suspension FORD MUSTANG 2003 User Guide

Clonk
A hydraulic knocking sound. Sound occurs with air pockets in a hydraulic system. Also described as
hammering.
Clunk/Driveline Clunk
A heavy or dull, short-
duration, low-frequency sound. Occurs mostly on a vehicle that is accelerating or
decelerating abruptly. Also described as a thunk.
Coast/Deceleration
Releasing the accelerator pedal at cruise, allowing the engine to reduce vehicle speed without
applying the brakes.
Coast/Neutral Coast
Placing the transmission range selector in NEUTRAL (N) or depressing the clutch pedal while at
cruise.
Constant Velocity (CV) Joint
A joint used to absorb vibrations caused by driving power being transmitted at an angle.
Controlled Rear Suspension Height
The height at which a designated vehicle element must be when driveline angle measurements are
made.
Coupling Shaft
The shaft between the transfer case and the front drive axle or, in a two- piece rear driveshaft, the front
section.
CPS
Cycles per second. Same as hertz (Hz).
Cracks
A mid- frequency sound, related to squeak. Sound varies with temperature conditions.
Creak
A metallic squeak.
Cruise
Constant speed on level ground; neither accelerating nor decelerating.
Cycle
The process of a vibrating component going through a complete range of motion and returning to the Klj . 4 ba
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Lateral runout means measuring the movement or "wobble" of a wheel or tire at the sidewall. Radial
runout means measuring the out-of-
round at the tread surface.
Rustling
Intermittent sound of varying frequency (100- 2000 Hz), sounds similar to shuffling through leaves.
Shake
A low- frequency vibration (5-20 Hz), usually with visible component movement. Usually relates to tires,
wheels, brake drums or brake discs if it is vehicle speed sensitive, or engine if it is engine speed
sensitive. Also referred to as a shimmy or wobble.
Shimmy
An abnormal vibration or wobbling, felt as a side- to-side motion of the steering wheel in the driveshaft
rotation. Also described as waddle.
Shudder
A low- frequency vibration that is felt through the steering wheel or seat during light brake application.
Slap
A resonance from flat surfaces, such as safety belt webbing or door trim panels.
Slip Yoke/Slip Spline
The driveshaft coupling that allows length changes to occur while the suspension articulates and while
the driveshaft rotates.
Squeak
A high- pitched transient sound, similar to rubbing fingers against a clean window.
Squeal
A long- duration, high- pitched noise.
Static Balance
The equal distribution of weight around the wheel. Statically unbalanced wheel and tire assemblies can
cause a bouncing action called wheel tramp. This condition will eventually cause uneven tire wear.
Tap
A light, rhythmic, or intermittent hammering sound, similar to tapping a pencil on a table edge.
Thump
A dull beat caused by two items striking together. Tick Klj . 9 ba
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z
Did any abnormal occurrence coincide with or proceed its appearance?
Use the information gained from the customer to accurately begin the diagnostic process.
Pre- Drive Check
It is important to do a pre- drive check before road testing the vehicle. A pre- drive check verifies that
the vehicle is relatively safe to drive and eliminates any obvious faults on the vehicle.
The pre- drive check consists of a brief visual inspection. During this brief inspection, take note of
anything that will compromise safety during the road test and make those repairs/adjustments before
taking the vehicle on the road.
Preparing for the Road Test
Observe the following when preparing for the road test:
zReview the information recorded on the NVH Diagnostic Guide. It is important to know the
specific concern the customer has with the vehicle.
z Do not be misled by the reported location of the noise/vibration. The cause can actually be
some distance away.
z Remember that the vibrating source component (originator) may only generate a small
vibration. This small vibration can in turn cause a larger vibration/noise to emanate from another
receiving component (reactor), due to contact with other components (transfer path).
z Conduct the road test on a quiet street where it is safe to duplicate the vibration/noise. The ideal
testing route is an open, low- traffic area where it is possible to operate the vehicle at the speed
in which the condition occurs.
z If possible, lower the radio antenna in order to minimize turbulence. Identify anything that could
potentially make noise or be a source of wind noise. Inspect the vehicle for add- on items that
create vibration/noise. Turn off the radio and the heating and cooling system blower.
z The engine speed is an important factor in arriving at a final conclusion. Therefore, connect an
accurate tachometer to the engine, even if the vehicle has a tachometer. Use a tachometer that
has clearly defined increments of less than 50 rpm. This ensures an exact engine speed
reading.
Verify the Customer Concern
Verify the customer concern by carrying out a road test, an engine run- up test, or both.
The decision to carry out a road test, an engine run- up test, or both depends on the type of NVH
concern. A road test may be necessary if the symptom relates to the suspension system or is sensitive
to torque. A drive engine run- up (DERU) or a neutral engine run- up (NERU) test identifies noises and
vibrations relating to engine and drivetrain rpm. Remember, a condition will not always be identifiable
by carrying out these tests, however, they will eliminate many possibilities if carried out correctly.
Road Test Klj . 5 ba
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NOTE:
It may be necessary to have the customer ride along or drive the vehicle to point out the
concern. During the road test, take into consideration the customer's driving habits and the driving
conditions. The customer's concern just may be an acceptable operating condition for that vehicle.
