Why Does Rear Windows of Some Cars Doesn’t Fully Rolls Down?


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Any reason why the windows roll down only 60%?? I mean this is new to me i have never heard of this before in any car!!
 
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Any reason why the windows roll down only 60%?? I mean this is new to me i have never heard of this before in any car!!
I think this for child safety. I think all fiat's car have this. Linea also might have.

Actually This happens in many other hatchbacks as well, due to wheel arches which doesn’t allows rear glass to roll down completely.

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350Z
I don't believe that, in modern age, there will be any technical challanges to achieve this.
 

350Z

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Not Really. The main reason for this is explained below:
When you roll down the rear window, It goes inside the door covering but due to the wheel arches, Its movement to complete bottom is restricted.

fiat_punto.jpg

If you carefully observe in some other hatches, Maruti 800 for instance or even a sedan. Their rear glass completely rolls down. Why? Look at the picture below:

maruti800wp02766034.jpg

The car has a quarter glass, So the area which will be occupied by roll down glass once you open windows wont be obstructed by wheel arches, hence glass fully disappears after rolling down.

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AFAIK the windows don't roll down completely because of the presence of the side impact beams. this holds good for the alto as i have seen the presence of the bar.
 
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Some said its design for air passage . esp for rear , where the owner sits and chauffeur drives

Some say child safety.

and i never felt the exact reason as vibhor said. Hope that must be exact one
 

350Z

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ilango[speed thirst];28290 said:
and i never felt the exact reason as vibhor said. Hope that must be exact one
It is actually the reason which is believed not only by me but among many other people who are into automobiles.

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Yes, even i am not sure the exact reason, but Vibhor's explanation does make sense.

I think even Polo does have same 60% roll down.

But if you see Figo side profile, it should not have this issue.
 

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350Z

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If I'm correct, the glass completely rolls down in most of the sedans and Yes, as sriharsha said, Side Impact Beams matters too.

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Let me add my bit.
What Vibhor said is exactly correct.
Full glass drop is affected by the wheel arch ... this can be avoided by either the M800 solution, so well illustrated by Vibhor again, or by using a sash with some area of opaqueness. This is the approach used in the Alto or the Figo etc. In this approach, if you want a full glass drop, you will need to have a larger area of 'black', but mostly, manufacturers compromise, and minimize the 'black' by letting the glass stay up maybe a couple of inches from full drop.
A very inventive approach to this problem in marketing is to say that this is a safety feature, if the rear glass does not drop fully, the chances of a kid leaning out (or falling out!!) or even throwing something out of the window are minimized.
Regarding the Door Beams being a factor in this, I would say no. Unless the design of the car is very very bad, you can always avoid the interference of the door beam with the glass travel. It is only a matter of ensuring the proper stack-up of all the parts in the depth of the door.
Additionally, if that were the case, we would have the same problem in the front doors too, would we not??
 
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Good explanation Vibhor and Adithya!!

Adithya skills to the fore after having worked with MSIL for building the Swift!!
 

350Z

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Absolutely correct Aditya, You got a valid point there about impact beams.

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350Z

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It is actually just a gimmick to present a drawback as feature! Does it means owners of Mercs, Volvos etc (read safe brands) allow kids to wave their hands outside windows? :biggrin:

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