Subaru Outback Moonroof Fix Kit

Project Milestones

Introduction

Many 2005-2009 Subaru Outback and Legacy Wagon models were equipped with a massive, multi-pane moonroof which gives an open-air, almost convertible feeling. This moonroof is a real highlight of the car, and so when my father's 2005 Outback XT's moonroof stopped functioning, I was determined to fix it. I searched the internet and Subaru Outback forums and learned it has become a fairly common problem as the cars have aged. Additionally, with the moonroof assembly being a non-serviceable and discontinued assembly, the only solution out there is to replace the entire assembly with a used salvage unit. That sounded difficult and expensive, so I went another direction, and this is the write-up for the development of the repair solution for this problem.

Project Requirements:

The repair solution must both fix broken moonroof mechanisms, and prevent future failure
The repair solution must be affordable and reasonably easy to install

The Glorious Subaru Outback Moonroof

Step 1: Root Cause Analysis

This was a very complex mechanism, and took many (many) hours studying its motion to determine A) how it works and B) why it stopped working over time. As with most car problems that only happen after 8-15 years, it came down to broken plastic parts.

The moonroof motor drives a cable, which pushes a plastic guide (RED ARROW)
To close the moonroof, the guide hooks onto a plastic mechanism shown to the left and pushes it forward
The motor knows when the moonroof is "closed" by sensing resistance force. The full force of the motor is sent into the small plastic mechanism every time the moonroof shuts.
When the motor's force is translated to this small plastic mechanism, it gets bent outward in the direction of the BLUE ARROW.
Over time, this force causes a stress fracture in the plastic mechanism, as shown below, and the plastic bends further and further out of alignment in the direction of the BLUE ARROW.
As the misalignment gets worse and worse, the small bushing (BLACK ARROW) either pops out of the aluminum rail it is in or it gets destroyed completely or both.
Once the bushing pops out or is destroyed on one side, the sunroof no longer can function.

Step 2: 3D Scanning

My best idea was to create a guide to support the mechanism, and prevent it from being bent outward. This guide would allow it to function as designed even with a stress fracture in the plastic. While this idea sounded simple, creating a guide which would use the existing phillips head fasteners would have been nearly impossible to design without a 3D scanner. The geometry was complex, and the moving parts made it very difficult to visualize where a guide would have clearance.

So, I pulled a (broken) sunroof assembly out of a salvage yard Outback, and prepared it for scanning with my Einstar Rockit. After scanning, meshing, and post-processing, I created 3 planes on the mesh and created a coordinate system, which would allow me to build a new guide that is aligned with the scanned mesh. This mesh was imported into Autodesk Fusion, and I was ready to create a 3D model of my "guide" concept.

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