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H2 CHASSIS TUNED TO OPTIMAL BLEND OF ON-ROAD COMFORT
AND OFF-ROAD PROWESS
The chassis of the HUMMER H2 was painstakingly designed and
engineered to provide a solid foundation for best-in-class off-road
performance, while maintaining a refined, comfortable ride on
pavement. Not only was the chassis specially tuned for superior
off-road performance, it was designed to optimize the off-road
balance between rock crawling and desert racing. Special attention
was paid in areas of obstacle clearance, suspension articulation,
wheel control and underbody protection.
From the start of development of H2's frame design, all components
were packaged flush with or above the frame rails. This provides
better protection during underbody impacts. It also allows the
vehicle to slide over obstacles more easily on the frame rail
or rocker protection-H2 is not as likely as other vehicles to
get hung up on any low-hanging components.
H2 was created with a long wheelbase, wide tread and short
overhangs to provide superior control for the driver in varying
types of road or terrain conditions. The short overhangs provide
high approach and departure angles, allowing the H2 to drive
right into a hole and out again, for example, without getting
hung up in front or rear.
With its standard LT315/70R17 tires and air leveling suspension,
the H2 has a 43.6-degree approach angle and 39.7-degree departure
angle.
Special underbody protection, including large skid plates,
helps define the H2's rugged character and enhance its performance
characteristics. A thick (4mm) stamped aluminum front engine
shield runs from right beneath the front bumper back to the transmission.
It angles prominently up at the front, with the H2 logo pressed
into the shield just below the bumper. A one-inch diameter tubular
steel, ladder-type shield protects the transmission and the exhaust
system's two catalytic converters. It is strong enough, when
necessary, to briefly support the load of the vehicle sitting
on a rock that it is passing over. A third, high-tensile strength,
galvanized steel shield protects the transfer case. It has a
special cantilevered design, which allows it to flex or spring
back after coming into contact with a rock. The shield is designed
so that the weight of the truck can move it up when traveling
over a rock. But, once the truck has passed over a rock and the
shield has done its job of protecting the transfer case, it springs
right back to its previous position.
Unique rocker protectors bolt through the frame. Large, standard,
black-painted steel tubes, running along each side of the vehicle,
protect its lower body and door panels against rocks and stumps.
The high-strength structural pieces bolt right into the frame
with heavy brackets and are designed to withstand off-road impacts
from beneath or from side angles. The rocker protectors are so
strong they can be used to pivot the entire vehicle on a rock.
The fuel tank also has its own heavy plastic shield, designed
to absorb abrasions and hits that would otherwise contact the
tank.
Such protective features greatly enhance the H2's performance
capabilities because they allow it go places competitors cannot
go.
Also providing superior off-road control is H2's solid rear
axle setup. It helps optimize suspension articulation and gross
motion control, giving the driver a precise sense of vehicle
control in the tightest of situations.
CHASSIS CONSTRUCTION: THREE-PIECE, FULLY WELDED FRAME
A fully welded ladder-type frame, with a modular, three-piece
design that incorporates a number of hydroformed components,
provides outstanding strength, stiffness and dimensional accuracy
for H2's chassis. The hydroformed front section helps create
the H2's high approach angle. To improve the frontal crush zone,
GM engineers added reinforcements in key box sections of the
frame, enhancing its ability to absorb energy, crush and collapse.
Uncommonly flat crossmembers are used around the transmission
mounting area to preclude any possible hang-up points. The tolerances
for powertrain mount positions have also been tightened to reduce
potential noise, vibration and harshness (NVH).
Because of H2's full-time 4WD system, GM engineers also took
great care to minimize the NVH transmitted by the front axle
to the frame, devising a special three-point mounting system
to isolate it. Two forward mounts vertically connect the axle
to the frame, while the rear mount attaches it to a crossmember
that fits between the two lower control arm brackets in the frame.
The front frame section incorporates a GM-first standard winch
receiver. It is designed to handle an impressive 9,000-pound
capacity winch for freeing a vehicle that's helplessly grounded.
An extension for the receiver could also be used for adding such
accessories as a bicycle rack. The receiver itself has the same
diameter as the standard integrated rear trailer hitch receiver.
Therefore, the front receiver could also be fitted with a hitch
that would allow pushing a boat into the water, for example.
The winch platform, including the receiver and a bracket, is
built right into a thick front crossmember as an integral part
of the vehicle's design. Paired tow loops up front complement
the distinctive HUMMER-style rear pivoting tow loops.
The mid-frame has a stamped-steel box section design, with
common inner and outer sections and a clamshell-welded configuration.
Its strength and stiffness help minimize ride and body vibrations,
contributing to a smooth ride on-road and providing the strength
and stiffness required to handle severe bumps and jolts. As in
other GM SUVs, the composite fuel tank (with large, 33-gallon
capacity) is mounted inside the left frame rail, ahead of the
rear axle, for maximum protection.
The hydroformed, short rear-frame section helps create a high
departure angle. It is heavily reinforced in key areas for H2's
8,600-pound GVWR capacity. The rear section incorporates a standard,
integral trailer hitch receiver. Unlike with most SUVs (whose
hitch receiver is added on), the H2's is built right into the
last crossmember of the frame rail and developed into the bumper.
