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Thread: Roof Spoilers-recommendation

                  
   
  1. #1
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    Roof Spoilers-recommendation

    Has anyone had any experience with roof spoilers across the upper rear window of a 1999 E36 M3, or 2 door E36? I see them advertised as installed with 2 sided sticky tape! Is that secure? I would like to continue to use a car wash occasionally. Any brand worth purchasing? I got my economic incentive check and it's burning a hole in my pocket. Thx, Chris

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    Senior Member Dirichlet's Avatar
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    My $.02, spend the money on a HPDE school.
    2000 323i
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    it was a beautiful day... the sun beat down
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  3. #3
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    Reminds me of when the spoiler on my 95 Fiat Uno 1.0ie (45 horses thank you!) flew over the roof and landed on the hood while I was in the car wash. Glued it back on and sold it

    But I think most of these spoilers comes with sticky tape. Not much else you can do really. There's a guy on eBay that sells pre-painted stuff like that. A friend of mine bought a product and it seemed good for as long as he had it (about a year). Can't remember the supplier though...sorry!

    You can also do HPDE and buy a spoiler

  4. #4
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    Roof spoilers are stupid, especially the ridiculous BMW applications. If you *must* buy a wing, buy one that works.

    ...but the only wings that are worth anything cost a hell of a lot more than your stimulus check.
    2006 GMC Sierra 2500HD 4WD Duramax LBZ/Allison 6-speed
    2002 BMW M3 - Alpinweiss III/Black
    1999 323i KP/GTS2 - Alpinweiss III (Black Hood, other stuff)
    1990 325is - Brilliantrot/Tan
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    1989 M3 - Alpinweiss II/Black (S62B50 in progress)



  5. #5
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    Remember with wings most on the downforce is generated at the ends. Wing needs to extend at least the width of the rear deck and have decent side plates and bend in the wing to be effective.

    In most cases with many so called aero aids the only downforce added is from the weight of the installed items.

    Chances are roof spoilers will effect your gas mileage more than anything else.

    I didnt get stimulus check damn Dems! So I brought my girlfriend some sexy La Perla lingerie and Jimmy Choos FMPs and we were both stimulated.
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  6. #6
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    AC Schnitzer once said their rear deck wing produced 21.3kg downforce at 90km/h on the E46 M3.

    http://www.ac-schnitzer.de/uploads/t...2_pages_01.PDF

    Also, if you look at Formula 1 aerodynamics, the airflow underneat the car and the rear diffuser contribute more to the downforce than the front and rear wing.

    Anyone think that they only got functional parts on their car? Even though BMWs doesn't have redicilous scoops that are blocked off (like the GT Mustang), some is pure cometics. I believe they consider cosmetics a large part of any design. However I am also a large fan of functional design.

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    Quote Originally Posted by Scany View Post
    AC Schnitzer once said their rear deck wing produced 21.3kg downforce at 90km/h on the E46 M3.

    http://www.ac-schnitzer.de/uploads/t...2_pages_01.PDF

    Also, if you look at Formula 1 aerodynamics, the airflow underneat the car and the rear diffuser contribute more to the downforce than the front and rear wing.

    Anyone think that they only got functional parts on their car? Even though BMWs doesn't have redicilous scoops that are blocked off (like the GT Mustang), some is pure cometics. I believe they consider cosmetics a large part of any design. However I am also a large fan of functional design.
    That's a lame spoiler. If you're going to drill holes in your trunk, it ought to be for something decent. Like this:
    2006 GMC Sierra 2500HD 4WD Duramax LBZ/Allison 6-speed
    2002 BMW M3 - Alpinweiss III/Black
    1999 323i KP/GTS2 - Alpinweiss III (Black Hood, other stuff)
    1990 325is - Brilliantrot/Tan
    1989 325is - Alpinweiss II/Black (S50B32)
    1989 M3 - Alpinweiss II/Black (S62B50 in progress)



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    Thanks for the replies. That were sincere.

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    If you are going for looks i dont think anyone can talk you out of what you want to do. Just do it.

    If you are going for functionality. Do something else. I doubt you will be traveling at speeds which would require a functional wing of any sort.

    BavAuto has swarovski letters/numbers for the trunk lid....At least the added weight will help traction on the rear right. and the sparkle will attract every ricer in the area (not that there is anything wrong with that)

    Save the money and put it in a savings account gets my vote.

  10. #10
    Member ChrisV's Avatar
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    Decent wings and spoilers start to function as soon as there is air flow over them. That's how a Piper Cub cabn fly at 35 mph. Spilers and air dams can be noticeably functional at speeds as low as 45-50 mph, which is why aero is so important for fuel mileage at street speeds. Even a small M style lip spoiler on the trunk *can* make an actual difference at street speeds.

    That being said, the roof spoiler is more functional as 1) a sunshade for the rear window, and 2) something to make the car look better to you.

    3M double sided sticky tape to hold it on works quite well, actually. It's the same stuff that most side trim is held on with and is actually kind of hard to get off once on. My M style rear spoiler on my 7 series is held on with it and it's not going anywhere.

