M416 to a M100

[redheep]

8-9-19

This is where she sits today. It's a reproduction M100 tub and fenders on a 2x3 .120 box tube frame that uses the brackets, pintle mount and suspension from the M416 I bought and scrapped because of the rust. It has a M100 axle tube with M416 hubs and brakes and NOS M416 wheels with 215/85R16 tires.

There isn't a lot of technical details, but everyone likes pictures so I thought I'd post some of the stuff I've taken pictures of over the last 6 months. The updates start down after my original posts.

4-13-17

I found a cheap M416 with a hideous wooden box on it on craigslist last december and brought it home. I knew it was a mess, but I only paid $350 for it and I knew I could part it out for that and then some if it was really bad. So we brought it home on the trailer.





It's a 60's era trailer but no data plate. The frame plate says US ARMy. The PO cut the back off to make an enclosed wood trailer with a tailgate. He's a furniture maker, so the box is built really well, but obviously not exactly what most normal people would do.

The frame has a couple channels that need to be replaced, just from first inspection in the daylight, and there's a ton of screw holes in the tub from the box and plywood he lined the inside with.

The tub has common corner rot where the panels meet the floor. It will have to be blasted to see the extent of the repair work. Axle is in good shape, all of the handbrake components are installed and all of the military lunette pieces with the safety chains are there.

The springs are in ok shape. Tapered springs look really different than regular springs, so I thought they might need replaced, but after I got them off they were ok.

PO said it was vietnam era, which looks pretty correct. It's not a M416A1. The PO said he thought he had the part he cut off, so he's going to look for the data plate, but he's also a 60's hippie pot smoker, so I'm not getting my hopes up.

 

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Fast forward to April. This has been sitting in my garage and it's time to get to work.

After a weekend of removing screws, this wood top built by the PO was still stuck to the trailer. I was out of ideas. The PO said it just needed the screws pulled out and it would pop off.

So out comes the sawzall.

And of course, there's hidden screws and a bunch of other stuff, so we keep on cutting.

And after about an hour of cutting through hardwood and screws, I get the damn thing to pop off.

The wood pieces that line the top of the tub are still very stuck. I ended up beating everything off with a mallet and taking all the screws out from the top, plus drilling a couple out that were fantastically stripped and removing what I thought was the whole piece.

Then I saw the real problem.

The PO screwed the first rail to the tub and then covered them up with another piece of wood that he built on top of it. No way this thing was coming off unless you destroyed it.

 

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So I worked my way around the tub, finding all these giant sheet metal screws and finally ended up with this:

The tub is pretty rusty and it has a ton of screw holes now. The PO did a hack job on the back, so I'm going to build a tailgate rather than try and find a panel or fabricate one. I'm having it blasted and then we'll get to work fixing the mess.

A couple hours with the impact and the tub is off. I only had to cut 2 fender bolts. Everything else came off or snapped the head. What we're left with is this:

Which honestly is a big disappointment. I knew there was a rusty corner, but the metal in this thing is junk. The back crossmember was replaced with angle iron and bolted to the Swiss cheese framerail and everything else is rusty steel.

So after some careful deliberation, I decided that new was better than rusty repaired old. I spent about 4 hours busting bolts and removing all the brackets and suspension bits and ended up with this:

Everything I could take off and reuse was removed and the portaband turned the frame into a nice landfill size.

 

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The boys and I built a small proof of concept electrolysis tank and we ran some rusty hardware through it to see how it works. Also cleans pennies really well

Since we know it works, we're going to build a Rubbermaid tub version and see if we can clean the lunette parts and the suspension brackets. My old blast cabinet got thrown away since HF doesn't exactly build to last. Probably pick up another one to finish these parts off for paint.

 

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I picked up a pair of M416 tail lights in the classifieds and opened them up. They're really clean inside thanks to the o-ring. Ordered some 1156 bulbs from superbrightleds and swapped them out. The tail bulb is 200 lumens, the stop bulb is 420 lumens and the blackout bulbs are 70 lumens, which is pretty close to the candlepower ratings I read on the web.

Hooked them up to the 12v power supply and bam, they work.

My wife said they're too bright, so mission accomplished.

 

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Yesterday after we hit the landfill from our garage cleanup, we went down to the steel supply joint to buy frame materials. 2 20 foot pieces of 2x3 .125 box tube ran us $108 and they did all the cuts for us. I had them cut an inch long on everything so I could do finish work at home.

I'm going to miter the corners and weld them, so a trip to TSC got us one of these:

Not the fanciest or best built, but I've needed one like 5 times in my life and I need this one to make about 15 cuts so no sense in spending a ton of money right now. This is costing me enough as it is.

I'm going to extend the tongue pieces from 41" to 60" and bolt them to the original lunette mount and weld them to the front crossmember for a longer tongue and more room for the tongue box.

