Rear roof spoiler

[Rustysalami]

Hi all. With the drought breaking in OZ (sort of), I've noticed the rear windscreen gets horribly grubby when it rains. I'm guessing the standard rear spoiler creates a big low pressure eddy over the rear window and sucks in all the mist and road grime.

Has anyone fitted a factory (eek - $750!!) or cheaper copy rear roof spoiler (MARS $199)?? Did it help or is it just all show?

You can also just buy stick on vortex generators, but they may look a bit daft.

Lesson in physics here https://www.carthrottle.com/post/vortex-generators-how-do-they-work/

Cheers

Rusty

 

[Arkatee]

I have the factory spoiler as above, and the rear screen gets filthy in the wet. All show I'm afraid.

 

[Rustysalami]

Thanks for letting me know. I just bought some small stick on vortex generators from AliExpress for $10. I'll give them a go. Nothing to lose. Seems the trick is to slightly angle them like on a Mitsubishi Evo.

I'm not doing it for any downforce. Just to stir up the low pressure air on the rear of the car.

 

[roAr]

i wondered why my back was getting filthy pretty quickly! hmmm....

 

[Guvna]

Just the car shape I'm afraid, all wagons and hatches have the same thing happen, that's why they have rear wipers. Sedans don't need them because they only get dirty on the back of the boot and below because the airflow stays attached to the rear windscreen and boot lid, as soon as the air leaves the boot lid (or hatch/wagon roof) the swirling drag attaches to the rear, whatever size that rear may be. Since the whole back end of our wagons is the 'rear' we gets dirty. I don't think any size spoiler is going to help that. I fitted the individual vortex generators you mentioned about a year ago, purely because I like the look of them but think the OEM Subaru one's fins are WAY too small, you really have to look to see them. They make zero difference to the dirty factor, and probably not as much function as on a sedan either, but I just got them for the asthetics. Their job is to keep the airflow attached to the car to reduce drag, but there is no car behind them so nothing to keep the air attached to really

 

[Guvna]

Thanks for letting me know. I just bought some small stick on vortex generators from AliExpress for $10. I'll give them a go. Nothing to lose. Seems the trick is to slightly angle them like on a Mitsubishi Evo.

I'm not doing it for any downforce. Just to stir up the low pressure air on the rear of the car.

Just a tip, when you say 'nothing to lose', may I suggest you just sit them on the spoiler where you're thinking of fitting them, take a photo and just look at it for a while to be sure you like the look, because the double sided tape they come with is strong as F@!%. Not necessarily something that can be removed easily without taking some paint with them. I've even seen dented roof panels from people trying to remove vortex generators, that tape is never letting go on its own. Just something to think about