Roof wing's affect on rain?

[S14DB]

I get a lot of hard rain throught the year. One problem I have with the S14 is no rear wiper on the USDM. I use rainx and all that jazz but the problem is the way the air flows around the car. Coats the rear window with a mist that's hard to see out of but not dense enough to bead and run. Also always have a ton of dust on the glass and trunk too.

If you have installed a roof wing how has it changed the flow of rain on your rear glass?

[98s14inaz]

My guess would be making it worse. The roof spoiler is going to divert more air away from the rear glass.

[2fast240]

It should create a low pressure zone on the rear window, if it is high enough, it should deflect the rain over the window at highway speeds. I'm sure some manufacturer has done air tunnel tests that has a graph that could show the airflow, since I'm bored at school I'm gonna try to find a graph or something.

[Matej]

In my opinion its effect on the rain would be very similar to an open sunroof's effect on the rear portion of the roof.
I can't get a roof wing because it would render my rear window sprayer useless haha, unless I wanted to wash my roof wing while driving.

[Jay Shev]

It should create a low pressure zone on the rear window, if it is high enough, it should deflect the rain over the window at highway speeds. I'm sure some manufacturer has done air tunnel tests that has a graph that could show the airflow, since I'm bored at school I'm gonna try to find a graph or something.

Maybe if you are traveling at a very high rate of speed, but probably not within the confines of the local area speed limits.

To the original poster- Learn to use your side mirrors if its that bad. I have 5% tint on my Z32 rear window and it has been rendered useless, but with SMs I have no problems....

[DaPCWiz]

I have a smaller roof spoiler on my S14. I don't think I've really noticed a difference in the rain on the rear glass. Truthfully I haven't specifically thought about it... but no notable difference has caught my attention.

my roof spoiler -
http://memimage.cardomain.net/member_images/9/web/2325000-2325999/2325110_66_full.jpg

[sbanzer123]

wow i really like the look of your car!

[S14DB]

To the original poster- Learn to use your side mirrors if its that bad. I have 5% tint on my Z32 rear window and it has been rendered useless, but with SMs I have no problems....

I would have side swiped a lot of people if I didn't learn to use them. It's just annoying to have a good portion of your rear view gone. Even worse at night.

[LongGrain]

i have the same problem with my fastback, but ive just learned to get used to it.

[hustlervibes]

That's odd, I've never had that problem with my S14. The rain normally just slides off once I get up to highway speeds. I noticed if I have my windows slightly cracked open (have rain guards) I can see the air flow change and go from the top corners and slope inwards toward the center of the back window. Also I use the window defogger and it seems to help a little.

[SW20Racer]

old chevy blazers and the like have roof spoilers that are used to keep dirt and dust from collecting on the rear glass. but those are usually at a funky angle, and they can be adjusted.

so i guess you could borrow the basic design and have it fabbed up to fit the 240

the idea behind their design is to angle the rear lip of the spoiler (which will become the "bottom") more towards the glass forcing the air it catches over the glass and moving the water/dirt et c.

[PoorMans180SX]

Vortex generators would solve your problem.

They create a small vortex that keeps the airflow stuck to your rear glass more.

Website looks a little cheesy, but do a little reading:
http://www.airtab.com/

[eastcoastS14]

buh rear defroster?

[S14DB]

Vortex generators would solve your problem.

They create a small vortex that keeps the airflow stuck to your rear glass more.

Website looks a little cheesy, but do a little reading:
http://www.airtab.com/

Like the idea but:
Each Airtab® is 3.25" wide x 4.76" long x 1" high.

kinda big for the rear glass.

[yokotas13]

that shit is HUGE
i was thinking about getting some for the roof and rera wing, but FUCK thats big

[LB.Motoring]

heres a pic on the rear,

I wanna try some on the bimmer, for the hell of it, around my shark fin lol.

http://www.airtab.com/Images/gallery/Jet/jetcar1.jpg

there only 2.50 each, so what the hell.

[S14DB]

What car is that?

[LB.Motoring]

2door chassis fiberglass shell,

a funny car,

but the same size as a regular car.

they are using it for 250mph stability.

[chituntang]

Does somebody make the roof spoiler like the one STI has?

[LB.Motoring]

Heres an article.

http://autospeed.com/cms/A_3061/article.html

[PoorMans180SX]

SCC used them (airtab) on their project Impreza
and tested them on their project Corolla.

or you could just use the Evo-esque ones like RHD japan has.

[LB.Motoring]

heres more Info,


alot of it,

http://www.cleanmpg.com/forums/showthread.php?t=1496


the evo ones are 20 bucks for 10 of them.

[Daniel.]

I have to attest to the effectiveness of vortex generators. I recently picked up a cf VG for my evo.

I have to say that before I got it, the rain would cover my entire rear glass. After I installed it, I hardly ever use the rear wiper anymore. Awesome.

