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?

[celicalibre]

My 1999 vert is garage kept and driven for pleasure and long trips. Also has been exposed to various weather conditions -- rain, storms, high winds, etc.

Never have I experienced any vibration or handling problems at low or high speed. In fact, just the opposite -- one of the most stable handling cars I have ever owned!

Question: Was your recent spin balance done because of the vibration or was it done before you noticed the vibration? First place to re-check if done before you noticed the vibration. If it is an alignment problem, then usually a front end gentle rock or sway might occur at low coasting speed. But the balance and alignment are basic items to recheck.

Next item are tires - is one of them "separating or developed a slight bulge in the tread?" This will definitely cause a new vibration!

____________________________________________________________
__________________________

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?

[thymeclock]

My 1999 vert is garage kept and driven for pleasure and long trips. Also has been exposed to various weather conditions -- rain, storms, high winds, etc.

Never have I experienced any vibration or handling problems at low or high speed. In fact, just the opposite -- one of the most stable handling cars I have ever owned!

Question: Was your recent spin balance done because of the vibration or was it done before you noticed the vibration? First place to re-check if done before you noticed the vibration. If it is an alignment problem, then usually a front end gentle rock or sway might occur at low coasting speed. But the balance and alignment are basic items to recheck.

Next item are tires - is one of them "separating or developed a slight bulge in the tread?" This will definitely cause a new vibration!

The spin balance was done when the 4 new tires were mounted. The tires are Kumho Ecsta 4X 's. They have about 1K miles on them by now, at most.

As I mentioned, the old tires were worn evenly, so it's not the alignment. While I was experiencing the vibration, of course I thought that the wheel balancing might not have been done properly - but that would not account for the vibration disappearing completely with the top down. (I've been driving for more than 40 years and have owned various convertibles throughout my adult life.)

There is only one other possibility that I can think of. My previous convertible was an '89 Celica that I bought used. I had that car checked by a mechanic before I bought it. After I bought it I noticed weird, unstable handling at speeds of over 50 MPH. The tires that came with it were Dunlops; when I checked the tire pressures I found that the previous owner had them inflated to over 40 PSI. I reduced the pressure to about 30 PSI and the unstable handling problem disappeared. I wasn't happy with the Dunlops and when they needed to be replaced I bought Sumitomo's which worked great, even when overinflated.

Now back to my current '99...

When I put the car on the road in May and installed the new tires, I inflated them to 40 PSI. Over-inflation gives a harder ride, but good MPG, as expected. Considering my previous experience with the Dunlops, this is the only other possibility I can think of that might be the cause. In this case it's not quirky handling, but rather vibration. Some tires have no issues with over-inflation, but some tires (as in the case of the Dunlops) apparently DO. (My wife's car has a cheap set of Kumho tires and shows no handling or vibration issues with their being over-inflated at 40 PSI.)

This link seems to affirm it: click here


After my trip I checked the tire pressures when cold and found them to be at 37 PSI. I have now reduced the pressures to 32 PSI. Unfortunately, since I live in a citified area, I can't drive much faster than 65 anywhere around here - so I won't be able to replicate the conditions of having top up and going 75-80.

It still doesn't explain why the condition disappears when the top is down though. (Which is why I started this thread...)

This post has been edited by thymeclock: Jul 25, 2013 - 1:27 PM