With the additional weight of our roof basket and the camping gear we carry in it, we began to notice some weakness in the roof. The roof didn't seem to be able to support a load in the front third of the factory load-bar track. Applying weight caused the track and roof to deflect downward, and the rack's inertia would cause the roof to vibrate while driving over rough terrain. During our recent trip to the Four-Corners area the vibrations went from occasion vibrations to non-stop vibrations even when we were driving on smooth roads and the interstate. It had become severe enough that it was time to investigate and see if I could stiffen things up.
What We Found:
To gain access to the roof I began by removing the headliner from the 4Runner. This required pulling all the interior plastic side panels out; from the rear all the way to the front A-pillar. This process is fairly straight forward and can be accomplished in very little time. Once the panels were removed, I began removing the grab-handles, dome lights, rear-view mirror, sun visors, and the four plastic push fasteners holding the headliner in place.
With the headliner removed, the structure supporting the weight of the load-bar track became visible. Each track is supported by a stamped sheet metal channel which runs directly below and sandwiches the roof between the two. Two braces run between the load-bar track supports to add overall rigidity to the roof structure. To allow room for the sunroof to be retracted, the front one-third of the roof is left unbraced. I believe this lack of bracing is the cause of our vibration issues.
You can read about the rest of our project on our blog by clicking here.
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