On my first Van I had a cargo carrier on the back of the roof with a ladder on the right rear door to access it.
I noticed that I was getting this buzzing vibration from it from time to time. This would go on most of the summer of that year and usually during mid morning. The cross pieces were stamped steel, but the side structures were aluminum tubing that were stamped flat on the ends or bolted up to where no air could enter them.
In time I came to realize that when the temperature was between 65 and 70 degrees F, that that's when the
buzzing vibration would begin. Above those temperatures or below it didn't happen.
The roof rack looked something like this:
I later purchased a pair of Ladder Racks that looked to be made by the
same company. I cleaned and painted them to where they looked like new
and took one of them and placed it at the front of the roof directly over the driver &
passengers seat.
Those racks looked something like these. I only used one of the two at the front.
I never got any vibration or buzzing sounds out of it. My reason for putting it there in the first place was to
attach my awning to it on the right side of the Van. (as seen in my Van Conversion website below)
Never could figure what the temperatures had to do with the luggage rack on the back though....but I could
bet on that happening every time the temperatures were in that range.
