Source: U.S. Military M416 Manual

NOTE: At this moment, this page is mostly just a gathering spot for all the M416 info that matters to our project. I WILL be organizing it and probably even making it it's own little project section right here at Jeeps Only. Don't forget to join the MSN M416 Jeep group (opens in a new window) for ongoing interactive discussions. It's new so you'll be one of the first. We have 2 kids, 2 dogs and a lot of gear. If you're like us you know short wheelbase Jeeps like the Wrangler and CJ don't have much room to begin with and barricading your kids/dogs in the back seat along with all your gear isn't a good idea. We've been looking at offroad trailers for some time now and although we're impressed with the quality and features of these trailers, we're not wealthy enough to be able to afford one for ourselves :-(. Alas while searching the Internet another option became clear. The Army and Marines had 1/4 ton trailers in World War 2 and the Korean War (probably Vietnam too) and these were well built, tough trailers. They were light enough to be pulled behind early Jeeps with 60+ horsepower engines, water tight and were built to take the constant abuse that was common during wartime. Unfortunately many years have past since these trailers were first sold as military surplus and for some reason they are very hard to find in the southwest (we're in Arizona). Sometimes they can be found being used by fire departments or city works departments but more often than not they seem to be sitting around in someone's backyard developing rust. With prices ranging from $250 on the east coast (needing work of course) to $1,200 on the west coast (in good shape), I set off looking for one of these trailers that didn't have any major damage, particularly to the tub which is difficult to straighten out. After about 6 months of looking I happened upon a tiny ad in the Collector Car Auto Trader and the seller was only 20 miles from my house. His trailer was in good shape and although I thought the $650 he was asking was a little high, I felt it was unlikely I would find another one so close in this good of shape. As a huge added bonus, this trailer already had an Arizona title which should make it easy to register here.

Neato standard features: water tight tub, spring loaded drain plugs, heavy duty springs and shocks, tonneau top hooks all around, handles all around, hand brake (some rare ones even had a runaway-trailer actuator that applied brakes automatically if you're trailer broke loose), built-in trailer stand and one of my favorites, a springed pintle loop that allows the trailer to twist and turn freely. Oh and the Army has a cool downloadable 286 page manual that explains everything you'd ever want to know about this trailer.

M416 trailer purists: I know some will deride me for taking a piece of military history and modifying it some for modern use but this was my intention from the start and camoflage doesn't match my Jeep. Also, I know I'm skipping alot of historical notes that hopefully someday I'll have time to add, such as the fact that the WW2 trailers were known as the BT3 (or the civilian BT3-C) and they had rounded fenders, etc. I also hope to make note of the M101a trailers used by the Canadian military until the 90's which are in MUCH better shape generally and are essentially the same trailer (they are hard to get unless you live near Canada).

So I just acquired this trailer in November 2002 and plan on sandblasting, painting and replacing the drums, tires and wheels on it in preparation for our annual visit to the Tierra del Sol Desert Safari the first weekend of March 2003. Keep checking this page for updates and I may even make this it's own project like Raptor. Eventually they will both share the same paint and wheels/tires. I'd also like to built my own tent top because we're getting tired of sleeping on the ground in March :-). I've searched and haven't found much info on building your own tent trailer or tent top so hopefully when I've assembled this info it will be of value to the anyone who wishes to do the same.

See the picture below for how the trailer looks today.

Misc. thoughts and notes (later I'll probably organize these more but posting this way allows me to make quick additions):

