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Hood Vibration

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Old 10-29-2018, 11:22 PM
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Default Hood Vibration
Every time I use a touchless car wash I notice a ripple effect on the hood when the car goes through air dry. I first thought it was optical distortion but it is not. Here is a video of a Q7 doing the same thing. Anybody else have noticed this?

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Old 10-30-2018, 04:07 AM
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As they are made from aluminium I guess this is normal for weight saving. Very easy to dent the bonnet and the front wings as well..
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Old 10-30-2018, 08:47 AM
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According to Audi's press materials, the hood and front fenders are still made from steel on the A4.
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Old 10-31-2018, 08:28 AM
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https://www.repairerdrivennews.com/2...more-aluminum/ Aluminium hood there, or bonnet as it is correctly known ;-)
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Old 10-31-2018, 12:46 PM
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The hood is probably flexing, it's not infinitely rigid. If the air drier is hot, there could be some optical distortion in there due to the changing refractive index of light through hot air.
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Old 10-31-2018, 02:26 PM
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Originally Posted by chych
The hood is probably flexing, it's not infinitely rigid. If the air drier is hot, there could be some optical distortion in there due to the changing refractive index of light through hot air.

It is definitely flexing. Looks like the A4 and Q7 have very light aluminum hoods.
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Old 10-31-2018, 02:41 PM
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It definitely flexes. I’ve noticed it in both my A4 and SQ5.
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Old 10-31-2018, 02:52 PM
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Originally Posted by marz1



It is definitely flexing. Looks like the A4 and Q7 have very light aluminum hoods.
The figure in the referenced link indicates that the hidden/bonnets cold formed steel. I checked it with a magnet and it is not aluminum.
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Old 10-31-2018, 09:00 PM
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The hood is mostly steel. Like SchwarzS6 mentioned the magnet sticks, and the guy that did paintless removal on my A4's hood only charged me the steel rate.
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Old 11-02-2018, 07:32 AM
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Yes you are correct, it is the Q7 that is largely aluminium:

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