Load-bearing body: The lower and side body parts, roof and rear fenders are welded together
A fully galvanized body has become something self-evident. The absence of through corrosion is guaranteed for 12 years. Unfortunately, rust is not the only problem that can cause damage to the body. Over time, due to constant loads, unpleasant phenomena such as knocking and sharp sounds occur.
True, you will definitely not hear these sounds for many years. Very high torsional rigidity significantly prevents the occurrence of noise due to aging of the body. Body parts that previously consisted of several parts are now manufactured as a single element. Individual structural elements are assembled using modern laser welding. The body frame is manufactured so precisely that the gaps are reduced to a minimum. This reduces both the unpleasant noise that occurs due to air flowing around the car and fuel consumption.
The body is load-bearing. The lower and side parts of the body, the roof and the rear wings are welded together. Repair of serious damage to the body, as well as replacement of the glued windshield and rear window, is best left to a specialized workshop.
The hood, doors and front wings are screwed on, they can be replaced with more or less expense. Of course, given that the parts must be installed very precisely, and the gaps must be even and of a certain size, this work requires experience and a fine sense. When installing body parts, it is necessary to observe the specified dimensions, otherwise, for example, the door will knock, or too much noise will occur while driving.
Dimensions of gaps at joints
Despite its clever design, the A4 is, in principle, made in such a way that it is easy to repair. You will understand this as soon as you start to replace a damaged bumper, wing or tailgate.
However, during any bodywork, the specified gap sizes at the joints between individual body parts must be maintained. Otherwise, the newly installed part may start knocking, or excessive flow noise may occur while driving. The gap must be uniform along the entire length of the joint. The permissible deviation is 1 millimeter. The size of the gaps can be checked using a special tool 3371. The figures show the most important joints for the sedan.
Dimensions of gaps at joints in the front part 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.
Dimensions of gaps at the joints between doors and the body: A = 4.5 ±0.5 mm; B = 4.5±0.5 mm; C = 3.5±0.5 mm
Dimensions of gaps at joints in the rear of the body: A = 4.0±0.5 mm; B = 2.0±0.5 mm.
Passive safety
When creating the new A4 models, great attention was paid to ensuring safety. The level of safety for which Audi cars have always been famous was raised to a new level in the A4. The impact strength of the body was increased, and in a collision the passenger compartment is deformed less than before. A new rollover protection system was presented for the convertible at the 2001 International Automobile Exhibition.
Passive safety of passengers, both in the limousine and the station wagon, is provided by a load-bearing safe passenger compartment. This is supplemented by a rigid body structure and impact-softening pads installed on both sides.
Occupant protection system in the event of a rollover in the new A4 Cabriolet
Glass and windows
The windshield and rear window do not provide much opportunity for independent repair. As a structural element, they are glued to the body. Without special tools, there is nothing to do here, that is, this is a typical case when you should contact a workshop. The same is recommended for dismantling door and window glass.
The doors themselves are not so easy to dismantle, and special difficulties arise when adjusting them. Therefore, we do not recommend that you dismantle these parts, and limit ourselves to describing the work with door handles and locks.
Bodywork
You can do most of the repairs described in this chapter yourself using a basic set of tools. Many parts are attached with star-head screws, so you will need to purchase an additional set of appropriate wrenches 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.