Vehicle Body Construction | Vehicle Body Anatomy With Theory.

Vehicle body construction means the making of the whole body of a vehicle. This work needs precise work and experience. The vehicle body is the main supportive structure of a vehicle. In this article, I will discuss the details of vehicle body construction.


Vehicle Body Construction

The body is the super-structure of the vehicle. The body is bolted to the chassis. The chassis and the body make the complete vehicle. The body is just like a cover to the chassis. A body consists of doors and windows.

Different types of bodies are attached to the chassis to make a complete vehicle. The electrical system in the body is connected to the chassis electrical units so that the battery and generator can finish it with electrical energy.

Vehicle bodies are shaped to minimize air resistance, improving fuel efficiency and stability. Ergonomics and interior space are critical aspects of design to enhance the overall driving experience. The body and frame are a single structure, common in most modern cars, providing better handling and fuel efficiency.

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Requirements for Vehicle Body Construction

The body of a motor vehicle should fulfill the following requirements:

  1. The body should be light.
  2. It should have a minimum number of
  3. It should have a long fatigue life.
  4. lt should have uniformly distributed
  5. It should provide sufficient space for passengers and luggage.
  6. It should have good access to the engine and suspension
  7. It should create minimum vibrations when the vehicle is running.
  8. It should have minimum resistance to
  9. It should be cheap and easy in
  10. It should provide clear all-round vision through the glass
  11. It should be attractive in shape and color

All steel sections of the body are stamped out by dies separately and welded together. Around the window and door openings, decorative molds and bands are formed. The tendency of all steel bodies to drum or rumble is overcome by using insulating and sound-deadening materials.

The closed car body provides a roof which may be used for luggage. The closed bus provides a large space for luggage. The open truck body does not have a roof. It consists of the surrounding side only. The rear side is only a half panel which may be opened down for loading and unloading. In some goods trucks, the lower side panels may also be opened down for unloading.

The car bodies have great wind resistance. Due to the increased speed of the cars, special attention is given to streamlining. Streamlining is the process of shaping the body to reduce air resistance. In the case of racing cars, where speeds are of the most importance, streamlining has a great influence on the car bodies.

A car body is formed by several pressed steel panels welded together. To attach the door, instrument panel, hood, truck lid, headlining, etc., attachment brackets are welded to the body.

The coach-built bodies consist of a timber framework reinforced by forged steel plates. Aluminum or steel sheet screwed to the timber framework is considered to be the skin of the modem coach-built body. Commercial vehicles usually have coach-built bodies.

Different Types of Bodies


Different types of bodies for different vehicles are listed as follows:

  1. Car
  2. Truck Punjab body or Straight truck.
  3. Truck half body.
  4. Truck platform type.
  5. Tractor.
  6. Tractor with articulated trailer.
  7. Tanker.
  8. Dumper Truck.
  9. Delivery Van.
  10. Station Wagon.
  11. Pick-up.
  12. Jeep.

Vehicle Body Construction and Repairs

The vehicle body has many different parts and these parts need additional repair for better operation. These constructional parts and their repair procedure are-

1. Body Shell

The body of flat 1I00 select and super select cars is made up of the following structural assemblies:

    1. Front door.
    2. Rear lower panel.
    3. Front panel.
    4. Rear floor and wheel boxes.
    5. Roof panel.
    6. Left side panel with fenders.
    7. Front cross beam and front wheel boxes.
    8. Right side panel with

The body of the Fiat Delight car differs from the above car bodies in the following: roof panel and its framing, door pillars, cross beam under the back, window, fuel tank filler housed in fender wi ng with hinged lid and lock.

Electric spot welding joins The body’s structural assemblies into a sturdy integral shell. While requiring the body, when spot welding is not available, an electric arc welding may be used. It is not advisable to use torch welding since parts may be deformed by heat.

Whenever possible, replace the damaged parts instead of repairing them, because replacement is easier than repairing. Therefore, spares for those parts that are liable to be damaged or deformed in an accident, are provided for repair replacement purposes, small selections may be cut from the new part when the damages are not such as to require the integral replacement of the whole part.

It is to be noted that the purpose of body repairs is not only restoring the car to its original appearance but also restoring the car to its original sturdiness.

