Audi TT 44 User Manual
Service Training
Audi TT Coupé ´07 - Body
Self-Study Programme 383
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Audi-Space-Frame ASF® of the Audi TT Coupé
The development targets for the bodyshell of the Audi TT
With a weight advantage of 48 % over a comparable all-steel bodyshell, in addition to an optimised weight
distribution, the new composite aluminium-steel spaceframe body of the Audi TT marks yet another milestone in the development of modern Audi bodyshells.
Crash safety of the bodyshell is enhanced by means of load-bearing structures at the front end, sides and rear
end, with a heavy emphasis on pedestrian safety.
To ensure efficient volume bodyshell production, various new joining and production techniques are
employed.
The repair concept is based heavily on the well-known aluminium repair concept. However, of course, the
materials combination of aluminium and steel necessitated that new approaches be taken.
383_001
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with respect to the correctness of information in this document. Copyright by AUDI AG.
Contents
Audi Space Frame of the Audi TT
Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Technological concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Contact corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Combination of steel and aluminium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Comparison of ASF concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Joining techniques and production processes
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Punch riveting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Clinching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
MIG welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Resistance spot welding and MAG welding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Structural bonding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
New joining technique: solid punch riveting (Kerb-Konus riveting) . . . . . . . . . . 16
New joining technique: Flow Drill screwing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
New joining technique: aluminium laser welding . . . . . . . . . . . . . . . . . . . . . . . . . 18
Repair concept
Aluminium repairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Steel repairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Aluminium-steel repairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Workshop equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Qualification of aluminium. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Bodyshell safety concept
Head-on collision, side impact and rear collision . . . . . . . . . . . . . . . . . . . . . . . . . 26
Pedestrian safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Electromechanical rear spoiler
The self-study programme teaches the design and function of new vehicle models,
new automotive parts or new technologies.
The self-study programme is not a repair manual!
All values given are intended as a guideline only and refer to the software version valid at the time of
preparation of the SSP.
For maintenance and repair work, always refer to the current technical literature.
NoteReference
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permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
Audi Space Frame of the Audi TT
Dimensions
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Audi TT Coupé ’ 07 2,0 3,2 quattro
Transmission Manual gearbox S tronic Manual gearbox S tronic
Kerb weight without driver in kg 1260 1280 1410 1430
Max. perm. gross weight in kg 1660 1680 1810 1830
cw (rear spoiler extended) 0.3 0.3 0.31
Boot capacity in l 290 (700*) 290 (700*)
Max. power output in kW 147 (200 bhp) 184 (250 bhp)
vmax in kph 240 250
Acceleration 0-100 kph in s 6.6 6.4 5.9 5.7
Fuel consumption in l/100 km 7.7 7.7 10.3 9.4
* with the rear-seat back folded forward
4
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permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
Technological concept
Sheet-steel parts are used for the first time in the
ASF of the new Audi TT in addition to aluminium
castings, aluminium extruded sections and aluminium sheet-metal parts. Collectively, they make up
the body structure. Vehicle weight distribution has
been optimised by using sheet-steel parts in the
rear body section. This has a direct bearing on
sporting characteristics, such as driving dynamics
and acceleration as well as safety characteristics,
such as stopping distance and driving stability
In spite of the partial use of sheet-steel parts, the
total body weight of 277 kg, including attachments
such as doors and lids, is considerably less than
that of a comparable all-steel body.
Although the new TT has grown in size, the gross
weight of the vehicle has been reduced through the
use of the aluminium-steel bodyshell.
The body structure of the new Audi TT has higher
strength and 50 % higher torsional rigidity than its
predecessor.
Aluminium extruded sections
Sheet-aluminium parts
Aluminium castings
Sheet-steel parts
383_003
5
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permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
Audi Space Frame of the Audi TT
Contact corrosion
Aluminium has a passivating oxide surface layer
which protects the material underneath from corrosion. This is why an unpainted aluminium part normally does not corrode.
However, if there is contact between aluminium and
a metal higher up in the electrochemical series than
aluminium and if an electrolyte, such as salt water,
is present in this region, contact corrosion will
occur.
Contact corrosion
The greater the difference in potential, the greater
the contact corrosion. As aluminium is normally the
lesser noble metal, it degrades.
383_005
Schematic of contact corrosion with example
Contact corrosion can only be prevented by taking
measures to stop the flow of electrical current
induced by the potential difference between
the two metals. This is best achieved by painting the
surfaces. However, the risk of corrosion is high even
if a tiny amount of paint damage occurs.
Reference
For detailed information on contact corrosion,
please refer to Self-Study Programme 239 "Audi
A2 - Body" .
383_004
In the case of the Audi TT, the following anti-corrosion measures have been taken:
– coating of all steel screws and fasteners such as
self-piercing rivets
– Galvanising of all sheet-metal parts (zinc and alu-
minium have a smaller potential difference than
steel and aluminium)
– Insulation by means of adhesive
– Sealing of aluminium-steel joints
6
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permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
Joining steel and aluminium
One of the challenges for the development of the
Audi TT bodyshell was the attachment of the sheetsteel rear-end parts to the aluminium body assemblies.
Thermal joining processes such as MIG welding can
be ruled out because it is not possible by these
means to make a joint which has the requisite structural and dynamic strength and will not result in
contact corrosion.
Steel
Aluminium
383_011
Aluminium-steel connections
383_006
7
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permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
Audi Space Frame of the Audi TT
Special requirements are made with regard to the
strength and corrosion protection of the joints
between aluminium body parts and steel parts.
Adhesive
This is ensured by non-thermal joining of parts
using coated self-piercing rivets and special screws
in combination with bonding.
Adhesive
Aluminium and steel joints with faulty corrosion protection can exhibit much higher corrosion rates than
all-aluminium joints or all-steel joints.When making
aluminium-steel joints, therefore, highest standards
of quality must be maintained at all times during the
production process and in the service workshop.
383_012
Adhesive bonding is the basis for the corrosion protection of corrosion-susceptible aluminium/galvanised steel joints in the bodyshell of the Audi TT.In
this way, the mating materials are superficially insulated, thus suppressing corrosion processes at the
point of contact. As a further measure, all composite joints either sealed with PVC or coated with wax
preservative after the cataphoretic dip coating (KTL)
process.
8
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permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
This illustration shows clearly what effects contact
corrosion can have if adequate corrosion protection
is not provided. A this joint, the flange was sealed in
the bodyshell without using adhesive.
Seal
Seal
The aluminium sheet shown here exhibits severe
contact corrosion, which has resulted in mechanical
failure of the punch riveted joint.
383_007
By way of a comparison, this illustration shows the
same flange with an adhesive bond and sealing.
Seal
Adhesive
Seal
In this case, the aluminium sheet showed no damage due to contact corrosion after exposure to identical environmental conditions.
383_008
9
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permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
Audi Space Frame of the Audi TT
Comparison of ASF concepts
Audi A8 (2003 ➔)
Aluminium extruded sections
Sheet aluminium parts
Aluminium castings
383_013
383_014
Sill section Audi A8
Three-chamber extruded section
10
383_017
A-post, Audi A8
Single-chamber extruded section
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