Special features of individual assemblies

Maintenance related information 0

00_01_14

A = Quantity difference of approximately 0.8 quarts (0.8 liters).

0.2 Special features of individual assemblies

General

After finishing a session of high-performance driving on the race circuit, “cool-down laps” must be driven in order to reduce the temperature level of the assemblies that are subjected to particularly high thermal loads (brake system, engine) in a controlled manner. Stopping the vehicle immediately would result in a further increase in component temperatures due to the resultant stationary heating process. In extreme cases, this could cause irreparable damage to individual components.

Certain motor sports equipment may not be legal on public roads, such as six-point seat belts, emergency-off switches or door struts and A-pillar struts on the roll cage. The same applies for the modifications to the chassis and aerodynamic components described in the next sections.

The purpose of the following vehicle checks is to ensure the proper condition and operational reliability of the vehicle for high-performance driving on a race circuit. Due to the particular stress and strain on the vehicle during high-performance driving on the race circuit, a number of additional aspects must also be taken into consideration. These are summarized for the most important assemblies.

Engine oil

An oil level of 3 segments above the minimum marking is recommended for optimal engine operation, also for high-performance driving on the race circuit. When adding engine oil, always keep in mind that the quantity difference between the minimum and maximum markings is approximately 0.8 quarts (0.8 liters). Never overfill with engine oil. In addition to the regular oil level check, the engine oil and oil filter must be changed after 6,000 miles ( 10,000 km) of high-performance driving on the race circuit.

Brake system

The stresses exerted on the entire brake system during high-performance driving on the race circuit are much higher than those produced during “normal” driving because of the braking accelerations that can be achieved and the associated higher component temperatures.

In addition, repeated hard braking in the ABS control range results in significantly higher temperatures in the brake system than controlled braking just before the ABS activation limit. The braking distance can actually be shorter if ABS is not activated. At the same time, the temperatures in the brake system and therefore the wear and tear on the brake components remain lower.

During high-performance driving on the race circuit, all brake pads (inner and outer) may exhibit brake pad wear characteristics that cannot be fully detected by the standard brake pad wear indicator (“oblique wear”). Therefore, it is absolutely essential to check the pad condition before and after driving on race circuits. The standard brake pads are also optimally suited for high-performance driving on a race circuit, which means that no special racing circuit pads are required.

While wear on standard brake discs in gray cast iron/aluminum composite design can be checked in the conventional way, wear assessment of PCCB brake discs must be carried out using a special electronic measuring device. This does not involve “assessment of residual thickness”, but a Carboteq measurement, which uses the current condition of the ceramic composite material as the wear criterion. Details of the Carboteq measurement procedure can be found in the PIWIS information system. The ventilation holes can become clogged with brake dust, particularly on the gray cast-iron friction ring of the standard brake discs. These must be cleaned if necessary.

Regular checking of the brake fluid (boiling point and fill level) is essential. Generally, the brake fluid should not be more than 12 months old if the vehicle is driven on race circuits. Before driving on race circuits, the dust boots on the brake calipers and all brake hoses and lines must always be checked for possible damage and replaced if necessary.

To ensure the necessary cooling of the brakes, special brake air spoilers and brake air ducts are fitted on the front and rear axle in order to route sufficient cooling air to the brake discs. These must be checked to ensure that they are in perfect condition and are secured correctly after every race track session. After finishing a session of high-performance driving on the race circuit, “cool-down laps” must be driven in order to use the airstream to cool all brake components to a much lower temperature level. The vehicle must never be stopped immediately after finishing a “fast lap” because of the additional thermal stress (stationary heating process). Maintenance related information 0

Checking PCCB wear 00_02_14

Brake air spoilers and brake 00_03_14 air ducts

Maintenance related information 0

Tires 00_04_14

Camber adjustment via 00_05_14 supporting mounts If driving is conducted in a particular style and if ambient temperatures are high, it may be necessary when driving on a race circuit to compensate for the increase in pressure for hot tires by letting out air. The general rule is that the specified tire pressure should not be significantly exceeded, (maximum 7.3 psi/0.5 bar) even when the tires have been driven until they are warm. For race circuit driving, different pressures from those used for on-road driving can be set and monitored in the Tire Pressure Monitoring (TPM) system. Letting air out of cold tires before driving on a race circuit can damage the tire structure. Air must only be released from tires that have been driven until they are warm.

The use of slick tires is not permitted because of the possible higher stresses for chassis and body components. The use of wheels of different sizes (rim width, rim offset, etc.) compared to standard wheels results in a change in the effective disturbing force lever, for example. Widening of the track as a result of a lower rim offset on the front axle, in particular, can clearly impair vehicle handling and can significantly affect driving performance at high speeds. The use of such wheels is therefore not permitted.

Other chassis-related topics

The chassis is adjustable with regard to track, camber, vehicle height and anti-roll bar position. However, the basic factory setting is suitable both for driving on public roads and for high-performance driving on race circuits. It also achieves a balanced compromise between high maximum lateral acceleration and excellent controllability on the race circuit. If the chassis setup is changed for driving on the race circuit, it is important to keep in mind that setting higher camber values reduces straight-running stability while increasing tire wear, particularly on the inside shoulders of the tires. When driving in the top speed range, increased camber values may result in overloading of the tire structure.

Camber adjustments on the front axle must generally be made using the adjustable supporting mounts. If an additional increase in camber is to be achieved by inserting camber shims on the lower wishbone, there must always be sufficient thread overlap (at least 22 mm) on the tie rod. Just like pure racing vehicles, the 911 GT3 is also very sensitive to small changes in the chassis settings. For optimum handling, it is absolutely essential that suspension alignment is carried out correctly with precise adherence to the nominal values and tolerances.

Vehicle height must be checked during the race circuit inspection as the vehicle height can indicate whether suspension alignment may be necessary. The thinking behind this is that an unintentional change in vehicle height generally means that the vehicle needs to be re-aligned. Depending on the individual stress and strain on the vehicle, an additional suspension alignment may be necessary even if the vehicle height is set correctly. Given the significant impact on handling, Porsche recommends that all chassis settings are checked at regular intervals (vehicle alignment).

Despite regular checks and irrespective of the proper condition of all relevant chassis components, certain components must be replaced after a specified mileage of race track use. This applies to the central bolts and the wheel hubs, including wheel bearings.

For information on the relevant replacement intervals:

Please refer to the “VEHICLE INSPECTION AND MAINTENANCE FOR DRIVING ON RACE CIRCUITS” on the following pages.

Aerodynamic components

The aerodynamic stability of the vehicle is significantly affected by the front lip and rear wing when travelling at high speeds. It is therefore necessary to check these components for possible damage on a regular basis and to ensure that they are secured correctly. The angle of attack of the rear wing can be adjusted according to individual needs for driving on race circuits. As for the chassis, the basic factory setting of the rear wing in terms of the aerodynamic overall balance of the vehicle also achieves a balanced compromise between the downforce values on both axles and the resultant drag on the race circuit.

For example, a steeper angle of attack not only causes more drag, but also moves the aerodynamic balance towards the rear axle. This means less downforce on the front axle and reduces any other possible side-effects (e.g. tendency of the vehicle to understeer, etc.). Maintenance related information 0

Central bolt and wheel hub 00_06_14

Rear wing adjustment 00_07_14