INTRODUCTION - PANELS AND FRAME

CONSTRUCTION SPECIFICATIONS

Introduction

The topics are covered with particular attention to the new technical features required for passing the various tests introduced by new legislation. The descriptions and operating information provided are limited to a discussion of principles, rules and minimum precautions.

For information on repair methods and vehicle specifications, see the specific sections on repair procedures.

Aerodynamics

The styling of the new car is designed to reflect great personality and originality and improves on the attributes of roominess, practicality and sturdiness achieved by previous models.

The front, sides, rear and underbody were developed with particular attention to aerodynamics and allow outstanding drag coefficient values. The following values are an example:

Version with basic specification:

• drag coefficient CX = 0.29
• drag coefficient by area Cd x A = 0.690

These values are the result of road testing and measurements carried out in a wind tunnel.

These results contribute to the noiselessness of the vehicle and significantly reduce wind noise. They also allow fuel saving.

Safety

The main aim of car manufacturers is definitely the total safety of the driver and passengers.

To adapt the vehicle to highly demanding European and international market regulations, the new vehicle was designed with great attention to detail in order to achieve an optimum response in all situations.

Torsional and bending strength

Specifications

The vehicle''s great torsional and flexural rigidity ensure good properties of passive strength and also offer a number of benefits:

• low noise due to fewer vibrations;
• no creaking from the trim;
• better handling by maintaining the correct suspension angles and thus an absolutely controlled drive for a sensation of stability and comfort in general;
• greater ability to withstand breakages caused by using the vehicle over particularly uneven road surfaces;
• sensation of vehicle compactiness;
• to ensure long-term overall vehicle quality.

Torsional rigidity

Diagram showing deformation due to torsion

Torsional rigidity values

Body with bonded windscreen: 9600 daNm/rad

Flexural rigidity

Diagram showing deformation due to bending

Flexural rigidity values

Body with bonded windscreen: 870 kgm/mm

SAFETY

Preventive safety

This concerns all factors that determine comfortable driving conditions and prevent situations that could distract the driver''s attention:

• very stiff body for greater driving safety;
• optimised engine mountings (barycentric) to minimise vibration and noise transmission;
• climate control system, dual zone (where fitted) with activated charcoal pollen filter with balanced diffusion throughout the passenger compartment. Well-arranged ventilation outlets allow excellent air exchange and improved transpiration and thermal comfort;
• an extensive glazed area allows optimum visibility;
• the tail-lights are shaped to optimise the indicator light functions;
• the arrangement of the pedals, steering wheel (with axial adjustment and height-adjustable), main controls and warning lights has been carefully considered to achieve a good balance between driving position and ability to reach the controls;
• the height-adjustable driver''s seat with lumbar adjustment allows the best possible driving position to be achieved;
• generous interior dimensions allow the vehicle occupants the necessary level of comfort;
• abundant use of sound-absorbent materials and the adoption of specific vibration-proof fasteners to reduce mechanical noise and achieve a noiseless, welcoming environment;
• interior trim that meets the toughest flame-retardant standards.

Active safety

This concerns features of the vehicle and specific components that help the driver overcome potential dangers while driving.

The following features contribute to the vehicle''s active safety:

• outstanding stability during driving and in terms of the vehicle''s dynamic performance;
• excellent braking system;
• good pick-up.

The vehicle offers features that are mutually complementary:

• the front suspension ensures great control of the vehicle during standard or sporty driving. It allows great driving precision and vehicle control over wet and slippery surfaces, a prompt, accurate response and an ability to absorb obstacles and roughness present on the road surface;
• multilink rear suspension with three transverse arms and one longitudinal arm designed to offer improved handling performance: the pressed steel crossmember guarantees ideal torsional rigidity for the suspension with an excellent balance between the front and rear of the vehicle;
• smart bushes attaching the rear axle to the body for limited self-adjustment to steering modulated by the stiffness of the bushes
• new design electrohydraulic steering system designed for a crisp, prompt response in all situations;
• braking system big enough to guarantee powerful, safe braking without fade, consisting of two independent cross-over circuits with an ABS/EBD system (the most advanced brake control system currently available) with four channels and four active sensors to reduce activation times, equipped with an EBD (Electronic Brake Distribution) device: that does away with the need for a load proportioning valve;
• ESP integrated traction control system with ESP/ASR/HH/HBA functions (where fitted).

