Description And Operation; General Description - GMC Chevrolet Camaro 1998 Service Manual

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General Information
Transmission Shims
If a transmission requires shims, order the shims
through GMSPO.
Installing most shims will change the transmission
angle approximately 112 degree.
When shimming transmissions, use a shim made from
steel stock at the necessary thickness. Ensure that
the shim contacts the full width of the area to be
shimmed. Do not use washers.
Description and Operation
General Description
Vibration Theory
The vehicle designs and the engineering requirements
have undergone drastic changes in this decade.
The following factors drive many of these
requirements:
• Increased fuel costs
• Decreased fuel supplies
• Corporate Average Fuel Economy (CAFE)
• Clean air legislation
• Foreign competition
• Crashworthiness
• Rising customer expectations
The vehicle designs have evolved from the full frame
construction, where multiple isolating body mounts
were used, to the lighter unibody designs of today. The
unibody designs transfer any noise or vibration
faster.
The use of heavier VS engines has been reduced,
being replaced with lighter, more fuel-efficient four and
six-cylinder engines. During this same period,
options such as A/C and PS have become more
popular. These types of options increase the engine
load, resulting in more unwanted noise and vibration.
The presence/absence of unwanted noise and
vibration is linked to the customer's perception of the
overall vehicle quality.
Vibration is the repetitive motion of an object, back
and forth, or up and down. The following conditions
cause most vehicle vibrations:
• A rotating component
• The engine combustion process firing impulses
Rotating components will vibrate with excessive
imbalance or runout. During vibration diagnosis, the
amount of allowable imbalance or runout should
be considered a TOLERANCE and not a
SPECIFICATION. In other words, the less imbalance
or runout the better.
Vibration Diagnosis and Correction 0-87
A vibration concern will occur when the firing impulses
of the engine are not properly isolated from the
passenger compartment.
A vibrating component operates at a consistent rate
(km/h, mph, or rpm). Measure the rate of vibration
in question. When the rate/speed is determined, relate
the vibration to a component that operates at an
equal rate/speed in order to pinpoint the source.
Vibrations also tend to transmit through the body
structure to other components. Therefore, just because
the seat vibrates doesn't mean the source of vibration
is in the seat.
Vibrations consist of the following three elements:
• The source - the cause of the vibration
• The transfer path - the path the vibration travels
through the vehicle
• The responder - the component where the
vibration is felt
95585
In the preceding picture, the source is the unbalanced
tire. The transfer path is the route the vibrations
travels through the vehicle's suspension system into
the steering column. The responder is the steering
wheel, which the customer reports as vibrating.
Eliminating any one of these three elements will
usually correct the condition. Decide, from the
gathered information, which element makes the most
sense to repair. Adding a brace to the steering
column may keep the steering wheel from vibrating,
but adding a brace is not a practical solution. The most
direct and effective repair would be to properly
balance the tire.