• The hubs on the M416 (or Canadian M101a) can be (I'm told) converted to a 5 on 4.5 inch bolt pattern so you can use wheels that match your Jeep and swap them if necessary. From the Bantam Trailer Yahoo Group - "Measure the bearing surfaces on your spindles. They should be 1 3/8" inner and 1 1/16" outer. If they are, you can purchase replacement 5 on 4.5" drums complete with bearings and seals at any trailer parts supply house." Also, 1/2 inch lug bolts. (Fri, 15 Nov 2002 10:32:56 EST). I should be able to get hubs that allow me to retain the use of the hand brake.
• The inside of the M416 tub down to the part that angles inward measures 72 inches long, 49 inches wide and 4.5 inches deep. I may build some plywood braces for the tub (3 total) and cut a piece this exact size to which I could mount a tent that could easily fold almost flat. Hmmmm. It would be a little tight but overall nice to have for a few days of camping.
• Just found out mine was missing a ubolt and the shocks aren't good anymore. Found a place that makes custom ubolts close to my house (Spectrac, Inc. in Chandler, AZ, phone 480-545-5533). I decided to replace the missing bolt and the one I removed on the other side to show Spectrac what sized I needed and I think I'll keep the other 2 I got for spares. I don't have an air rachet so it took about 45 minutes to remove two old nuts from the one ubolt alone. Ubolt size is 7/16x14 inches long (round bent). Cost was $5.99 each and that included nuts and washers. Spectrac says you shouldn't reuse ubolts and $6 seems reasonable to me. Want a template so you don't have to remove an axle ubolt for sizing? Click here and print the picture you see. Warning: make sure your printer settings aren't set to "shrink to page" or similar or the sizing will be off. Acrobat is the program that needs to print this file and if it's not working for you, you probably need to visit www.acrobat.com to download the free viewer. To verify you have the right sized printout, measure the acrossed the bolt from the outside of each threaded sections and that should measure 3.25 inches. This picture should print the actual size of the ubolt with thread pattern and everything. Nuts are supposed to be torqued to 45 ft lbs per their instructions and the bolts are grade 5. Spectrac also has other trailer parts, hubs and all so I'll take my M416 over there to ask about a new bolt pattern (5 on 4.5 like my YJ) while keeping the hand brake. They do custom work also so maybe they can figure it out.
• Another option for fitting Jeep wheels to the trailer would be to use a wheel spacer/adapter (hub-centric). Mountain Offroad (M.O.R.E.) custom makes these for around $99. A company called Performance Wheel also makes since spacer/adapters for $50 each, plus shipping. This might make a nice alternative to switching the trailer to the 5 on 4.5 lug pattern to match my YJ. I could carry one adapter so my Jeep spare would work on the trailer also.
• My shocks need replacing and I'm considering using Rancho 5000's. Pete from the M416 Yahoo Group mentioned he's using RA 5119's (Rancho model number - about $39 each) on his. Internet research has shown that others are using a Napa shock as a replacement (NAPA 94038 - which is said to be for a mid 1970's CJ-5 with a 4cyl engine ). I took off one of the old shocks and it measure 17.5 inches at full open (end to end) and 11.5 inches at full close (end to end). The cylinder end connection style is said to be "12 ring", whatever that means.
• I needed new shock bushings and you probably will also. When I bought shock replacements, the new shocks didn't come with bushings. I visisted my local 4x4 shop and bought a set of standard 3/4 inch hourglass shaped urethane bushings for each shock and they fit perfectly. Don't forget a little grease for inserting them into the shock holes. I also ended up using a vise to help pop them in. BTW, the ones I am using are from Energy Suspension, part number 9.8108R. Cost was about 5 dollars a pair.
• There are so many coats of paint on the nuts and bolts that I'm finding I have to replace them all. The two ubolts on the front of the frame are 1/2 inch by 12 inches with a square bend. I'm not putting the new ones on because I'm thinking I'm going to disassemble the trailer for sandblasting. I want to do it right.
• The U.S. Army has an excellent 268 or so page manual prepared in Adobe Acrobat for the M416 military trailer. They want to give it to you for free! Download it for complete documentation. I love this manual and by the way this link works to find manuals and documents on other military vehicles as well, such as Jeeps. I only wish we could modify the document for our own use to include aftermarket part #'s and where to buy replacement stuff.
• I would like to have a tarp to cover the bed and have found a few sources. To save some money at first, I'm thinking of buying a 5.5x9.5 inch el cheapo plastic tarp (with grommets) from Harbor Freight (camo would be cool) and using some ball-bungee cords from Walmart. Eventually I'd like to get either a Canadian Military issue cover (about $90 plus shipping from www.willysacres.com - pic).
• Timken bearing # LM501349. Timken axle seal # 472018
• To remove the hubs, you'll need a 2- 1/16" bearing locknut socket (also called a spindle nut socket). One can be found at Four Wheel Drive Hardware using this link (opens in a new window) for $9.95 and at the time of this note, no shipping charge.
• The stock M416 wheel bolt pattern is 5 on 5.5, which is the same size pattern found on Dana 44 axles as well as Ford 9 inch axles. Some wheel manufacturers make wheels that are drilled for both 5 on 4.5 and 5 on 5.5 patterns so technically you could get wheels that would work on both your trailer AND your Jeep so you have all-around spares, if needed. This would eliminate the need to swap hubs to get a newer Jeep bolt pattern (see note about).
• If you decide to keep the stock wheels but you want to avoid using tires with tubes, you should be able to buy radials that fit. The size on my M416 right now: 235 70 R16, although other M416 owners have also recommended LT215-85-R16. The wheel height is 16 inches. I think you could also run a 30 or 31 inch tire but remember the stock wheel width is only 6.5 inches. My local tire center (Costco) recommended I try 225 75 R16 since this is a very common size on dually pickups.
