Dirty Butt Syndrome: Does a spoiler help?
Thread Starter
Melting Slicks
Joined: Feb 2009
Posts: 2,857
Likes: 234
From: SW Nuh Hampsha
2018 C5 of Year Finalist
Dirty Butt Syndrome: Does a spoiler help?
I'm sure I'm not alone when it comes to finding dirt and dust hanging out under the taillights and license plate area, even within minutes of washing the C5 (after a short drive). The dirt must come up from underneath and deposit there due to the airflow under the C5.
I'll bet a good diffuser would help to alleviate this, but I haven't seen any yet that I would want on my car. Has anyone noticed a decrease in dirt accumulation after putting on a rear deck spoiler? I'd imagine the airflow changes a bit with a spoiler, depending on the design, but is it enough to counter and/or alter the under-car airflow? There's a spoiler in my future, but am wondering if one is better than another when it comes to affecting "backwash" or whatever it's called.
I'll bet a good diffuser would help to alleviate this, but I haven't seen any yet that I would want on my car. Has anyone noticed a decrease in dirt accumulation after putting on a rear deck spoiler? I'd imagine the airflow changes a bit with a spoiler, depending on the design, but is it enough to counter and/or alter the under-car airflow? There's a spoiler in my future, but am wondering if one is better than another when it comes to affecting "backwash" or whatever it's called.
Pro
Joined: Dec 2009
Posts: 606
Likes: 1
From: Waco Texas
Yep this has been covered and asked about before, but as far as a solution I am not sure there was one. I, personally tried the spoiler method and it made lil or no difference in accumulation. I agree, as others have, that a diffuser of some sort would cure this issue. Really sux on a black Vette.
Le Mans Master
Joined: Oct 2007
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From: Kelso Washington
St. Jude Donor '09, '13, '15
I would think the only way to reduce the collection of dirt would be to fill the vacuum created behind the car. The only way to do this would be a "diffuser" that directs air INTO the void, not creates a bigger void like a spoiler would.
Burning Brakes
Joined: May 2008
Posts: 1,106
Likes: 6
From: Georgetown Texas
Like on the back of the roof on a SUV to keep road film off the back glass.
Drifting
Joined: Jun 2010
Posts: 1,434
Likes: 2
From: Harrisburg Pa.
you would think that a lip style spoiler would just direct air up and over the void, but that a spoiler like a 98-02 camaro would scoop some air directly into the void helping push the dirt away.
well it doesn't. my black ls1 z-28 had just as much dirt on her *** as my c5.
well it doesn't. my black ls1 z-28 had just as much dirt on her *** as my c5.
Le Mans Master
Joined: Jun 2006
Posts: 6,478
Likes: 20
From: guthrie oklahoma
I think the dirt under the taillights problem is due more to the fact that the car is wide open underneath allowing the dirt to come in from the bottom when you are driving, but not possitive
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On other cars that I'd had that had spoilers on them, it made no difference on the dust accumulation. It's just a price we all pay when we drive the cars.
Burning Brakes
Joined: Mar 2009
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From: GRAYSLAKE IL
Oldtimer
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I have a spoiler & it didn't help. I did the flush mount taillights & they helped some (less space for the dust). I use a small brush to clean the area after driving...
Thread Starter
Melting Slicks
Joined: Feb 2009
Posts: 2,857
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From: SW Nuh Hampsha
2018 C5 of Year Finalist
So ya gotta wonder why no one has come up with a decent diffuser for the C5 yet. We've got plenty of splitters, spoilers, skirts and wings, but not one good diffuser. What's up with that? 
Tech Contributor
Joined: Jan 2004
Posts: 20,030
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From: Wylie TX --> Less is More, except under the hood !
Strange but true...
I'm finding that after my CCA oil catch can install I have less "black" specs on the rear of my car.
The catch can does not help with the dust, but it seems to help reduce the black specs.
Toque
I'm finding that after my CCA oil catch can install I have less "black" specs on the rear of my car.
The catch can does not help with the dust, but it seems to help reduce the black specs.
Toque
Race Director
Joined: Mar 2003
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From: Northern Illinois
Oldtimer
The back of my car is much cleaner since I added a catch can. Now if someone can design one for dirt, grass, etc.
Heel & Toe
Joined: Oct 2009
Posts: 18
Likes: 0
From: Greene Maine
Yep this has been covered and asked about before, but as far as a solution I am not sure there was one. I, personally tried the spoiler method and it made lil or no difference in accumulation. I agree, as others have, that a diffuser of some sort would cure this issue. Really sux on a black Vette.
Drifting
Joined: May 2010
Posts: 1,342
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From: Elizabeth City, Outer Banks NC
Thank you both for posting that. Maybe that is the answer.
Heel & Toe
Joined: Oct 2009
Posts: 18
Likes: 0
From: Greene Maine
buddy you an toque just got my attention. Both of mine look tough after a short road trip. Got ticked at the guy that said his wife was out cleaning it. Busted. I do that at fuel stops. If you think silver shows up bad, try yellow. Thank you both for posting that. Maybe that is the answer.
Thank you both for posting that. Maybe that is the answer.