    Oh, and as for BMWs and non functional things, don't talk to quick about blocked off scoops on Mustangs until you look at the rear air diffuser design on an E36 M3...
    2001 740i Sport/2005 330ci ZHP

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  11. #11
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    Quote Originally Posted by ChrisV View Post
    ...don't talk to quick about blocked off scoops on Mustangs until you look at the rear air diffuser design on an E36 M3...
    I gotta admit I don't picture the M3 diffuser very well in my head. But as far as I know it serves it's purpose right. Doesn't it? Giving the under car airflow longer way to travel underneath the car, thus keeping low air pressure and downforce in the rear. It doesn't have the Ferrari style flow improvements it seems. But as far as I understand that's for stability, or less turbulence. The Ferrari got a smoother underside than the E36 M3 so it wouldn't matter too much I guess. I might be horribly wrong of course That's just how I have perceived the aerodynamics, and would not mind being corrected.

  12. #12
    Member ChrisV's Avatar
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    Ther BMW rear duffuser has a fake lower spoiler and fake holes where the air should come out above the fake rear spoiler as well as fake ribs holding the fake rear spoiler. If you look at it from underneath, it actually catches air in it, rather than letting it flow through and do the job it's designed to look like it does.



    If you look at it closely, it's designed to look like a lower wing under a rising diffuser, with ribs that are to look like they support the "wing."

    A real rear duffuser would have the ribs to make the airflow straight, and go way under the car to allow the air to smoothly flow up and creat downforce from both the wing action and the low pressure created by the rising upper surface (which on the M3 would exit above the fake wing, in teh recessed area that is designed to look like that rising part)



    or




    I love BMWs and the E36 M3 in particular, but that whole rear air diffuser is fake and does absolutely nothing that a standard rear bumper cover doesn't do.
    Last edited by ChrisV; 08-27-2008 at 07:48 AM. Reason: typos
    2001 740i Sport/2005 330ci ZHP

    http://www.midatlantic7s.com

  13. #13
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    Yeah, you're right. I guess the diffuser spoiler doesn't go back(forward) under the car at all, making a standard bumper equally significant if it stretches back and down equally far Though you won't need to let air through, and up, for it to be functional. I believe the typical Corvette and Viper diffusers try to keep the air down as far as possible. The fins and letting air smoothly rise up seems to be more a smooth flow issue (which again in turn creates better airflow and thus better aero or downforce). I understand it so that you got several functions of the diffuser; keep air under the car at low pressure, stabilize the air when it exit out the rear, and avoid turbulence when it mixes with air going over the car.

    I know the thread is about a roof spoiler, but I can't help to be facinated by aerodynamics, though I know very little about it

  14. #14
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    Carroll Smith's books are great primer for racing and schools. One has an excellent section aerodynamics I just cant remember which one. All are a great addition to your library. I know it was "Screw to Win"

    Mr Smith's explanations are easy to understand and you dont need several college level physic courses to grasp the concepts. For example more than 70% of the downforce of a rear wing on a sedan or coupe comes from the wing ends. And they need to extend the full width of the car.

    Porsche's ducktail was used to balance off the front spoiler I believe.

    Since I got the Element aerodynamics and downforce arent really that important when you are pushing a brick through the air.

    Spoilers, wings, diffusers aretricky purchases since sometimes the only downforce they add is the additonal weight of the component.

    That is about all I remember. We can discuss reading sheep ro getting your herding dog to run 800 yards out in the field to round up the sheep and bring them to you. Or we can discuss the pluses and minuses of the different herding breeds. I am more comfortable discussing this. Forgot most of the car stuff I knew. Or we can discuss how to train your dog to outrun, lift and fetch a beer from the fridge.

    Dave Apker and the collis

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    Member 87325is's Avatar
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    Yea a wing works, but you are dealing with a light object with a large wing span on said piper.

    Even nicks wing above (i am not an expert but).....High in the flow of air, winglets and extends width maybe + of the car, would make it work and work well, but i wonder how much force there is on a turn at 25-35mph. It should provide something. for the street forget it get tires or something. On a sweeping turn i bet it is a lot of fun to have.


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    Quote Originally Posted by ChrisV View Post
    Decent wings and spoilers start to function as soon as there is air flow over them. That's how a Piper Cub cabn fly at 35 mph. Spilers and air dams can be noticeably functional at speeds as low as 45-50 mph, which is why aero is so important for fuel mileage at street speeds. Even a small M style lip spoiler on the trunk *can* make an actual difference at street speeds.

    That being said, the roof spoiler is more functional as 1) a sunshade for the rear window, and 2) something to make the car look better to you.

    3M double sided sticky tape to hold it on works quite well, actually. It's the same stuff that most side trim is held on with and is actually kind of hard to get off once on. My M style rear spoiler on my 7 series is held on with it and it's not going anywhere.

    Oh, and as for BMWs and non functional things, don't talk to quick about blocked off scoops on Mustangs until you look at the rear air diffuser design on an E36 M3...
    Last edited by 87325is; 08-28-2008 at 12:44 PM.

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