A Class 3 trailer hitch is standard.
UNIQUE SUSPENSION INCLUDES NEW SELF-LEVELING REAR AIR SPRING
SYSTEM
The H2's standard independent front torsion bar and five-link
coil spring rear suspension provides excellent on-pavement ride
comfort and control and a high degree of strength, control and
rear-axle articulation off-road. An optional self-leveling air
spring suspension for the rear takes comfort, control and off-road
axle articulation to an even higher level.
FRONT SUSPENSION
The independent front torsion bar has 46mm monotube gas-charged
shock absorbers, a large 35.9mm diameter tubular front stabilizer
bar and unique tuning. The axle has a 4,000-pound capacity.
The front shocks contain unique features for off-road performance.
They have a large, high-strength 40mm center tube and a secondary
integral bump stop feature, which allows them to absorb jolts
at two junctures. Full-size trucks typically have only one urethane
front jounce bumper. When severe bumps push the suspension toward
the frame, it acts like a final cushion to protect the suspension
from hitting the frame. The H2 also has a secondary jounce bumper
built into the shock. So, rather than taking all the load at
the bump stop attached to the frame rail, it takes some of the
load with the shock's built-in bump stop, slowing the suspension's
travel before it hits its final cushion. The design is ideal
for absorbing the extreme forces exerted on the jounce bumper
during high-speed desert racing.
REAR SUSPENSIONS
There are two suspensions available for the rear: a standard
five-link trailing arm coil spring suspension and optional self-leveling
air spring suspension, available with the off-road package. The
package also includes an air compressor and tire inflation accessory.
The standard five-link coil spring suspension's basic linkages
include two forged-steel upper control arms and two stamped-steel
lower control arms with bushings on each side for better isolation.
These components control the solid rear axle's fore-aft and vertical
position; a track bar controls the axle's lateral position. This
suspension is inherently much smoother than a leaf-spring system.
H2's suspension also features brand new variable-rate coil springs,
longer shock absorbers and different linkage positioning-all
designed to provide more articulation for the rear axle during
off-road operation.
The new variable-rate coil springs have a dual stage design
for on-/off-road comfort and increased suspension articulation
under demanding off-road conditions. On-road (or under lightly
loaded conditions), their low or soft spring rate optimizes comfort.
Off-road, the springs adjust themselves to varying road conditions.
If a driver starts running through undulating terrain or speeding
over rocks, the spring rate will progressively stiffen to help
prevent high input forces at the rear from being transmitted
to body and to keep the suspension from bottoming out. The springs
actually progress from a low rate to a transitional and then
a high rate. Aside from their excellent ride characteristics,
they also provide good handling because, due to their progressive
nature, they don't transfer weight to the same degree as conventional
coil springs, thereby minimizing vehicle roll.
A specifically tuned, 30mm diameter rear stabilizer bar helps
enhance off-road control. It has a tubular design, with a 5mm
wall thickness, designed to provide high strength in a lightweight
design. Like the stabilizer bar used with the air spring suspension,
it is also specially contoured to help protect the more delicate
drop links.
The optional, self-leveling air spring suspension system is
brand new for GM. The system is available with the off-road suspension
package. Targeted to dedicated off-road enthusiasts, it includes
a high-capacity air compressor and inflation accessory. Rim protection,
a reinforcement of the tire design that extends the durable rubber
over the rim of the wheel, and triple sidewalls are standard
as well. Rim protection adds extra protection to the tires and
prevents them from slipping off the wheels when aired down.
The air spring suspension system's numerous benefits include:
· A smooth on-road ride. The air springs provide a
4.3-Hz rating (natural frequency), compared to the 4.5-Hz rating
of the standard coil spring suspension.
· A longer suspension stroke for off-road operation.
Longer, 719mm length shocks are used to provide an additional
20mm of rebound travel over that of the coil spring suspension.
This improves traction by helping to maintain wheel contact with
the ground over undulating terrain. The shock absorbers, although
having the same 46mm diameter as those with the coil spring suspension,
also feature a larger-diameter-size rod for increased durability.
· Automatic load leveling. If a customer loads up the
rear of an H2, for example, the automatic load leveling suspension
system will detect the drop in ride height and pump more air
into the springs to restore a level condition. It has height
sensors attached to the suspension links, which monitor and determine
deviations from the standard height, and the system adjusts accordingly.
The system includes an air dryer, which removes all the moisture
from the air to prevent it from contaminating or degrading the
springs. Because it's a closed system, once the springs are charged,
they won't lose pressure.
· A driver-selectable rear suspension height elevation
("extended ride height") provides extra ground clearance
at the rear and improves the vehicle's departure angle. Off-road,
if the truck is in the "4 LO" transfer case mode, the
driver can raise the rear suspension by 50mm (about two inches)
using a ride height switch on the instrument panel. This increases
the H2's rear departure angle from 35.9 degrees to 41 degrees.
Once the vehicle's wheels are freed and driver leaves the rock,
the system can be returned back to normal. Anytime the vehicle
exceeds 20 mph, the system automatically restores the rear suspension
to its standard height. Also, at freeway speeds (beginning around
50 mph), it will lower the rear end slightly to further improve
the vehicle's stability.
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