ride height noise roof

[Rodolfo]

I noticed that the back of my car is quite high.Also I have a lot of trembling wind noise at higher speeds with softtop and hardtop . But not if I accelerate at those speeds (nose comes up then).So is it possible  I have more noises of the wind just because the backside of the car is to high? Anyone had same experience ?

Rudy

Ps if some bad spelling : typed on a phone

[Peter van Es]

Search for "ride height" on the forum. You'll find many posts on here about what ride height is correct and how to measure it.

Don't know if it should affect wind noise though... Could it be noise from the suspension that you are hearing?

Peter

[Rodolfo]

Thanks Peter for your hint.

But although I saw some articles about ride height, I didn't saw anything mentioned about the wind noise connected to it. But this is what I seem to experience. If the suspension in the back turns out to be too high and this affects the air noise, I can look in these forum subjects how to lower the back end of the car.

But what I am really interested in is that the wind noise would go down. This idea comes to me because when I drive for instance 120 km/h the soft-top is wobbling: I can feel that by holding my hand against it. In engineering terms: there are waves in it at an "Eigen frequency". (so called resonation). The soft-top although is fitted tight. If I then accelerate the wobbling goes immediately away as long as I accelerate (car nose goes up under this, of course). But as soon as I put my foot of the accelerator it stops. At any speed above 100 km/h. So it is definitely influenced, it seems, by the attack angle of the frontal wind.

Also with hardtop installed I notice this effect (no wobbling, but now a whistling noise of the wind goes don (PS I retract the antenna, to suppress that effect)). Front rubbers seems ok on both roofs.

If this seems to be caused by the height of the back , I will dive deeper in how to lower the car at the back end.

Anyone else had this effect?

Rudy

PS anyway I could give it a try to load the car in the bonnet quite heavy as an experiment. This  to find out by a lower back end I would have less whobbling caused by wind.

[Peter van Es]

With my car I notice no pronounced front or rear droop, it appears "normally" level (but I've done no scientific research).

I do know that when driving at speed (120km/h++), I prefer to drive top down. When driving with the soft top I can feel soft top wobbling as well. That would appear normal to me. With the hard top, I just hear lots of noise, and when I go that fast, the windows want to pop out of their rubbers (there is a hint on this in the MB handbook as well, see post: http://www.sl113.org/forums/index.php?topic=18185.msg127266#msg127266)

Peter

[stickandrudderman]

Interesting observation. Any mention of angle of attack (AOA) always peaks my interest!
It is strange that the noise goes away when you are accelerating.
I just recently drove a car that had the same resonance from the soft top at speed, something I haven't noticed before. The roof on the car I drove is very tight as it's a new one that hasn't been left in the up position for any length of time on order for the material to stretch.

[Cees Klumper]

I just drove from Geneva to Guoynvelle (260 km) at speeds upwards of 100 km/hr with the soft top up, and there no windnoise or wobble. Never noticed it before either, at any speed. The canvas is tight. Also I don't remember anyone else reporting this problem before here. Try lowering the rear and see what happens.  Does your top latch tightly, and do you have a good seal between the top and the top of the windshield?