Passive safety

Because in statistical terms head-on impacts account for 60% of accidents, side impacts account for 30% and the remaining 10% are accounted for by shunts, fires and rolls, the vehicle structure has been designed and developed to crumple in controlled manner in the case of impact and to absorb the energy developed without affecting the living areas of the passenger compartment.

To safeguard the vehicle occupants, the seat anchorage points and seat belt attachment points (a three-part belt is also available on the central rear seat) have been reinforced.

There is a protection for the occupants of the front seats with dual stage activating that includes a driver''s Air bag, pretensioners with a load limiter for the seat belts, a passenger side Air Bag (that can be manually disabled using the key in a special in the panel on the right hand side), two additional frontal impact detection sensors (driver''s side and passenger side) that assist the main electronic control unit and bringing forward the intervention of the Air Bags compared with a traditional system, reducing the risk of minor injuries as a result of the activation of the Air Bags. The vehicle is also equipped with (optional) front and rear Side Bags for the driver, the front passenger and the rear seats and head bags that extend along the roof on the left and right sides providing protection agains any side impacts to the head of the occupants of the vehicle and air bags for potecting the driver''s knees (optional).

In addition, the model is equipped with ISOFIX mountings on the rear seats for transporting even the smallest passengers in safety.

If the body is repaired, the structural reinforcements should always be replaced if deformed.

Resistance to frontal impacts

General specifications

The body is made up of differential crumple zones and is fitted with reinforcements to strengthen the survival cell. These enable the car to withstand head-on impact by ensuring the passenger compartment remains intact to offer the greatest protection to its occupants and minimise the effects of impact.

The main actions taken on the body to achieve the required aims are as follows:

• front structure with differential crumple zones designed to crumple at pre-established points to absorb and distribute the impact force over the structure due to a front sacrificial beam bolted to a crash box that can absorb even off-centre impact.
• reinforcements on the side members and the lateral dampers connected to a box section crossmember under the windscreen that ensure transverse strengthening of the passenger compartment forming one piece with the side panels at the height of the waistline;
• reinforcements under the floorpan that increase the solidity and stiffness of the floor to limit deformation as much as possible;

• collapsible telescopic steering column.

  reinforcements on the front pillars;

  reinforcement on the pedal assembly.

Impact forces are further absorbed and distributed by the engine attachments that discharge the forces to the front reinforcement and prevent excessive load on the passenger compartment.

These features of the structure, together with the fastening systems and the interior energy absorbing parts allow the vehicle to achieve a high level of safety and pass all the tests imposed by standards.

Composition

1 Front crossmember connecting struts

2 Reinforcement on the struts

3 Longitudinal reinforcements under the floor

4 Reinforcements on side pillars

5 Centre pillar outer element

6 Centre pillar reinforcement

7 Centre pillar inner element

8 Reinforcements on the front pillars

9 Reinforcement on the pedal assembly

10 Box section crossmember under the windscreen

11 Headlamp carrier front crossmember

Resistance to side impacts and roll over

General specifications

The body complies with all the most recent European standards on side impacts and rollover and is able to assure a high level of occupant safety by crumpling in a controlled fashion to prevent damage to the survival cell.

The above has been achieved by:

• reinforcing the underdoor reails between the front pillars and the central pillars;
• reinforcing the central and rear pillars at the rail attachment points, at the seat belt anchorage points and in the lock striker areas;

• inserting a box section reinforcement beam between the underdoor rails.

  inserting a crossmember joining the centre pillars under the roof.

The doors described below contribute significantly to the vehicle''s ability to withstand side impact.

Composition

1 Underdoor rail reinforcement

2 Reinforcement beam between underdoor rails (front seat support)

3 Crossmember joining pillars

Structure of the doors

General specifications

The door structure is of fundamental importance to the safety of passengers in the case of side impact and the door panel geometry and stiffness is therefore designed to maintain survival spaces at the sides and minimise possible injury to passengers. The structure of the doors is supported by a frame where all the components such as the window opening device, door locks, speaker, interior door opening handle are fitted to allow the opening of the door after frontal and rear impact tests laid down by regulations.

