Mighty Max (pickup) Expedition/Utility/Rally Support Trailer Build.

irish44j

Well-known member
This project is going to start pretty slow as I do some planning, but figured I'd start up a thread now to keep my thoughts in one place (my mind is a bad place to keep my thoughts....). I'll probably cc some of the work in the my Raider build thread (in the Mitsubishi section here) as well, since this is related to that, but I'll document everything here.

This is the Raider, in case you care

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So anyhow, I'm always on the hunt for a new build of something I don't have and that fulfills certain automotive needs (if you happen to be on Grassroots Motorsports forum, you've seen my budget builds). I have my 4x4 offroad/adventure rig (the Raider), my tow vehicle/long-haul rig (Sequoia), my sportscar, my racecar, and my daily driver (and a car hauler 16' trailer). So most of the boxes are checked. But since selling my 5x8 utility trailer when I bought the car hauler, I've found myself missing it, since the big trailer is a pain in the ass to pull out to do regular utility stuff, and the Sequoia is good for certain big things but not for bulk items (mulch, for instance).

While browsing around Marketplace, out of the blue I see a guy pretty much giving away an entire 1992 Mitsubishi Mighty Max, in parts (he apparently chopped it up into sections). However, he had a decent-condition bed box there, so I got to thinking. As you probably know the Mighty Max is essentially the pickup truck version of the Monteor/Raider (more accurately it's the Triton, but that's splitting hairs a bit lol). More specifically, it has pretty much the same cosmetic lines to it (body lines, wheel well shape, etc). So what the heck, a trailer seems like a reasonably inexpensive project that won't involve building engines or doing interiors or paying for insurance, etc.

GOALS: So I have some ideas, but not sure exactly what direction this will go. Here's some requirements and/or thoughts:

1. Obviously, general utility. Hauling mulch, picking up furniture, whatever. Suburbia stuff.

2. "Expedition stuff?" I honestly don't see a reason to tow a trailer when wheeling, since I can fit all my gear in the Raider, and sleep in it, and my trips are not very long, usually. But, let's say I'm going a long way and want to bring extra gear or whatever, I guess it could be useful in certain instances. So this trailer will *be able to* survive being dragged around on offroad trails, etc, but won't be built *specifically* as an expedition trailer or anything. I likely will set it up to use the same wheels as the Raider (standard Toyota/Mitsu 6-on 5.5 bolt pattern) so I don't have to carry a spare for it.

3. Motorcycle. I don't have one,bBut I have friends who have offroad bikes and let's say we want to go someplace far away to do some Raider-bike adventure trip stuff (Kentucky Adventure Tour, or up to New England, or something), it would be useful to be able to throw a bike in the trailer so the friend doesn't have to ride hundreds of miles on a KZR or whatever.

4. Rally! Of course (In case you don't know, I compete in American Rally Association stage rally in an old BMW). Anyhow, if you do rally, you know that you usually can't bring the car-hauler to the service locations, which means transloading the toolchest and other gear into the tow rig (which is usually already full) or putting it on a hitch-mount basket (what we've been doing). It's logistically kind of a pain in the ass and requires a lot of loading, unloading, and organizing stuff during a 3-4 day rally event. So I've been thinking if we had a smaller trailer that could be towed behind either the service rig or the recce rig, that could just be a dedicated service trailer. Something the Raider can tow, or that Jim's Tacoma can tow, or Stephen's 4Runner, and that's small enough to fit into our service spot at rally. Plus, a lot of that gear crosses over to expedition/adventure trips.....racks for fuel jugs, tool compartments, etc.

So, those are the ideas, and the goal is to make something that can do ALL of them well with minimal reconfiguration. So why use a pickup bed and not just build (or buy) a full trailer? First, it already has good structure on both the floor and sides, rather than me having to fab up sidewalls, etc in wood or metal. Second, it already has fenders. Most offroad and utility trailers have fenders outside the bed, so the bed is narrower than the entire trailer. WIth a pickup bed I get full-width capacity. Third, I can buy off-the shelf stuff made for it (like a tonneau cover, or cap, or gearboxes, etc). Not that I necessarily will, but it's nice to have that option. I already have a large flatbed trailer, and have built/owned smaller regular utility trailers. Not reinventing the wheel here, but hopefully can do some fun things with this build, and I am pretty much locking myself into a total budget of $1000 all-in, just to challenge myeslf to do more of my own fabbing and to find used/repurposed parts. We'll see.

