There are two principal types of body construction, Frame body and Uni-body (in which the body and frame are constructed as an integral unit). Vehicles damaged by a collision must be repaired to their original shape, strength and durability. For that purpose, repair technicians have to comprehend the original body structure.
The body and frame are separated from each other as shown in the figure.
The Frame body type vehicle is characterized as follows:
Noise and vibration transferred from the road to the body are reduced. This reduction is accomplished through rubber mounting between body and frame.
Increase in vehicle weight and height.
In the Uni-body Construction, as shown in the figure, individual metal parts are welded together to make up the body assembly and provide overall body rigidity through an integral all steel welded construction.
The Uni-body type vehicle is characterized as follows.
More occupant space can be easily obtained.
Susceptible to corrosion and damage caused by stone chipping because the underbody is close to the road and is made of thin sheet metal.
FRONT BODY CONSTRUCTION
Generally, the thick side members and the front end crossmembers are arranged in a double cross pattern to support most loads. As the impact absorbing mechanism, the side member is concaved, curved, or reinforced partially to absorb energy by deforming when impact is applied.
The double cross sub-frame normally contains quiet and damping functions. In addition to these functions, the function to improve collision performance is added to the double cross sub-frame for certain vehicle types.
The sub-frame is fixed onto the front body with bolts. Vibration and noise from the engine and suspension are not directly transmitted to the body.
CENTER BODY CONSTRUCTION
The passenger compartment area occupies the major portion of the center body. The center body consists of a floor, sills, pillars, and roof panel. To minimize the passenger compartment deformation in a collision, pillar strength has been enhanced. In addition, by multiple reinforcing of the joints with roof and sills, the reinforcing structure has further been improved, compared to the closed sectional construction.
Construction of typical Nissan Uni-body vehicles are shown.
Panel parts will be available either as assembled or individual parts so that only the damaged part need be replaced. To obtain the service parts, refer to the parts catalog for each model.
NOTE: A phosphate coating treatment and a cationic electrodeposition primer (ED coats), which provide an excellent anti-corrosion effect, are employed on all body components.
Nissan Genuine Service Parts also are treated in the same manner. Therefore, it is recommended that GENUINE NISSAN PARTS or equivalent be used for panel replacement to maintain anti-corrosive performance built into the vehicle at the factory.
UNDERBODY COMPONENT PARTS
There are two principal types of drive positions, FF (Front engine Front drive) and FR (Front engine Rear drive). The body structure for engine mounting and suspension is different between these vehicle types.
This figure shows FR type.
BODY COMPONENT PARTS (I)
There are several kinds of body shapes: Sedan (2 or 4 door), Hardtop, Hatchback, Coupe, Wagon (Van) and One box type. This figure shows sedan type.