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2. Doors

In Fiat 1100 select and super select cars, the four doors are all hinged on the central pillar. However, in the Delight model, the rear doors are hinged on central pillars, and the front doors are on front pillars. Each door is provided with a check arm consisting of an articulated plate secured on the pillar and sliding into a slot in the door.

A rubber pad on the check arm tip prevents the arm from sliding out of its slot, thus checking the opening of the door. Polished metal reveals with frame on door windows are held by fasteners.

(A) Handles and Locks

Doors are provided with locks which may opened by handles either from inside or outside. The driver’s side door handle is provided with a key control lock. Other doors may be locked from the inside by a handle-controlled safety device.

Doors may be opened when the handle is horizontal and locked when the handle is turned down vertically. when replacing a lock, care should be taken to locate exactly the position of the striker which is secured to the body by two self-tapping screws. If the door does not, close well relocate the striker as required.

(B) Weather Strip

Around the doors, rubber weather strips are bonded with a special compound. The door opening weather strip is provided with a velvet trim which must be fixed to the sheet metal edge by special fasteners. To replace the weather strip, proceed as follows:

    1. Detach the old weather
    2. Clean its seat with gasoline to remove all rubber, bonding compound, and rust
    3. Clean new weather strips with graphite or talc; and wash with gasoline the side to be bounded and then let it
    4. Apply a coat of bonding compound on the side to be fixed by a brush and let it dry for about 15 minutes.
    5. Fit the weather strip on the door without pulling or The join must be located as at the original assembly. Press it starting from the center to the ends.

For bonding a partially detached weather strip, either remove it completely or a long portion around leaking points and bond it again in the same way as described above.

(C) Window Regulator

The unit is of the lever type with gear control. It consists of a gear train that transmits the crank movement to the lifting lever with a high reduction ratio. Depending on the crank rotation direction, the glass moves up or down sliding in its guide.

(D) Panel

Panels are applied on the inside surface of the doors. They are secured to the doors by stiff clips at the top and by spring clips at the bottom. Before fitting a panel on the door, place a waterproof plastic sheet over the slot in the door frame cross-member and secure by spring fasteners. It will prevent water leakages. For the same purpose, tarred felts are glued on the door between the frame and the firm panel. The padded armrest is secured on doors by two screws.

3. Glazing

Vehicle glazing involves the use of specialized techniques and materials to securely fit and seal glass components onto the vehicle’s structure. This process is crucial not only for providing visibility to the occupants but also for contributing to the overall structural integrity, safety, and aerodynamics of the vehicle.

(A) Windshield and Back Window

To improve visibility, the windshield and back window are They are also provided with weather strips and bright. Metal reveals. Reveal ends are fixed by a fish plate. The glass panes can be removed very easily. The tilt wiper arms, push the glass outwards and remove the complete windshield assembly. Similarly, the back window pane can be removed.

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(B) Front Swivelling Glasses

Besides the drop windows, front doors are also fitted with lever-operated swiveling glasses, mounted in a polished metal frame and pivoting on two The swiveling glass frame is provided with a weather strip and is secured in place using screws.

4. Body Inner Trimming

The car body is lined with special paints, sound deadening, and waterproofing compounds as well as stuffing and covering materials. It is done for the following two main purposes:

    1. To deaden mechanical component vibrations.
    2. To improve car appearance and comfort.

(A)Tarred felt pads-paints

The body floor, hood, deck lid, and door inner panel under-sides are sprayed with sound deadening The complete body shell is given a coat of primer. Externally, the body is paint finished. The floor’s inner face is covered with tarred felt insulating pads glued in the different locations.

(B) Mats

The mats lining the car floor are of rubber and are secured by special rubber studs and bonding.

(C) Interior trim Linings

The complete passenger compartment is lined with leather and cloth. The headlining is stretched steel bows inserted in holes drilled in the roof’s upper side rails. Rubber linings in the bows for anti-vibration purposes. In front, the headlining is kept in tension by two hooks; and the edge is glued on the windshield opening and secured by spring fasteners above the doors.

The rear recess cover panel, of leather upholstered Masonite, is bonded to the back window lower edge and is clip-fastened to the seat backrest panel.  This rest panel performs as a partition between the passenger compartment and the luggage compartment, is felt-lined, and is fixed at the top by clip·

At the bottom, it is pressed between the two rear wheel boxes which are felt-stuffed and covered with cloth or imitation leather. The instrument panel bottom is in imitation leather lined and is secured to the panel by tab plates and clips. Dashboard sides are leather lined and fixed by screws.