• The giant bolt holding on the safety chains on the front of the trailer is 6 inches long with a 3/4 inch shaft, grade 5 or 8. I was able to pick one up for $3.62 at my local nut and bolt shop (Copper State Nut and Bolt in AZ). On my M416, that giant bolt want bent so I had to cut the bolt head off with a hacksaw to get it out. While I was at it I got some replacement bolts for the pintle adapter (4 total).
• My M416 was missing safety chains and you can't just go out and get new chains since because there is a angled bracket attached that allows the giant bolt and nut to tightened squarely. Fortunately I was able to find some NOS chains at the Army Supply Warehouse (not an Army store, that's just the name they picked). Visit their website and search for "1/4" and one of the results should be "1/4 ton Jeep Trailer Safety chains". Price - $12.95 for a pair and they are new, sealed in box. What a deal.
• At the AZ Department of Transportation while transferring the title from the old owner to me, I found out my trailer was bought in 1967 by the Arizona Department of Corrections and NOT the U.S. Army, as I had originally thought. It doesn't matter to me, really, since I'm not restoring or collecting it. By the way, the price they paid for my M416 in 1967? $2,309! Good grief, that was a lot of money back then, wasn't it? Makes my modern $650 acquisition cost seem small. Also, I discovered that my trailer will have a permanent registration for as long as I own it which costs me $125 (ouch!). Oh well, at least I don't have to have it renewed every year or so.
• After WWII, Mitsubishi made exact copies of the U.S. 1/4 ton trailers (look for the Mitsubishi tri-tipped logo - the same one they use today - stamped somewhere). Apparently come German company replicated them also.
• More parts vendors to try (all links open in a new window): TNJ Murray, RAPCO Parts (dead link?), Midwest Military.
• If you're looking to buy an M416 or M101, try: Cold War Remarketing, and of course, the Collector Car Auto Trader (where I found mine). White Owl Parts sells the Canadian M101 which is VERY similar to the M416. Last time I checked, M101's in almost new condition were selling for $700 in North Carolina.
• I recently found a set of 15x8 white spoke wheels from a local Jeep club member for $10. I bought them and someone from the club sandblasted them for me (thanks Mike!). I then primered and painted them black. I didn't want to invest a lot of money in tires just yet, especially since the trailer isn't going to get THAT much use so I called around to almost all of the Discount Tire centers in the Phoenix area until I found one that had some used BFG Mud Terrains for sale. So for $25 a tire (plus the usual extra fees) I got a decent set of tires that match my Jeep (31x10.50x15). I can't wait to post the pictures - they look great on my M416! A little wider (they stick out almost 2 inches) but it looks so tough! I'll post pictures when I get them back.
• Sandblasting: I've decided to buy a pressurized tank sandblaster ($79 on sale at Harbor Freight) to do my own blasting. I have heard that commercial sandblasters want to move quickly and their equipment could blow some holes in the tub. Plus they wouldn't be as careful as I would. There are some major health concerns with sand blasting though, so much so that I almost took back the blaster I bought the very day I bought it. It seems that silica sand, the most popular type of sand for hobby sandblasters, has a HIGH risk of some terrible condition called Silicosis. Invisible silica dust enters your lungs and never leaves, causing a shorter lifetime and pulminary problems. My M416 isn't worth that so I looked for alternatives. Dupont makes an alternative with less than 1% silica called Starblast XL, but I couldn't find anyone locally that sold it. I finally found an abrasive supply shop here in Phoenix, Arizona (Peck's Coating Supply Co. 602-269-6279) and someone there recommended copper slag. Although copper slag contains arsenic, the rep told me I probably wouldn't be using enough to cause any health problems, especially since this is a one shot deal. Also, Starblast and copper slag don't have near the visible dust that silica sand has. Now I am not an expert here so don't take my word for it, I'm just telling you what people have told me. I *think* I'm going with the copper slag at $8.95 for 100 pounds. I'll let you know how it turns out. Lone Arrow Enterprises in Gilbert Arizona (480-507-8074) supposedly sells Starblast XL but I haven't been able to reach them by phone.
• After sandblasting the frame and axle and undercarriage stuff, I'll be using POR-15. POR-15 is a VERY strong "paint" that requires no priming and can even be applied right over rust. Check out their website for more specifics. I bought a "starter kit" to sample the product and figure out how much it takes to cover an area. This stuff is amazing, but expensive.
• Wiring issues seem simple but the lights on my trailer didn't use the standard wire coloring system so I had to get out a tester to see which was which. The trailer has a 4 hole round connector now and I was planning on converting it (snip and splice) to the current standard 4-flat system that most small trailers us these days. Then I read somewhere how another guy decided to use a round connector on his trailer because then he would have an excuse for not lending his trailer to friends and family since they probably wouldn't have the same off connector on their vehicle. Sounds good to me! I'm not going to rewire my Jeep, though. Instead I plan on creating a custom adapter that goes from 4-flat to 4-round or 4-flat to 5 or 6-round so I'd have an auxilary power source for something like a backup light, etc. or an offroad assist brake. I'm going to post a wiring diagram for my 4-round connector because I couldn't find one anywhere on the Internet. I could find the 5 and 6-round diagrams but not the 4. If you need to buy connectors on the Internet, East Marine Online seems to have a decent selection. I haven't bought from them yet.
• The grease fittings on the lunette adapter (where the lunette) were both worn and needed replacing. While at Harbor Freight I noticed they had a box of grease fittings of different sizes for about $5. It turns out the size the lunette adapter takes is 1/8 - 27. One is needed for the top and one is needed for the bottom.