[sideview_180sx]

a guy in portland tested them on his cooper S. both on street and at the track. he went slower and his gas mileage didn't change. it also created a whistle on the back of his car.

[SW20Racer]

a guy in portland tested them on his cooper S. both on street and at the track. he went slower and his gas mileage didn't change. it also created a whistle on the back of his car.

the aerodynamics on that car are also really twacked out.

i'd put money on the claim that my tercel has better flow characteristics than a cooper

[S14DB]

wonder if I can get away with these on the glass or will I have to mount them to the roof.

[SW20Racer]

wonder if I can get away with these on the glass or will I have to mount them to the roof.

they should be at a slight angle. you might be able to place them on the glass, just test fit them while comparing to the relative placement on an evo. when you get close to the same angle you should be good (in terms of proper air flow) in regards of where they are placed, would it be a problem if they were on the roof instead of the glass? (looks wise) like would that be a deal breaker?

[S14DB]

I would have to mount them to the paint and paint them to body color. I can leave them black on the glass and then just scape them off if they don't work out.

[buku_points]

yea what this guy said, i believe they come one the 07-08 sti's? i wanted to buy on and test fit it on my s14 but i got no luck so far.

Does somebody make the roof spoiler like the one STI has?

[PoorMans180SX]

a guy in portland tested them on his cooper S. both on street and at the track. he went slower and his gas mileage didn't change. it also created a whistle on the back of his car.

Read that article link above. They don't really help when put on the trailing edge of cars that have a boxy rear profile.

S14DB, stick them on the roof the day before it rains with something easy to remove. Test them in the rain before putting any work into them, and do what you want after that.

I really don't think they look bad when painted body color, and plan to do some yarn testing on my fastback (even though I know it has good aero) just to see what's up.

Maybe I'll mount some under my bumper like that article says.

Oh, and BTW, for everyone interested in real aerodynamic improvements, roof wings don't help, they hurt. True wings (GT wings) are so much better at creating downforce with less drag, because they don't increase the area of vacuum anywhere around your car like spoilers (roof wings) do. Obviously there is some personal taste involved in the looks department.

[DaPCWiz]

Okay - so to revive this thread... and back to the original question.

I've been watching my rear window in the rain lately. Also noticed this over the winter with ice.

When there is anything on my rear glass... from the bottom part of the glass, it works its way UP the glass to about the middle. From the top part of the glass it works its way down to the middle. It then hangs out kind of almost making circular or up/down patterns in the middle of the glass, slowly working its way to the outside and then finally off the glass.

Its very noticeable with chunks of ice... its somewhat noticeable in the rain. The glass is usually fairly clear of water based obstruction below this line where everything likes to migrate to.

I also have a navan spoiler... so idk how that effects air flow / rain flow...

[INeedNewTires]

use rain-X and fog-X and you should be fine... Rear defroster helps too, are you in S13 or s14 though you never specified? if S13 get rear wiper, if S14 and your REALLY needing something then mod in a R34 rear wiper... you can find writeups around the net...

[DaPCWiz]

use rain-X and fog-X and you should be fine... Rear defroster helps too, are you in S13 or s14 though you never specified? if S13 get rear wiper, if S14 and your REALLY needing something then mod in a R34 rear wiper... you can find writeups around the net...

Talking to me or the original poster of this thread? If its me... I got not issues, just posting my experience.. lol. But yeah rear wipers are ftw... I've thought about trying to do a conversion a number of times, but never got around to looking into it.... oh well.

[95Blue240sx]

use rain-X and fog-X and you should be fine... Rear defroster helps too, are you in S13 or s14 though you never specified? if S13 get rear wiper, if S14 and your REALLY needing something then mod in a R34 rear wiper... you can find writeups around the net...

S14DB...I wonder what he drives...Its mind bottling.

Im ordering up a raceon cf roof thingy so I'll let you know how it turns out.

[Om1kron]

I would have side swiped a lot of people if I didn't learn to use them. It's just annoying to have a good portion of your rear view gone. Even worse at night.

To be honest the rear window wing on my car trips me out because when I drive now water travels upward and out to the sides. I need to get a video of it because it was tripping me out.

[PoorMans180SX]

It's because the roof wing makes an even bigger vacuum over your rear glass. Wind is circling around to fill it in, pushing the rain up your back window.

[98koukile]

Why use an R34 wiper when the EDM s14 has one and you have the bracket built into the rear shelf

[INeedNewTires]

Why use an R34 wiper when the EDM s14 has one and you have the bracket built into the rear shelf

Either way who cares, you have to REALLY be needing to see out that glass and i mean, it seems to me at least like its way too much effort to go through just for a rear wiper....... but to each his own...


And "DaPCWhiz" i was origionally posting to the OP