The above has been achieved by:

• fitting Omega type tubular side impact bars, using reinforcements at the waistline with vertical frames above the waistline and locks along the pillars to make up an ideal high-strength door ring;
• fitting high-strength locks and strikers;
• fitting energy-absorbing interior door trim without sharp corners designed to ensure minimum impact against the body in the event of an accident.

Composition

A: Rear door

B: Front door

1 Waist reinforcements

2 Pillar reinforcement

3 Tubular side-impact bar

4 Lock reinforcement

5 Vertical frames above waist

Structure of the roof

General specifications

The specific structure of the ceiling makes the passenger compartment more rigid and contributes to passenger safety in the event of side impact or roll-over which, despite being much less likely to occur than the other types of impact, is one of the most dangerous accidents.

The following features increase the solidity of the passenger compartment structure:

• transverse connecting box sections between the panels by the upper part of the windscreen and the tailgate;

• lengths of structural adhesive along the edges of the upper transverse box sections for the windscreen housing and the tailgate housing which, in addition to bonding the parts with good mechanical resistance, prevent vibrations and resonance.

  centre connecting crossmember secured to the side pillars.

These features allow outstanding levels of strength to be achieved during the static and dynamic crushing and rollover tests required by European standards.

Composition

1 Upper windscreen box section beam

2 Upper tailgate box section beam

3 Roof panel

4 Upper side member

5 Centre crossmember connecting side pillars.

Resistance to rear impacts

General specifications

The vehicle''s resistance to rear impact is very high and passes the tests specified by the toughest standards in force in Europe.

This performance is ensured by:

• a reinforced rear box section beam;
• reinforcements on the attachments between the rear beam and pillars;
• tailgate with reinforced ribbing;
• reinforced side and rear tailgate ribbing.

Composition

1 Left rear rail

2 Right rear rail

3 Rail connection beam

4 Rear beam

5 Rear crossmember

WINDSCREEN AND WINDOWS

The fixed windows are a further safety feature.

To increase the vehicle safety level, the windscreen is in laminated glass. This solution prevents the glass from shattering if struck by stones or gravel to assure visibility at all times and above all to offer a high level of protection if struck with the head.

The windscreen is bonded to the bodyshell, thereby contributing to increasing the structural strength of the vehicle: the seal on the window contributes to reducing the noise due to oncoming air (wind noise).

Safety against fire

This is achieved by a FPS (Fire Prevention System) consisting of:

• fireproof interiors, all trim meets the toughest US flame-retardant standards and will not catch fire if it accidentally touches a heat source (e.g. a cigarette) and limits the flame propagation rate;
• inertia switch to cut off the fuel pump;
• antimisfiring shields (overheating of the catalytic converter, for petrol versions) that insulate the catalytic converter and protect the brake and fuel pipes;
• electrical equipment protected by maxifuses that cut off the fuel flow in the case of short-circuit or overheating that could occur in the event of fire;
• battery secured in the event of impact or roll-over;
• cut-off valve to prevent fuel leaks if the vehicle rolls over;
• plastic fuel tank with high mechanical strength and fire-resistance, secured firmly to the body in a shielded position;
• arrangement of the electrical equipment, fuel pipes and brakes designed to minimise the possible risk of fire in the event of accidents or failure.

Sound insulation

General specifications

To meet EEC standards, the vehicle''s exterior noise levels must be lower than 74 decibels.

Driving comfort and living conditions inside the passenger compartment have been improved by:

• optimising the body through a thorough examination of all parts subject to noise, which have been made stiffer and fastened more securely;
• choosing contact materials with great care;
• by improving the insulation against noise transmitted from the road surface, from mechanical parts and from the suspension;
• by taking great care over parts assembly, aerodynamics and all parts with shapes that affect acoustic comfort, such as door handles, door mirrors, bumpers and other outlines;
• by fitting new generation engines with high-tech features designed to improve acoustic/vibrational factors;
• by fitting a new barycentric engine mounting.

