Biggest cargo box that can fit? What roof rails would you get?

[thegrapeguy]

I'm wondering what's the best way to max out the roof area... I have a lead on a Thule Atlantis 1800 (about 7 feet long) for a good price. It seems it would be a bit large but - could I get something that large to work? (i.e. still being able to open the tailgate enough to get things out of the trunk but maybe not all the way open). I've read about cargo boxes hitting the shark fin and folks getting aftermarket horizontal rails to raise the cargo box higher. But if you were trying to do this what stuff would you buy for the rails and how big a cargo box would you get? Thanks...

 

[McFlyfi]

See thread here:
http://www.mazdas247.com/forum/showthread.php?123817270-Roof-Racks-Roof-Boxes-Sharkfins

This is my setup. Crossroads 450 feet, ancient Thule bars, and a Thule Evolution 18.
The Evolution is 91" x 31", and the Atlantis is 84" x 34", so yours is slightly shorter and wider than mine. I'm sure it would work with a similar setup to mine. I'd be leery of going for anything longer- there's not much room for adjustment left on mine, but it does work just fine.

 

[thegrapeguy]

I read your thread, thanks. You said you doubt the factory cross bars would allow a roof box to fit. Is that because of the width (34") of my Thule Atlantis? i.e. bars not being wide enough (because they're the "flush" style) to allow the Thule brackets to catch it? Or is it because the lower factory cross bars would cause the roof box to hit the shark fin?

Today I did a ton of research and it seems the best way to get the cross bars forward (to allow large roof boxes to fit and not sit back and interfere with the hatchback) is to get the Whispbar system with tracks you mount through the sheet metal.

I really want the flush type cross bars but I believe the factory cross bars would allow the box to hit the fin. Your Crossroads 450 feet would raise it just enough to sit the roof box just over the fin, I believe...

 

[McFlyfi]

I read your thread... Or is it because the lower factory cross bars would cause the roof box to hit the shark fin?

This
The factory crossbars mount insidethe roof rails, not on top of them. It is my opinion that the factory crossbars would not allow the box to clear the sharkfin. The the bottom of the box would be set 1/2"-1" down below the top of the rails, not 1 1/2" on top of them, creating clearance problems.
I hadn't thought about the width-I haven't measured the space between the bars.

With crossbars on top of the rails, you now can use the full width of the bars. I can put my box on one side, and my mountain bike on the other, or the box and my 9' surfboard- you certainly couldn't do that with the factory crossbars.

One other thing to consider- there are mounts that bolt directly to the hard points (where the roof rails are bolted), eliminating the need for the roof rails altogether. It's a pricey solution, and if you already have the rails installed, may not be cost effective.

I've gone in this direction because I've already got a Thule rack system, with lots of different attachments, and it just cost me the Crossroads feet to put it into service.

I'll go out on a limb here- your box will work with a solution similar to mine-it's shorter than mine, and mine works just fine.

EDIT:
I got to thinking- your box is 7" shorter than mine. if you look at this pic:

The box as it is mounted is only overhanging the fin by a few inches.

I wonder if that 7" will make the box short enough to not even reach the sharkfin (whn mounted as far forward as possible). I am assuming the mount for the box is similar to mine and has some measure of fore-aft adjustment.

I think the only way to make sure (short of buying the whole rig) is to take some accurate measurements to determine placement. Maybe mock up some crossbars out of cardboard, and use a 84" length of cardboard to simulate the box. Then you'd know pretty much for sure.