Spent so far -

Future Upgrade Considerations

• Exoskeleton-like tubing to assist with potential rollovers. Eventually we may roll the trailer and rather than there being certain damage to the fenders and tub, I'm considering fabricating some tubing that would allow the trailer to more easily rollover without crushing either. This is just a thought right now. I'll have to come up with some drawings. Anything like this will likely require cutting into the tub so I'm going to be darn sure I want to do it before I start cutting. See, I told you I'm not an M416 purist :-).
• Air ram brake helper. This idea came from TommyJeep, a guy from a Jeep site I frequent called Jeepaholics. Tommy is much more mechanically inclined then I am so I'm probably going to just copy his design. He uses an air ram with a 12 volt solenoid that he controls from in cab. Basically if he's going down a steep decline and wants to keep the trailer from trying to pass the Jeep on the way down, he can apply power to this air ram which activates the parking brake. Tommy built a custom bracket so that the air ram AND the hand brake both function. I'm trying to see if he's willing to write a project report on how he did it so I can link to it. I'd like to find a way to be able to apply partial pressure on the brakes in addition to full pressue. I'm not sure if that's how Tommy's setup it or not.

<report end>

Craig, Salt River Marine Inc 4015 E Madison St Phoenix, AZ (602) 273-9012 - frame. Gets in at 6:30 AM. I can dissasemble in their yard.

Ode's Custom Sandblasting, (480) 892-3785 1410 W Houston Ave - says it might cost only $50 for the frame and $50 for the tub.

TexTrail seems to have reflectors that look identical to the M416 reflector - for $1.63 each! 888.756.0547 or 800.333.1745. Mt. Pleasant and Odessa, Texas. They call them "Aluminum Oval Reflectors".

Discussion on Jeepaholics about an air ram braking system is here (with thanks to TommyJeep).

Reports from the Bantam Trailer group on Yahoo Groups indicate that having someone commerically sandblast the trailer leads to some serious pitting/potting of the metal which in turn makes it difficult to end up with a smooth paint job.

Someone suggested a chemical dip rather than sandblasting. Apparently a chemical dip removes all rust and paint and since a trailer would be submersed in the chemical, the rust/paint removal would be thorough. The process takes 5-7 days for a trailer and would cost from $300-$500, about the same as some of the higher end sandblasting jobs. Plus, since there is no abrasive blasting, the metal is said to come out like it was clean and fresh, prior to original painting many decades ago. One additional benefit is that the trailer could be dunked while still together, minues the tires, wheels, lights and wiring. In the Phoenix, Arizona area, the company that provides this service is Redi Strip of Phoenix, 103 South River Drive, Tempe, AZ, 480-968-9702. The proprietor's name is Roger.

As I found it	Tent attachment idea 1	New (used) tires and recycled wheels

Join the MSN modern M416 group      MSN Groups

Others with M416 Project sites/pages (all links open in a new window):

Pete in Las Vegas
Mike Boyink's Bantam BT3-C