Fiberglass M416/M100 Military-style Trailer Tub Kit

jscherb

Expedition Leader
I've been working on a new fiberglass trailer kit idea, this one is patterned after the military M100/M416 trailers. Maybe because military-style trailers are so popular among the adventuring, overlanding and off-road crowd, reasonably restorable original military examples are getting very hard to find. The new versions of these trailers offered by trailer vendors are very expensive, so I've designed and am building a fiberglass military-style tub kit that's intended to be very affordable and assembled in a home garage or driveway by a DIY-er.

I've built a set of 1/4 scale molds to test the design and assembly concept of the trailer, here are a few photos of two 1/4 scale trailers I have built using tubs that came out of these molds. On the left is a 6' tub (same as the original military trailers), and on the right is a 4' version.



Here's a more "optioned" view of the 6' tub (I'm calling the 6' version the M-72 :)).



Both of these models are sitting on scale models of Harbor Freight trailer frames. The 4' version frame has the original 12" wheel/21" tires that come with the frame, and the M72 is sitting on scale replicas of 31" tires on Jeep Moab alloy wheels, which share the 5-on-4.5 bolt pattern of the larger HF frame. Here's the model 4' tub sitting next to the model Harbor Freight Mini Trailer frame:



The 6' tub can also be bolted to an original M100 or M416 military frame to replace a rusted or beyond-restoration original military tub.

In this thread I'll post the steps of this project, from the design process to the construction of the molds to the build of the first prototype trailer or two out of those molds, and I'd really appreciate as much constructive feedback from you as possible. If there are features or capabilities you think I should add to the design, please post them.


BTW, in 2011 I built another fiberglass trailer tub kit - that one was styled like a Jeep tub. It's been on the market since May 2012 from a company called Compact Camping. That tub kit is at www.dinoot.com.

 

jscherb

Expedition Leader
If anyone is wondering how large a 1/4 scale military trailer is, here I am experimenting with jerry can placement...



After working in small scale, I'm looking forward to building the full scale molds and tubs :).
 

jscherb

Expedition Leader
These are the main requirements that guided my design process:

1. Very affordable. The parts for the tub kit must be cost-efficient to manufacture so the kit can be offered at a very affordable price.

2. Military trailer styling. The goal isn't to create a 100% "rivet counter" correct trailer tub kit in fiberglass, the goal is to create a reasonable replica with appropriate modifications to make it easy and cost-effective to manufacture and ship, and affordable and straightforward for the DIY-er to build.

3. Frame choice. The tub kit must be installable on an original military trailer frame for those who need to replace a rusted-out or damaged M100 or M416 trailer tub, but it also must be installable on inexpensive Harbor Freight trailer frames, or custom-built welded trailer frames.

4. Modular. The tub kit must be modular so that different versions and options can be offered and built; modularity should also allow the unassembled kit to be shipped UPS Ground instead of Truck Freight to keep costs down.

5. Tailgate. Unlike the original military trailers, which don't have tailgates, this tub kit must support the installation of a tailgate.

If anyone has any additional requirements they think this kit should meet, let me know.

All of the above sound like I'm designing a commercial product so I should explain something... although I'm just a hobbyist who designs and builds these things for fun, I always design things so they could be commercial products - a number of my designs have been picked up by companies and are now on the market.
 

jscherb

Expedition Leader
Based on the requirements I listed, here are the main design features of the tub kit:



- Modular assembly. The kit will consist of two end panels and two side panels. There will be both "solid" end panels and "tailgate" end panels. A tub can be assembled with one of each end panel type, or two solid ends (like the original military trailers) or with two tailgate ends.

- Tailgate. Cutting a tailgate opening into an original military trailer greatly reduces the structural integrity of the tub. This tub kit is designed to be strong with a tailgate opening. The tailgate opening is the same size as the Jeep CJ, YJ and TJ tailgates, so there are lots of options. The Dinoot smooth fiberglass tailgate will fit for those who don't want a Jeep-styled tailgate.

- Multiple versions. Also because the modular design, several different length versions of the tub can be molded, up to 6' long. I envision a 4' long version to install on the very affordable Harbor Freight Mini Trailer frame for people on a very tight budget or for people who just don't need the space a 6' trailer provides. There are photos of a 4' concept model in first post in this thread. For the time being I'm calling the 6' version the M-72 and the 4' version the M-48.

- Frame. The tub can be installed on an original M416 or M100 frame to replace a rusted or damaged original, or it can be installed on any frame of the user's choice, including a budget-friendly Harbor Freight frame.

- Fenders. I've also designed sheet metal replacement fenders for the original M416's and for this kit. They could cost-effectively be manufactured in both 9.75" wide (same as the original M416), or in 12.75" width to cover wider tires, in the case where someone wants to run the same tires/wheels on the trailer as he does on his tow vehicle.
 

grimbo

Explorer
I guess also that shipping cost and ease will need to be a factor. Will they be flat packed for assembly or do they come somewhat assembled?

