Sloping rear glass and water

[PNWmisty]

Everybody knows water flows downhill. Living in wet Western Washington I might know the implications of this better than someone from a drier climate.

Still, I was surprised to discover that rainwater that beads on the rear glass tends to accelerate down the glass when opening the trunk and it shoots right inside (the trunk). Most cars have steeper rear glass and a wide gutter to catch this water and channel it to the ground. But the Model 3 just has a little blade type seal (in addition the thick rubber seal around the perimeter of the trunk). The thin blade seal acts like a ski jump for the water running down the rear glass and the water lands right on whatever is in the trunk.

I think this is a design flaw. Anyone else noticed this?

 

[scaots]

Yes! Was raining the other night and maybe it is ok running off the glass if not heavy rain, but when the extra from the trunk lid drops on it definitely runs into the trunk. There isn't much of a space there to catch it.

 

[PNWmisty]

Yes! Was raining the other night and maybe it is ok running off the glass if not heavy rain, but when the extra from the trunk lid drops on it definitely runs into the trunk. There isn't much of a space there to catch it.

I noticed it in a light rain, just enough to cover the rear glass with water beads. Then, when they decide to go, they merge with other drops and pick up speed going down the glass which is what allows the shedding water to follow the slight upward angle of the blade seal into the trunk. In other words, it's not how hard it's raining, it's the speed the water attains.

I think it could be solved by replacing the blade type seal with a curved seal so the water would follow the downward curve into the rain gutter. It looks like the only purpose of the blade seal is to reduce air pressure around the main trunk seal. But the trailing edge needs to point downwards (not back and out) to direct the water downwards.

 

[Nilroc]

I noticed it in a light rain, just enough to cover the rear glass with water beads. Then, when they decide to go, they merge with other drops and pick up speed going down the glass which is what allows the shedding water to follow the slight upward angle of the blade seal into the trunk. In other words, it's not how hard it's raining, it's the speed the water attains.

I think it could be solved by replacing the blade type seal with a curved seal so the water would follow the downward curve into the rain gutter. It looks like the only purpose of the blade seal is to reduce air pressure around the main trunk seal. But the trailing edge needs to point downwards (not back and out) to direct the water downwards.

Someone Tweet Elon. He will fix it. Just like he did with the Brake issue.

 

[garsh]

Someone Tweet Elon. He will fix it. Just like he did with the Brake issue.

A video demonstrating the issue would be quite useful here.

 

[PNWmisty]

A video demonstrating the issue would be quite useful here.

Sprinkling some water on the roof/back window while the trunk is open should demonstrate the issue. I will note that the car was facing a slight incline when I really noticed this and I don't think I've tested it with the car facing downhill or level. It should be possible to park on at least a slight incline without experiencing this issue.

 

[LUXMAN]

I assume ya’ll are just talking about when you have the trunk open while it is raining, just to be clear.
I t doesn’t go into the trunk while the trunk is closed, So I am not sure I would classify it a design flaw. More of an oversight or better yet, a trade off in design. Personally if it is pouring rain out, I am not standing there with the trunk open, and if I need something from the trunk during that time, it will be quick in most cases

 

[PNWmisty]

"It doesn’t go into the trunk while the trunk is closed, So I am not sure I would classify it a design flaw. More of an oversight or better yet, a trade off in design. Personally if it is pouring rain out, I am not standing there with the trunk open, and if I need something from the trunk during that time, it will be quick in most cases"

Wow! Maybe being from Lantana, TX explains your "devil could care" attitude about water from the roof draining into the trunk. But from my perspective in the Pacific North West, it's a definite design flaw. We spend 6 months of the year with cold, grey skies, getting constantly sprinkled on, occasionally it will rain moderately. If water is being channelled inside the car every time it rains and you briefly open the trunk, interior humidity levels rise, fog condenses on the windows, visibility is impaired and a general dank funk will develop. Don't get me wrong, I love rain and mist and cold weather, but no way does it belong inside my car - enough water already comes in hitchhiking on my jacket, pants and shoes. Not opening the trunk when it's raining is not an option, the trunk would stay closed for weeks at a time! In fact, the first time I noticed this I was in my covered carport. Just pulled in out of the rain, opened the trunk and proceeded to watch a couple of tablespoons shoot off the "ski jump" and land on the trunk contents. Being quick is not going to help. Those of you who live in drier climes can more fully appreciate this by reading "Sometimes a Great Notion" by Ken Kesey, a master of capturing the dark rainy climate that is the PNW much of the year. One of the best American novels ever written.

