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CHECKING WHEEL AND TYRE RUN-OUT
When preparing the car for a suspension or steering check, the wheels and tyres must be checked first for run-out
During the suspension or steering checks, the points of "run-out" are positioned well away from the contact points of any gauges that may be in use.
1. Jack up the wheel to be checked for "run-out
2. Spin the wheel while holding a piece of chalk close to the wall of the tyre.
3. Move the chalk progressively nearer the tyre until It makes contact with any "run-out".
4. Mark the centres of the "run-out" with a cross.
5. Lower the car to the ground but before making any suspension or steering checks, roll the car forwards and backwards to position the wheels in their normal running attitude.
NYLON TYRES
Nylon tyres may develop temporary flatting after standing for some time and cooling off, following a long run during which high, temperatures have been reached.
These flat spots can be run out quite quickly but it may be necessary to approach the speeds and temperatures which have led to the flatting. For example, flats on tyres which have developed after a long fast run may be difficult to remove if the car is then used for local "pottering" especially if the weather has become colder and wetter. Before balancing nylon tyres it is desirable to ensure that these flats have been fully run out, otherwise a false balance may be obtained.
TYRE AND WHEEL BALANCE
In the interests of smooth riding, precise steering and high stability, all tyres are balance checked to pre-determined limits. Coloured spots may be found on one bead indicating the lightest part of the tyre, which should be fitted near to the valve.
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Where balance weights have been fitted to the wheel rims, it is advisable to detach them before tyre removal to avoid the possibility of their inadvertently falling inside the tyre. If the same tyre is to be refitted, the positions and amounts of these balance weights as well as the position of the tyre on the wheel should be marked with chalk on the rim, so that the subsequent replacement may restore the original balance as far as possible.
The original degree of balance is not necessarily main-tained in service, as it may be affected by uneven tread wear, by cover repairs, or by tyre removal and replace-ment. Normal wear of moving parts may also render the car more sensitive to unbalance.
Rebalancing of tyre and wheel assemblies should be carried out with the aid of approved equipment capable of measuring both static and dynamic balance.
CHOICE OF TYRES
Only the tyre fitted as original equipment must be used as replacements.
When the car is to be used for track or circuit racing
further advice on the choice of wheels and tyres should be sought from the Sunbeam Competitions Department.
WHEEL TRIM DISCS
A wheel trim disc is fitted to each of the four roadwheels and therefore must be removed from one wheel, before the spare wheel is fitted. The wheel trim disc has a hole for the tyre valve and is held in position by the nave plate.
To remove and refit
1. Remove the nave plate from, the roadwheel.
2. 2. Ease the wheel trim disc from the nave plate studs.
3. Refitting is the reverse of the removal.
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