Exo/Roof Rack advice..

[jeepdreamer]

I'm still in the thinking stages of a roof rack for my CJ8. Being that the full hardtop is fiberglass I don't think it would live with a roof rack/RTT/whatever all piled on it so I'm gonna do my own. To that end I have a few questions..
I've been looking at all sorts of racks...both in person when I see them and online. My idea is somewhere in the exo-cage family design-wise but not looking for the weight of a Roll cage for this. I'll try and find pics of ideas...
The last one I made was on a tight budget so it was made out of 1" gas pipe. Don't laugh...it worked and didn't look bad at all, esp. considering the material used. But it was/is heavy...Very heavy! So I am wondering about sizes and thicknesses of tubing and what could/would work. I wish I could do aluminum but I've never welded that before and steel seems like it should be less expensive...?
So does anyone have any input? I will be making some "crusher" style corners for the back of the tub and rock slider/rocker protection for the sides...both of which will make good mounting points for the uprights of the rack...And I may tie it into the windshield area as well...
The big question is tubing. What would be stronger/better to use...something in the smaller diameter/thicker wall or thiner wall bigger diameter? The bigger D "looks" more beefy but I don't care about the looks near as much as the function. Throw me some ideas or thoughts...anyone! You Landy and Yota folks help out too please! You've been doing the expo thing longer than us heepers!

 

[poriggity]

Are you going to be relying on the rack to also be an exo cage? If so, DOM tubing or HREW tubing is the way to go... I'll be interested to see what you come up with.
Scott

 

[jeepdreamer]

Not the intention...

Scott...Nah, I'm hoping to not have to rely on the rack as a exo-cage. To that end using DOM or Hrew in sufficent size/wall would make the rack heavier than I' would like. The idea is something strong enough to support the RTT/fuel and whtever else finds its way up there for exploring while keeping the interior for valuables or easier access like the F/F and kitchen stuff. The racks tubes (I hope) will only be called on to deflect the occasional odd tree branch or whatever. I have an internal cage already in the planning stages but just for dvr/pass since I don't have a wife or kids...

 

[jeepdreamer]

Really diggin' this..

With a huge nod to Sven I'm really diggin his rack..uh...that didn't sound right. His roof rack is well thoughtout and closer still to what i'm hoping for!
Incase anyone has missed the XXXperience..

 

[Mr. D]

Looking forward to what you design. good Luck

 

[jeepdreamer]

Design...?

Thanks Mr D...
I don't know if you'd call what I come up with "design" but I can only hope it works out. Time is going to be my enemy here. And I also have to remember it needs to still fit in the shipping container...haha. I'll keep everyone posted. And I'll tryvery hard to take pics...even if they don't get added or a build writtten until after the fact...
Too bad I have zero computer skills...sure could do some "design" work on a drawing program...oh well, maybe paper and pencil will work for me!?!:wings:

 

[matthewp]

If the choice was mine, I'd go with the DOM tubing. All the way up on the top of the Jeep, there's going to be a lot of vibration and extra torsional forces that will be magnified because it's up there. I learned this from the catastrophic failure of my factory roof rack on my Libby. Centrifical sway can be considerably more than you'd think up on the roof.

 

[wjeeper]

Personally I would just run with CREW tubing. DOM is great when you need tubing that has a more precise inside or outside diameter. DOM tubing usually starts its life as ERW tubing from what I have been told. I think that as long as you face the weld seam of the tube away from where it may impact things splitting along the seam is not really going to be a problem. I think many projects that are made in DOM would be just fine in in ERW tube but its the "bling" factor of being able to say its DOM.

Chromoly is something I don,t know much about. I know its like 25% stronger (dia and thickness the same) and it costs way more. Welding it is also trickier without making it brittle and I am pretty sure you are suppose to stress relieve the welds..........don't quote me as I don't have much experience with chromo tubing

I usually use A-500 tubing or pipe. Its cold rolled so it holds up better than gas pipe which I think is usually hot rolled. A500 is a bit harder to bend and springs back more after you bend it.

The Home Depot pipe I have used bends easily in a bender and held up ok when used for sliders. The A500 i used held up much better and it didnt gouge or bend on contact as easily. Obviously your not making sliders but I think its somewhat applicable.

As far as what size diameter/ wall? I think its a lot of personal preference as far as diameter goes......wall thicknesses i usually run .120 wall stuff. Mostly because its not so thick its difficult to bend, but not so thin it kinks or dents easily.

FYIW I am planning a roof rack build for my YJ that will go over the hardtop and hold my RTT that is going to be 1" sch 40 A500 and usually its sold as "structural steel pipe" :sombrero:

 

[jeepdreamer]

Compromising...

I think HREW is the likely candidate for this one also. I just need to find it with an acceptable wall that is not super heavy. I'm not looking for a exo cage here. And thanks for the info on the applied stresses. I have some knowlegde on this and I think I can manage to avoid to much issue with a little head scratching and thought. Unlike Sven's rack, I am hoping to mount mine to steel "crusher" style corners and rocker gaurds. The current idea I have is using some weld on tabs and some bushings to insulate the rack from...uh, wracking itself to much? It should allow a little give to offset vibrations but not enough to cause flexing stresses great enough to create a failure.
I also don't have access to a high end tubing bender so I just use the little benchtop one I bought at Harbor freight tools...Its slow but it works ok for me.

 

[JIMBO]

:sombrero: Just a suggestion-you might look at the MBRP JK Rack for design and function, here's a pic of the prototype a couple years ago, but on their website it'll show an optional full rack/basket/windshield bar/lights--

This rack can support over 700lbs--A thought-

:costumed-smiley-007:wings: JIMBO

 

[jesusgatos]

Why not just pierce through the fiberglass hardtop and tie into the existing rollcage. I just built this roofrack for my Tacoma, and you could easily make it bolt through the hardtop so that you could still take the top on/off. Would be lot cleaner than all those wrap-around-the-hardtop-racks I've seen.

