GMC chervolet camaro 1999 Service Manual page 61

0-58 Vibration Diagnosis and Correction
Balanced Axles
Beginning in the early 1990's, the manufacturer began
system balancing rear axles. During the build
process, these axle assemblies were spun with a
slave fixture. A balance weight was attached to the
outboard edge of the companion flange dust slinger. A
system-balanced rear axle companion flange differs
from a non-balanced flange. You must diagnose
and service this flange in a unique way.
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Some pinion flange assemblies have a U-shaped
deflector designed to hold a system balance weight on
the outside diameter.
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Other pinion flange assemblies have a runout
compensation weight on the face of the deflector. The
pinion flange assemblies that are system balanced
do not use runout compensation weights.
General Information
Measuring the runout on a system-balanced
companion flange is very straight-forward. A balanced
flange that is good will have a measured runout
between 0.00-0.38 mm (0.00-0.015 in). If a balanced
flange has more than 0.38 mm (0.015 in) runout,
replace the flange or reindex the flange 180 degrees
on the pinion. If you replace or reindex a balanced
flange, you must system balance the rear axle again.
Correcting Vibration at .. the Pinion Nose
Most first-order driveline vibrations originate at the
pinion nose end of the driveshaft. Ensure that
the vibrations are at a minimum at this location in
order to achieve acceptable results. Reduce the runout
of the components to a minimum. Balance the
driveline as a system when necessary.
1. Measure the runout of the propeller shaft and
inspect the tolerance.
2. If the tolerance is excessive, mark the position of
the shaft for future reference and rotate the shaft
180 degrees.
3. Reinstall the shaft and reinspect the runout.
Inspect the level of vibration in order to determine
if the vibration is lower or corrected.
4. If the runout is still excessive, or if the vibration is
still present, refer to Measuring Pinion Flange
Runout. Replace the pinion flange or re-index the
flange 180 degrees if the pinion flange runout
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exceeds the tolerance. , (
Remove and reinstall the pinion flange only once
on axles utilizing a crush type sleeve. Replace
the sleeve with a new sleeve if the sleeve is
crushed. Removing the sleeve requires removal of
the ring and pinion set. Replace flanges with
excessive runout. Regardless of the method used,
measure the pinion flange runout in order to
ensure that the.flange is within tolerance.
5. Reinspect the propeller shaft runout if the vibration
is present after the pinion flange runout is
corrected. If the propeller shaft runout is still
· excessive, correct the runout before doing
a driveline system balance. Either replace the
shaft with a shaft that is within tolerance or sublet
the shaft to a reputable independent for
straightening and re-balance. Ensure that the new
or rebuilt shaft is within runout tolerance before
continuing.
6. Once the propeller shaft and pinion flange are
within runout tolerances, inspect to see if the
vibration is still present. If the level of the vibration
is still unacceptable, perform a driveline system
balance procedure.
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