Another area of improvement has been the passenger compartment insulation. The following action has been taken:

• highly efficient sound-absorbent materials with optmum thickness and layout on the vehicle;
• fitting of a sound-absorbent undershield in the lower part of the engine compartment for acoustic insulation;
• elimination of acoustic holes (areas where sound can pass between the engine compartment and passenger compartment) by fitting double-lipped seals, thicker rubber plugs;
• by fitting the various sound-insulation parts together more tightly to avoid uncovered areas;
• extensive use of sound-absorbent seals;
• sound-proofed coating of panels with heat-bonded materials applied before painting;
• lining of the bulkhead and front steps to remove the sensation of the engine''s presence;
• application of heat-expanding materials inside the box sections prior to painting to reduce noise transmission. During body cataphoresis process, the volume of these materials expands ten times to fill the box section effectively.
• lining the boot compartment appropriately to reduce rolling noise;
• carefully examining the fitting and size of parts liable to squeak such as the facia, heater and seats: the anchorage and fastening points have been reinforced.

To maintain the high level of acoustic comfort achieved, the specifications adopted during manufacture must be restored exactly in the event of repair.

Diagram showing application of heat bonded materials to the vehicle

A: Right hand drive version

B: Left hand drive version

PROTECTION OF THE BODYSHELL

Anti-corrosion protection

The bodyshell on the New Fiat Croma has been designed to withstand environmental conditions in the most severe markets such as Central Northern Europe where salt is used on the roads to prevent freezing.

Design features have been introduced with this in mind to guarantee complete accessibiity of the bodyshell to the protection and painting processes (in particular the anti-rust treatments and cataphoresis) and ensuring that all the elements are the correct shape to prevent any possible dampness forming in the internal structures.

This includes the design of the panel joins (shape and dimensions) in order to make them suitable for the sealing operations, which is essential both in terms of water tighteness and sound inslation of the vehicle.

Galvanized panels

The zinc deposited in a continuous layer on the surface of the panel constitutes the first line of defence against corrosion of the steel. The zinc layer acts as an active chemical protection for the steel, known as a sacrificial layer, that combines with the subsequent protective systems to guarantee outstanding long-term corrosion-proofing.

The galvanizing of the panels takes place directly through two different technological processes, both capable of ensuring constant thicknesses of zinc with a high standard superficial finish:

Galvanizing: the panel is immersed in a solution of zinc salts where a layer of pure zinc is deposited through the electrolytic effect; the normal thickness of the zinc deposit is 8 - 10 micron.

- Hot galvanizing: molten zinc is deposited on the panel due to the effect of heat. In this case too the normal thickness of the zinc is 8 - 10 micron, but thicknesses of up to 20 micron can be reached using this process and it should be used for the parts most exposed to corrosion.

The two processes allow galvanizing on both sides of the panel.

It is therefore possible to produce simultaneous protection for both the inside and the outside of all panels and, in particular, protection of the surfaces in contact with several elements welded together.

The bodyshell of the New Croma comprises panels galvanized on both sides for 85% of its weight.

In particular, all the parts that make up the chassis, most exposed to corrosive agents, are 100% galvanized with zinc thicknesses of 10 micron.

Of these, the structures defined as safety structures, such as the suspension mountings and reinforcements for the seat belts are made from panels with a high thickness of zinc, up to 20 micron.

The body is made entirely from galvanized panels 8 micron for the doors, bonnet, boot lid, side panels, wings, roof.

The exception is some of the inner parts of the passenger compartment because there is no risk at all of oxidation such as, for example, the dashboard mounting brackets.

Anti-corrosion tests

All the anti-corrosion provisions made on the New Croma have been subjected to laboratory tests and they have performed well in accelerated tests on vehicles carried out in special test areas where the most stringent conditions of the central north European markets have been reproduced.

Anti-corrosion objectives

The anti-corrosion provisions adopted make it possible to satisfy the following anti-corrosion warranties:

- 3 years of the vehicle''s life without cosmetic corrosion points

- 8 years of the vehicle''s life without panel perforation in the most harsh Northern European climates.

