Unimog
406 and 416
The Unimog 406 (sales designation U900) and the 416 (sales designation
U1100) represent one of the ultimate vehicles for off-road use,
be it as an implement tractor on a farm or worksite, a rock-crawler
or as a remote expedition vehicle. Stock 406/416 Unimogs are more
capable than most custom “built” 4x4s and the engineering
standards exceed that of other 4x4’s. The 406/416 has ground
clearance, low gear ratios and axle articulation on a level that
few other vehicles can match. That, combined with the torquey, heavy
duty 5.6 diesel, bullet proof drivetrain, large tire options, power
steering and awesome approach and departure angles make the 406/416
one of the most capable off-road vehicles anywhere. The 406 and
416 are specifically designed to take a large number of PTO and
hydraulic implements and one Unimog can easily be used as a front
loader, backhoe, snowplow/blower, dumper, and agricultural tractor.
The 406, and its long wheelbase sibling the 416, have many variations
and there are other similar versions of the 406/416, such as the
403 and 413, 417 and 419. The 406 was introduced in 1963 and the
416 followed in 1965. They were built until the late 80’s
with some derivations being produced into the 90’s. The 406
has a 94 inch wheelbase while the 416 is virtually identical but
has 114 inch wheelbase. The 406 and 416 use the same cab, which
was produced in several variations including a two door soft top,
two-door hardtop and four door DoKa. This cab is a vast improvement
over the 404 but still spartan and somewhat awkward by modern standards.
The 406 and 416 share the same engine, gearbox and axles.
The 406/416 are powered by the Mercedes 6 cylinder, 5.7 liter, OM
352 that generally produces between 85 to 110 hp depending which
application it is in. Unlike earlier Unimog engines that were based
on automotive engines, the OM352 is a low revving, heavy-duty truck
engine. This engine is famous for its strength and durability and
is still used throughout the world in trucks, boats and heavy-duty
machinery. Generally in the 406, the engine produces 85 hp and in
the 416 it produces 110hp. However it can easily be tuned to 125hp
for both the 406/416 by upgrading the injector pump.
The 406/416 gearbox comes in two shift patterns. The first is a
six speed forward, two speed reverse gearbox similar to the 404.
The other variation is a 2 x 4 four speed with eight forward ratios
and four reverse ratios. The 2x4 is virtually the same as the 6
speed except for the shift pattern. This gearbox has a four-speed
shift pattern with an additional hi/low range shifter similar to
other 4x4 systems although it does not use a two-speed transferbox.
Both of these gearboxes can be mated to the “Cascade”
auxiliary gearboxes which provide up to three reductions with crawl
ratios from 100:1 to as low as 4000:1! Torque converters, double
clutch units and front and rear PTOs are also possible with this
gearbox depending on the configuration. All 406/416 come with HD
power steering and power brakes. Early 406/416 came with four-wheel
drum brakes while the later models came with four-wheel disk brakes
with automatic load proportioning. As with other Unimogs the 406/416
use portal axles with reduction hubs. The standard final axle ratio
is 6.5:1 although 6.0:1 and 5.3:1 are also available. With the standard
gear ratios and 12.5R20 tires, the 406/416 has a top speed of about
52 mph (@2800 rpm) while with the high-speed axles and 14.5R20 tires
speeds of 65+ mph (@2800) are achievable. The OM352 will cruise
for extended times at 2800 rpm no problems although it is a bit
loud in an uninsulated 406/416 cab.
The 406/416 make truly awesome off-road vehicles, suitable for anything
from wilderness emergency vehicles to extreme expedition vehicles.
They are used by armed forces and emergency crews world wide for
their ability to safely, quickly and comfortably access areas that
most vehicles are unable to even get close to. They are also popular
as expedition vehicles because in addition to providing more capability
and freedom than other popular expedition vehicles, they also provide
more space and cargo capability which provides a higher level of
freedom and comfort. Finally, because of their awesome ground clearance,
articulation, and low gearing, Unimogs are respected by extreme
off-roaders and rock crawlers. It is not uncommon for a Unimog to
spend its first decade as an emergency vehicle or tractor, followed
by a decade of driving through Africa, the Sahara and Asia as an
expedition vehicle and then to be used as a trials off-road truck.
