Roof rack and wind deflectors

Submitted: Thursday, Jan 22, 2004 at 09:51
ThreadID: 9941 Views:2359 Replies:6 FollowUps:7
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Hi,

Hoes anyone have some actual experience with the benifets of fitting wind deflectors on roof racks. Do they make a noticable difference?? I know they will assist in improving the resistance and possibly wind noise but is it significant ie have you noticed it in fuel consumption etc. The vehicle is a GQ patrol with a TJM roof rack.

Thanks
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Reply By: Vince NSW - Thursday, Jan 22, 2004 at 10:02

Thursday, Jan 22, 2004 at 10:02
Ray,
I have not taken fuel readings after adding, but it seemed to help.
Other advantages are lower wind noise and no splattered bugs on the gear stored on rack so helps to keep the better half happy.
I made mine out of a sheet of PERSPEX from BBC (Bunnings) for $15. Cut with fine tooth hand saw and bend with heat from wifes (or your) hair dryer. Hold in place with stainless screws. Whole lot $20.

Hope this helps
Vince
AnswerID: 43931

Follow Up By: flappan - Thursday, Jan 22, 2004 at 10:37

Thursday, Jan 22, 2004 at 10:37
Good tip . . . onto that.

As far as fuel consumption goes, I haven't noticed any difference with my roof bag on or off, but heck, the noise is substantial.

I'm gunna build one just to reduce the damn noise.
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Follow Up By: Member - Mal (Brisbane) - Thursday, Jan 22, 2004 at 10:52

Thursday, Jan 22, 2004 at 10:52
You're probably better off using polycarbonate (which is used for headlight protectors etc [hope I got that right]). It is MUCH stronger. You can heat it up to bend it using an iron with a tea towel over the polycarbonate.

Mal T.
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FollowupID: 306154

Follow Up By: Lyds - Thursday, Jan 22, 2004 at 14:12

Thursday, Jan 22, 2004 at 14:12
ARB charges $150 (or thereabouts) for their wind deflector and it is fastened with double sided tape.Cheers,
Stuart
- To err is human, to moo bovine -
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Follow Up By: Member - Rohan K - Sunday, Jan 25, 2004 at 16:35

Sunday, Jan 25, 2004 at 16:35
Polycarb is also far more UV resistant than perspex which will become brittle before too long (but at $20 you could afford to replace it every year or so).Smile, you're on ExplorOz
Rohan (Sydney - on the QLD side of the Harbour Bridge)
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Reply By: paul - Thursday, Jan 22, 2004 at 14:37

Thursday, Jan 22, 2004 at 14:37
Mal

Where do you get sheets of polycarbonate from in brissy ?
AnswerID: 43973

Follow Up By: Member -Bob & Lex (Sydney) - Thursday, Jan 22, 2004 at 19:00

Thursday, Jan 22, 2004 at 19:00
Places that do awnings & pergolas but its expensiveRegards Bob
Where to next
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Follow Up By: Member - AndrewPatrol - Thursday, Jan 22, 2004 at 20:03

Thursday, Jan 22, 2004 at 20:03
look in the Yellow pages under plastics suppliers or similar
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Reply By: Member - Peter- Thursday, Jan 22, 2004 at 21:35

Thursday, Jan 22, 2004 at 21:35
Ray I've used a deflector made out of thin aluminium sheet for years on a 3/4 rack on a 75 series troopy.
The roofrack lops around 2mpg off the fuel consumption travelling at 95 -100 kph.
Fitting the deflector did little to the consumption but made a huge difference to noise and buffetting. Also as someone else said it keeps the fauna off the rack bag, also deflects tree branches up and over if it is close enough to the roof.
The roof rack was composed of three heavy duty loadrails (gal ones) with a gal pool fence panel as the base covered with marine type carpet. Load consisted of a spare 7.50 x 16 tyre case, a 4 foot square rackbag and a small bag with a rolled up fuel bladder. The rackbag only had sleeping gear and light stuff in it nothing heavy.
The wind deflector was mounted off the front edge of the fence panel with aluminium flat bar brackets from approx 1" off the roof to the height of the tyre case at an angle of about 45 degrees.
AnswerID: 44039

Reply By: David O - Thursday, Jan 22, 2004 at 22:33

Thursday, Jan 22, 2004 at 22:33
I made mine from a sheet of acrylic (perspex). bent by careful use of the barbecue (enclosed type). Cost less than $20. TJM roof rack on 1990 Rangie.

Effect???? HUGE REDUCTION IN WIND NOISE!!! HUGE HUGE HUGE!!!!

Fuel consumption not measured, but I work on the theory that all that noise requires some energy. Less noise = less energy required, unless it is being turned into some other form of energy ie heat which I doubt.

Anyway if it cost me more fuel, I'd be happy 'cause I could't stand the noise
AnswerID: 44049

Reply By: Diesel1 - Friday, Jan 23, 2004 at 20:14

Friday, Jan 23, 2004 at 20:14
G'day Ray,

I've got a mate who specializes in aerodynamics (aircraft designs) and a while back we got talking about wind deflectors on roofracks and whether or not they do improve fuel economy. He told me that the only way to improve the aerodynamics of practically all 4wd vehicles would be to completely remove the front end bodywork and replace it with the nose off the XPT train. In other words, just about all 4wd vehicles have the aerodynamic design of a backyard shed and the fitting of a wind deflector to the roofrack would have such a minimal beneficial effect on fuel economy that it would not be noticeable.

Another thing to consider is the angle of the deflector and the only way to determine if you've got it right is a wind tunnel test or you could fork out around 25 thousand dollars for state of the art computer software that simulates wind tunnel testing.

The bottom line? They're good for keeping bug guts off your load and thats about all.

Diesel1
AnswerID: 44145

Follow Up By: G.T. - Tuesday, Jan 27, 2004 at 15:19

Tuesday, Jan 27, 2004 at 15:19
Diesel 1 ------- Q. What is the last thing to go through the mind of a bug when it hits your roofrack/ windscreen etc ??
A. It`s a--- hole
Regards G.T.
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Reply By: Ray - Tuesday, Jan 27, 2004 at 14:31

Tuesday, Jan 27, 2004 at 14:31
Hi all,

Thanks for the replies. I see what you all mean by the wind noise, if I can't reduce it with the deflector the roof rack is coming off.
AnswerID: 44472

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