Me and my friend (fiveseven) both have this problem i ahve an white 89 rs and he has a white 88 iroc-z we both ahve the same spoiler the wrap around kind and no matter what i do everytime i wash my car as soon as i hit the street the back bumper gets filthy!! is it because of the spoiler is it all 3rd gens?

Happens to me too.

The bumper on my '91 RS got so dirty that it would not come clean no matter what I did to it. I think it was residue from the exhaust. My '84 is getting like that too.

same here, it collects dust like mad, and exhaust fumes i guess cuz its wet sometimes and has oily like appearance.

Would it help to have tips exiting under the bumper than coming out like my flowmasters?

I think it's just the areodynamics of the car that sweep the dirt up there like that.

Definitely not "exhaust residue"... I know that because I get it too... and my exhaust comes out the side, under the door

I think its just the... uhh.... vacuum?... thats behind the car when you are driving. Sucks up dirt and crap? :shrug:

mine gets very dirty too, also a problem i have is when right after i wash it, i guess water gets under the tailight and mixes with the dirt inside there, so after i drive around a little bit i have brown streaks all over my bumper. really sucks

Happens to me on both my 85Z and the 89 GTA. Major pain......

well it looks likes theres no hope for the dirty bumper problem jus make sure u got a bottle of quick detial with ya at all times lol

I get it too on my white IROC..thought it was from the rich exhaust, but after putting turndowns on it, it still happens. Oh well

happens to my white '83 T/A, too... I always thought it was because my driveway was dusty... I guess we all have that problem, tho.

*wonders* does neone kno where theres pic of a 3rd gen ina wind tunnel if any even exist?

get some rubbing compound it will take the stains right out without damaging the paint, or orange cleaner, but i find rubbing compound works on the serious stuff (i have bad stains in my paint, that only rubbing compound will get out)

Same here... Lately it has been oily and that turned out to be the rear end spraying gear oil all over the back bumper.

It must be the way the air is moved around the car, i had it pretty bad then put on the big ole hawks 5" and amplified my problem about 10 times. I can go aroudn teh block, paved neighborhood and it will be dusty as hell when i get back.

I could ask my engineering professor. :shrug:

It's a low pressure zone, which sends all the dust/dirt up in that area. I always have a ton of it underneath my license plate.

I always carry a California Duster and Meguiars Spray detail with me at all times, just to clean it off real quick.

Is there any ways to install some dividers under the bumber to help even out the flow like on road race cars? It would make the air flow in smoother pattern and add downforce.

That won't get rid of the low pressure area....I wonder though, if the Z-28 high rise spoiler has the same problems, or maybe not as pronounced

tunedport335 has that wing and he has same problem but not sure if it is as bad as it is with iroc spoiler. He posted a few up from this one.