Pontiac Fiero 1988 Service Manual page 210

TIRES AND WHEELS 3E-7
WHEEL TRAMP
ADD BALANCE
WEIGHTS HERE
C O R R E C T I V E WEIGHTS
_ G33963-3E-AN
Fig. 13 Static Unbalance Correction
Dynamic balance is the equal distribution of
weight on each side of the centerline so that when the
assembly spins there is no tendency for it to move from
side to side. Assemblies that are dynamically
unbalanced may cause wheel shimmy.
General Balance Precautions
Deposits of foreign material must be cleaned from
the inside of the wheel. Stones should be removed from
the tread in order to avoid operator injury during spin
balancing and to obtain a good balance. The tire should
be inspected for any damage, then balanced according
to the equipment manufacturer's recommendations.
Whenever a heavier, solid locking wheel nut is
used to replace a standard nut, it should be installed
nearest the valve stem, and a 1/2 ounce balance weight
should be added 180° opposite the locking nut on the
wheel's inboard side.
When rotating tires, always re-install the locking
nut nearest the tire valve stem so that it remains
opposite the 1/2 ounce balance weight. This procedure
will improve the on-car wheel balance by compensating
for the heavy locking wheel nut.
Off-Car Balancing
Most electronic off-car balancers are more
accurate than the on-car spin balancers. They are easy
to use and give a dynamic (two plane) balance.
Although they do not correct for drum or rotor
unbalance as does on-car spin balancing, this is
overcome by their accuracy (usually to within 1/8
i
CL OF SPINDLE
HEAVY SPOT 5
WHEEL SHIMMY
ADD BALANCE
WEIGHTS HERE
C O R R E C T I V E WEIGHTS
G33964-3E-AN
Fig. 14 Dynamic Unbalance Correction
ounce). When balancing off-car, the wheel should
locate on the balancer with a cone through the back
side of the center pilot hole (not by the wheel stud
holes).
On-Car Balancing
When needed, on-car balancing will help correct
vibrations due to brake drum, rotor, and wheel cover
imbalance.
The rear suspension should not be allowed to
hang free. When the CV joint is run at a very high
angle, extra vibrations can occur, as can damage to
seals and joints. Always follow the equipment
manufacturer's instructions.
When balancing on car, do not remove the
balance weights from the off-car dynamic balance. If
more than one ounce of additional weight is required,
it should be split between the inner and outer rim
flange.
N O T I C E :
The driven tire and wheel assemblies
should be spun using the engine. Limit speed as
stated in the following Caution.
C A U T I O N : D o n o t s p i n t h e d r i v e
w h e e l s f a s t e r t h a n 3 5 m p h ( 5 5 k m / h )
a s i n d i c a t e d b y t h e s p e e d o m e t e r . T h i s
l i m i t i s n e c e s s a r y b e c a u s e t h e
s p e e d o m e t e r i n d i c a t e s o n l y o n e - h a l f
of t h e a c t u a l w h e e l s p e e d w h e n o n e
d r i v e w h e e l i s s p i n n i n g a n d t h e o t h e r
d r i v e w h e e l i s s t o p p e d . P e r s o n a l i n j u r y
a n d d a m a g e m a y r e s u l t f r o m h i g h
s p e e d s p i n n i n g .