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Dirty Rear Window

7K views 34 replies 21 participants last post by  JimmyH^_^ 
#1 ·
hey,

Just wondering if anyone else living in cold/snowy areas are getting this issue. The bottom window of the trunk which is on the back just above the license plate seems to get so dirty I can't see through it anymore. I've gotten out of the car and used snow to clean it up and not even an hour later it was all dirty again.

anyone else have that issue or is my neighborhood extra dirty? lol
 
#22 ·
Um, every 2-3 days at most. :p

I've noticed that part gets super dirty. We've had a ton of snow this winter already & it's filthy all the time. I've just been running the defroster a lot (which helps melt the ice/snow & it runs down the back & cleans it off a bit) & wiping it off every couple fill-ups (as well as physically brushing it when I'm cleaning the snow off--which has been every few days). Oh, and I've ran it through the cheapo car wash a few times to get off the salt & clean up that back part.

Intrigued by the polymer stuff...some night's it's so bad I can barely see through it when I'm parking (street/parallel park it).
 
#12 ·
Due to the aerodynamics of the car, yeah, dirt collects on the rear end badly.

I've been using this stuff, Opti-Clean, that cleans it and leaves a layer of polymers on the car.. The polymers are hydrophobic so repel water and grime as much as possible.. And also they aren't really meant to bond w. the paint like a sealant, so it's easy to wipe away.. I'm not explaining it well, but basically dirt just falls off the car.
I've been seriously impressed.
There are other similar products from most of the modern polymer sealant companies....

-- edit -- actually, thinking about it, I also have a layer of the polymer sealant on the car.. Opti-seal in my case, but Zaino and the other polymer sealant brands are similar. They all shed water and dirt very well.. So if you haven't used one of them, I'd recommend it. This is the first car Ive ever used these polymer sealants on, and like I said a sec ago.... Ive been very impressed! dirt doesnt stick.
 
#17 ·
I think the aerodynamics of our car is the problem with dirty rear. Its not just the window, it gets dirty where licence plate goes. Iv been noticing hatches get dirty in the rear fast.From my understanding, All the dirt and airflow that comes through bottom of the car turbulates and hits the rear window area and then leaves with the flow of wind thats coming fromthe top of the car.
 
#19 ·
Dirty Back Window

The reason the back window is getting dirty so fast is because of what is called the station wagon effect. Water and dirt comes up from underneath the rear of the car and coils around to stick to the verticle surfaces (such as the small window). If you have ever had an SUV you may have noticed that the back of the vehicle always accumulated the most dirt. Same thing. The only solution is to have a spoiler on the rear which has a space between it and the body. This type of design grabs air and directs it down to counteract the air coming up from underneath the rear of the car. So far I have not seen this type of design offered. I installed a factory spoiler on my car but it is flush mounted so it is of no help. I am toying with the idea of remounting the spoiler a bit off the car but the thing is so flimsy that I think air pressure beneath it might just destroy it!
 
#20 ·
The reason the back window is getting dirty so fast is because of what is called the station wagon effect. Water and dirt comes up from underneath the rear of the car and coils around to stick to the verticle surfaces (such as the small window). If you have ever had an SUV you may have noticed that the back of the vehicle always accumulated the most dirt. Same thing. The only solution is to have a spoiler on the rear which has a space between it and the body. This type of design grabs air and directs it down to counteract the air coming up from underneath the rear of the car. So far I have not seen this type of design offered. I installed a factory spoiler on my car but it is flush mounted so it is of no help. I am toying with the idea of remounting the spoiler a bit off the car but the thing is so flimsy that I think air pressure beneath it might just destroy it!
Mugen spoiler?
 
#21 ·
ugh i hate how dirt and dust gathers into the rear=.= i try to open the hatch carefully so i dont get my hands dirty from the car.lol....
 
#24 ·
Tried RainX, It doesn't help. The rear just collects dirt. The spoiler doesn't seem to help either. The rear window is useless. The wiper is for the most part useless. Get good with the side mirrors.

I wash this car several times a week and the rear is still always dirty.

I think I need car wash therapy.
 
#27 ·
Flaps won't help much- the crud isn't coming up off the road so much as being pulled around the sides of the body, and down off the roof, and being "pasted" onto the glass by airflow. Same as the backup camera's lens being a raindrop magnet.

Trivia bonus: VW did aero studies in the eighties- a roof rack would cost 15% in drag, and mudflaps -regular "stylish" splash flaps, not trucker flaps- cost 7%.

At least we have a wiper for the roof. rolleyes.
 
#29 ·
Trivia bonus: VW did aero studies in the eighties- a roof rack would cost 15% in drag, and mudflaps -regular "stylish" splash flaps, not trucker flaps- cost 7%.
That seems like an unrealistically exaggerated number for splash guards and since its from the 80s is very outdated automotive data.

We know now that adding surfaces and things that look like obstructions that would impede airflow or fluid dynamics can actually be a benefit, like the CR-Z having the plastic 'strakes' in front of each tire. Those actually create turbulence, or breaks up the linear direction of air in front of the tire that improves aerodynamic efficiency despite the fact that they would appear to the untrained eye to be plastic air stoppers. A few members incorrectly removed them thinking they were detrimental to aerodynamic efficiency when in fact they're the contrary, a benefit to aerodynamic efficiency.

Modern mud flap designs on large trucks for example can actually reduce drag to the point where its impact is nearly 0, the same with or without them and they can help prevent the recirculation of water and air improving vehicle performance.
 
#31 ·
...Or that all them slats and strakes and ladders and everything are on Formula 1 cars for anything more than looks.

This season starts Sunday. Don't forget.
Thanks for the F1 reminder--I never missed a race back when Senna was in the mix, but since then, I just keep up sporadically.

But, doesn't Formula 1 have a fix for dirty visors--Tearoffs. Our CR-Z babies need a tear-off diaper of sorts for that lower rear window. I'll start working on that now, Lol.:wink2:
 
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