So let's get to it...

As it happens, a buddy needed to get his Volvo up to Quakertown PA, about 200 miles from me, to have a rally roll cage built. And the Mighty Max stuff was about 25 miles from there. So worked out a deal with him and towed his Volvo up there in exchange for gas money.

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After I left I headed out to a house in a very wooded area with a 1/4 mile driveway that looked like a rally stage and hauled the trailer into an extremely slick and muddy culvert area behind the guy's house (after walking it to make sure I'd actually be able to get back up the steep hill on the way out. Apparently a guy who came the day before for some other stuff got his dually stuck and had to be towed out by a bulldozer....

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Loaded up the pickup bed, as well as the rear half of the Mighty Max frame and the rear axle (since it has crossover parts with the Raider and will give me spares). Handed him a few bucks, and climbed back up to the driveway with ease.

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Today I unloaded the stuff (some effort, by myself, since it's all quite heavy) and took a look

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Stuck the frame on it just to see what the lines looked like. However, I likely won't use any of the original frame, other than maybe a few of the mount brackets that I can cut off. It's heavier than I need and I don't want the drop-down at the front (for the cab, etc). Plus a few parts of it were already chopped off so I think It'll be easier to just scratch-build a frame.

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So the bed overall is an old bed that has definitely gotten utility use. Plenty of dents on the inner wheel wells but overall almost entirely rust-free

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Other than one small area, which shouldn't be too hard to fix.

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There is some damage to both lower rear corners (one side is pretty mild, the other side pretty mashed), but I may or may not cut off those lower areas anyhow (and/or repair them). We'll see, at some later time.

It's also nice that all the wiring is still in place, which should make lighting, etc pretty easy to do

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And he had the original taillights which are in pretty nice shape, so I can re-use them

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Unfortunately he didn't have the tailgate, so I'll be keeping an eye open for one of those (the ones from the Mighty Max or Dodge D50 will both fit, since they're the same), or I'll just build something.

Anyhow, sorry this isn't the most exciting build, but I'll document it just in case anyone wants to follow along. I expect I'll get moving on it in a few weeks once I can get some materials and parts together, and then go from there. BTW, i fully plan to use a trailer axle (not the Mitsubishi one that weighs a ton) and build my own frame for it. But always open to any suggestions/comments, so fire away if you feel like it.
 

irish44j

Well-known member
One thing I'll throw out there is any thoughts (from you) on what rate springs to use on this (I'll be using standard twin-eye leaf springs with shackles). I'm going to go with a 3500# axle but don't want spring rates that high and am thinking more around 2000# for those, which I think would be more approprite for the ultimate weight of this thing and what I'll carry in it.
 
Looking forward to seeing what you come up with.

I had a little mighty max in high school - loved that little truck!
 

irish44j

Well-known member
Today I rolled down to the local steel place and picked up 40 feet of 2x3 .120 wall square tube, cut into 10-foot lengths, which will give me the right sizes for my cut-ups (and also fit in the Sequoia!)

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When I got home, I cleared out my other garage bay and needed to move the bed from my backyard up to the garage. By myself, since nobody was around to help out. Before I did that I got the hose out and washed it good since working on dirty/muddy stuff sucks. Then made the move.....had to improvise

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Then blocked it up and shimmed the blocks to get it sitting perfectly level and square, so when I build the frame it won't have any twist to it.

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After that, today's goal was to get the two side rails for the frame in place. Compllicated a bit since the truck's original frame had some curves to it so the mounts on the bed are not in a straight line. So Basically I aligned to a forward and rear mount spot and used the factory mounts. I had to move the fronts over an inch or so to make sure the rails run parallel. I'll build L-brackets for the other two offset mounts sometime this week.

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Access holes through the bottom for the nuts

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Then did some more shimming and leveling to make sure the main rails are perfectly level, even, and vertical

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So that's basically where I stopped for the day. I did grab the spare tire off the Raider just to see what my clerances are going to look like and get an idea of whether I want to go axle-under or axle-over.

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old_CWO

Well-known member
You probably know this but: make sure you stretch the tongue and put some weight forward. When using a pickup box the axle ends up too far forward for normal utility trailer tongue weight and can induce sway. It's no biggie, you just need to account for it.

