wind deflectors on roofracks

Thanks Roachie,
Looking at your rig, it looks as though your deflector comes down close to the roof. Last night I was having a few problems navigating through the archives and gave up. But one post said 3/4 racks are quieter than full length because they don't interfere with the wind flow off the wind screen. You appear to have attempted to address this. And it still doesn't work! Is your deflector in line with the windscreen angle or is it set back a little?

Thanks
Black Jack

Mate, it's set back a couple of inches. The gap between the bottom of the deflector and the roof is also only an inch or so. I have seen people put a length of rubber along the gap between the roof and the rack, but I've never spoken to any of them to see what the effect was.
Good luck.

John, I've seen the pipe deflectors and had some questions. Do think they split the wind forcing some under? Shouldn't the leading edge be closer to the bottom of the rack? Having asked that, a friend has a pipe for carrying poles across the front of his TJM rack on a duel cab Nissan and it cut the noise dramatically. I thought that the wind would circle in behind the pipe and create a different noise. I've pulled the mesh off the floor as it was broken in a few places and many welds had also broken. I'm going to go a solid ply floor. There are supports every 300 mm and 12mm ply will do the job. I am hoping this will reduce some noise as well.

Thanks
Black Jack

Black Jack, have though of the solid ply floor but have to ask myself why I what the extra kilo or so up there. It is hard to know where each part of the noise is from but there was a considerable reduction as Captain says below was the case with his. You won't aliminate it all though - noise I mean.

John,
I had 3 ply over the top of the mesh to stop the travel bag from getting chopped up by the mesh. When I removed the ply to inspect the welds I was surprised at how much extra noise there was. This was with an empty rack though. Since the mesh was in poor condition (bent and broken in places - wrong mesh for the job) I thought I'd just go with the ply. I considered new mesh and then put the 3 ply back on I don't think 12 mm ply is such an extra weight.

Thanks for your reply
Black Jack

Captain, your rack sits as far forward as mine and if the split poly pipe does the trick it may be the simplest and most effective way to go. My original question included what angle should the deflector be at, and the answer seems to be it doesn't matter. It's one of those 'such it and see' things where what works on one vehicle doesn't work on another. One of Thomo's shows where he had two identical Landcruisers in muddy situations. One had a bull bar and the other didn't. The one with the bull bar attacted a lot more spray than the one that didn't, concluding that the bull bar interfered with air flow over the vehicle. If this was true then maybe the interference with air flow starts at the bonnet. (The bull bar stays - a bit of mud does a lot less damage than a one ton bull)

If Roachie's Big Mutha of a deflector didn't work, then the humble poly pipe is the way to go.

Thanks
Black Jack

Thanks Andrew, I've decided to try the pipe. It seems to work as well as anything else.

Black Jack

Peter, the 3/4 rack keeps popping up as the quiet option, and if I go to buy a new rack it will be a 3/4. The bigger the rack, the more I can put up there. But you can't put that much up there and be safe, so why have such a big rack in the first place. Getting the front of the rack away from the wnidscreen airflow seems to be important. I can slide it further back than I do now. My first rack was a half size on Thule rails and sat up high and I don't remember there being a noise problem with it. When this rack was advertised I couldn't let it pass. It sits snug to the roof, but unfortunately has this noise issue. Oh well, it gives me something to think about in my idle moments. Thanks for your feedback.

Black Jack

Thanks Wllem. I can see the sun reflecting off your deflector in your rig photo. Another use of perspect deflectors - they will see you coming across the desert before anyone can see the shape of you car LOL. You are right, everything is a compromise. I could get by without a rack if I got rid of the kids - then I could fit everything inside. But then who would I have to share those beautiful moments of discovery with if they weren't with me.

Black Jack