heavy duty bed extension

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Hello all. Fisrt off great forum, lots of great info especially for a beginner like me.   Now Iv done a search for truck bed and hitch extension projects and found a couple of projects that are what I am trying to build, but I need a little more help in building mine to a more heavy duty design. Basically I want to haul 2 quads in the bed of my GMC Sierra. With the tail gate down I get 8' 4" of cargo space. I need 12 ft total to fit the second quad which is an extra 3' 8" longer.   I want to make an extension stick out 3 feet with a 40" cross bar at the end, then bolt a set of loading ramps from the cross bar to my bed for the second quad to sit on.   My dilemma is this, I have 2 ways of building my rig. The 1st is using 2" (.250 wall) square tube 3 feet out from my receiver, another piece of tube mounted virtically at the end straight up 10" tall with the horizontally mounted 40" cross bar welded atop of it. So that design comes straight out and straig up to a "T".   The 2nd design is similar but instead of straight out, I want the 2" tube to come out of the receiver a few inches then angle upward 20° until it intersects with the loading ramps. Id prefer this design to gain ground clearance under the extension.      My question is will angling it upward put too much strain at the angled weld just past the receiver, as opposed to the tube being one solid piece straight out? As I go back and read this it sounds confusing but it's very sipmle. I'll come up with a few drawings tonight and post them. I have all the materials including 1.5" square tube for internal reinforcement and 3/16" plate steal to make gussetts.
Reply:I forgot to mention, the quad weighs 350lbs but the extension will only see half that load (about 125lbs) since the front tires will be resting on the back of the bed. I need it to withstand multiple 450 mile round trips to the desert which is the reason for the heavy duty concept.
Reply:Just thinking out loud, but I would think your angle set-up would be best. My non-engineering thinking says the weight will cause less flex with a short stub coming out from the receiver as apposed to a long "beam". Like a diving board: longer = most flex. Plus you have to account for grounding out on curbs when entering and exiting a driveway, for example. The angle will help avoid this. Definitely use some plate to gusset the angle. Triangular piece on either side of the joint will help remove flex. Flex is not your friend. Other option would be another piece of the square pipe at an angle as a brace. Run it from the section of pipe that is just outside the receiver up high on the piece angling up.Make sure it clears the tail gate.Just tossing around ideas in my noggin. 200amp Air Liquide MIG, Hypertherm Plasma, Harris torches, Optrel helmet, Makita angle grinders, Pre-China Delta chop saw and belt sander, Miller leathers, shop made jigs etc, North- welders backpack.
Reply:Check out JD's hitch rack. Great plate gussets there.http://weldingweb.com/vbb/showthread.php?t=41977200amp Air Liquide MIG, Hypertherm Plasma, Harris torches, Optrel helmet, Makita angle grinders, Pre-China Delta chop saw and belt sander, Miller leathers, shop made jigs etc, North- welders backpack.
Reply:Here is something I made to be able to haul two four wheelers in my truck but I still had to be able to pull my camper so I had to go with a little bit different design.  Besides the scary ride up the ramps, it worked very well.  I build it out of what pieces I had left from other projects so it might seem a little pieced together but it is mostly 2x3 and 2x2 11ga.
Reply:That rack is slick, and with an electric or manual winch on a sliding mount up front you could recover non-runners too. Lots of storage space underneath!
Reply:I would go for a rack like this not a extension of of a reciever hitch. Most reciever hitches are only rated at 300-500 lbs verticle load. add a 2 or 3 ft extensin and you are asking for probs. were you planning on leaving your tail gate on? I wouldn't carry that much weight on the cables and a reciever extension. Have seen too many broken cables and wouldn't want to scrape my 4 wheeler off the road.Millermatic 252millermatic 175miller 300 Thunderboltlincoln ranger 250smith torcheslots of bfh'sIf it dont fit get a bigger hammer
Reply:Thank you all so much for the great info. I never thought of triangle gusseting on either side of the angled weld, that sounds like the answer I was looking for.      As for the rack, I completely agree, it's slick and adds a ton of cargo space considering there are 2 quads in the back. Great job.   My receiver is a class III and is rated for 800 lb tongue weight, is that not enough to handle for my project? I'm completely over thinking this and am probably over building it as well. I had a structural engineer at my work run a load stress test on some load software with 2'' square tube .250'' to see how much weight it could handle 3 feet out from the receiver. Turns out it can handle 750 lb before it yields, granted it's only a test but it's gotta count for something. Here's a picture I drew up. As you can see my software isn't so fancy haha. The picture is one I found on google, this is the same concept I am going. I'll consider the rack, i just don't have the storage for it when it's not in use.    Anyway after you guys look at the pictures let me know what you think. Thank you.
