Reducing wind noise at highway speeds? Raingutter Fillers...

gerrelt · Last edited by gerrelt on Sun Apr 19, 2009 7:00 pm; edited 3 times in total

Hi There,

I've made several trips now with my Alfa Romeo powered 1303 Beetle. Most of these were on the dutch highways on which I drive around 130 km/h (speed limit is 120 km/h

).
Now it drives really well on these speeds, but one thing annoys me. The sound of the engine is not the hardest sound anymore, now that I've gone water cooled. The wind noise is very loud!

I was wondering, could things be improved in this area?

I understand I can't change the basic design of my beetle, so it will never be as quiet as a modern car. But would, for example, changing the outside mirror for a more aerodynamic one would make any difference?

Does anybody have any experience with this?

Greetings,

Gerrelt.
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rjes · Posted: Wed Oct 01, 2008 11:05 pm Post subject:

Not sure, but I suspect a lot of the noise comes from the 'external' gutter design, and single door seals. T25's are pretty bad for wind noise, and the factory had a reasonable go at solving it on higher spec models by adding a second seal on the leading edge of the doors. There's not much room to add a 2nd seal on a beetle though.

You could easily find where the noise comes from with a bit of experimenting. Take the mirrors off and see if the noise goes. Try making the air flow over the A post gutter more smootly by taping from the gutter edge forward at an angle, or tape the door glass closed on one side, and see waht, if any effect it has. If you try, it'll be interseting to see how you get on.....
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sven · Jedi Guardian Joined: 27 Dec 2006 Posts: 814

1. Use ear plugs.
2. Drive slower.

I would go with the first option, the first Lambo Countach had headsets. That's the coolest gadget ever. Happy

gerrelt · Posted: Fri Oct 03, 2008 7:07 am Post subject:

@rjes: Yes, that's a good idea. I think I will do some test-runs without (or folded in) mirror and I will push the antenna in too.
I allready put the windscreen wipers on at that speed, but that didn't change the noise at all. So, I think it's not the wipers.

@sven:

1. Can you picture me and my wife in front, my 6 and 4 year old daughters in the back (in booster seats), in my beetle all wearing headsets? Laugh Out Loud

2. Can't compute, error.

Wink

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doppelganger · Posted: Fri Oct 03, 2008 3:56 pm Post subject:

better stereo perhaps? Grin

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ElusiveStranger · Posted: Fri Oct 03, 2008 11:57 pm Post subject:

ricola · Posted: Sun Oct 05, 2008 9:45 am Post subject:

My friend's 964RS has little infill pieces that go in front of the gutter to blend the front side into the bodywork. It was an aftermarket mod by Ruf but is very subtle and works very well.

http://www.rufautocentre.com/parts/pdf/964.pdf page 9

Rich
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gerrelt · Posted: Sun Oct 05, 2008 3:11 pm Post subject:

@ElusiveStranger: Yep, the kids have some music that is definitely not my taste.. Although the youngest one is a big fan of Mica, which isn't too bad to listen to.
I send Jurgen a PM through the aussievedubbers forum.

@Ricola: Hmm..that's a good idea! I was thinking I would have to remove the rain gutter for improvement, but filling them with a removable piece is a very good idea. That might even look reasonably good too.

BTW:
Some interesting info on aerodynamics can be found here:

autospeed.com Porsche New Beetle aerodynamics
Doing your own "wind tunnel" testing without a wind tunnel!
Extra interesting because they use "beetle shaped" vehicles.. Happy

Here is the "how-to": wool tuft extravaganza!

this one is interesting too, it's about the aerodynamics of an outside mirror (not VW though):
Aerodynamic Development on Mirror

And there are more interesting articles on that autospeed.com site!
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gerrelt · Posted: Mon Oct 06, 2008 8:23 pm Post subject:

I found this thread: Link to Pelican Parts Forum

If you ignore the useless hijack discussion in that thread, there are some people who say that it will make a difference in wind noise. Other threads on that forum say that removing the rain gutter has the same effect. I don't want to do that, but that could mean that filling up the rain gutter at the A pillar really works.

Here some more examples (taken from that thread) of rain gutter pillar fillers:

I might give this a try. I am thinking fiberglass or aluminum sheet to fabricate a rain gutter pillar filler (what a complex description for a piece of plastic...
Laugh Out Loud

).

But first I have to finish my LED conversion, and do some maintenance on the engine (distribution belts).
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ElusiveStranger · Posted: Mon Oct 06, 2008 10:28 pm Post subject:

Don't waste your time bashing metal for a prototype.

Steal the kids Plasticine Wink

Our very own Neil-C is a dab hand at molding fibreglass. I'm sure he'd be happy to give you trips
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ricola · Posted: Tue Oct 07, 2008 12:40 pm Post subject:

Must be pretty easy to make one of those, but to test I'd just use some duck tape...
To make one, I'd cover the bodywork in masking tape and then just fill with fibreglass filler and make it a solid piece... Should pop out nicely fro final finishing afterwards.
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gerrelt · Posted: Wed Oct 08, 2008 7:28 pm Post subject:

@Ricola: Yes, I was thinking along those lines too. I will probably incorporate some sort of channel so that he rain water can drain down.
Before I am gonna smear fiberglass on my beetle I will test it first on some old pieces of my beetle that I have lying around (pieces from installing the radiator Happy

), to see if it won't bond through the masking tape to the car.

I did a test-run tonight, I used duct tape to tape over the rain gutter:

After I took this picture I put another smaller piece of tape on the top of this piece of tape, to close the hole at the top and to make it more smooth.

And it seems to work, on the first run (with tape) I noticed the engine sound was now louder than the wind noise. There was still wind noise audible. But it seemed to come from the outside mirror or the upper door hinge (which is sticking out too on the beetle).
I drove on the freeway at 130 km/h (according speedometer) to a city nearby, aprox. 5 kilometers. Then drove back to my home-town on the same highway.

Then I removed the tape and drove the same highway again at the same speed. The sound seemed louder, and the wind noise was louder than the engine noise.
I can't back it up with hard figures, I don't own a decibel counter.
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