For springs I assume you plan to use regular old trailer springs. That's an okay low cost solution for what you're doing and I would surely default to a little lower rating rather than higher since they are so stiff. I might even start with a 3 leaf 2K pair and remove the bottom leaf. Little trailers seem to cube out before grossing out so they can sometimes get away with pretty light springs.

Cool project. Those Mighty Maxes were super popular back in the 80s with the slammed mini truckers.
 

irish44j

Well-known member
You probably know this but: make sure you stretch the tongue and put some weight forward. When using a pickup box the axle ends up too far forward for normal utility trailer tongue weight and can induce sway. It's no biggie, you just need to account for it.

For springs I assume you plan to use regular old trailer springs. That's an okay low cost solution for what you're doing and I would surely default to a little lower rating rather than higher since they are so stiff. I might even start with a 3 leaf 2K pair and remove the bottom leaf. Little trailers seem to cube out before grossing out so they can sometimes get away with pretty light springs.

Cool project. Those Mighty Maxes were super popular back in the 80s with the slammed mini truckers.

Yep, next post will talk about the tongue! And I always listen when a Warrant is speaking ;)

For springs, I have a buddy with some 3500# springs he's giving me, which are certainly overkill for this, so I'll probably remove a leaf and see how that does. If anything, replacement springs are cheap so I can always change later (as I expect I may want to, as you note). The upside of running all-terain tires on it is that I can probably run pretty low pressures, which should keep the bouncing down.
 
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irish44j

Well-known member
Flipped the frame today to do all the underside welds (well, the top-side I guess).

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At the front of the neck I made cuts and folded down the open ends of the diagonal side bars, so now they're all closed up.

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I also drilled out the spot welds on a couple of the stock bed mount brackets and relocated them over a few inches to align with the new frame, which was more work than I expected it to be...

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In any case, the whole frame is now welded (some welds prettier than others, but such is life for an occasional welder), and I have all eight of the bed mounts aligned and set up. I have a few other smaller things to do on the frame (a few brace pieces) as well as the suspension mounts once they come in.

In addition, a new toy came in today, something I've been considering for years but finally pulled the trigger on now that they're getting so inexpensive. This one seems to have really good reviews, and from what I can tell it's good quality.

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Tested it out on a variety of pieces and it works great (though I need to work on being smoother with it). Only issue is that I had it plugged in to my highest-amp garage (110) circuit, which my small HF air compressor is also on. So when the compressor kicked on halfway through the cut, it tripped the breaker. Oops. I really should get some 220 installed in this garage already, or a couple extra high-amp 110 circuits.

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irish44j

Well-known member
Plodding along trying to finish up the frame. Flipped it again to do the remaining things on the top (bed) side. Because I'm overly paranoid about things not being strong enough (lack of confidence in my welding, IDK), I added some frame reinforcement up in the neck area. I had some 6x6 1/8" plate sitting around so I cut a couple of them up with the plasma cutter (which keeps tripping my garage circuit breaker, so that's a project that needs some upgrading soon). Still getting in practice with use of it, but on a fishplate that nobody will see, it's good enough

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Also needed to make some brackets to level off the two angled bed stringers, which were made to fit the curve in the OEM frame. So a bit more cutting....

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Also, this dude landed right outside the garage to check out what I was up to..

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Anyhow, with that stuff done I think that's all I need to do for now on the top side of the frame, so went ahead and painted that side of it (and will do a second coat) so I can flip it back into place while it awaits suspension/axle stuff to arrive.

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Oh and here are those brackets actually welded on

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So, probably will be a few days before I do anything else on this since I have a couple projects to do on the rally car and on the Raider. Thanks for bearing with me on the boring early parts of this build :)
 

old_CWO

Well-known member
Maybe consider thinning that paint with around 10-15% mineral spirits and lay it out with a foam roller on the parts of the frame that will be visible.
 

irish44j

Well-known member
Maybe consider thinning that paint with around 10-15% mineral spirits and lay it out with a foam roller on the parts of the frame that will be visible.

That photo was immediately after painting. It actually dried totally smooth (it's also a satin finish when dry). But I may do the foam roller on the second coat.
 

irish44j

Well-known member
While doing other projects today I did take a quick break to do a bit of rust repair on the bed. From what I can tell, this is the only area where there is any real rust on the bed, it's righ at a seam between the main bed panel and the wheel arch panel, and it looks like moisture got into the undercoating and rusted it from in there.