In addition, the protective package made up the medium-high thickness galvanizzed panels plus cataphoretic treatment of the entire structure makes it possible to comply with the European regulations concerning safety features (10 years of the vehicle''s life without structural weaknesses).

Painting

Specifications of the painting cycle

The aim of painting the bodyshell is to:

- protect the sheet metal against corrosion due to exposure to environmental effects;

- achieve high levels of gloss and colour richness and maintain them in time.

Before painting, the bodyshell undergoes a pre-treatment known as bonderization.

- during which an initial degreasing stage is carried out followed by a phosphating treatment.

The latter forms a crystalline layer of phosphate which make up the base on which the subsequent painting layer is applied through cataphoresis.

Painting through cataphoresis is a fundamental treatment for the protection of the structural elements.

It allows the paint to be deposited in areas of the bodyshell that would otherwise be inaccessible such as the internal box structures.

The process takes place through immersion in an electrically insulated vat containing an acqueous solution of paint product.

The solution is negatively charged whilst the bodyshell is positively charged. During immersion, a layer of paint is deposited (22 microns on horizontal parts and 20 microns on vertical parts) that can be adjusted by altering the bath voltage, the bath temperature and the length of time the body remains in the solution.

The body then undergoes a process of stoving in an oven at 160° for 20 minutes.

Heat bonded materials are then applied to the prepared body and then all the joints between the body panels are sealed to prevent corrosive agents leaking through. An abrasion-resistant coating is then applied to all areas exposed to gravel from the road.

The body is now prepared by adding a primer coat (40 microns thick) before undergoing a further stoving cycle in the oven.

Lastly, the application of the enamel layer follows with high resistance properties to external agents (humidity, solar radiation) and baking in the final oven.

The table illustrates the painting process for the New Croma.

Identification

The vehicle colour range includes:

- pastel colours (two-coat);

- metallic colours.

The vehicle colour type and specifications are shown on the identification plate that shows the following information.

A, paint product supplier;

B, enamel colour and type;

C, code;

D, type of product to be used for touching up and painting in the event of service operations.

New croma bodyshell painting cycle

RECYCLABILITY OF MATERIALS

RECYCLING OF MATERIALS

Main specifications

According to EEC ELV (End of Life Vehicles) directives, all metallic and non-metallic parts must be recovered from the vehicle and reused, 80% to produce new material and 5% for recovered energy. Nowadays, some 75% of a vehicle''s weight is made up of metal that can easily be recovered by melting when different metals can be separated by heating to their different melting points. All the remaining part of the vehicle, amounting to 25% by weight, must be recovered before this stage. The solution to the problem of recycling plastics is resolved at the design stage: the possibility of re-using the material on future components must be assessed at this time:

The aims to be considered at the design stage include:

• ease of component disassembly;
• choice of noble materials in the recyclable polymer chain (giving priority to parts made up of a single family, e.g. PP).

Recycling does not allow the production of a part that is the same as the original part because the material may not be able to guarantee the necessary levels of reliability or it may not be financially viable.

Plastics may be recycled in a cascade pattern. For example:

• insulating material for the building industry is obtained from seat padding;
• the material used to line the wheel arches is obtained from the bumpers and then goes on to produce sound-proofing elements. In the end, it becomes a fuel for energy production.

This model has been designed to ensure that all its plastic and elastomer parts (rubbers) weighing over 50 grams are marked with coded symbols to identify the material during recycling and also to ensure that all its components are recyclable.

The recyling process therefore afffects three successive vehicle generations to help save raw materials.

Other materal reuse processes are also being examined outside the motor industry, following the lead taken by the F.A.Re (Fiat Auto Recycling) partnership in the Eighties and Nineties.

Another important point to note concerns the use of heavy metals in the motor industry. The metals in question are hexavalent chrome (Cr6), Mercury (Hg), Cadmium (Cd) and lead (Pb). These are banned (Cr6) or permitted only in tiny amounts when their use must be indicated by labelling or by including information in the documents supplied with the vehicle.

