sorry guys, but I did a search and didn't find what I was looking for.

the weather has broken here and it's top down time again.
after golf yesterday I dropped the top for the ride home and got that ol' feeling again, at speed vibrations.

last year, I went standard low profiles (michelin pilot sport a/s plus) and was happy with the new ride.

over the winter with the top up, the ride is perfectly stable. with the top down attributed vibration has surfaced again. the tires are inflated within spec (no warning light), so the question is, what have you done to address the top down vibration issue? stabilizer bar? if so, what did you do? anything else?

thanks for the advice. jimmer

 

can you be a little more specific about the vibration. Like the whole car shakes or just the steering wheel? and you only notice this when the top is down? can you tell if its coming from the front or rear. Normally vibrations on lexus's are caused by the rims/tires out of balance, sometimes alignment.

 

Could be something as simple as retorqueing lug nuts.
After switching off the run flats to standard tires, the folks that did the swap said to bring it back in after 200 miles to retorque the lugs. I did, and they needed it. May not be related to your problem, but it's something simple worth checking.

 

hey,
the vibration is a total car body thing. quick, repetitive, not quite jaw jarring, but annoying.
it can be diminished or resolved by adjusting the lane position.
that said, it could be the lug nuts, but after the new wheels were on for 150 miles, I did have the tire shop readjust them. I may need to go there and try again. thanks for the thought.
before the new wheels and tires, I did have it 'road force balanced.' that helped a lot.
with the new wheels/tires the vibration seemed to go away. then the other day, first time this year with the top down, the vibration came back. I'll try the retorque tip and let you know how it worked.

jimmer

 

I hada similar problem when my car was new -- you could see the rear headrests vibrating in the rear view mirror. It turned out to be a rear wheel allignment issue.

 

my tire guy did a complete check-up, nitrogen, alignment and found the right front out of whack. I haven't had the top since, so we'll see if that was it the next time the top's down.

 

OK, I fixed the alignment issue, but back to why I originally posted, car stability with the top down.
what have you done to help eliminate the wobbly feel when driving over uneven road surfaces, with the top down.
seems that without the top up, the car looses structural stiffness.
any suggestions to firm up the ride?

 

My opinion is that any convertible has less structural integrity than a hardtop. Our cars seem to have more integrity, and tend to mimic a hardtop's integrity, with the top up. What you may be experiencing is what is commonly called "cowl shake". When hitting bumps or driving over uneven surfaces with the top down, you can sometimes feel the dashboard, and see the windshield, flexing from side to side. Since ours cars were built to be a convertible, this behavior has been reduced, but not eliminated. Drive an old ragtop from the 70's, and you will get a lot of cowl shake. Just another minor issue to put up with when open top motoring. Don't worry - be happy!

 

thanks, marksblusc.
I owned a '72 Merc 450SL that was as solid and firm with the top down as it was with top up (a manual rag top). That's what I have to compare to the SL430. It's no deal breaker -- I love the car, but thought there may be a suspension adjustment or stabilizer bar addition that would remove some of that cowl shake and wobble-effect . I'm afraid, that at some point, the car may really loosen up with miles and years of top down shakin'.