The Unimog is equally at home in any of these roles.
Of course, 406/416 are designed to be used as a tractor and/or implement
carriers and at this they excel. Both the 406 and 416 make excellent
medium duty tractors and usually come equipped with PTO’s
and hydraulics; including 540 rpm, high speed, double clutch PTO’s
and five circuit hydraulics with heavy duty pumps. The PTO’s
use standard shafts and standard three point hitch units and can
be mounted front and rear. As a result, these Unimogs can take everything
from backhoes and frontloaders, to brushhogs and mowers, to snow
blowers and plows. Other useful features such as 3-way dump beds,
and air compressors with air brakes for trailers are available.
A 406/416 will take as many implements as most John Deere or Kubota
utility tractors, but do it better and for less money. Furthermore,
you can drive to the worksite with a Unimog which adds even more
to its versatility.
In their standard form, 406 and 416 are awesome off-road vehicles.
However, driving a typical standard 406/416 can come as a shock
to somebody who hasn’t driven a Unimog. They will certainly
seem slow, loud and somewhat crude. This takes a little getting
used to but few find it a problem once they get accustomed to it.
Nonetheless, it is pretty simple to make the 406/416 much more comfortable
and practical for road use. This has largely to do with adding more
insulation to the cab and engine cover, installing high speed axle
ratios, installing larger tires and upgrading the injector pump.
These modifications transform the 406/416 into a whole other league,
dramatically improving the on-road characteristics while at the
same time actually increasing off road ability.
Unimog 406/416
Options and Upgrades:
Engines:
The OM352 can easily
be tuned to 125hp using Mercedes approved specifications in both
the 406 and 416. The OM352 can also be custom tuned up to 150hp.
It is also possible to turbo charge the OM352. However, unlike the
435, a turbo is not a direct swap and involves modification to the
cab. The turbo is a very tight fit and intrudes into the cab. As
a result this is not a straightforward or practical modification
but with some ingenuity it is certainly possible.
Special Drive Train configurations:
There are no overdrives
or gear-splitters available for the 406 and 416. However, for those
who want to increase the top speed, there are two options; "fast
axles" and/or larger tires. "Fast axles” involve
installing lower ratio ring and pinion gears. This will provide
approx 20% increase in top speed. “Fast axles” are not
recommended for the 406. The short wheelbase, combined with the
large tires and high center of gravity, make the handling on a 406
unpredictable and potentially unstable at higher speeds, especially
if there is poor traction.
As with other Unimogs, increasing the tire size gives a higher top
speed, better cruising rpm and more ground clearance. 14.50x20 tires
fit with little or no modifications.
PTO units include:
540-rpm front PTO
High-speed variable rpm front PTO
540 front rear PTO
540 front rear PTO double clutch driven
540/1000 RPM shiftable PTO double clutch driven
Underdrive Gearboxes:
The 406/416 were available
with the “cascade gearbox” which essentially adds
three additional ratios ranges giving the vehicle High, Intermediate,
Low and Super Low. Just like Hi/Low on normal 4x4s, all gears
on the gearbox are available in each range giving a total of 24
gears on the six speed. The ratios are a follows:
| High |
1:1 |
| Intermediate |
1.27:1 |
| Low |
4.67:1 |
| Super Low |
42.9:1 |
Comfort:
Unimog 406/416 cabs
tend to be pretty loud seeing as the occupants are virtually sitting
next the big 5.6 liter diesel engine. However, Mercedes did little
to sound proof the cab so there is room for lots of improvement.
Insulation, sound deadening mats and carpeting can bring the noise
levels down quite a bit and add to overall comfort. Of course
the 406/416 will never be a quiet vehicle by modern standards
no matter how much soundproofing is used but it can be certainly
made tolerable.
Click Here for a detailed list of
406/416 specifications and weights
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