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Rebuilding a military M416 trailer
#1
Back in January, I was lucky enough to find my Unicorn. It was something I've always heard of, seen in media, but never in person... you know, a unicorn! My unicorn was the Military M416 trailer.

I always thought that it would be the perfect companion for a Jeep. Since my Jeep JK purchase in Nov 2010, I've been searching for the right one. Either it had to be close to perfect and I would spend up to $1,000 or "needs a little TLC" and I would offer up $600.

My search ended early January 2012. You can read more about it on my original post listed below.

http://www.higherground4x4.com/forums/showthread.php?4556-I-found-my-unicorn!&highlight=unicorn








Monday: I invested in some air tools and a friend loaned me his 30gal 7.5hp vertical compressor.

Wednesday: We spent several hours installing the compressor and updating it with a new air filter, air regulator, and an oiler.

Thursday (last night) @ 6pm, I wheeled the M416 trailer into the garage and got to work. My dad joined me in the fun and we started to tear down things so we can separate the tub from the frame and inspect the electrical.




The lens is removed by loosening the 6 visible screws. The screws don't come all the way out of the lens. They are retained by a little crush washer. The seam was stuck because the lights were painted over. A razor blade solved that problem.

One of my lens covers were cracked. Both of them had bad seals, and moisture got in. The bottom bulb held some water and corroded the contacts. The front lens portion is also plastic. Probably not worth salvaging. I can buy new ones for about $15 each. The rear housing is plastic. I think I can take it all apart, wire brush the metal components and/or put them into a vibrating tumbler filled with sand, and restore them.



The license plate holder w/ light can't be original. It was pretty garfed up. I pulled it off and straightened up the bent areas. The light was another story. Pretty corroded and the plastic lens was milky white. I did find a replacement for $15.00. This part is going into the trash.



The two jerry can holders were in decent shape. One had a bent in corner. My dad fixed it with a hammer.



The tires were pretty seized up on the hub. After removing the tire lugs, I had to use a crow bar to break them free.



Next came the fenders. Normally there are 5 bolts that hold the fender in place. The bottom two on each side were missing. Strangely, the 6 bolts that were present, most of them were different sizes and lengths. That's not a good sign. I may need to replace every serviceable bolt to keep them consistent.

Once the fenders were removed, there are only 8 bolts left to remove the tub from the frame. There are 3 in the back and one on each side towards the front. They are quite visible, as the tub had mounting tabs. On the underside, there are suppose to be 3 more bolts that attach the tub to the cross-members for the frame. They were not present.

Years of debris, two coats of military and forestry service paint, made removing the tub quite difficult. In a perfect world, it should lift straight up. Darn thing was stuck. So, I broke out the rubber mallet and started banging on every seam and connection of the tub to the frame. Then, I sprayed those areas with WD-40. After 15 minutes, I climbed to the front of the trailer, stood on top of the landing leg, gripped the tub and dead-lifted the sucker.

Note: There is only 2 ways to get the tub off. Pull the tub straight up with equal pressure, or jerk the front like I did, then jerk up the rear, insert several blocks/spacer to get the tub mounting tabs to clear the frame, and slide the whole thing forward to clear the frame's lip... then up.




It's was now midnight and my arms feel like soggy noodles. Friday after work I will get started again.
#2
Friday: Now that there was light, I could inspect the tub. There are some areas that have small holes (2mm). Some areas have larger holes (1/4").






Those could probably be flattened and filled in. Ug, right near the front, there is a large gash. That's where the tub was rubbing on the front of the frame.



Ok you welders out there. What do you think? Should I cut out the large gash and bigger holes, weld in a replacement piece, or cut the whole bottom off and weld in a new piece? I await your opinions.

In the mean time, I'm going back out there and get a few ours in. Fridays are good for me because I don't have to help my kids with their homework. I get to put in 5 solid hours. Tonight, I'm going to tackle the A1 style lunnete, the master brake system, brake lines, and electrical.
#3
Wow! Totally awesome aquire and build.
#4
Friday (cont.): I didn't get very far today. Ran into some major issues with the Lunette and hydraulic brake system.



I started by removing the cap from the cylinder assembly to check the condition of the brake fluid. I barely twisted the cover and... snap.



The cover had all this powder on it, as if the aluminum was eaten away by the brake fluid. I peeked inside the container and all I saw was powder. Looked like aluminum mixed with magnesium, mixed with dirt... This thing is toast.




