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l really wish l had done the gutter removal when l had my car painted but l didn`t have enough faith in the body shop.l`m using the carbon fiber A-pillar filler strips l got from Perf.Prod but they don`t address the lift issues created by the rear section of gutter.l have plans to lay up a filler piece that will smooth the transition from the gutter to the top of the rear window.This will be done in carbon fiber to match all the other goodies on the car.l`m thinking it`s maybe a bit ricey but l`ve got clears lenses all around so why hold back now?
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Old 06-24-2005, 07:47 AM
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NASCAR's exaggerated rain gutters are regulation and are used to prevent the car from flipping in the event the car went sideways at speed, when the roof behaves like an airfoil.
Old 06-24-2005, 08:03 AM
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some yello-byrds had gutters.... personal choice? owners trying to save some $$? better directional stability as tradeoff for top speed since the 211mph HAS been reached and is no longer needed?.....hmmmm







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Old 06-24-2005, 08:16 AM
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shave your gutters. shave your armpits and your legs. personal choice maybe for you but not for me.

That yellow bird is cool.
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Old 06-24-2005, 08:28 AM
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Quote:
Originally posted by }{arlequin
better directional stability as tradeoff for top speed since the 211mph HAS been reached and is no longer needed?.....hmmmm
Just wondering where you came up with "better directional stability"? Not seen that mentioned in any Porsche, Ruf or Frere documentation. In fact it makes it pretty clear the opposite is true from the info those same sources provide.

23% more lift with the gutter on means the car is going to be less stable at speed, not more stable.

I can attest to my car. It is much more stable at speed (100 to 160) now (much less affected by cross winds) with a seemingly less effective aero package on tail and spoiler than before.

You may not like the cosmetics of no rain gutters or be offended by the costs but the aero benefits are pretty well documented by well respected sources.

Originally the gutters were cut off to make the car's body more rigid. The aero advantages were a positive side effect. Water in the cars depends on the condition of door and window seals.

If your race car has plastic windows and poor door seals you'll have water in the car when it rains. Yellowbirds without the gutters did not.

The 3 and 23 numbers obviously can't be translated directly to our street cars.

My understanding is it has always been an option.


quote:
--------------------------------------------------------------------------------
Originally posted by Sameer
Guys I spoke to the boys at Ruf Gemany and this is what they had to say:

"For your 930 BTR, we are happy to offer the following information:

The roof of your Porsche is made up of three metal sheets. One over the roof, one over the rear fenders (the C-Pillar), and one along the side, which goes inside the car. These three plates were originally hammered together at the Porsche factory to form the rain gutters. They are not bound together in any other way. Through our gutter conversion, the area where the three pieces fold together is cut off, and then all three are welded together. Welding of the plates greatly increases their strength, and definitely makes the body much more stiff all around and along the roof line. Cutting, welding, and repainting are the only processes undergone in this conversion. No other parts or procedures need to be assembled or carried out.

Our Rain Gutter Removal can only be performed at our factory in Pfaffenhausen, Germany."
--------------------------------------------------------------------------------

Last edited by rdane; 06-24-2005 at 09:11 AM..
Old 06-24-2005, 08:57 AM
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Did RUF do conversions on early cars (the posting above is obviouslly a 72)? Maybe its not a real RUF conversion? Im just curious.
Old 06-24-2005, 09:06 AM
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The original YB cars did have a '72 style oil filler. By the looks of the 10" flairs, roll bar, forward rake, aero pacjkage on teh rear window and the '72 style oil filler I would guess it is the real thing.
Old 06-24-2005, 09:13 AM
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Quote:
Originally posted by rdane
Just wondering where you came up with "better directional stability"? Not seen that mentioned in any Porsche, Ruf or Frere documentation.
basic aero airplane design... dragsters, salt flats speed racers etc.
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Old 06-24-2005, 09:19 AM
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I'm guessing that the gutters keep the air from spilling off the roof - less air going over the roof = less lift.
-Chris
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Old 06-24-2005, 09:46 AM
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Quote:
The original YB cars did have a '72 style oil filler
Well, cool. You learn something everyday

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Old 06-24-2005, 09:51 AM
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Chris do you mean somethng like this?