Do they come ready for paint or can they specked as a colour?

When you ready for either an original frame or a Harbor Freight frame does that mean two different types are being offered or are the mounts the same? If not dies that need to be specified prior to purchase? Also how are the mounting systems setup? Captive bolts or does the purchaser need to sort that out?
 

jscherb

Expedition Leader
Ok some of my questions have been answered in the time I took to reply
Here are some answers anyway...

I guess also that shipping cost and ease will need to be a factor. Will they be flat packed for assembly or do they come somewhat assembled?
They would ship completely disassembled. I've already done some design for shipping - the box would be roughly as shown below, and of course a little longer than the length of the side panels (dimensions below are approximate, and are in inches). In the US anyway, the box should qualify for relatively inexpensive UPS ground shipping.



Do they come ready for paint or can they specked as a colour?
That would be up to whatever company markets them; they can be molded with a colored gel coat (like boats) so that no painting would be required (maybe an olive drab gel coat?), or they could be molded in white, or they could be molded in a gray primer gelcoat. Any of those could also be painted.

When you ready for either an original frame or a Harbor Freight frame does that mean two different types are being offered or are the mounts the same? If not dies that need to be specified prior to purchase? Also how are the mounting systems setup? Captive bolts or does the purchaser need to sort that out?
I'll cover the mounting details when I build a prototype trailer with the first tub kit to come out of the mold.
 

NMC_EXP

Explorer
Nice - good luck.

(I have an M416 in good condition....and an M101A2....and a Pioneer Tool Trailer).

Regards

Jim
 

brushogger

Explorer
Jscherb, I love your design threads. Do you sleep at night or is your brain constantly buzzing with ideas? Any plans for a "lid"?


Sent from my iPhone using Tapatalk
 

Dennx

Adventurer
Looks tempting as a DIY project. X2 on a lid. Could the lid support a tent? Looking forward to this.
 
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jscherb

Expedition Leader
Jscherb, I love your design threads. Do you sleep at night or is your brain constantly buzzing

with ideas? Any plans for a "lid"?
Thanks. I've got far more ideas than I have time to build :).

Looks tempting as a DIY project. X2 on a lid. Could the lid support a tent? Look forward to this.
This tub kit is designed as a DIY project for several reasons - first, to make it very affordable so more people who want this style trailer can own one, and second, because many people really enjoy building their own stuff and configuring it exactly to their needs. The way it's designed, it can be successfully assembled by a DIY-er in his driveway with just basic home maintenance tools.

And yes, I've got several designs for both soft and hard covers for the military tub, I'll post them later in the thread
and I'll be looking for everyone's input to help me decide which ones to build. In my view, the hard covers wouldn't be much good unless they could support a tent, so that's a key design requirement ;). I've got ideas for both an easy-to-build DIY hard cover and a several fiberglass ones. More on that later in the thread.

BTW I designed both my custom Jeep hardtop and my fiberglass Jeep-tub trailer to support tents on top, so you know that will be a part of this design too...

 

grimbo

Explorer
What about utility trailer type top unit. Basically a box that bolts on with three swing up doors to reveal three compartments, one each side and one to the rear. Rear compartment would be the kitchen/ pantry with shelving and swing out two burner stove.
This still gives room underneath for a pull out fridge slide, electrical system behind that, water tank on other side and another pull out drawer for cooking gear etc

Each of the side compartments would be dust proof for cloth and sleeping gear storage while other side for chairs tables etc.

Roof top tent and Foxwing awning and I'd be good to
 

jscherb

Expedition Leader
What about utility trailer type top unit. Basically a box that bolts on with three swing up doors to reveal three compartments, one each side and one to the rear. Rear compartment would be the kitchen/ pantry with shelving and swing out two burner stove.
This still gives room underneath for a pull out fridge slide, electrical system behind that, water tank on other side and another pull out drawer for cooking gear etc

Each of the side compartments would be dust proof for cloth and sleeping gear storage while other side for chairs tables etc.

Roof top tent and Foxwing awning and I'd be good to
I've done a few concepts for fiberglass caps, one of those concepts sounds like it's pretty much what you're describing. Here are some drawings of two versions of one the concept I've done with swing-up sides. These would also be modular and designed for DIY assenbly.

 

jscherb

Expedition Leader
If you develop a lid that will fit a metal M416, I'd be interested in seeing such. My latest plan for a lid is sending my son to welding school... ;)
Here are a few concepts I did on the 4' version of the trailer. The one on the left is a flat cover, the one on the right is raised a bit to provide more storage room underneath. Both would be reinforced to handle installation of a RTT.

I'll decide on hard covers, utility caps, camper caps, etc. later in the project, first thing is to get the molds for the basic tub done, I'm working on those now.

 

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