After grinding down:

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Then cut out the whole area and made a patch piece

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And welded it up and painted. When I flip the bed over at some point I'll do some more work from that side, but didn't want to deal with that right now since flipping the bed is a big process as it currently sits...

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irish44j

Well-known member
Not that exciting, but I went ahead and painted the underside of the bed today after cleaning up a few surface rust spots. In this pic it's still wet, but it's actually flat black, as if it matters. Now I can put the frame on and bolt it in place in preparation for installing the suspension, whenever that gets here.

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irish44j

Well-known member
My hubs came in last night. Or, more accurately, the box they were supposed to be in. Apparently at some point during shipment the box tore open and one of the two hubs and all the bearings, lugnuts, etc fell out. So FedEx person just picked up the box and taped it back shut (without putting the stuff back in it) and it arrived with just a single hub and no packing material. Top notch stuff from FedEx once again (literally, ******** that company for the 100th time....). If anything, the vendor is shipping me a second box with everything, so hopefully that one gets here.

Somewhat worried since they are also delivering my axle and springs, so I'm sure something will be damaged...

I did get my spring hangers in, so after about 20 minutes of measuring diagonals to make sure they are exactly square to the frame and neck, I tacked them down and then excessively welded them to the frame...

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Once all four were done I went ahead and painted this side of the frame so when the other stuff gets here in a feww days I can assemble the whole suspension, etc.

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Oh, also got a hitch for it. I was considering doing a pintle setup, but I think that's pretty unnecessary since I don't plan to drag this trailer on any hardcore offroad stuff, and that would be more of a hassle if I want to use the trailer with other vehicles. In any case, the hitch is just bolted on so if I want to change it later I can.

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irish44j

Well-known member
So a few things today: First, FedEx arrived with my springs but NOT the axle (which was scheduled to be here today as well). So, FedEx continues to suck. Whatever. The box the springs were in looked like it went through a war on the way here, but nothing fell out so again, whatever.

Anyhow, these are 3500# springs (so, 1750 each), which is too heavy for what I want with this trailer. So, I removed the 2nd-longest leaf from both of them, which by my calculations gets the overall rate to about 2400# (so 1200 per spring) which I feel is about right for this trailer, but we'll see.

So there's the removed leaves

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And did a loose install to see the height.

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So they should deflect about 3" at full load, which is pretty close to maxing out tire clearance in the wheel well if I go axle-over (as the brackets are shown in the pic above). So I'll likely mount axle-under to get some additional height/clearance.

---

Second thing: So I probably mentioned I've been looking for some wheels and a tailgate. Been to a few junkyards in the past few weeks and come up empty, and everyone parting out stuff seems to be too far away. I really wanted to get matching "pomegranite" wheels liek the Raider has, but none for sale closer than Michigan at the moment.

Then out of the blue I come across a FS post for an '88 Dodge D50 (aka Mighty Max) in Catlett, which is about 20 miles from me out in farm country. It's listed as being pretty rusty, but complete, for $500. More importantly, it has Pomegranites on it and a tailgate. So I message the guy to see if perhaps he'd sell me the wheels and tailgate for $200. He says no, but if I want the whole truck I can have it for $250. DONE.

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So I bust out the trailer and drive the country roads to get there this morning. Truck is actually a pretty rare manual-transmission 4x4 model. Rear frame rust is BAD (it was a farm truck) but the rest of it was in pretty good shape overall, and complete. I figured I'd take the wheels and tailgate, sell off some easy-to-remove parts, and then scrap the truck and more or less make my money back.

Got to use my little hitch-mount winch in the trailer receiver, which seemed to do fine (though my front trailer bar was flexing more than I liked, so may need to reinforce that...)

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Dragged it home...

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The wheels I want

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Magic knobs

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Four-banger

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And tailgate....paint is a mess, but overall it's in good shape other than a broken latch, which should be easy to fix.

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So after that, I decide maybe I'll post it up online for $250 and see if I get any bites, rather than parting/scrapping it. It's a pretty cool little truck and I'd love to see it brought back to nice - though I have no need for such a project myself (seeing as I'm building a pickup-truck bed trailer that will do the same thing with less maintenance/insurance lol).