Last edited by rdane; 06-26-2005 at 07:29 PM..
Old 06-24-2005, 10:05 AM
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"lift issues created by the rear section of gutter"

- I want to see a show of hands from those who think this has any significance whatsoever.
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Old 06-24-2005, 10:35 AM
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How can I do this on my Targa? The structural stability is marginal as it is, but think the look would be worth the effort. Would it be possible to remove the gutters, weld them up correctly and gain some structural integrity? Hmmm....this just may solve that age old question.....
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Old 06-24-2005, 10:46 AM
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Quote:
"lift issues created by the rear section of gutter"
Im sure it makes a measurabe (however small) difference. The RUF/porsche #s back it up. Now we just have to come up w/ a group consenus to what "significant" is

The theory should be easy enough to prove. Go tape tufts of yarn along the tip of the gutter on the C pillar. If they lay down parallel to the pillar then there is no lift. If they try to lay "in" or up against the rear window, then there if flow perpendicular to them and forces at work. Surely its somewhat turbulent back there and some "visual averaging" will be needed.

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Old 06-24-2005, 10:47 AM
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Quote:
Originally posted by ChrisBennet
I'm guessing that the gutters keep the air from spilling off the roof
exactly.... thanks Chris
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Old 06-24-2005, 11:50 AM
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"drive these cars with no spoilers & no tails @ 100MPH"

- Gosh! Who would do that? Esp. in Oregon where they take your license.

- But I think you guys are misinterpreting the data - 935 wasn't it? I would not be worried at 140 mph with rain gutters.

Never confuse a plausible qualitative argument with quantitative data...
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Old 06-24-2005, 06:15 PM
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Quote:
Originally posted by randywebb
"lift issues created by the rear section of gutter"

- I want to see a show of hands from those who think this has any significance whatsoever.
if you can see their hands that`s a better trick then taking those gutters off the right way.The lift created is well documented,search and you will find but easier still just look at your car. A front view shows clearly the gutters are little airfoils and by their position must create lift.The figures l found were from the 935 project and the measured lift was not insubstantial.Porsche and RUF both found the mod worthy for their vehicles and at the 170mph + my car will travel,l`ll listen to the real experts on what works and what doesn`t. even if the mod did nothing but look cool...it sure looks cool
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Old 06-25-2005, 02:24 PM
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again I think you are misinterpreting the 935 data!

Look again and look at the size of them. Don't confuse a qualitative with a quantitative effect. I might be wrong, but in science, the affirmative has the burden to prove a significant effect.

And, BTW, on what track are you spending signfinicant amounts of time > 170 mph?
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Old 06-25-2005, 05:22 PM
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I think you have missed the point all together Randy, which surprises me. You started another thread and still have not looked at (or choose to ignore) Porsches own developemental work on how the factory decided to make the cars more rigid for competition.

(see that thread for a comment made to me today)

Good number of benefits from loosing the rain gutters but the first reason Porsche did it on the race cars was to make the unibody more rigid.

Your thought that the numbers quoted for th 935s are a misinterpretation is no more founded or factual that the numbers quoted apply directly to a street 911 like mine. (but no one has said they did)

The difference is I know by Porsche's research that it did have an obvious and substantial effect on the 935. Enough so that it was illegal in all but one race group.

WE can't justify chopping the gutters by the top end performance past 100mph on a street car. WE can't justify the performance enhancement to make the car more rigid as Porsche's factory drivers obviously could.

But I can justify chopping the gutters simply because I like it. Easier to trust Porsche's numbers even if they don't diirectly apply to this situation than any opinion experessed on Pelican

Helps to think and feel my car is faster and more rigid but it is only a street car so who cares besides me! Or are just pissed because the welded roof line is going to be stronger in a roll over that the folded seam?



Ya just gotta wonder why a winning 2.2 vintage racer, with no aero package and a full cage would bother to have a shaved rain gutter? Old news to many obviously.

Last edited by rdane; 06-25-2005 at 06:19 PM..
Old 06-25-2005, 06:07 PM
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rdane, I'm still not clear why you shaved your gutters. Are you racing with your car, and how much time do you spend at or above 150mph? I think Tim T, the original poster, is a racer, so that probably makes sense. I'm just confused why the owner of a street 911 would consider spending money on this mod?
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Old 06-25-2005, 07:36 PM
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