5. Seats

The bench-type front seat consists of a metal framing on which the stuffed, cloth, and imitation leather upholstered seat back is A lever projecting laterally to the cushion disengages the slide catch for seat position adjustment. The cushion is just press-fitted in the framing. The rear seat is in two separate parts:

  1. The back is fitted between the rear wheel boxes and rests against the luggage compartment partition.
  2. The cushion rests directly on the floor and is positioned by two rubber studs.

6. Hood

The hood is made in a single piece, hinged at the rear to cover the engine compartment. Around the edges of the engine compartment on which the hood r::sts when closed are fitted rubber bumper pins. The hood is kept closed by a locking catch. A safety hook is provided to avoid accidental opening.

The hood is held open by a prop inserted in a bracket welded to the dashboard and loaded with a spring which has also the task of opening the prop. The catch-release mechanism is controlled by a handle.

7. Deck Lid

The deck lid is opened and closed with the help of a handle. To keep the lid closed, a catch is engaged in a striker. The luggage compartment opening edge is lined with a rubber weather strip. In a well at the bottom of the luggage compartment is housed the spare wheel.

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8. Bumpers

The rear and front bumpers consist of a single bar provided with two ornaments. The rear bumper is screwed by screws of ornaments and by two side screws covered with chromium-plated bosses. The front bumper is screwed through the ornament stud screws and nut in two brackets welded on the body.

Floor Assembly in Body Construction

Generally, the floor of the body is assembled first, and after that, the pillars, rails, and panels are welded to find the complete body, Fig shows the noor pan assembly of a typical car body. It is made up of three stamped sheet steel panels.

Each unit is shaped in such a fashion that ultimately gives a lower profile and accommodates more passengers. Capping strips of metal have been welded at different places to the noor pan to reinforce it.

To give rigidity and prevent excessive vibrations, the beads, and channels are pressed into each of the panels. After this, the rear wheel housing er panels and rm:ker panels are welded to the floor. The wheelhouse panel provides a wheel well thus giving clearance for the up and down movement of the rear wheels during car movement on the road. The box-shaped rocker panels give great strength to the floor pan.

Cowl Assembly in Body Construction

The cowl assembly is made up of much smaller panel stamping of steel as shown in Fig. The various parts are discussed below  :

  1. The windshield opening frame is meant to accommodate the glass.
  2. The top outer cowl is even vented in some designs of vehicles to allow fresh air to enter the car.
  3. The dashboard has different warning and indicating devices required to operate the car. Generally, the instrument panel is welded to the cowl but even in some designs, it is bolted to the cowl.
  4. The hinge pillars are meant for fastening the front door hinges and the cowl side panels.
  5. The fire Well. It is insulated in such a way that it does not permit the engine noise to penetrate inside the body.

The cowl assembly is normally welded to the rocker panels and floor pan. The assembly is also used of for supporting accessories like the windshield wiper, steering column, etc.

Roof Assembly in Body Construction

The rear doors and hinges are supported by the center pillars. The center pillars also support the striker plates of the front doors. The roof rails and center pillars are usually box sections to give maximum strength to the body.

The roof panel is welded to the side rails of the roof. the rear window and windshield frames by pot welding technique. The drip molding is a U-shaped channel. It is welded to the side rails of the roof. Its purpose is to catch water from the roof and direct it to the back of the car.

Engine Hood Assembly

The engine hood is constructed in the same fashion as the trunk lid. It has inner and outer panels. The inner panel acts as the reinforcement and provides mounting locations for the hood lock and the hinges. The outer panel is formed in such a fashion that it has a blending effect with the contour of the fenders and body.

The hood is attached with the help of hinges which have slotted holes for adjustments. The hinges are even provided with coil springs or torsion bars to counterbalance the weight of the hood, thus holding it up when it is opened.

The engine hood is kept closed by a manually operated hood lock and safety catch. The safety catch does not allow the hood to open when the vehicle is moving in case the main lock fails.

Front and Rear Seat Assembly

The seats used in the cars are of various types such as rigid, folding back, and bucket. The front seats may be single-type or full-bench-type construction. Both types are made up of two main parts, namely the seat cushion and the seat backrest.

