Bearing body: The lower and side parts of the body, roof and rear fenders are welded to each other
A fully galvanized body has already become something for granted. The absence of through corrosion is guaranteed for 12 years. Unfortunately, rust is not the only nuisance that can cause damage to the body. Over time, due to constant loads, such unpleasant phenomena as knocks and sharp sounds occur.
True, you will definitely not hear these sounds for many years. The very high torsional rigidity greatly reduces the generation of noise due to body aging. Body parts that used to consist of several parts are now manufactured as a single piece. Individual structural elements are mounted using modern laser welding. The body frame is manufactured so precisely that gaps are reduced to a minimum. This reduces both the unpleasant noise caused by the air flow around the vehicle and the fuel consumption.
The body is load-bearing. The lower and side body parts, roof and rear fenders are welded together. Serious damage to the bodywork and the replacement of bonded windshields and rear windows are best left to a specialist workshop.
The hood, doors and front fenders are screwed on and can be changed at a greater or lesser cost. Of course, in view of the fact that the parts must be installed very accurately, and the gaps must be even and of a certain size, this work requires experience and subtle flair. When installing body parts, the specified dimensions must be observed, otherwise, for example, the door will knock, or excessive noises will occur during driving.
Dimensions of gaps at the joints
Despite the ingenious design, in principle, the A4 is made in such a way that it is convenient to repair it. You will understand this immediately, as soon as you begin to change a damaged bumper, fender or tailgate.
However, during any body work, the specified dimensions of the gaps at the joints between individual body parts must be maintained. Otherwise, the newly assembled part may start to knock, or excessive wind noise will occur during driving. The gap must be uniform along the entire length of the joint. The tolerance is 1 mm. The size of the gaps can be checked using the special tool 3371. The illustrations show the most important joints for a sedan.
The dimensions of the gaps at the joints in the front of the body: A - 5.5±0.5 mm; B = 5.5±0.5 mm; C = 3.5±0.5 mm; D = 4.0±0.5 mm; E = 1.5±0.5 mm; F= 1.5±0.5 mm; G = 1.5±0.5 mm.
The dimensions of the gaps at the joints between the doors and the body: A = 4.5±0.5 mm; B = 4.5±0.5 mm; C = 3.5±0.5 mm
The dimensions of the gaps at the joints in the rear of the body: A = 4.0±0.5 mm; B = 2.0±0.5 mm.
Passive safety
When creating new A4 models, great attention was paid to safety. The level of safety that Audi has always been known for has been taken to new heights in the A4. The impact strength of the body has been increased, in the event of a collision, the passenger room is deformed less than before. For a convertible at the international automobile exhibition in 2001, a new passenger protection system was introduced in case of a rollover of the car.
Passive safety of passengers, both in a limousine and station wagon, is provided by a carrying safe passenger room. To this is added a rigid body structure and pads installed on both sides to soften the impact.
Rollover passenger protection system in the new A4 Cabriolet
Glass and windows
The windshield and rear window do not provide many opportunities for self-repair. As a structural element, they are glued to the body. There is nothing to do here without special tools, that is, this is a typical case when you should contact the workshop. The same is recommended for the dismantling of glass doors and windows.
The doors themselves are not so easy to dismantle, special difficulties arise when fitting them. Therefore, we do not recommend that you dismantle these parts, and limit ourselves to the description of work on door handles and locks.
Body work
Most of the repairs described in this chapter can be done by yourself using a basic set of tools. Many parts are attached with star-shaped screws, so you need to purchase an additional set of appropriate keys for them. Parts such as the hood and tailgate are quite bulky and difficult to fix when dismantling, so you should have an assistant. Another tip: it will be easier to install the hood and tailgate if you mark the position of the hinges during dismantling, for example, with a felt-tip pen.
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