Well, I had to continue and look what's inside the lunette housing. From the repair manual, it shows that the lunette has a spring and a shock. Getting this off was a pain, as the bushings were all seized up. Once I finally got it out, it was apparent that the shock was no good. I wonder where I can find a replacement? Maybe Teraflex has one? It would match my Jeep. :)



So, I have to make a decision. Do I buy another cylinder assembly, and restore this trailer back to original, or ditch the brake system. Either way, I had to remove the shock from the lunette. This shock HAS to be there, otherwise the lunette will just slam back and forth. Well, this was no easy task. The bolt was seized by the metal sleeve inside the bushing. I had to grind, hit it with a torch, and chisel it off. I'll take it with me to an auto parts store and see if they can find me a suitable one. Probably a shock from a motorcycle, UTV, or a golf cart.

Next, I removed the hand brake assembly and the brake cable. Pretty easy. No drama here. Happened so easily and quickly, I forgot to snap pics.

I fell behind on the electrical. I was hoping to get it all removed so I can start restoring the taillights. All the rubber waterproof connectors were dried up. So, I clipped the wire at the connector. The metal cover that covers the main electrical connection is held in by self-taping screws. Those suckers are on tight! At the end, I snipped all the wires. The original harness was looking kinda sad.




It's 1am. I give up for tonight. I should be able to tackle the rest of the braking system tomorrow and finish up the wires. I'll stop at Home Depot tomorrow, grab a bunch of wire, and start making a new wiring harness.

Dang! It's taken me 30mins to write this because I kept nodding off at the keyboard and my palms kept pressing on the ddddddddddddddddddddddddddddddddddddddddddddddddd key.
#5
Nice work so far James.
Laughed at the falling asleep part.
#6
Monday Feb 20: Decided to take a small break today and not work too long (or too early) on the trailer. I got sidetracked yesterday and didn't get to finish up the electrical and brakes. This was the project today.

Electrical: Man, I hated to do this. The factory wire loom was not working out. Every connection had a male/female rubber cup seal and they were all dried or stuck. I have to remove it for the sandblasting, and the only solution is to cut it. With a replacement cost of $75, I may have to forget keeping it original and just wire loom it. Sucks.



Other than this, the electrical removal went pretty easy.



Brakes: Yeah, the drum is pretty shot. I did find a possible replacement for $50. The lunette shock is around $80. Turns out, Toledo Actuators makes a duplicate setup and is still currently used today.



All the brake lines came out fairly easily. A little brake cleaner and an airgun cleaned out the metal brake lines. The rubber one that distribues brake fluid to the two hubs was not cooperating. It was blocked on both ends and nothing was working. I even tried to shove a wire close hanger through it. I guess 15 years of gunk finally cemented itself inside the hose. :(



I enlisted the help of Daniel, Michael, and Geoff. They pretty much said the same thing. "If blowing air, spraying with brake cleaner, and sticking a wire through it doesn't work, it's toast. Any chemical soaking will eat away at the rubber components." Yeah, I figured as much.

Geoff gave me some hope. I drove the hose down to him and he assured me that it's something that is replaceable for around $20 and still common.

Well, since it's replaceable for only $20, I will try a drastic measure. I took a drill and a small diameter drill bit to it. It took a few minutes of slow drilling, but I was able to get past the blockage. I blasted 1/2 can of brake cleaner and it finally disolved the blockage.

Thanks for your help, guys.

The rest of this week, I won't get much wrenching time. It's hunting season and I'm headed to Tucson. Javalinas are scarce down there, but the camping and fun times are a plenty!

Hey! I discovered something pretty cool! I was planning on buying new lens covers because these ones were pretty sun faded. I accidentally dripped some brake cleaner on one of the lenses and, to my surprise, the dripped area cleared up! So, I blasted the front and back of both of them, then quickly blew the airgun on them and dried off the brake cleaner fluid. I didn't dare rub on the lens, as brake cleaner melts/softens most plastics pretty quickly.

Wow! What a difference!

Before and after pics.


Lenses all dirty, weathered, and cloudy.


Looking almost brand new!

Now, before you guys start spraying down your plastic auto headlights, remember that brake cleaner can dissolve paint and plastics! So mask the areas well, and do at your own risk! :)
#7
Wednesday 2/22: There will not be much work done for the rest of the week. It's Javalina season and I'm leaving for my hunt on Friday. Tonight, my dad and I went through and removed all the part off the frame that we could, in preparation for sandblasting. We also removed the shocks and will drop the axle and leaf springs tomorrow.

