The Repair of Vehicle Bodies

Andrew Livesey

• Publisher: Routledge
• Year: 2018
• ISBN:
  9781351230636
• Edition: 7
• Topic: Technology & Engineering
• Subtopic: Automotive Transportation & Engineering
• Index: Technology & Engineering

The revised and updated seventh edition of this best-selling reference manual on vehicle body repair brings the book up to date for the current body repair trade. It serves as a comprehensive guide covering the vocationally related qualification (VRQ) required by the modern student and apprentice, as well as providing the CPD essential for all working professionals.

The entire book is overhauled to reflect current industry trends with regards to materials, processes and procedures. New additions include:

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• An entirely new section on the work of the MET technician (mechanical, electrical and trim)

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• New developments in body repair methodology such as repair pods and the greater use of alignment equipment

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• Greater emphasis on the environment with new sections on hybrid vehicles and the hazards of starting current vehicles with high levels of technology

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• Details on both the historic and the current joining methods for the vintage and modern markets

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• Full coverage on the legalities surrounding insurance work for bodyshop staff

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• Updated tables and illustrations

This book not only provides the knowledge and skills for body repair, it helps to develop a real understanding of the how and why behind this information. It will be essential for anyone studying Levels 1-3 Vehicle Body Repair, Vehicle Refinishing and MET courses, including the new apprenticeships and technical certificates from the IMI, Pearson-BTEC and C&G. HNC and degree Automotive Engineering students will find the text valuable to develop skills and knowledge for practical project work. Industry professionals, vehicle restorers and car DIY enthusiasts will continue to find it an essential and comprehensive source of information.

1
Car body construction

Starting out

It’s worth starting out by asking the question why do we have car bodies in the first place? Then moving on to why are they made like they are? This will help you to understand more about your job. So, let’s have a detailed look at vehicle bodies in a general sense.

We now have more variations in designs of car bodywork than we have ever had; we’ll come back to that later in this chapter. When the early car designers, probably better known as inventers and engineers back in the day, wanted to get their cars on the road they needed to do it quickly and cheaply so that they could sell their products and thereby make a living – like us in the body repair industry now. So, about 120 years ago, with no online auction sites, in fact not even a telephone, they sourced their materials locally. All towns and villages had blacksmiths, and bigger towns had horse-drawn cart and carriage makers; these were the source of parts. The early cars were made by little more than attaching a petrol engine to what would have been a horse-drawn carriage.

The early cars had the engine underneath the carriage, meaning that the body and its passengers were high off the road, giving a high centre of gravity (CG). This meant that the cars were unstable and liable to roll over if the driver tried to take a corner too quickly.

As the number of cars started to grow, other engineers started to research and design separate parts of the car. These engineers made money by patenting their designs and selling the right to use their designs to car manufacturers or making the parts for manufactures to use. You probably have heard of some of them, such as Acker-mann, Lucas, Borg Warner, Bosch, Girling and Dunlop.

Obviously, a petrol-engined carriage would not suit everybody. What’s more, the cost of them was horrendous. An early car cost about £2,000 when the wage of a skilled worker was about £1 per week. Yes, 40 years to work to pay for it. So lots of variations started to appear: engines and gearboxes and transmissions in different locations and, more important to us, lots of different body types.

Vehicle construction techniques tend to follow a number of similar patterns from the variety of manufacturers. In this chapter we will discuss some of the general principles involved in how cars and light commercial vehicles are made. You will realize that many vehicles are sold with different names, as though made by different firms, which are almost identical apart from their badges and levels of trim or options. This is referred to as badge engineering; it has been used since the dawn of motoring. The reason for this is that it offers economy of scale in manufacturing and greater customer choice – it is win–win for us all. For the body repairer or vehicle restorer, it means that some parts, for example a sill panel, may fit many different makes and models of vehicles. These parts are also frequently available from independent parts dealers at lower prices than through dealerships

Vehicle safety testing

Figure 1.1a Frontal impact test

Figure 1.1b Protection rating colour coding

Figure 1.1c Side impact test

Figure 1.1d Pole test

EuroNCAP – one of the main reasons why cars are designed and made as they are is to make them as safe as possible. With smaller cars, this must be done within a tight budget, as cars must be priced to fit within what are referred to as price points. That is, if you look at the motoring magazines and web-sites, you will see that each of the vehicle manufacturers makes cars which are very similar in performance and specification at very similar prices. They tend to be fairly equal when it comes to safety of the driver, the passengers and other road users. EuroNCAP is an abbreviation for European New Car Assessment Programme and assesses the vehicle safety using a number of standard tests.

• Frontal impact test – the test for frontal impact is carried out at 64 kph (40 mph). The car strikes a deformable barrier which is offset from the centre. This is similar to many road accidents in which one car strikes another during an over taking accident or strikes another object like a road bollard.
• Side impact test – this is similar to many accidents in which one car is hit in the side by another – often referred to as ‘T-boning’ after the shape of a piece of steak. The deformable trolley is towed on rails into the driver’s side of the car at 50 kph (30 mph), typical of accidents at road junctions.
• Pole test – about a quarter of all serious or fatal accidents happen because of side impacts. The car being tested is propelled sideways on a trolley at 29 kph (18 mph) into a rigid pole. The pole is similar in size to a telegraph pole or lamppost. The main reason for this test is to assess head injury to the driver. The roof strength and operation of side airbags are important to prevent head injury.
• Pedestrian impact tests – a series of tests are carried out to replicate accidents involving both child and adult pedestrian impact at 40 kph (25 mph). This speed is now being adopted as a maximum in high-density build-up areas to reduce pedestrian deaths. This series of tests has led to vehicles having smooth rounded fronts with the absence of bonnet badges or other protruding features.
• Star ratings – each vehicle which is tested is given a star rating for its protection of adult occupant, child occupant and pedestrians. The star ratings are made up from points scoring against each test. The ratings of current vehicles can be found on the EuroNCAP website www.euroncap.com.

Figure 1.1e Pedestrian impact tests

Figure 1.1f Typical drivers

Elements of vehicle construction

Front end construction – the main purpose of the front end is to locate the engine, the gearbox and the front suspension. The type of construction depends on the drive layout of the vehicle. If the vehicle is of conventional layout – that is, front-mounted engine driving the rear wheels – then it is usually of integral (or mono) construction with the passenger compartment. With this type of construction, the chassis rails will be similar at the rear of the vehicle to locate the rear axle and final drive. When being constructed in the factory, the engine and the gearbox are usually lowered into the body assembly. With the sub-frame type of construction, the engine and the gearbox are mounted onto the sub-frame and offered up to the body during manufacture. It is important that the front end of the vehicle is correctly aligned to ensure that the vehicle runs straight and true.

Floor pan – this is the main strength of the passenger compartment. The ribs and pressed-out shapes are there to make the floor pan stiff and strong. This type of construction was invented by Porsche for the first VW in the 1930s to make it light and simple to construct. The floor pan must be strong enough to locate the seats and seat belts as well as connect the front of the car to the rear. The floor pan is usually made of thicker metal than other body panels. Various cross members and the sills are attached to the floor pan to give the passenger compartment extra strength. The floor pan must be resistant to twisting.

Figure 1.2 Front end construction (a) integral or mono (b) composite and (c) front and rear sub-frames, these are bolted separately to the body assembly

Body side and roof – this is assembled onto the floor pan to complete the passenger compartment. Each of these panels is pressed out and welded together to form a tough cell-like ...