It's definitely a design flaw AND an oversight. It's not a trade-off in design. This problem has a solution that doesn't involve changing the aesthetic design (or the functionality). The trailing edge of the blade seal needs to curl downwards so it doesn't act as a ski jump but instead uses the natural surface tension of water to direct it to the existing rain gutter that surrounds the trunk opening.

 

[JeffinAZ]

Only rains a couple of times a year here in AZ but when it rains it pours!

 

[MelindaV]

being also in the PNW, 95% of the 'rain' I see here is misty drizzle and have not seen anything like the rain I've come across in Texas . They know how to do downpours

 

[LUXMAN]

Wow! Maybe being from Lantana, TX explains your "devil could care" attitude about water from the roof draining into the trunk.

Those of you who live in drier climes can more fully appreciate this by reading "Sometimes a Great Notion" by Ken Kesey, a master of capturing the dark rainy climate that is the PNW much of the year. One of the best American novels ever written.

Wow! Is right

 

[Kizzy]

Sprinkling some water on the roof/back window while the trunk is open should demonstrate the issue.

I'll head down to the nearest showroom to check that out. /s

It's definitely a design flaw AND an oversight. It's not a trade-off in design. This problem has a solution that doesn't involve changing the aesthetic design (or the functionality). The trailing edge of the blade seal needs to curl downwards so it doesn't act as a ski jump but instead uses the natural surface tension of water to direct it to the existing rain gutter that surrounds the trunk opening.

As someone who cares about water getting into the trunk of my car, this concerns me. I'm happy to hear that some consideration was made to channel water around the trunk opening. I too would be pleased with a modification to discourage water (more than the drips that are inevitable without some kind of force field tech) from free flowing into the trunk.

 

[2pix]

The water ski jump into the truck is real when you open it. I had to put a cloth in the truck to soak water back up. Just happens to be a rainy July/Aug in North Carolina. Has anyone been able to give this feedback to Tesla?

The thin blade seal acts like a ski jump for the water running down the rear glass

 

[MelindaV]

The water ski jump into the truck is real when you open it. I had to put a cloth in the truck to soak water back up. Just happens to be a rainy July/Aug in North Carolina. Has anyone been able to give this feedback to Tesla?

we have passed this comment over to tesla and it was being passed on to the engineering team.

 

[Hugh]

Nice examples after 2:20

 

[breadfan35]

I do think of it more as a design flaw. The same thing happens if it is raining or has rained and you roll down the window like say at a pharmacy or food drive thru. FWIW, it seems to be an issue with the Model S (and presumably the Model X) too. Demonstrated in this video:


This vid also demos the trunk issue as well. Hopefully we get an after market solution or Tesla themselves can design a better lip guard that seals as well as blocks the water better soon.

 

[garsh]

The root cause is the hydrophobic coating everybody puts on that rear window. I'm not saying that it's a bad thing to do - it's a great thing, has many benefits, and I will be doing it as well. But that's what causes water to accelerate down the rear window and gain enough speed to jump the trunk seal.

I'm thinking that a very simple solution to this problem is to put a hydrophilic (opposite of hydrophobic) coating on the bottom 1" or so of the rear window. This should cause the water to both slow down and spread out, hopefully to the point that it will no longer jump the gap into the trunk.

If nobody tries this out before I get my car, I'm going to do it. But I'd love for *somebody* to test my theory.

 

[iChris93]

The root cause is the hydrophobic coating everybody puts on that rear window. I'm not saying that it's a bad thing to do - it's a great thing, has many benefits, and I will be doing it as well. But that's what causes water to accelerate down the rear window and gain enough speed to jump the trunk seal.

I'm thinking that a very simple solution to this problem is to put a hydrophilic (opposite of hydrophobic) coating on the bottom 1" or so of the rear window. This should cause the water to both slow down and spread out, hopefully to the point that it will no longer jump the gap into the trunk.

If nobody tries this out before I get my car, I'm going to do it. But I'd love for *somebody* to test my theory.

Do you have a suggestion on what to use for the hydrophilic coating?

 

[garsh]

Do you have a suggestion on what to use for the hydrophilic coating?

I don't. Here's an Amazon search:
https://www.amazon.com/s/?rh=k:hydrophilic,i:automotive

It looks like most of the "anti-fog" products say they are hydrophilic. I think they're meant to be used on the inside of a windshield. I'll probably try one of those.

 

[MelindaV]

Just as a test, a strip on painters tape could see if garsh’s theory is worth applying any chemical substance to the glass