Unusual Rack Extension?

[SFarrell]

Hello!

I'm an infrequent visitor, but still manage to gain inspiration from the overlanding community. I introduced myself years ago as a "microlander" since I travel with a focus on utility in my small car (but no off-roading). I started carrying my roof rack full-time in 2021 due to my ham radio pursuits. I have a "naked" roof, so my rack uses clips at the doors instead of it being a real bolt-thru rack. It's been great, but sometimes I wish it was longer and had a third crossbar. I've even considered building a Prinsu-like solution, but I won't try to fool myself into believing that there are reinforced points under the roof's sheet metal.

I have a Rhino Rack Vortex series and use a combination of Superstrut channels to accomplish my loading goals. Total load usually does not exceed 100 lbs, but I've carried 165 up there a few times. Here's a photo of my Superstrut setup to present what I'm considering:

The channels are ~32" long. I've had them as long as 40", but cut them shorter since I wasn't using the extra length. Now I'd like to extend again. I can go as long as 54" without interfering with the hatchback.

I don't want 26" of unsupported channel behind the rear crossbar. So, I'm considering a dicey plan: First, I'd add a third crossbar that consists of a transverse length of Superstrut. I thought about supporting it with a pair of magnetic foot pads and threaded rod, but I suspect that magnets would slide around on the paint. Then I recalled that I have some Seasucker mounts with D-rings. The mounts also have 1/4" threaded holes. Best of all, they won't slide around so long as I check their suction from time to time.

I would use a length of 1/4" threaded rod, perhaps with aluminum sleeves, that's sufficient to reach the third crossbar and keep the level of the fore-aft channels even. I'd use jam nuts to keep everything tight. I'm not planning to put a lot of weight along that span, maybe a 30-35 lb Pelican-like case at most. I think that span would be unloaded most of the time since I usually have a cargo box mounted:

What do you think? Am I out of my mind?

 

[RalphJeepGuy]

what kinda rack you running? if you're just trying to add more space a lot of guys just weld or bolt on some tubing to extend it. super simple honestly. my hemi JK has a custom setup in the back and it was literally just angle iron bolted to the existing crossmembers. depends what you're carrying tho, weight distribution matters

 

[sandraC_2f9968]

Out of your mind? A little. But I respect the creativity. I'd test that suction mount setup with a sandbag before putting anything valuable up there though. Threaded rod flex is real.

 

[genocache]

I run a diy super strut rack also. How much overhang are you talking about from the back crosspiece? Sounds like maybe 18in? I don't think the strut would flex much. I would move the rear crosspiece back as far as possible and try flexing the unit.

My rack spans 46in unsupported across and 32in from crosspiece to crosspiece.

From my blog; Roof rack gets updated

 

[grubworm]

they make a taller strut that wont flex as much. I use this a lot to mount solar panels on top of my camp trailers, etc
I wouldn't try additional mounts that touch the roof, magnetic or otherwise. asking for damage

 

[SFarrell]

Thanks for the responses, everyone!

Out of your mind? A little. But I respect the creativity. I'd test that suction mount setup with a sandbag before putting anything valuable up there though. Threaded rod flex is real.

HAHA! Nice! Seasucker does not appear to rate their cups for vertical capacity. Instead, they tout the amount of force that the cups hold before releasing. One of their products is a RotopaX tank holder that supports up to 3 gallons or water or fuel. That's ~25 lbs if it's water, plus the jug and RotopaX hardware, all held to a vertical surface. I don't think I'll exceed 35 lbs. I'll explain more below.

How much overhang are you talking about from the back crosspiece? Sounds like maybe 18in? I don't think the strut would flex much. I would move the rear crosspiece back as far as possible and try flexing the unit.

I've extended my Superstruts and shared photos below. The unsupported spans are 23 inches. You're right: The overhangs don't flex much with moderate pressure applied. My goal is to seize all flex at the end of the overhang. See more explanation below.

they make a taller strut that wont flex as much. I use this a lot to mount solar panels on top of my camp trailers, etc
I wouldn't try additional mounts that touch the roof, magnetic or otherwise. asking for damage.

My first setup used the full-height struts. Given my loads, one shown below, the extra strength was simply unnecessary and doubled the weight of the rack alone. I appreciate the idea, though! As for the third row with mounts, I think only a portion of the weight carried will actually transmit through the Seasuckers and into the roof itself. As mentioned above, the struts don't flex too much.

I finished the first test fit last night. I adjusted the new crossbar to ride as far aft as practical without interfering with the hatchback or the cargo box. Here's the initial result:

This photo shows that the struts sit just a little higher than the cargo box since the box has recessed crossbar openings that enable it to ride closer to the roof.

Here's how the curvature of the roof affects the angle of the Seasucker vs. the struts...

What I'm not showing yet is the actual uneven junctions. Some of these parts just arrived. I will do a combination of grinding an angle into the aluminum sleeves as well as the addition of malleable beveled washers where appropriate.

I'm removing the cargo box tonight so that I can prepare for a radio event this weekend. Soon, my "micro-tower" will be up and ready for the road...

The hitch-mounted antenna is part of the reason why I want to carry an external box on the roof. The antenna prevents me from opening the hatch. Yes, I can remove it when I really need to (as I did for a flat tire last year), but I'd like to have a few things easily available if I don't actually need to unload the car.

The rotating antenna array, mounted just 4-6 weeks per year, is part of why I don't want too much additional weight on the roof. Believe it or not, the roof load with that thing up there is still less than 60 lbs. I do need to change my driving behavior, though, since the tall load can add a cantilever effect at the roof rack mounting points.

Coincidentally, I figured out what I'm going to start with as an experiment. I'll add another "crossbar" (no additional supports) ~15 inches forward of the new crossbar so that I can use this Boco Custom lockable mount to hold a Husky Build-Out case.

I'll weigh whichever box I plan to carry to ensure that I keep it less than 35 lbs. I'll share the end result when I get there. Thanks again for the ideas and thought process!