[TWX]

Been thinking about the rear bumer a lot lately, with a mind on how the factory rear bumper has a hitch-structure in it good for 3500#, but when adding a proper hitch this heavy component becomes redundant. It doesn't even do a good job with that rear bumper, the bumper bends and contacts the body too easily (as mine was when I bought it, which I fixed, then backed into an immovable object and bent it right back again). Plus the hitch hangs down.

I was randomly browsing and saw that Curt sells a hitch for RVs that has a 2.5" OD 2.0" ID crosstube that is 68.5" wide. It's meant to be installed with adjustable flanges that then are tightened down or welded down at the right width. I got under the truck and took some measurments of the factory hitch and checked spare tire clearances:

Tape measure housing is 3.5". what I concluded is that the Curt 68.5" crossbar is just a smidge narrower than our rear bumper, and if the factory flanges had the factory hitch crossbar cut free of them, the Curt crossbar would barely clear under the quarter panels.

I had looked at the ARB Navara rear bumper, it's not as high as a true high-clearance bumper, but it is about 2" higher than the OE hitch. Basically the drawbar would sit where that factory structural crossbar on the rear bumper sits.

This got me thinking about the large gap between the ARB bumper and the back of the truck, and the gap that would be present if this Curt hitch were used in the fashion i'm thinking. This leaves room for swingouts, where the swingouts hinges tuck deep inside, allowing for some creative engineering to let them swing and stay close to the truck even when open, to avoid interfering with say, a trailer.

This is what I came up with:

The idea is to use .120 wall DOM 1" tubing bent in such a fashion that it results in three dimensions of material, to increase strength without adding a whole bunch of weight. If I've done the calcs on the tubing itself correctly then I've added less than 50# over just the Curt hitch itself, irrespective of the spare and fuel cans themselves obviously.

We'll see if I try to build this or not. If I can make this work then it might not come in any worse than the factory rear bumper and hitch setup when it comes to weight.

 

[Antennahead]

I like the swing out spare carrier! Putting gas cans on the back not so much. Reminds me of the Pinto from a safety view.

 

[TWX]

I like the swing out spare carrier! Putting gas cans on the back not so much. Reminds me of the Pinto from a safety view.

I'm not too concerned. These are retired German or Swiss military fuel cans made of steel and welded at the seams, and they're up pretty high in what I have in mind. Nevermind that most likely they'll only be present (and the swing itself only present) when going on the sorts of trips where that extra fuel may be necessary.

Basically my idea is that the swingouts are not on the vehicle most of the time anyway.

 

[StomperMN]

First off, awesome adaptation ideas! Secondly, WHERE did you find the Frontier on "graph paper" and what program are you using to design with? I'm old-school with the REAL graph paper still for anything I design before actually working into the C.A.D. (Cardboard Aided Design) templates.

 

[TWX]

Took some additional measurements/pictures of the location of the factory hitch relative to the bed.

Started out taking two of those 2" by 2" cardboard angles that are used as pallet corner protection to shove into the inside of the crosstube, wrapped with a dead piece of cable to hold them tight:

Then I put a scrap of hardwood across the top of the bumper, pressed against the bottom corners of the bed right below the tailgate, then placed a plumb-bob and measured from the string to the wood to figure out where the back of the hitch crosstube is:

It's about 6" from that corner point of the bed, or based on the curvature of the tailgate, it's around 7" from the back of the sheet metal at the rearmost point of the truck ignoring the bumper.

Then I got a measurement of how far from the top of the hitch is from the bottom of the tailgate:

Basically 9".

And a measurement how far it is from the top surface of the lowered tailgate and thus approximately how far it is from the floor of the bed:

Basically 12".

So I'm not off by a whole lot with my dimensions.

This makes me wonder though, could one built some kind of swingouts that simply slot-in to either the aftermarket hitch I'm thinking about, or even into the factory hitch, then come up along the sides of the truck?

I'll work on some designs.

 

[TWX]

First off, awesome adaptation ideas! Secondly, WHERE did you find the Frontier on "graph paper" and what program are you using to design with? I'm old-school with the REAL graph paper still for anything I design before actually working into the C.A.D. (Cardboard Aided Design) templates.

I don't remember exactly. Technically the line art drawings are for the Navara, and they're unfortunately not the highest resolution.

This is "draw.io" or "diagrams.net" which has a downloadable version as well. I've monkeyed with the graph lines coloration too.

 

[ssundet]

Following, very cool!! I haven't seen swing outs like this before. I'm into it.

Only other person I've seen build a swing out is from this build, may help with any ideas. Starts at post #41 2014 Frontier - The Hippo

 

[TWX]

Pulled the rear bumper off the truck to take some additional pictures.

Boy those back corners were dirty.

This let me take pictures to figure out dimensions for how the body and frame are aligned to eachc other:

In my graphics editor I tried to use a find-edges tool for some basic line art. It didn't quite work but I got a pretty picture out of the deal:

 

[California Gator]

@TWX , what are you using for a 3D modeling program? You may be able to import the above photo and then dimension one of the strait edges. Then create a wire frame for the back end for reference and then create models of the mount points.

