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3E-6
1977 PONTIAC SERVICE M A N U A L
STANDARD AXLE
LIMITED SLIP AXLE
Fig.
3E-8
Rear Wheel Balance Jacking Set-Up
Anti-Spin Axle
On cars equipped with an anti-spin differential, the
following procedure should be used (Fig. 3E-8).
1. Raise both rear wheels with a jack under the
differential. Put jack stands under axle as a safety measure,
but do not put car weight on stands.
WARNING:
DO
NOT
ATTEMPT
TO
BALANCE A TIRE ON A DRIVE WHEEL
WITH THE OTHER DRIVE WHEEL ON
THE GROUND. THE CAR M A Y DRIVE
THROUGH THlS WHEEL A N D CAUSE
THE CAR TO MOVE UNEXPECTEDLY,
RESULTING I N PERSONAL INJURY AND
PROPERTY DAMAGE.
-
-
2. Remove one wheel.
3. Reinstall lug nuts and tighten securely to retain the
brake drum.
4. Balance the remaining wheel using engine power t o
ppin the wheel.
WARNING: ON CARS WHICH HAVE
ANTI-SPIN
DIFFERENTIAL,
DRIVE
WHEEL SPIN SHOULD BE LIMITED TO
70 MPH. THlS IS TO PREVENT TIRE
DISINTEGRATION
RESULTING
I N
SERIOUS
PERSONAL
INJURY
AND
EXTENSIVE PROPERTY DAMAGE.
5. Reinstall the second wheel and balance.
VIBRATION
Wheel unbalance causes most of the highway speed
vibration problems. However, if a vibration remains after on-
car balancing, it can be caused by three things (Fig. 3E-9).
1. Tire runout
2. Wheel runout
3. Tire Stiffness variation
Measuring tire and/or wheel free runout will uncover
only part of the problem. All three causes are easily checked
by using a Tire Problem Detector (TPD). If a T P D is not
available, the more time-consuming method of substituting
known good tire and wheel assemblies on the problem vehicle
can be used.
Correction Non-Uniform Tires
If a replacement tire cannot be obtained, there are
several ways to correct tires which cause a vibration even
though they are properly balanced. The best method uses an
automatic machine which buffs small amounts of rubber from
selected spot on the outer two tread rows. Correction by this
method is usually permanent and, if done properly, does not
significantly affect the appearance or tire tread life. Tire
truing with a blade-type machine is not recommended as this
reduces the tread life substantially and often does not
permanently correct the problem.
Another method which quite often works is to dismount
the tire and rotate it 180 degrees on the rim. It is important
that this be done on tire assemblies which are known to be
causing a vibration as it is just as likely to make good
assemblies worse.
STYLED WHEEL HUB CAP
RALLY WHEEL
Remove and Install
WARNING:
BEFORE
RE-INSTALLING
ALUMINUM WHEELS, ANY BUILD UP OF
CORROSION
ON
THE
WHEEL
MOUNTING
SURFACE
AND
BRAKE
DRUM OR DISC MOUNTING SURFACE
SHOULD BE REMOVED BY SCRAPING
AND WIRE BRUSHING. INSTALLATION
OF
ALUMINUM
WHEELS
WITHOUT
GOOD METAL-TO-METAL CONTACT AT
THE
MOUNTING
SURFACES
CAN
RESULT I N LOOSENING OF THE WHEEL
NUTS
WHICH
C A N
EVENTUALLY
ALLOW THE WHEEL TO COME OFF
WHILE THE VEHICLE IS I N MOTION,
CAUSING LOSS OF CONTROL.
1. Remove wheel and tire assembly from car.
2. Depress spring retainers on cap using screwdriver
from rear side of cap and remove the cap.
3. Replace cap by placing one or two spring retainers
into wheel opening and then use screwdriver to guide
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