Reply:weld up your main tube before you put your t on and do all the work slide it in and find someone who weighs 200 or so jump on the end of it and see what it does. If it looks alright than continue your build. I would maybe find some sand bags or something cheap to give it a good test before hauling the quads very far.Millermatic 252millermatic 175miller 300 Thunderboltlincoln ranger 250smith torcheslots of bfh'sIf it dont fit get a bigger hammer
Reply:You could also maybe support from the end back to anchor points on box or stake pockets with ratchet straps to help carry some of the load.Millermatic 252millermatic 175miller 300 Thunderboltlincoln ranger 250smith torcheslots of bfh'sIf it dont fit get a bigger hammer
Reply:Will do. I had planned on loading it up with a couple of weights from my weight bench with lag bolts through them and driving around but I like your idea better. If sand bags come lose no big deal.
Reply:As long as no one is tailgating and if they are should be good deterentMillermatic 252millermatic 175miller 300 Thunderboltlincoln ranger 250smith torcheslots of bfh'sIf it dont fit get a bigger hammer
Reply:Look for a "sled bed".  This is a routine operation for snow machies so that 2 can be carried on a pickup.  Wheelers are also easily carried on a "sled bed".
Reply:Mototrig, I'm just going to be blunt with you and honest.  I'm not being a jack#$%, but any state trooper would state the obvious . . . YOU NEED TO BUY A TRAILER!  Projects like the one you're thinking of are dangerous for highway use.  Is your 450 miles round trip on interstate or any public roads?  How is it fair to other motorist when a 350 lb projectile comes flying off your truck and kills their passenger?  I wouldn't hessitate pulling you over and chewing your $%# into the ground.  Sincerely, -Sarge-MikeThurston WeldingHuntington, IN
Reply:The hitch extension is an abortion.Consider putting a regular FLATBED on the truck.  It's the best of all the options, with strength, versatility, and extra width. Sierra beds are easy to pull. The bolts come up from the bottom, so a half-inch breaker bar, an (18mm usually) socket, and a couple of extensions get it done. The filler neck and electric connectors are easy to reach, and if you pull the bumper first it's even easier to do.There are plenty of very slick bed options that have a greater cool factor than a stock bed, and if you can afford four-wheelers you can afford to build a custom flatbed to transport them in style while being able to haul lots of other cargo.Stock beds can be made into utility trailers which sell easily.If you can find a larger flatbed at a scrap yard, they can be cut down to fit which reduces fab time and metal cost.