You may need to also import a side view so that you get the offset away from the tailgate. I use autodesk inventor, so it's got some pretty powerful capabilities. I might be able to lend a hand.

 

[TWX]

@TWX , what are you using for a 3D modeling program? You may be able to import the above photo and then dimension one of the strait edges. Then create a wire frame for the back end for reference and then create models of the mount points.

You may need to also import a side view so that you get the offset away from the tailgate. I use autodesk inventor, so it's got some pretty powerful capabilities. I might be able to lend a hand.

I don't have a 3d modeling program. I'm doing my designs on the digital equivalent of graph paper, from two different orientations.

 

[California Gator]

Got it. Well, give me a couple weeks to get my truck under me and settle a ew other things. But I could help with the design if you want.

I have a goal to create a 3D model of the bed.

I had thught about designing my own bumpers, but the ones that are out there have so much more pedigree than me. So I figure I'll buy one or buy a kit and weld it up (or get someone to weld it for me). Same with the sliders (eventually).

 

[TWX]

Got it. Well, give me a couple weeks to get my truck under me and settle a ew other things. But I could help with the design if you want.

I have a goal to create a 3D model of the bed.

I had thught about designing my own bumpers, but the ones that are out there have so much more pedigree than me. So I figure I'll buy one or buy a kit and weld it up (or get someone to weld it for me). Same with the sliders (eventually).

Since I'm doing this for fun, anything you want to do is great.

This is another variation on the theme.

It's not perfect, but could be workable perhaps. Red: essentially two thick and one thin pieces of C-channel are made into a C-shape that would bolt to the frame where the bumper normally bolts on. The thicker parts are the ends, the thinner part is the cross piece. Green: swing arm and hinge, rectangular tubing that fits snugly into the c-channel. White: bumper attachment that is welded to the swing arm. Blue, purple, and gray triangles are gussets. Orange is the bumper that attaches to the hitch and to a piece of angle iron (blue) welded to the hitch.

Dimensions need to be refined. But they are fairly close to-scale.

 

[California Gator]

I think I get it. Is each of those squares 1 inch? So about 86 inches wide (yellow beam).

FYI, structural channel (what you call c-channel) is kind of tapered inside the 'C'. They also make stuff that's actually square like you'd probably want, I think it's called architectural channel. But it would be nearly impossible to find it off the shelf.

So you might need to make the c-channel that goes from one side of the chassis to the other out of flat stock and then weld into a 'C'. You'd want to gusset that as well so that it doesn't deform while welding.

The end pieces that attach to the frame could be standard structural c-channel.

Looks like there's a little interference with the tire and body. Might need to move the tire further out or move the hing outboard a little bit.

To save weight, you could make the red out of aluminum since it doesn't have to be tough to handle being struck while wheeling.

In photo 3, the piece that attaches to the hinge that goes to the tire...you'd probably want to run that through the swing out piece to give it extra rigidity and strength in addition to the gussets.

Looks doable.

 

[TWX]

I think I get it. Is each of those squares 1 inch? So about 86 inches wide (yellow beam).

FYI, structural channel (what you call c-channel) is kind of tapered inside the 'C'. They also make stuff that's actually square like you'd probably want, I think it's called architectural channel. But it would be nearly impossible to find it off the shelf.

So you might need to make the c-channel that goes from one side of the chassis to the other out of flat stock and then weld into a 'C'. You'd want to gusset that as well so that it doesn't deform while welding.

The end pieces that attach to the frame could be standard structural c-channel.

Looks like there's a little interference with the tire and body. Might need to move the tire further out or move the hing outboard a little bit. Or I might be simply representing the truck as too wide at the outer walls of the bed at the tail lights.

To save weight, you could make the red out of aluminum since it doesn't have to be tough to handle being struck while wheeling.

In photo 3, the piece that attaches to the hinge that goes to the tire...you'd probably want to run that through the swing out piece to give it extra rigidity and strength in addition to the gussets.

Looks doable.

Yeah, one square is basically one inch. Scale's not 100% but it's close enough for conceptualizing.

I've worked with telco rack channel that is basically three flat sides. I'm also not opposed to just cutting a piece of rectangle or square tube. Though with only either an angle grinder or a vertical metal-cutting bandsaw that might take awhile. Might have to get one of those metal-cutting circular saws that Evolution sells if I do build it this way.

Yeah, the design isn't perfect with the position of the tire when it swings, but then again the dimensions on the truck are also approximate. I could lengthen the arm that the tire sits on or change how far to the right the hinge point is.

Depending on prices and availability i might make the bumper (orange) out of aluminum square tube in addition to the red thing. I'm even wondering if I could use a sufficient wall thickness to use that hollow space as compressed air storage. Might not be worthwhile though.

 

[TWX]

Late last night I did some additional measuring and as a result did some more tweaking of the design. Moved pivot for the swingarm and lengthened the swingarm to further reduce interference.

And superimposed on the truck itself:

It might be necessary to trim on the curved bit on the underside of the bed near the corners. The swingarm might interfere at this point.

