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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?
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
- 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
- Timken bearing # LM501349. Timken axle seal #
- 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
- 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
- More parts vendors to try (all links open in a new window):
TNJ Murray, RAPCO
Parts (dead link?), Midwest
- 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
- 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
- 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
- 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 -
|- Acquisition cost (11/2002)
- new axle ubolts, nuts and washers (4 total)
- new frame ubolts (1/2 x 12 inches) (2 total)
- spindle nut socket - to remove the big hub bolt (tool)
- 1/4 ton Jeep Trailer Safety chains (pair, plus shipping)
- AZ title transfer ($4 plus late fees for waiting to do it)
- Giant safety chain bolt and misc pintle adapter bolts
- 2 Used 15x8 wheels with 5 on 5.5 bolt pattern, spray paint and primer
- 2 Used BFG Mud Terrains 31x10.50x15, mounted and balanced
- POR-15 Starter Kit (undercarriage coating)
- 100lb bag of copper slag for sandblasting (don't use silica)
- 4 red reflectors (replacements)
- replacement drain plugs (2) (eBay)
- replacement shocks (2) (eBay)
- Permanent ADOT registration (Arizona) - no renewals
- new urethane shock bushings
|Total 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
- 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
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.
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
Others with M416 Project sites/pages (all links open in a new
in Las Vegas