Rolls- Royce Silver Shadow
8
Bentley
T
Series
Workshop
Manual
Chapter
R
3.
'To determine the low spot on the tyre, mount This type of balancing machine enables any small
the tyre on a rim \~hich is known to be true and amount of run-out which exists in the tyre, wheel,
rotate it
011
a balaricing machine. Mark the low spot
hub and brake disc, to be virtually balanced out.
on the tyre.
4.
Fit the tyre and inner tulle (if fitted) to the
wheel so that the
lowrst spot of the tyre is aligned
with the high spot of the wheel bead seat, then
inflate the tyre to the
recon~mended pressure.
New tytes
After fitting the tyres
to
the wheels as described
previously, balance
c%acli wheel.
On no account should tyres other than those
approved in this Workshop Manual or in subsequent
Service
Bulletirls be fitted to the car, as this could
Wheel and tyre balance
Wheels can be balanced using either a vertical or
horizontal type of balancing machine.
For the earlier non-spigotted wheels the
Dunlop adapter plate WH13 and balancing machine
WBM3 are approved. For the later spigotted wheels
the
Dunlop adapter plate AP30 has been designed
for use in conjunction with the balancing machine
WBM20.
Alternatives to the Dunlop balancing machines
can be obtained from the following;
Hofmann
Balancing Techniques I,imited, Carl Schenck
(U.K.) Limited and Leycock Engineering Limited.
If the specified balancing equipment is not
available reference should be made to Figures
R9
and R10. These illustrations show two types of
small adapter collars which convert existing wheel
balancing equipment for use on spigotted road
wheels.
When fitting the adapter collar, it must be
accurately centralised on the adapter plate.
The manufacturer's
instructiorls must be observed
when using the balancing equipment, and the
following points noted.
1.
When checking wheel balance on the car, it
is essential that the weight of the car is removed
-
from the tyres as soon as possible after stopping
the car. This prevents temporary 'flats' from
forming on the tyres. It is pointless attempting to
balance wheels on which flats have formed, as the
static
balance rnay be affected by as much as
720 gm.
cn.
(10 oz. in.).
2.
Before balancing ensure that the tyres are
inflated to the correct cold inflation pressure.
3.
The static and dynamic balance of the wheels
should be within
216
gm.cm. and 360 gm.cm.
(3 oz.in. and
5
oz.in.) respectively.
4.
Balance weights can be removed and fitted
-
with a special tool supplied by the manufacturer
of the wheel balancing machine. When fitting the
weights to the rim, only sufficient force should be
used to secure them; excessive force will only
tend to slacken
them.
5.
After fitting balance weights, paint the steel
fittings to prevent them from rusting.
6.
If an 'on
the car' wheel balancing machine is
available, it should be used to check the balance
of the front wheels after they are fitted to the car.
have
u~ldesirable effects on the handling and
stability of the car. Therefore, when fitting new
tyres, reference should be made to the latest
Service Bulletin.
When new tyres have been fitted, sustained
speeds of
112
k.p.h. (70 m.p.h.) or over, during the
first 800 km. (500 miles) must not be undertaken.
Fast cornering, hard braking and harsh acceleration
must also be avoided. This is important as heat
generated by a new tyre, until it is sufficiently
flexed,
makes driving at speed inadvisable.
When
fitting new tyres, fit new valves also and
balance the wheels.
After fitting new radial-ply tyres, wheel
vibrations may be felt during the initial running-in
period. This is quite normal, but it is recommended
that after the initial running-in period the tyres on
all four wheels are again balanced, both statically
and dynamically.
Legal requirements
All Distributors, Retailers and Dealers are advised
to familiarise themselves with the legal require-
ments covering tyres and tyre wear, for the country
in which they operate. The
fc~llowing are examples
of requirements which apply in the United Kingdom.
1. Tyre tread.
The legal requirement for tyre tread is as follows.
Tread depth must not be less than 1 mm.
(0.039 in.), in a continuous area extending to a
minimum of 75 per cent of the tread width and this
area must extend around the complete circumference
of the tyre.
2. Tyre combination.
The legal requirements with regard to tyre com-
binations are as follows.
(a) Under no circumstances should radial-ply tyres
be fitted to the front wheels with cross-ply tyres
fitted to the rear wheels.
(b) Cross-ply and radial-ply tyres should not be used
on the same axle.
(c) Best results are obtained by fitting either
radial-
ply tyres to all wheels including the spare, or, on
early cars only, cross-ply tyres to all wheels
including the spare.
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