Outer Limits 4x4 Board

Guys I have a steel roofrack which is very much like the TJM style. Not sure what it was off but going to mod it to suit my 80 series. It's just the right length for waht I need whilst still just stopping behind the sun roof so as not to hamper that, I just have to widen it a bit. Presently it has 19mm RHS cross bars for the floor so I'm sure what I want to do about them when I widen it. I don't really like the bar type floor as I don't see it as totally practical unless you are onyl really carting bigger stuff up top.

I'm tossing up putting a solid sheet floor in it that has been dimple die punched like truck tread steps. You know about 10mm hole with dimple.

Just wondering how bad this might be for wind noise compared to the more traditional designs of bars or expanded mesh. I can get the sheet cut and dimpled for not much more than material cost and then fold the edges so it can drop neatly into the base and stitch it in. I like the idea of the material as it allows any size item to be carried anywhere on the rack and I can even bolt removeable eye nuts through the dimple holes if I need a bungy hook point in a certain spot but like I said I wonder if the airflow noise would be more hassle than it's worth.

Anyone know or seem a similar design to base an opinion from.

I did this on a steel ARB rack, no increase in wind noise, but dimples were 25mm dia. Did have problems with vibration/humming as its hard to keep the sheets from vibrating against the roof bars unless you weld and weld and weld and weld!! In the end I got it quiet, but rack came off 4 times. Also, consider the temperature of the sheet as it will get very hot and is a pain to move around on for packing things.

I tried 10mm ply, no heat but heavy and sucked up a bit of water over time.

I tried gal mesh, noisy and could not get rid of the drumming. I still have this system, and have learned to live with it - not really a good choice in the end, but its done.

Thanks man. Forgot to clarify that I intend to remove all the floor bars and replace with the sheet. The reason therefore for the dimple holes is twofold - to reduce the weight and to give strength to the flat sheet. Was thinking for additional strength if needed that I would retain one or 2 cross bars or say one lengthways down the middle.

I want to remove the bars to reduce weight and so I don't have to cut, sleeve and reweld all of them when I widen. Keeping the drumming out between any bars and the sheet is easy you just sikaflex (or equivelent brand) between them before fitting or even run a nice bead along the corner of both underneath after.

Apart from supporting the middle of the sheet, and this rack is only about 1200/1300mm wide, I do not need the cross bars to retain the sheet. I can get the sheet cut with the correct radius corners to allow me to fold down all the straight sides then I can stitch weld it in place. I don't see heat as a major issue either as I do not intend to be walking around on it. We don;t need it for major storage just as something stronger and more practical than a pair of roof racks. Might have an extra spare fromt time to time, some water, couple of lighter camping items etc or if I'm lucky a canoe.

Was still thinking the smaller dimples like truck steps to provide all my strength to the sheet so I don't need any cross bars. Could do them in strips rather than across the entire sheet but number is not an issue as they will be turret punched and not manually applied.

I don't think the dimpled sheet will support your weight without bars under it - either across 1200mm wide or perhaps in the other direction. I understand the load doesn't include you walking around on it - just think it will sag and hit the roof without some support - only takes once!
We support this type of sheet for platforms every 400mm, but it is for traffic, not storage.

Yeah I had that concern in the back of my mind but then again at 400mm centres it's only really 2 cross bars so that won't effect weight too much. At the moment it has them at about 150 centres so there's a few. did think about folding a few ribs into it but that just makes the design a bit of a pain and you have to allow for it in the side ffolds so it gets a bit fiddly again.

Might just work on 2 cross bars and one central one even and space my dimples around them to allow flat space for bending and fixing down.

I would be suss on the 10mm dimples. I made some ladder racks for a ute once out of 50x50 SHS and drilled 10mm hole in it for hooking tiedowns in to. it wistle so much I had to tape the full length of the rack to stop them wistling.