In the case of two-door cars, the back is integral to the base. The construction of the rear seats is practically the same except that a lighter framework for seats is unlisted. In both cases, the springs, layers of padding, foam rubber, etc., are used for the construction of the seats.

Front seats are provided with an adjustment that allows the seat to move back and forth. The cars with bucket front seats have separate adjustments so that the driver and passenger can adjust their seats independently. The front seats may be provided with six-way adjustments, namely up and down, tilt forward and backward, and back or forth. These adjustments may be done manually or the adjusters may be operated electrically by small motors which utilize battery current.

Glass Assembly

The safety glass used in cars, buses, and trucks is of special design. It differs from ordinary house window glass. The safety glass, when broken, does not form sharp pieces like the ordinary window glass. It i essential since sharp pieces will seriously cause injury to the driver or passengers of the vehicle.

Two different types of safety glass, namely, laminated safety glass and tempered safety glass, are used in practically all vehicles. The laminated type of safety glass consists of two layers of glass bonded together with the help of another inner layer of vinyl transparent plastic under heat and pressure.

When this glass is fractured, the center layer of the plastic holds the pieces of glass together, thus not allowing them to fly. This way the occupants of the car are not subjected to any damage. It is generally used in the windshields of the vehicles.

The tempered safety glass is made from a single piece of case-hardened or heat-treated glass. Firstly, this glass is cut to the required shape and then heated until it becomes soft. After this, it is blasted with cold air which cools and shrinks rapidly its outer surface.

This way, sufficient tension is created between the inner soft glass and its outer hard skin, thus making it four to five times harder than ordinary glass. This glass resists extremes of heat and cold after its tempering. When it breaks, it does not form sharp-edged pieces. It crumbles into harmless granular-like particles.

The tempered glass is commonly used in the side or rear windows of the vehicle. However, it is not suitable for the windshield because the complete glass breaks into granular-like particles through which the driver cannot see.

Fit the weather strip to the glass. Lay the cord of 3 mm diameter in the weather strip groove, starting from one side and returning to the starting point. lt may be ensured that the cord is fitted snugly all around in the groove. Now, push the glass to the frame from the outside and pull, one end of the cord from the inside while pounding on the lip, thereby fitting the strip to the frame.

Continue this process while pulling the cord out progressively until you come back around to the starting point.

Body Paint

It is very difficult to touch up the stoving enamel surface. However, the following technique may be adopted for touch-up work to get better results.

  1. Chipping. Chipping at door edges to be touched up with Hylux or Glolac by brush.
  2. Small spots :
    • Sand thoroughly the damaged part of the stoving enamel film with 400 pieces of waterproof paper and water with rubber After this, the affected portion should be sanded with 600 paper.
    • Whatever metal is exposed, the C. primer surface should be sprayed.
    • After proper flash time (4 hours), the N. primer surface should be wet sanded with water and 400 waterproof paper. After this, 600 papers should be used in this area.
    • Hylux paint of l.C.I. or Glolac paint of additions is to be used for touch-up work.
    • One coat is to be sprayed first on the primer surface film After some time, apply a second coat of the paint starting from the inner side of the area. After 5 minutes of flash time, spray Hylux thinner or Glolac thinner, as the case may be, on the dry spray area to wet it. Now, dry it with an infrared lamp for 30 minutes, and keep it for 48 hours to air dry.
    • Now, rub car polish with a soft cloth on the touched-up


Vehicle body construction is a complex process that requires a balance between strength, weight, safety, and design considerations. Advancements in materials and manufacturing technologies continue to shape the evolution of vehicle body construction, leading to more efficient, safer, and visually appealing automobiles.

Frequently Asked Questions(FAQ’S)

How do safety features factor into vehicle body construction?

Vehicle bodies are designed with safety in mind, incorporating features like crumple zones, side-impact beams, and reinforced structures to absorb and distribute impact energy in the event of a collision.

What role does aerodynamics play in vehicle body construction?

Aerodynamics is crucial in vehicle body design to minimize air resistance, enhance fuel efficiency, and improve stability. Spoilers and underbody panels are often included to optimize aerodynamic performance.

What are the key considerations in designing a vehicle body for aesthetics?

Aesthetic considerations in vehicle body design include brand identity, market trends, and overall visual appeal. Ergonomics and interior space are also essential aspects of the design process.

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