Reply:I think you'd be way better off with a side by side solution, along the lines of Springer 45's design.Wow, apparently they sell these racks.  check out http://www.discountramps.com/atv-truck-rack.htm  They've even go one priced below $1000, http://www.discountramps.com/haulall-atv-truck-rack.htmI think you are going to be way overloaded for the hitch receiver.  Remember its not just pure weight that is the issue, its also the way its loaded at the receiver.  Its dead load, but its also moment that counts.  Moment is a load applied over a distance, that results in a torque.  When viewed from the side of the hitch, a 800 lb normal trailer load is generally applied at the hitch ball, call it 6" away from the end of the reciever.  That means your hitch reciever, while holding a 800 lb load, will be see 400 ft-lbs of torque (800x0.5) at the reciever tube end. In your case the moment arm is a LOT longer.. lets say 250 lbs (half of a heavy quad) + 50 lbs for steel (guestimate) but the moment arm is now 3ft long.. Now you are talking 300 lbs of vertical load BUT 900 ft-lbs of torque (300x3), more than twice what the receiver mount would see with an 800 lb load on a trailer applied at a ball hitch, 6" away.  (and frankly from your sketch, and your comment that a quad needs 6 feet of length, I'm not clear that 3 feet is long enough.. I'm thinking it's more... but its not clear if your sketch is to scale or not..)   Not a good thing at all.  good luck with it. --zipOne comment, from looking closely at the photo with fore/aft load.  If you take the long ramps the quad is sitting on (make 'em 11 feet long), and bolt it down to the bed near the cab so they are cantilevered off the end of the bed, that would really help support the load.  they'd have to have a pretty deep cross section, but that in combination with the receiver hitch would certainly improve the load capacity.Last edited by zipzit; 05-27-2011 at 05:24 PM.
Reply:Sarge--Definitely no offense taken. If I wasn't willing to take criticism I wouldn't have asked for comments and ideas. However, weather it be a quad hanging off the back or 2 quads mounted above the bed rails, the mechanism of failure is still present. The bed rack does seem a little safer as far as sturdiness. I have a 7' lift and 35' tires on my truck so parking the quads above the bed rails throws the center point of gravity real high. Either way Iv put a LOT of thought into this build and a quad flying off the back into someone's hood has gone through my mind quite a bit. Even if I go through with whatever I want to build, if it doesn't look or feel sturdy or safe I'm scrapping it. Thank you all for your thoughts, for now Im going to re-think this whole thing I. Maybe it's not such a great idea after all.
Reply:Little trailers are cheap.....My name's not Jim....
Reply:[/QUOTE]Yep. But I'd add gusset's and struts to the "T" part too, to prevent side to side wobble. And like others have said, test the chit out of it. I'd drive the rig out on a dirt road unloaded, with sand bags in the main bed( great idea) the load it up and beat the chit out of it on the dirt road. Better to break something here than anywhere else that risks you or others. I can appreciate others suggesting a trailer, but you can't always tow a trailer effectively where you want to go. That's why we bought a truck camper. Good idea too regarding the support ties to the stakes.200amp Air Liquide MIG, Hypertherm Plasma, Harris torches, Optrel helmet, Makita angle grinders, Pre-China Delta chop saw and belt sander, Miller leathers, shop made jigs etc, North- welders backpack.
Reply:Yes the support ties are a good call. Trust me severe testing will be had, I don't take safety light heartidly. Thank you for the advice and encouragment.
Reply:If your dead set on building something build a tow dolly and drag the extra 4 wheeler.
Reply:First option: a good quality utility trailer or dedicated ATV trailer can be found for reasonable prices.  It can also be used for lots of other jobs and is easier to load than the bed of a lifted 1/2 ton (or heavier) pick-up.Second option: the sled bed type of flatbed -  mounted atop the stock bedrails.  Provides lots of storage space beneath and for some models, it's secure and weatherproof storage.  You're right though, it will place the truck's CoG up high, especially if the truck's lifted.  Driving up on the ramps may also be exciting.Another option to consider - I've seen it done lots but it really depends on the particular models of ATV involved and the length of the truck bed.  Basically, drive one up into the bed and lift the front wheels up onto a small ramp or shelf at about the height of the top of the sides.  The ATV should be close to vertical on its back wheels.  Then drive #2 up and lift it up as well, placing its wheels somewhere on or against the wheels or rear rack of #1.  #2 is essentially piggybacked onto #1.  This pic sort of shows what I'm talking about where #1 is vertical but #2 is on all four wheels.Obviously, it may not work depending on the specific machines but it's worth a shot.  I've seen guys carry two mid-sized ATVs on a half ton like this and make enough room to carry a couple of bob-sleds AND some firewood.If you have a headache rack, you might be able to rig some ramps to it to help driving/lifting the front of ATV #1 up.  If your ATVs are suitable, a headache rack and couple of ramps are cheaper than a utility trailer or even sledbed.  The upside with this is the whole load is contained within the bed and it's not as high up as if the machines were up on a sledbed.I also like the idea of replacing the stock bed altogether with a flatbed - they offer a lot of options but that's admittedly a major modification to your rig.Last edited by Hardware; 05-28-2011 at 08:38 PM."These instructions are at our present level ofknowledge. Legal requirements do not exist.Technical issues subject to change."_________________________________________Lincoln MIG PAK 180Lincoln AC-225
Reply:Those are all great ideas, I'v put thought into all of them and greatly appreciate all the different responses. Ive tried standing up one quad with the other on it's wheels and the rear quad just barely holds on the lip of the tail gate, not safe. Iv put thought into a trailer and have decided that is the last thing I want to do is spend more gas towing something and be confined to the right 2 lanes (not that I would drive any faster than 55 or try to pass people with a crazy dual quad setup on my bed). The original posting was to figure out how to make a heavy duty hitch extension. I am a self taught welder but by no means a certified welder. I'll tac-weld everything where I want it and let the certified structural welders at my work bead this thing up. My point is my knowledge of fabricating is minimal and would like the experience of this forum's advice. Maybe your experience says not to do this, not sure.
