2Z26281 layout. I examine the factory-molded rubber edge encapsulation running the full boundary of the solar-tinted glass to confirm there are no splits, pinches, or flat spots. Because this perimeter seal directly compresses against the painted roof aperture to prevent highway cabin buffeting, even minor molding flaws will cause wind rush later. I also verify the ceramic frit border on the glass underside and inspect the integrated metal guide brackets bonded beneath the glass edge, checking that the threaded Torx receiver points are completely free of manufacturing burrs so the mounting hardware threads cleanly without binding.
Mechanical Alignment Along the Aperture
Once the glass is set into the opening mechanism frame (factory code C2Z22298), height and pitch alignment against the roof skin must be checked at all four corners. The panel is fastened directly to the sliding guide shoes, and any slight deviation in Torx bolt torque or tilt adjustment leads to annoying cabin clicks over rough pavement. I test the clearance between the rear edge of the glass and the sheet metal roof panel, ensuring the glass sits approximately one millimeter below the leading roof edge and flush or marginally above the trailing edge. If your glass broke suddenly and left the car exposed, I can generally be on-site around an hour after you book to get the cabin sealed against the elements. Correct physical alignment also avoids pinching the manually operated interior sunshade trim panel (C2Z15643) that travels on separate tracks just below the molded headliner assembly and side air curtain runners.
Cassette Drainage and Travel Limits
After the mechanical fasteners are torqued down, checking the cassette drain perimeter prevents moisture from ruining the interior trim. The drainage framework incorporates four corner spouts feeding down the A-pillars and rear pillars; I always confirm that water directed into the collection channels drains freely past the guide rails rather than overflowing toward the overhead switch console. Finally, the electrical drive system run by motor unit C2Z22297 requires a physical limit check. If the battery was disconnected during servicing, the module loses its position memory, disabling one-touch tilt and slide functions. I run the overhead roof console switch through its manual hold-and-release sequence to relearn the hard-stop boundaries, ensuring the anti-trap safety feature functions properly and the panel parks fully flush against the weatherstrip without binding against the motor tracks.
