# Why do the Model 3's windows roll down when you open the door?



## PatrickM

Does any one know why Tesla designed the doors and windows on the Model 3 such that they roll the window down slightly when you open the door? I can see it's so that the windows clear the trim, but why did they do that? Why not just make the windows such that they go past the trim without that little pull down of the window? Is it for aerodynamics or something else?

Thanks for any insights.


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## Rich Nuth

As you stated, its to clear the trim. The reason for this is to ensure a tight seal to eliminate wind noise. Without the overlap, the window system can allow flex and enable air leaks at the gasket which can be really annoying. The overlap alows for a tight window to gasket seal.


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## Brokedoc

And repeated use of the manual release door handle (which doesn’t cause the window to drop) will tear the rubber trim.


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## TrevP

It’s to clear the chrome trim and create a positive seal for the windows


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## PatrickM

Thanks everyone. It still seems like a complex solution to the problem, but I'm glad that I know understand why they did it.


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## Dogwhistle

I guess the follow-on question, why not just do framed windows? Less complex, right? Easier to seal?


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## Maevra

Dogwhistle said:


> I guess the follow-on question, why not just do framed windows? Less complex, right? Easier to seal?


Maybe to save a bit on weight, but my guess is mostly just aesthetics.


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## MichelT3

Frameless windows are more aerodynamic, because the frames cause drag. 
I expect that when windows move up they also tighten against the trim and in the door. Preventing rattle and airleaks.


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## Guest

MichelT3 said:


> Frameless windows are more aerodynamic, because the frames cause drag.


Only if framed doors are design poorly. Same applies to poorly designed frameless windows.

Reason why Tesla does frameless style is due to simplicity. Framed windows, AFAIK, are noticeably more complex with not a lot of pros.


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## garsh

arnis said:


> Only if framed doors are design poorly.


There's still an extra cutline for the door frame, no matter how well it is designed.


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## Maevra

garsh said:


> There's still an extra cutline for the door frame, no matter how well it is designed.


So... frameless windows = less panel gaps = less headaches for Tesla?


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## Guest

garsh said:


> There's still an extra cutline for the door frame, no matter how well it is designed.


But it is (can be) flat... aka frame is on the same plane as body. In terms of aerodynamic drag, it doesn't change Cd. I bet inconsistent panel gaps Tesla produces matters more.


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## OrangeJulius

PatrickM said:


> Thanks everyone. It still seems like a complex solution to the problem, but I'm glad that I know understand why they did it.


Other manufacturer's cars do this window hop as well. It's not unique to Tesla.


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## MichelT3

Obviously, inconsistent gaps are just that; inconsistent. Thus, gaps that shouldn't be big. AFAIK there may have been inconsistent gaps at the beginning of production for Tesla workers, but they are not there any more in the current production models.

Further: by definition a frame can be in the plane of the body panels, but the glass will never be - with frames.
However, frameless glass can be in the plane of the body panels. And it is.

Actually, doors with frameless windows are more complicated; controlling the position of the window.

EDIT: Yes, @OrangeJulius, 'window hop' is also done by other carmakers with frameless windows. Often those windows also move inward on that last inch.


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