Since I want to run the cable through the frame to the back, I needed that stuff on hand before we started building. Amazon loves me this week.

7 wire connector and junction box from Conex:

25 feet of 7 wire cable. This cable has 1 10ga, 2 12ga and 4 14ga wires in it.

2 7 wire junction boxes for the back. I'm going to run the cable down both sides of the frame. 4 wires for the lights on each side, which gives me a 10ga wire and 2 12ga wires on each side to hook accessories up to now or in the future if we decide we want a fridge or camp lights or whatever.

Plus the obligatory Chinese led lights for under the frame.

I've got a 6 switch panel with circuit breakers, USB ports and a cigarette lighter port on order that should be here today. I'm planning on 2 6v golf batteries in the tongue box wired for 12v and I ordered a RVIbrake towed vehicle charge controller to install in the box to protect the rig from melting the power wire to the 7 wire connector.

 

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It's been a long time since I started this, but I wanted to follow up with what I did to finish the project to the point it is now. I copied the picture uploads and comments from another build thread, so apologies if some of it might not make sense. I still have a bunch of electrical stuff to do and some other things I'd like to get done to make it more practical on a camping trip, but I've used it a few times now and I'm very pleased.

The plan changed a lot. I went with a M100 reproduction tub, I had to swap in a M100 axle which meant issues with M416 hubs and bearings and a lot of the stuff I expected to reuse had to be replaced.

I plan on doing all of the frame measurements in a diagram and posting it in case anyone would like to build a frame and slap a repro tub on top.

 

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So after a retirement, 2 job changes and 2 house moves, I’m making progress. Our new house in PA is about an hours drive from DL Bessinger.

So since the trailer I bought was rusted to hell, it was stripped of all the brackets and I went with a new reproduction M100 tub for $950 with fenders.

Started measuring and cutting tube for the frame.

The m416 brackets were thrown in a tub of vinegar for about a month. Seriously impressed with how little work it takes to clean them up after the rust falls off.

Pulled the leaf spring brackets out to measure for the crossmembers. Military drawings are approximate at best and I’m using brackets made for a C channel frame on 2x3 box tube.

 

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I centered the axle pin on the center of the fender. I have no idea if the repop factory is making them to exact spec so it’s close enough.

Built a box.

Started mocking up the tongue with the m416 pintle fitting.

Had to cut a side out to mimic the original channel and then bolted it up.

Logan helped me check that we were in the ballpark.

Cut metal.

Fit metal.

 

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Welded. Yes my welds suck.

Started fitting the spring brackets.

Drilled holes on the backside for a socket.

The m416 axle is 6 inches wider than the m100 axle. I didn’t realize this was a problem until Nate and I started talking about moving spring perches.

I found a guy in GA with NOS m100 axles. Same brakes, same hubs, just 6 inches narrower. (This will bite me in the ass later)

Looks like I’ll be able to bolt it up as is. The spring brackets will be done this weekend and I just need to order new u bolts to make it a roller.

My new axle showed up.

Got all of the spring brackets mounted.

 

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Did some leaf spring mounting stuff.

Swapped the hubs and brakes from the m416 axle to the m100 axle.

A little narrower.

 

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Mocked up the piece of the original frame to mark the holes for the safety chain/lunette fitting bolt.

Drilled some holes and test fit the bolt and brackets.

I ordered axle u bolts. After I mount the axle I need to figure out where the shock mounts are going to be on the frame.

Next is putting the frame and the tub back together and welding the mount tabs and installing the rivnuts to mount the tub to the frame.

 

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Got it back on the tub tonight after I picked up some of my mess.

Mocking up the mount brackets. Original m100 trailer tubs were welded to the frame. I’m going to weld mount tabs to the tub and use rivnuts in the frame rail to mount the tub.

Very similar to the way the later m416 tub is mounted. 6 on each side and 3 on the front and the back.

I finished up 1 side and the back of the frame with rivnuts before I realized I didn’t have any more 3/8” ones.

 

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So I started putting 1/4x20 rivnuts in where I wanted to clamp the 7 wire cable from front to back.

I decided to run the wire on the bottom of the frame rail so I didn’t have to drill more holes in the crossmember.

The cable will run to a 7 wire junction box and then split to two 4 wire cables for the tail lights on each side. The other 3 wires are for whatever I want in the back that needs power, like lights or something.

I’ve owned enough trailers to know that wiring doesn’t last the life of your trailer so I’m planning ahead to replace it when the time comes.

Some progress today.

Ran clamps for the tail light harnesses.

Finished the rivnut install on the other side.

Welded the tabs to the tub on both sides.

 

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Now the tub is mounted on both sides. I had to order more tabs for the front and the rear.

Working on the last couple mount tabs and closing up the corners today. My welds are mine and thankfully not on anyone else’s gear.