Attention convertible owners: READ THIS!, Vibration from design of convertible top Options

[thymeclock]

I recently experienced a bizarre situation with my Celica convertible and I would like to hear comments and experiences from other convertible owners.

I have a ’99 Celica convertible that I only drive in summer and it is garaged the rest of the year: It has 57K miles, with brand new tires that were recently spin balanced. I live in suburbia and most of my driving is local, with occasional highway speeds of 65 MPH at most. If it isn’t raining, the top is always down, so I rarely drive with the top up.

I recently drove 200 miles on a trip into the rural countryside. Due to a thunderstorm my car was all wet so I had to drive back with the top up, as the weather was unsettled. The rain had stopped, it was merely cloudy and there was no wind. While driving on an interstate highway at speeds of 75-80 MPH I noticed an unusual vibration in the steering wheel and throughout the entire car. It seemed worse on a downgrade and somewhat better when turning or on level ground. This was very disturbing, as considering the excellent condition of the car and having practically new tires, there was nothing to account for it. The vibration condition continued for 50 miles, during which the sky cleared and the top became dry. I stopped at a rest area and put the top down. I continued my trip, purposely driving at the same relatively high speed – and the vibration disappeared entirely. With the top down, there was NO further vibration whatsoever!

There is only one conclusion I can draw: The convertible top on a ’99 Celica plays havoc with the aerodynamics of the car when driven at higher speeds. My previous convertible, a ’89 Celica didn’t do this – but that car had a much narrower track width and a smaller convertible top.

Comments? Has anyone else noticed this?