TBD:

• Figure out the fuel can swingarm.
• Figure out the latching system.
• Determine material and wall thickness, and if any material can be reduced in dimension.
• Determine if the 4" by 6" bumper tube is going to be used for compressed air storage or not.
• Figure out the stop-system when it swings open to avoid contact with the body.
• Figure out how much all of this is going to weigh.
• Figure out how much all of this is going to cost for materials.
• Figure out if any of the more exotic materials (ie aluminum) need someone else to be paid to weld them.

This is my fourth interation, and I am becoming increasingly efficient at this circle-jerk.

 

[TWX]

Got bored and made some more annotations on the drawings to reflect particular assemblies.

 

[TWX]

Since there was some question about how this aligns compared to the OE bumper...

Orange is the proposed aluminum 4" tall bumper. Purple is the stock bumper. Yellow is the stock hitch. Red is the replacement crosstube for the hitch.

 

[TWX]

Based on the diagram this is a tentative materials list. I have not yet determined material thickness though.

24" 4x2" thick C-channel

48" 4x2" thin C-channel

18" 3.5x2" thick rectangle tube

64" 2x2" square tube

9" square of 5/16" steel sheet

6 Nissan wheel lugs

56" 6x4" aluminum square tube

8" 6x2" aluminum square tube
-OR-
16" 3x2 aluminum square tube

66" 1" or 1.5" aluminum angle channel

7/8" or 1" bolt 4" unthreaded

Bearings for bolt

Outer tube for bearings

Misc 1/4" steel sheet for gussets

 

[TWX]

Still at it.

Back in June I did this:

Cut some 4" by 4" 1/4" wall square tube to make these brackets that go on the ends of the frame at the back. Also took a piece of pipe and cut it and squeezed it to reduce it to fit trailer bearings. I decided that my hinge is going to be light-duty trailer bearings, 1" ID, just under 2" OD, and I'm going to use a 1" diameter bolt as my pivot. Unfortunately I was not having a lot of luck finding 1" fine-thread so I'm going with coarse, so 1" x 8TPI. It'll do though.

This required cutting some metal off the bed to clearance to fit the square tubing. This was enough for the square tubing itself but is inadequate for the the retaining nut that goes on top (welded on to the square tube) so I had to later remove more material. This is the driver's side where the fuel can swingarm will eventually go, from here on out I'm focusing on the tire carrier on the passenger's side.

Once the 4" by 4" by 1/4" were fitted, I took a piece of 4" by 6" by something like .120 or .080 wall and welded it to the ends. I did have to modify the truck here, there are some plates for the hitch retainer that stick out, I cut them flush with the end of the frame box.

Skip forward to December...

I finally got around to cutting the extra ~2" of that 4x6 off a couple of weeks ago, to turn that box-channel into a C-channel. This unfortunately resulted in the remaining 4" trying to squeeze in, but that won't actually affect the arms as they're narrow enough to slide-in anyway.

On the truck. The squeeze effect is evident.

I dry-fitted the pivot, the arm that tucks into the channel, and the part of the arm that sticks out from the channel. The tire is 32" diameter, with the added gap from the 4" by 4" square tube to the outer body edge I'll just clear the visible taillight from the back. There'll be a vertical part that welds on like this:

and then another horizontal part. I haven't decided if I'm going to use this particular material for the vertical or not. This is 3" by 3", .120 wall I think. I'm tempted to go 3" by 2" with something a little heavier-walled so that it doesn't stick out the back as far.

You can't see it, but for mounting a plate I put a piece of angle material underneath the bottom of the channel, bolted on using some machine screws into tapped holes in the channel. The hardware on the top is actually a pair of lighted bolts. These allow the plate to be illuminated without requiring some bulky lamp assembly. Not sure how good they are, they claim to be weather resistant but I didn't see any sealing, so we'll see, if I have to order something different from a catalog then I will.

...to be continued...

 

[TWX]

...continuing...

I measured several times before drilling the holes for the bolt. I got the pivot point about .035" from the 4" by 4" 1/4" wall. I had to use numerous bits to enlarge from the inital pilot holes up to the 1" bit for the final, then file off all of the protrusions and sharp edges. The fit is VERY tight.

I then (inexpertly) welded the first span of the swingarm (after having cut a relief to radius match the pivot) to that pivot.

More pics:

And pulled the arm to show just the bolt installed. You can see how I had to open-up the clearance under the bed at that sheet metal just a bit more. I also ground the trailing edge of the nut a bit too. The nut isn't really doing the work, the hole drilled in the 1/4" wall square tube is, the bolt just keeps it in place. I'll probabably end up using locktite blue on it so it doesn't loosen up on me.

With the first bit of arm removed, this is basically how the rest of the arm will be constructed. The bit of 1/4" cutoff represents a piece of material I'll need to weld in to the bumper crossbar, so that the clamp's claw has somewhere to attach.

Still have quite a bit of work to do. Will update as I work. Truck is drivable as it is. We'll see if I can do the swingarms fully on Monday as I have the day off from work for Christmas.
Closeup of the clamp.