The tables in the chapter "GENERAL INFORMATION AND TECHNICAL DATA - OPERATING DATA" show symbols for and descriptions of recyclable materials present on the vehicle. This is to ensure that the best available products are used to wash the interior, paint plastic parts and carry out repairs, bonding etc. The aim is to avoid the possibility of damage by using incompatible products. Labelling also allows organic materials to be selected on the basis of their chemical composition. During service, it is also advisable to separate materials on the basis of their composition to ensure that they can be recycled more easily.

Diagram showing the reuse of recycled materials

Labelling of part of the recyclable material

TYPICAL BODYSHELL MEASUREMENTS

ADJUSTMENT OF MOVING PARTS

Measurements for the adjustment of the moving parts

To facilitate and verify mobile part disassembly operations, the existing gaps are shown (in millimetres) to allow appropriate adjustment.

The adjustment procedure is described in the sections describing mobile part removal and refitting procedures.

View of the vehicle (front three quarters) with the position of points for measuring the gaps between mobile parts.

Measuring points of the gaps 1 to 5

Measuring points of the gaps 6 to 11

Measuring points of the gaps 12 to 18

View of the vehicle (rear three quarters) with the position of points for measuring the gaps between mobile parts

Measuring points of the gaps 19 to 24

SEALANT APPLICATION

When it is not specified the sealant used is the interior thermal hardening type.

Front view of the vehicle showing the sealant application areas.

Detail showing sealant application in areas 1 to 5.

(***) High consistency thermal setting filler

1 Inner side panel - front suspension attachment damper

2 Front strut inner part

3 Front strut - chassis mounting front reinforcement

4 Upper suspension attachment damper

5 Inner side panel - air intake chamber - rear dashboard - inner side panel - underwindscreen crossmember - box section

Detail showing sealant application in areas 6 to 9

(***) High consistency filler putty

6 Dashboar partition reinforcement - front floor - tunnel connection - dashboard bulkhead

7 C.S. front strut - C.S. dashboard

8 Guard for front panel - outer panel cover - front pillar reinforcement

9 Roof lining - outer panel

Rear view of the vehicle showing the sealant application areas

Detail showing sealant application in areas 10 to 14

(*) Anti-abrasion adhesive seal Ø 25 mm

10 Rear floor

11 Roof - rear rain gutter crossmember

12 Light base - outer panel - rear rain gutter

13 Rear floor - rear lining

14 Rear floor - rear lining

Detail showing sealant application in areas 15 to 20

(***) High consistency thermal setting filler

15 Reinforcement for rear rain gutter - rear lining - lower reinforcement - lower floor

16 Outer panel - lower guard

17 Lower rear guard - side member rear closing bracket

18 Outer panel - frame rear guard - inner and outer rear wheel arch - lower guard

19 Rear side member - suspension crossmember mounting - rear suspension crossmembers

20 Side frame - rear frame connection

Detail showing sealant application in areas 21 to 22

21 Inner rear wheel arch - rear side member - seat belt mounting bracket - seat belt mounting bracket reinforcement - suspension mounting rear reinforcement - wheel arch front reinforcement

22 Dashboard inner side reinforcement - centre floor - dashboard side reinforcement box section - side member - C.S. outer panel - outer panel - panel frame - side panel - front guard - dashboard side reinforcement

Detail showing sealant application in areas 23 to 27

(***)

23 Floor front side member - centre tunnel

24 Rear floor - front side member - centre floor - side member

25 Rear floor - centre floor

26 Inner side panel - front wheel arch

27 Rear rain gutter - outer panel

Detail showing sealant application in areas 28 to 31

(*) Anti-abrasion adhesive seal Ø 25 mm

(**) Thermoexpandable sealant

28 Bonnet lid frame - bonnet outer cover

29 Front side door frame - front side door outer cover - anti-intrusion crossmember

30 Rear side door frame - outer cover - anti-intrusion crossmember

31 Tailgate frame - cover

Diagram for checking underbody

This chapter shows the specified vehicle dimensions to ensure the best results are achieved when carrying out repair operations.

The comparative dimensions, expressed in millimtres, may be subject to differences (about 2 mm). Repairers must use their experience to decide whether this is due to impact damage or manufacturing tolerances.