I'm still trying to figure out if I am going to flip the axle or not. In other posts from military web sites, it seems that even when you flip the axle and try to run 33" the fender will rub when there is a decent load on them.

I may just keep running these unidirectional tires. New replacements are around $100 each. The Falkens I have are $210 each.

I created my shopping list for replacement parts. Here's what I have so far.

1. Master Cylinder: I was able to find a replacement master cylinder for the surge brake. http://www.kaiserwillys.com has one for the 1953-64 CJ-3B Willy. They are identical. That's a whole lot better than buying one from Toledo Actuators, which was $129.

2. Wheel Cylinder: We cleaned out the wheel cylinders. they look good. Just need some replacement 2" rubber covers, and we should be good there. I was told of a place called "Year, Make & Model" on 43rd and Bell. They make have them. They can't be more than a few bucks each.

3. Shocks: Replacement shocks will be from NAPA # RR 94038. A nice price at $18.00 each.

4. Trailer wires: I've ditched trying to restore the factory wiring. I decided to use standard 4-wire and wire loom it. I figure $9.00 wire harness and $10 for wire looms. I can reuse the metal wire clampdowns to secure the wire loom.

5. Trailer Lights: I'm rebuilding the original light housings, but am changing the lamps. I'm converting them to the same standard bulb that's on my Jeep. $30 for all the bulbs and hardware. If by some chance, I can actually restore the original connectors, then that will be the way to go. Only time with the dremel will tell.

6. Misc nuts/bolts/washers/cotter pins: Once I get an inventory, I'll be off to Mark's Nuts & Bolts.

7. Tires and tubes: Discount Tire can order the Cooper tires I need for around $130. Tubes are pretty cheap, at around $5.00 each.

8. Shock Dampener: The only source I can find for this shock dampener is from Toledo Actuators. eTrailer.com has them for $60.95. Stock #1844-2.

9. Pivot Bushings for Surge Brake: Etrailer.com has them for $5.09 each. Stock #1745. I will need 8 of them.

10. Replacement tub floor: Need to get me a 6' x 3.5' 14ga steel with a 1/2 lip on longer side. No idea of a price yet on this.

11. Paint or Powder Coat: Need to decide if I should paint or powder coat the trailer. Cost is about the same.

12. Decals and stickers! Micheal will be coming in handy on this one. )
#8
Friday 2/24: My hunting trip got delayed so I took the opportunity to order all the stuff I needed.

Good news! I found a possible solution for the wheel cylinders. They seem to be the same ones that are used on marine trailers with a 10"-12" drum.

I went ahead and ordered a pair. Picked up the Monroe shocks, ordered all my wiring harness, brake lines, master cylinders, and shock dampeners.

I spent an hour cleaning out the original tail light housings. With a dremel in hand, I polished up all the light bulb connectors and cleaned out all the gunk on the metal parts. I'm going to rewire it, but only use 2 of the 4 bulbs. One for turn and one for driving/brake.

My dad has sorta taken over my project. He took out all the pieces of the frame and power washed them. During this process, I noticed that the shock mount (that I thought was welded on) moved a bit. I banged it with a hammer and it finally popped off the frame.

So, the ball is rolling. I'm going to drive the frame parts to Glendale Powdercoat on Tuesday and get an estimate on powder coating the frame, parts, and axle.

Below is just a few pics that were sitting in my phone. It's 3:11am and I'm off to my Javalina hunt. Wish me luck!





#9
For record I have worked my jeep in pajama pants and slippers. Is very comfortabe attire for wrenching on a project.;)
#10
Ha ha. That's my dad. He's a simple man and likes to be comfortable.

Sent using Tapatalk.
#11
I like your dad already. Give him a thumbs up from me.
#12
Very cool build Jimmy. Have fun with it!
#13
Tuesday 2/28: Had a slow start today. Still recovering from a hard weekend hunting trip. I finished off the final breakdown of the trailer, loaded up all the pieces and took them down to Glendale Powdercoating.



The estimated cost to get all the work done is around $200. That's the entire frame and axle. The turnaround is about 10 days. That's perfect, as it gives me time to prep the tub for sandblasting and order in the new steel for the tub bottom.

I chose a textured black finish. It's close to traditional OEM chassis color, but textured to hide road rash and to give it some added strength.