Anyhow, within an hour I get a message about it and after some discussion we agree on $200 and he'll come get it tomorrow (bringing his own wheels). Ironically, he wants it for an engine and manual transmission swap on his Raider (which has a seized engine), which looks just like mine. More ironically, he asks if I'm "the rally guy he talked to on Expedition Portal forum a few weeks ago." So, totally small world as always in the automotive hobbyist area (i'm terrible with names so always forget people I've talked to a dozen times lol). In any case, he's gonna come get it tomorrow (along with the rear half-frame I have here in case his brother wants to build the truck up instead of scrapping it). Either way, I got four wheels and a tailgate for an outlay of about 50 bucks, which is less than I could have bought them for separately. I'm probably losing a bit of money just selling the truck for 200 rather than parting/scrapping it, but this is easy and may allow the truck to continue to live on. And he's getting his engine and transmission for a few hundred bucks as well (and can get some scrap cash for it if he scraps it). So everyone wins, it seems.
 
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irish44j

Well-known member
So busy day with regard to the trailer.

First thing, the guy showed up to pick up the D50 (and the rear half of the frame from the other Mighty Max) and towed it back up to PA. He may refurb it to use, or may pull the drivetrain for his Raider. Apparently when they got it home, they jumped it and it started right up and ran "like new" so that's great for them.

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In any case, that thing is out of here and out of the story, so back to the trailer.

Oh, of course he brought his own wheels, so I'm left with four more pomegranites, as planned

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First, the axle showed up today. Amazingly, FedEx didn't damage it, so that's a plus. After some measuring decided to do axle-under to get the right height so mounted it up that way. Props to Champion Trailer down in Louisiana for making this axle so quick, by the way. The fit is perfect to my measurements and it arrived a week after ordering, which is pretty great for a custom-made axle.

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So once that was on it was time to flip the trailer right-side up, so I enlisted my neighbor to give me a hand and we flipped everything (separately) and I got the bed bolted down.

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Then I fitted the tailgate, which of course fits perfectly.

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So while I'm looking at that area, time to take a better look at the damage to the bed corners. So here's the left, which isn't too bad and should be easy enough to pull out.

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The right side was mashed in pretty good up top but I think I can probably get it back to tolerable, we'll see. Not that I have much of a choice. The bottom section is totally mashed and will be going away regardless. Still deciding what I want to do there.

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And with the tail lights on.

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Did a test-fit with one of the wheels and the one hub I have (no bearings so it's not sitting quite straight).

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One note, as it sits empty the tongue weight is VERY low with the tailgate on (like maybe 20lbs) so that's why the tire is sitting up there. I plan to add weight up front so that will be taken care of. Ideally I'd like tongue weight to be around 80-100 lbs with the trailer totally empty.

So I also started "chopping" the lower valences. The rears are damaged anyhow and need to come off, but decided I'd just chop them all off to increase departure and approach angles (and I have a related plan which you'll see eventually). They're just spot-welded on so came off pretty easily once I figured out where the welds were.

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I'll do the other three tomorrow or this week at some point.

While I was standing around thinking about what to do on the neck forward of the bed, it struck me I have a hitch basket in my shed. I got it a few years ago and we use it to take our toolchest to service at rallies (which has worked out pretty well)

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However, half the reason for this trailer build is to haul our gear to service at rallies (and make it more accessible), so I don't expect to use the basket any more. So I dug it out to take a look

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Conveniently, the hitch receiver part actually just bolts on to the basket itself. So I unbolted that and decided to see how it would fit on the trailer. As it happens, it fits pretty damn well. You can see the angle iron welded onto it in the exact size of the toolchest, incidentally.....

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So the plan will be to build some mount brackets on the frame for it so I can just take it on and off as I please. In any case, I think that will work out well. I know the expo guys put big gearboxes up there and such, but I really have no need for that kind of storage on the trailer and a basket works better (and adds some tongue weight, since this thing is pretty beefy). Incidentally, that leaves me just about 3 feet of tongue forward of the box, which is sufficient to be able to jackknife the trailer 90 degrees with either the Raider or the Sequoia with a few inches to spare - which was a key consideration when determining the trailer neck length.

So, time to watch some football. A rare year where both my teams made it into the playoffs. WFT (ex-Redskins) kind of a joke, my adopted team living in the DC area for the last 25 years. But the Bills have always been my team since I was a kid (Dad is from Rochester) watching Jim Kelly, Thurman Thomas, Lofton, Reed, Bebee, etc. So awesome to see them in the playoffs again finally after years of ineptitude.

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