 

[jeepdreamer]

Now THATS what I'm talkin' about!

Awesome intel guys! The larger OD I can do without too much problem...just need to find a wall thickness I can live with and afford. I'd even go up to 2 1/2ish if I can find what I'm after. First thought that comes to mind (don't laugh) is the pipe they use for chain link fences...haha. Ok, you can laugh a little. Though I have to wonder if this would be to thin...? Not sure honestly but I bet i could bend it pretty easy in the manual bender and its already galvanized. Not sure but I'll have to think on that idea. I would only guess but that stuff may only be 1/8th wall or thinner? May have to go thicker but who knows? Only headache is cleaning off the galvanization where it needs to be welded then reapplying it along with primer and paint/final coating.
I did think of going through the hard top but I honestly don't care for that. The simple idea of drilling into an already watertight and expensive full hard top seems..wrong? And I am fairly sure my almost 30 year old hardtop won't take well to carrying the load itself.
The MBRP kit is nice...I like the look and general design but I honestly don't know how you would expect the thin walls of the fiberglass top to carry that 700lbs for a great deal of time without causing failure? Maybe I am just to novice in design work but the image I get is either overloading the mounting point areas or a moderate tree/branch/rock strike doing some nasty carnage should it contact just one of those uprights?
The front end tie in I am still thiking on. There are a lot of ways people get that done. And I agree, the top of the w/shield fram is NOT the answer. Bad ju-ju. But I can't decide if tying into the w/sheild hinge is the better option either. The way Sven did it, making mounting plates to go directly to the cowl seems better. If I do it correctly I may even still be able to drop the windsheild? Though I gotta be honest...lat time I did that was 15 years ago on my YJ! And only a couple time before that! It was a little more common on my CJ2As for me to ride around that way though?
So this is proving to be a great help guys...Please keep any thoughts or ideas, no matter how off the wall you think they sound...I'm almost out of Iraq and should be wrenching in a couple weeks...YEAH!

 

[JIMBO]

:sombrero: Heh Heh, that galvanized fence pipe is usually 1/16" wall and not very strong-

Awesome intel guys! The larger OD I can do without too much problem...just need to find a wall thickness I can live with and afford. I'd even go up to 2 1/2ish if I can find what I'm after. First thought that comes to mind (don't laugh) is the pipe they use for chain link fences...haha. Ok, you can laugh a little. Though I have to wonder if this would be to thin...? Not sure honestly but I bet i could bend it pretty easy in the manual bender and its already galvanized. Not sure but I'll have to think on that idea. I would only guess but that stuff may only be 1/8th wall or thinner? May have to go thicker but who knows? Only headache is cleaning off the galvanization where it needs to be welded then reapplying it along with primer and paint/final coating.
I did think of going through the hard top but I honestly don't care for that. The simple idea of drilling into an already watertight and expensive full hard top seems..wrong? And I am fairly sure my almost 30 year old hardtop won't take well to carrying the load itself.
The MBRP kit is nice...I like the look and general design but I honestly don't know how you would expect the thin walls of the fiberglass top to carry that 700lbs for a great deal of time without causing failure? Maybe I am just to novice in design work but the image I get is either overloading the mounting point areas or a moderate tree/branch/rock strike doing some nasty carnage should it contact just one of those uprights?
The front end tie in I am still thiking on. There are a lot of ways people get that done. And I agree, the top of the w/shield fram is NOT the answer. Bad ju-ju. But I can't decide if tying into the w/sheild hinge is the better option either. The way Sven did it, making mounting plates to go directly to the cowl seems better. If I do it correctly I may even still be able to drop the windsheild? Though I gotta be honest...lat time I did that was 15 years ago on my YJ! And only a couple time before that! It was a little more common on my CJ2As for me to ride around that way though?
So this is proving to be a great help guys...Please keep any thoughts or ideas, no matter how off the wall you think they sound...I'm almost out of Iraq and should be wrenching in a couple weeks...YEAH!

The MBRP rack actually will hold over 1000lbs (I've seen it), but

It only uses the composite hardtop to hold the rack on the jeep-the structure of the rack is also an added roll cage, for the rear of the JKU, it's vertically supported by 4 extruded brackets that attach to the jeep hub, (inside the top)the only force applied to the hardtop, is probably lateral and there ain't much of that !!

Good luck

:costumed-smiley-007:wings: JIMBO

 

[jeepdreamer]

Good info again..

So it is very well engineered and the top is prob a real PITA to remove.?. Well, that makes me go simpler...I like how it looks though? *blush*
The fence pipe was kind of a passing thought...not very realistic since it is not very stout and the galvanization is a big pain to grind off to work with (did a little research!). Not something I want to mess with or breathe...
So the HREW is coming back around again...though I just dropped a good portion of the funds on something for the drivetran so the rack may get pushed back a little...wonder how hard to build IN Germany it would be...

 

[JIMBO]

:sombrero: Just a quick-

So it is very well engineered and the top is prob a real PITA to remove.?. Well, that makes me go simpler...I like how it looks though? *blush*
The fence pipe was kind of a passing thought...not very realistic since it is not very stout and the galvanization is a big pain to grind off to work with (did a little research!). Not something I want to mess with or breathe...
So the HREW is coming back around again...though I just dropped a good portion of the funds on something for the drivetran so the rack may get pushed back a little...wonder how hard to build IN Germany it would be...

The MBRP rack internal brackets are secured by the SAME BOLTS the HARDTOP uses and thats all, if you don't have a hoist, it makes taking the hardtop off EASY (handles) !!

:costumed-smiley-007:bike_rider: JIMBO