The rest of the frame parts have been ordered. Some have arrived, while others are in transit.

I took the leaf springs to Glendale Springs. I had hoped he can separate all the leaves so I can inspect for rust, wirebrush, paint, and reassemble. He told me that there WAS rust in between the leaves and that they are ruined. Huh... they are still stiff and I was not about to drop $300 for new ones. I'm either going to just pressure wash, then paint and keep using them. If/they fail, I will buy new ones at that time. Personally, I think the guy was full of bull.

The rest of the day was spent wire brushing the backplate, drum, and manual brake lines in preparation for paint.
#14
Wednesday: 2/29: Well, ain't that just dandy.

As my research deepened, I noticed I screwed up on the bearings, races, & seal. Apparently, the M416 and M416-A1 w/ surge brake, uses different axles. Whoops!

WHOA! Stop this train! What did I miss????

Did I screw up here? Bearings and Race. Is my M416A1 not the same as the M416?

The M416 uses 4 of the same bearings for both wheels. I purchased two of the SET45 kits from Timken.

I just read on G503.com's forum that the M416A1 has two different sizes. The internal one is smaller than the external one???

The post reads:

The 416 has a non-tapered shaft and uses the same bearing on both inner and outer aspects of the drum (bearing #8762093 & race #7536132). The inner seal is #516992.

The m4161A uses two different bearing sets. The larger,inner one is bearing #L68149 and race #L68111. The smaller, outer set uses bearing #L44610 and race #L44649.
The inner seal is #15529.


I would have seen it eventually, I guess as I am reading the manual from cover to cover. Glad I ran into it now, as the bearings I ordered just arrived. Had I found it later, I would have been past my 30 day return policy.
#15
Sunday 3/5: I've spent the last couple of days organizing parts and trying to figure out what to do with the issue of the bearings for the axle. I was able to find a nice resource, Arizona Axle Products. They are located at 5323 W. Montebello Ave in Glendale. The owner is pretty old school. He doesn't even have internet or email. LOL. He was a wealth of knowledge and gave me two options.

1. He had the bearings/race/seals to rebuild my hubs. I can continue using my existing tires/rims and replace the tires when they finally wear out. Cost will be around $50.

2. For $90 each, he can fully replace my drum (including hardware) and give me one with a 5x5 bolt pattern. This will allow me to add a 2" spacer (which I already have) and use matching Jeep rims/tires (which I also already have).

I had a 3rd option. I could go with his option 1, then get 2" adapters to space out the drum and adapt the 5x5.5 to 5x5, then add my Jeep rims/tires. Those adapter will run about $120.

Geez. for now I think I will choose option 1 and continue to use the original military tires. This will cut my costs down and, who knows. By the time the tires wear out, I may just buy new rims for the trailer AND my Jeep. So, I will save the $$$ for a future upgrade.

All my parts came in. The Willy master cylinder was an exact replacement for the surge brake cylinder. Woot! Saved me $100! I ended up ordering the Toledo shock dampener, as this was my only option. The standard 10" drum Dexter trailer wheel cylinders seem to be correct so I'm glad I ordered those, instead of trying to rebuild the original ones. The replacement flex brake line is questionable. One end attaches through the frame, and is held in by a snap ring. The gap is rather large.. maybe too large. I can probably fab up a spacer or find some washers that can fill the gap. I'll figure it out.

I went to Home Depot and purchased some wire connectors, wire looms, and two rattle cans of Rustoleum Hammered Black. This isn't a perfect match to the textured powder coat, but it's close and will add a bit of contrast to the frame.

So, tonight the project was paint. I had wire-brushed all of the parts and removed as much paint as I could. Other than that, I just textured and smoothed out the imperfections and degreased everything. Time to spray.










Tomorrow, I'm going to wire up the modified tail lights within the housing. I can't do much more until the frame gets back from Glendale Powdercoat. If time permits, I may make a trip to Harbor Freight and look their tumbling media. I would love to find a coarse media that can take off all the old paint off the nuts, bolts, and washers. This will save me from having to inventory all of them then hunt down replacements.

Until the frame comes back, I will turn my focus to the tub. The tub is something that I will need help with. I need a plasma cutter, a welder, and someone who knows what the heck he's doing with them. Geoff came to mind. :) Dude's got some MAD skills and he's less than a few miles from my house. Geoff is a super guy. We're going to schedule a time for him to come by (soon) and take a look at the tub, give me some suggestions, and hopefully, he can find time to help me put it together.



