Roof rack question: Unistrut, thule, yakima, or L-Track

[batgirls]

Hello!

I have a 92 extended Sportsmobile with a Fresno penthouse. I'm thinking about adding a rack system for solar, kayaks, maybe a yakima rocket box for lightweight cargo.

I found some good discussions about using square tubing or unistrut (especially alluminum) for a rack base rather than Thule or Yakima rails here:

https://www.sportsmobileforum.com/fo...hts-18024.html

Has anyone used aircraft L-Track for a rack base? It seems ideal.

e-trailer has small bits of L-Track for a lot of $$.

Other vendors have it for about $10 a foot. There are tons of bolts, tie-downs, and ratchets made for L-Track, which makes it a bit more attractive than unistrut.

Of course, aluminum Unistrut looks like it runs $3-$4 a foot.

If anyone has experimented with L-Track, I'd appreciate hearing about your results.

[SteelheadJones]

If I remember right, Rallypanam used unistrut on his roof years ago. I think he mounted solar panels and MaxTrax on it. (Yep, took me a minute but found it here.)

Not sure if the roof would support all the weight you might carry with a rack? Maybe if you mount the unistrut as far outboard as possible, put backing plate on the inside, and do your best to distribute the load over a large area?

[gcvt]

Originally Posted by SteelheadJones

If I remember right, Rallypanam used unistrut on his roof years ago. I think he mounted solar panels and MaxTrax on it. (Yep, took me a minute but found it here.)

Not sure if the roof would support all the weight you might carry with a rack? Maybe if you mount the unistrut as far outboard as possible, put backing plate on the inside, and do your best to distribute the load over a large area?

I copied Robb's idea after talking to him and seeing what he did. Both options being discussed here will work but I really like the unistrut.

[1der]

Aluminum Uni-strut works really well. Spring loaded nut plates and aluminum angle / C Channel make great easy/cheap mounting points.

Re all the items you mention for your roof gear - any solar panel will be ineffective with shadowing from box, kayaks, etc. Remember the solar panels need to be mounted above any cross bars to prevent the bar shadows from keeping the panels from producing any power.

L Track is heavy and imho has no place on a fiberglass roof. You are then locked into the $pecialty brackets and hardware.

Here are pics of Thule/Yakima rails (staggered front/rear due to roof tapering.) and Uni-strut rails (White van)

[Big_ern_101]

Aluminum Strut is what CCV uses and thats good enough for me!

[batgirls]

Thanks for all the responses, everyone. Sounds like aluminum unistrut is the way to go.

1der, thanks for the advice about solar. I was going to put the solar panel up front and away from the other roof top stuff.

In terms of spreading the load, I was thinking of installing 4 rails:

2 outboard rails with backing rails outside the penthouse tent fabric.
2 inboard rails mounted onto the through-bolts that attach to the scissors lift inside.

One problem with the inboard rails, I know at least one of the through bolts (for the driver's side latch) isn't lined up with the others. Given the general build quality, I imagine all of them vary.

However, my top needs a fresh gelcoat, co I might could move the bolts a bit port/satrboard to line them up with a unistrut.

I'd apply two-sided eternabond to all the struts, especially the inboard ones, to prevent leaks.

Thoughts? Bad idea?

[1der]

The load on the outboard rails is where you want it all.

The vertical support/forces are all going to the lifting bars no matter where you load the roof. The weakest part of the roof is the inboard section. Place the rails outboard of the canvas but close to the canvas and you will be fine.

Distribute the loads fore/aft along the rails. This is important because the SMB scissor lift pivot point has to deal with the vertical load at a single point. Heavy at front or rear of roof will mess things up, that pivot point is a teeter totter.

[batgirls]

Originally Posted by 1der

The load on the outboard rails is where you want it all.

The vertical support/forces are all going to the lifting bars no matter where you load the roof. The weakest part of the roof is the inboard section. Place the rails outboard of the canvas but close to the canvas and you will be fine.

Distribute the loads fore/aft along the rails. This is important because the SMB scissor lift pivot point has to deal with the vertical load at a single point. Heavy at front or rear of roof will mess things up, that pivot point is a teeter totter.

That makes a lot sense. Thanks!

That scissor is a weak (as numerous threads prove)

[moorefc]

Just a word of caution to add to previous posts, downside of roof loading....getting the top up and down is drastically affected with a non electric top after about 30+#. Lots of discussions can be found related to this, plus the cross members are not that strong given larger loads, and van suspension is affected when loaded with high center weight....
Easy to test by putting some lumber etc on the roof and exercising up and down, driving...
Some find it necessary to remove loads to raise and stabilize the roof as an alternative...a bit of a camping compromise.
Also be careful to seal roof penetrations since the inner roof sandwich is wood.

[batgirls]

Originally Posted by moorefc

Just a word of caution to add to previous posts, downside of roof loading....getting the top up and down is drastically affected with a non electric top after about 30+#. Lots of discussions can be found related to this, plus the cross members are not that strong given larger loads, and van suspension is affected when loaded with high center weight....
Easy to test by putting some lumber etc on the roof and exercising up and down, driving...
Some find it necessary to remove loads to raise and stabilize the roof as an alternative...a bit of a camping compromise.
Also be careful to seal roof penetrations since the inner roof sandwich is wood.

Thanks, that's good advice.

Given the advice above about loading the outboard edges, I don't think I'll be penetrating the interior ceiling. I should be able to keep all mounting points outside the tent.