Reply:What quad are you putting on the back? I've been going to the sand dunes in Oregon for years and if you have a sport quad on the back and build it to your design you will be fine. The guy that has the yellow Raptor in your picture has many miles with no issues. Here is a link from when he built it. Bed Extender One suggestion in the thread is about mounting lights back on the extender.Last edited by RaptorDuner; 05-29-2011 at 10:10 PM.Millermatic 200Hobart Handler 120Victor O/A & Ramco BandsawLincoln 225 ACSnapOn AD HoodMiller XMT304/22AHypertherm Powermax 1650 G3Lincoln Idealarc DC600 w/Extreme 12 VSMiller Digital Elite "Joker"
Reply:Don't forget to snap some pics and let us know how the testing goes. I think done right, you'll be happy.And, to me, you don't sound like an idiot. I encourage those who, and you , for getting the experienced guys at work to weld up something your big enough to acknowledge is beyond your level. 200amp Air Liquide MIG, Hypertherm Plasma, Harris torches, Optrel helmet, Makita angle grinders, Pre-China Delta chop saw and belt sander, Miller leathers, shop made jigs etc, North- welders backpack.Originally Posted by RaptorDunerWhat quad are you putting on the back? I've been going to the sand dunes in Oregon for years and if you have a sport quad on the back and build it to your design you will be fine. The guy that has the yellow Raptor in your picture has many miles with no issues. Here is a link from when he built it. Bed Extender One suggestion in the thread is about mounting lights back on the extender.
Reply:Originally Posted by bert the welderDon't forget to snap some pics and let us know how the testing goes. I think done right, you'll be happy.And, to me, you don't sound like an idiot. I encourage those who, and you , for getting the experienced guys at work to weld up something your big enough to acknowledge is beyond your level.
Reply:Originally Posted by mototrigAttachment 67912
Reply:That's a good idea, welding rings with straps or chains would be real sturdy.
Reply:When loading the second (rear) quad, how do you get the ramps with the quad on it, up on the truckbed and past the T-hitch insert?Brute force to lift and hold the ramps and quad uP, while the other hand inserts the T-hitch insert?...or....Blackbird
Reply:I have two sets of identical loading ramps made of galvanized steel rated at 1000 lbs per set, 1 set will be bolted to the bed and T on the extension, the 2nd set will come up from the ground and somehow latch to the T and will be used to load the quads.
Reply:Raptors are 396# dry so they are not very heavy. I was refering to 600#+ utility quads. I tried the link and it worked for me but their is not a bunch of build pics. More or less just "done" pics.Millermatic 200Hobart Handler 120Victor O/A & Ramco BandsawLincoln 225 ACSnapOn AD HoodMiller XMT304/22AHypertherm Powermax 1650 G3Lincoln Idealarc DC600 w/Extreme 12 VSMiller Digital Elite "Joker"