Another decision will have to be made soon and I'm open to suggestion.

What color for the tub? I'm going to powder coat the fenders to match the frame (textured black). I'm also going to Line-X the inside of the tub and do it in black. Should I just sand blast it and rattle can it Hammered Black, like the accent pieces? How about make it silver to match my Jeep? Glendale Powder Coat has all sorts of colors. I can probably get the silver to match up pretty good. Or, just powder coat it in the same textured black (as the frame and fenders).

Any opinions?
#16
Monday 3/6: Worked til 4am on Sunday and crashed til 10am. There was a few more items to be painted. I got to the last three pieces, the tire rims, and ran out of paint.



The electrical was a bit easier. The trailer wire connector I purchased from eTrailer.com (#A35W42B) was set up for easy wiring. It's a standard 4-wire, but they added a 2nd brown, which is for driving/accessory lights. Normally, the brown goes to one side of the trailer, then you tap off to go to the other side. This cool little setup saves you from having to tap off.

Normally, the white wire of the 4-wire set is the chassis ground. Commonly, the white wire is secured near the hitch. The lights are grounded to the frame, and the circuit is completed by the frame.



Since my M416 lights have 4-bulbs, it has 4-wires that come out of the back. The wires pass through a rubber insulator and it protects it from shock, cuts, and moisture. The ground for the bulbs is inside and attaches to the frame via the mounting bolts.

I wanted to retain the use of the rubber insulator and look of the original 4-wire. I was only using 3 bulbs, so I wired each bulb separately and wired the ground to come out with the other wires.

The original bulbs are 24v. I found a 12v replacement that "seems" to work well. I'm only using the top 3 bulbs. The 4th bulb is for the Black-out lights, which I am not configured for, nor was the 4th bulb connector is good physical shape.

I digressed. From top to bottom, I'm using bulb 1 and 3 as driving lights. Bulb 2 as the brake and turn signal. Bulb 1 and 3 are smaller bulbs. I found #7007 fit well, but they are only 5w bulbs. Bulb 2 is larger and I found #7506 to be perfect. It's a 21.5w bulb is bright.

I covered the bulbs and socket with dielectric silicone grease and buttoned it all up.





#17
This thread as so much win...

Well done Jimmy.
#18
Very cool build Jimmy! Look forward to the finished product.
#19
Wednesday 3/7: Geoff (showboat) stopped by and gave me some good suggestions about replacing the tub floor. At the same time my buddy Richard asked me to haul the tub to his place. He's taking it in for sandblasting. Other than painting a few more items, there isn't much to do.

The frame should be back soon, and the work will begin.


Thursday 3/8: Picked up the tub. Man, sandblasting brings out all the uglies and imperfections. Now, I can see all the dents and dings. It will take a little time to straighten some of them out, but it shouldn't be bad. There were some "extra" holes when it came back. LOL. Just goes to show how thin some of the metal is.





My neighbor (the fab guy) said the can fill in the holes.

Now, just need to mask of 3/4" off the side of the floor, then cut the sucker out.

Frame, axle, ancillary parts, and repacked hubs should all be back on Tuesday 3/13.
#20
Sunday 3/11: Spent most of the day hiking South Mountain with my son's boy scout troop. Ironically, the trail was called "Fat Man's Pass". Man, I sure felt like a fat man because the trail wore me out!

Fat Man's Pass is named as such because of a rock formation at the end of the trail. Several LARGE rockscapes sandwiched themselves together and left only a slither of a path. The two pics below are not of our group, but something I found online. Kinda cool. It's a 1.8 mile hike to get there.




By the time I got home it was 5:30pm and I REALLY wanted to get the floor of the tub cut out.

Per Geoff's instructions, I taped off 3/4" border and used the tape as a cutting guide.



I used an angle grinder airtool but the 30gal compressor struggled to keep up. After 20mins of cutting, I only got 7" of cut.



This was pretty sad. Luckily, I had an electric one and prayed that I can get it finished with only 5 cut-off wheels. So, here I went...



An hour later it was evident that 5 cut-off wheels were not enough. I managed to get 80% done. Plus, there were areas where I could not get the electric unit into. Especially near the drain plugs and the mounting tabs. I ended having to finish off with the air tool. In the process I managed to nick the air hose and it was almost Game Over.



A standard "Man Tool" is the duct tape. LOL. It allowed me to get back to work and limp through the rest of the cuts.

An hour later... Success!