Balancing/Optimising Wheels; General - Porsche 996 TT Repair Manual

44 Balancing/optimising wheels

General

Balancing/optimising wheels
Balancing weights
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General
Excessive wheel imbalance not only produces vibrations and causes the steering wheel to shake, but also
results in increased wear on various parts of the running gear.
Even if the wheels are correctly balanced, excessive geometry errors (radial and axial runout) and misshapen
tyres, e.g. accumulations of material at one point of the tyre structure (spring action of tyre changes as the tyre
rolls), can cause rolling and steering imbalance.
Note
• Achieving a good result requires utmost care, observance of the instructions and procedure, and
attempting to eliminate even the very last gram of imbalance.
Recommendations / prerequisites
• Wheel suspension elements must be in good technical order.
• The wheels must be clean and without foreign objects in the tyre.
Use a tyre measuring gauge, e.g. V.A.G 1435, to check axial and lateral runout values on wheels
•
without flat spots. Values less than 1.0 mm
In order to achieve low radial runout errors or to optimise smoothness of rolling, it is expedient
•
necessary in individual cases
to the wheel). Tips and mounting instructions, also about tyre mounting paste under => Tyres.
• If the rims (wheels without tyres) are true but the complete wheels have large axial and radial runout
values (due to ply breakage or other damage), tyre replacement may be necessary.
Balance used wheels only after they have been warmed up by driving, otherwise flat spots will
•
simulate imbalance. Never perform matching in the case of flat spots.
• Correct tyre pressure is an important prerequisite.
• Place the balancing weights at the prescribed position. Refer to => Balancing weights for information
about putting on the balancing weights.
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Balancing/optimising wheels
The entire process is subdivided into four operations.
1. Mounting the tyre on the
rim.
2. Stationary balancing of the wheel (eliminating the static and dynamic imbalance) with optimisation of the
rolling smoothness.
3.
44 Balancing/optimising wheels
better around 0.5 mm
to match the tyre (i.e. to mount it in a favourable position with respect
are desirable.
and
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