Porsche 996 TT, Repair Manual

Page: 352 / 2099

A value of 80/80 g should not be exceeded. A greatly different distribution, e.g. 30/70 g is very unfavourable;
this usually indicates incorrect mounting. Problem wheels of this kind often have pronounced radial and axial
runout values.
This can be remedied by matching (use correct mounting paste). Improvement is possible with uncontrolled
matching (manual); significant improvement is possible in almost all cases with rolling smoothness
optimisation program (controlled matching).
The tyre pressure must not be less than 1.5 bar overpressure during balancing.
Permissible residual imbalance less than 3 g, or max. 3 g per plane.
Further to 3: Mounting the wheel on the vehicle
Note
Never use an impact bolter! •
Observe grease specification and information on the two−piece wheel bolt! This is described in the
section describing wheel removal and installation (mounting wheel on the vehicle) => Removing and
installing the wheel − Turbo and GT2!
•
Mount wheel with suitable commercially available tools.
If necessary, mark the position of the wheel on the wheel hub before removing the wheel. Use a piece of
adhesive tape to mark the wheel and the wheel hub. This will preserve any optimum balancing result
previously achieved by means of fine balancing (finish balancers), even after the wheel is re−mounted.
Screw in wheel bolts by hand and then tighten evenly. Start at the top when tightening. Always
observe the specified tightening torque of 130 Nm (96 ftlb.).
Prescribed tyre
pressure.
Further to 4: Electronic fine balancing
For electronic fine balancing of the wheels on the vehicle, refer to the operating instructions from the
equipment manufacturer for information about handling the equipment.
When performing fine balancing on all wheels, start with the front axle (4a).
Due to the all−wheel drive, all four wheels must be raised and must be able to turn freely.
Fine balancing of the front wheels to correct torsional vibrations of the steering wheel at approx. 120
km/h.
•
Fine balancing of the rear wheels to correct vibration at 180 km/h and speeds greater than 230 km/h. •
The following applies to both the front axle and rear axle:
the measured−value pickups must always stand on a firm surface, •
the measuring stand support must be located as close to the wheel as possible, •
doors and lids must be closed and the vehicle must not be touched during the measuring operation, •
ensure that the lifting equipment used (jack, platform lift) does not touch the vehicle. •
einordnung
Further to 2: Stationary balancing with optimisation of the rollingsmoothness 289