The following is a brief overview of each test in the order in which it appears. A review of this
information helps to quickly identify the most appropriate process necessary to make a successful
diagnosis. After reviewing this information, select and carry out the appropriate test(s), proceeding to
the next step of this process.
zThe Slow Acceleration Test is normally the first test to carry out when identifying an NVH
concern, especially when a road test with the customer is not possible.
z The Heavy Acceleration Test helps to determine if the concern is torque- related.
z The Neutral Coast Down Speed Test helps to determine if the concern is vehicle speed- related.
z The Downshift Speed Test helps to determine if the concern is engine speed- related.
z The Steering Input Test helps to determine how the wheel bearings and other suspension
components contribute to a vehicle speed- related concern.
z The Brake Test helps to identify vibrations or noise that are brake related.
z The Road Test Over Bumps helps isolate a noise that occurs when driving over a rough or
bumpy surface.
z The Engine Run- Up Tests consist of the Neutral Run- Up Test and the Engine Load Test. These
tests help to determine if the concern is engine speed- related.
z The Neutral Run- Up Test is used as a follow- up test to the Downshift Speed Test when the
concern occurs at idle.
z The Engine Load Test helps to identify vibration/noise sensitive to engine load or torque. It also
helps to reproduce engine speed- related concerns that cannot be duplicated when carrying out
the Neutral Run- Up Test or the Neutral Coast Down Test.
z The Engine Accessory Test helps to locate faulty belts and accessories that cause engine
speed- related concerns.
z The Vehicle Cold Soak Procedure helps to identify concerns occurring during initial start- up and
when an extended time lapse occurs between vehicle usage.
Slow Acceleration Test
To carry out this test, proceed as follows:
zSlowly accelerate to the speed where the reported concern occurs. Note the vehicle speed, the
engine rpm and, if possible, determine the vibration frequency.
z Attempt to identify from what part of the vehicle the concern is coming.
z Attempt to identify the source of the concern.
z Proceed as necessary.
Heavy Acceleration Test
To carry out this test, proceed as follows:
zAccelerate hard from 0- 64 km/h (0-40 mph).
z Decelerate in a lower gear.
z The concern is torque related if duplicated while carrying out this test.
z Proceed as necessary. Klj . 6 ba
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Neutral Coast Down Speed Test
To carry out this test, proceed as follows:
zDrive at a higher rate of speed than where the concern occurred when carrying out the Slow
Acceleration Test.
z Place the transmission in NEUTRAL and coast down past the speed where the concern occurs.
z The concern is vehicle speed- related if duplicated while carrying out this test. This eliminates
the engine and the torque converter as sources.
z If the concern was not duplicated while carrying out this test, carry out the Downshift Speed
Test to verify if the concern is engine speed related.
z Proceed as necessary.
Downshift Speed Test
To carry out this test, proceed as follows:
zShift into a lower gear than the gear used when carrying out the Slow Acceleration Test.
z Drive at the engine rpm where the concern occurs.
z The concern is engine speed related if duplicated while carrying out this test. This eliminates the
tires, wheels, brakes and the suspension components as sources.
z If necessary, repeat this test using other gears and NEUTRAL to verify the results.
z Proceed as necessary.
Steering Input Test
To carry out this test, proceed as follows:
zDrive at the speed where the concern occurs, while making sweeping turns in both directions.
z If the concern goes away or gets worse, the wheel bearings, hubs, U- joints (contained in the
axles of 4WD applications), and tire tread wear are all possible sources.
z Proceed as necessary.
Brake Test
To carry out this test, proceed as follows:
zWarm the brakes by slowing the vehicle a few times from 80–32 km/h (50–20 mph) using light
braking applications. At highway speeds of 89–97 km/h (50– 60 mph), apply the brake using a
light pedal force.
z Accelerate to 89–97 km/h (55–60 mph).
z Lightly apply the brakes and slow the vehicle to 30 km/h (20 mph).
z A brake vibration noise can be felt in the steering wheel, seat or brake pedal. A brake noise can
be heard upon brake application and diminish when the brake is released.
Road Test Over Bumps
To carry out this test, proceed as follows: Klj . 7 ba
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NOTE:
A serpentine drive belt decreases the usefulness of this test. In these cases, use a
vibration analyzer, such as the VA, to pinpoint accessory vibrations. An electronic listening
device, such as an EngineEAR, will also help to identify noises from specific accessories.
Remove the accessory drive belts.
z Increase the engine rpm to where the concern occurs.
z If the vibration/noise is duplicated when carrying out this test, the belts and accessories are not
sources.
z If the vibration/noise was not duplicated when carrying out this test, install each accessory belt,
one at a time, to locate the source.
Vehicle Cold Soak Procedure
To carry out this procedure, proceed as follows:
zTest preparations include matching customer conditions (if known). If not known, document the
test conditions: gear selection and engine rpm. Monitor the vibration/noise duration with a watch
for up to three minutes.
z Park the vehicle where testing will occur. The vehicle must remain at or below the concern
temperature (if known) for 6- 8 hours.
z Before starting the engine, conduct a visual inspection under the hood.
z Turn the key on, but do not start the engine. Listen for the fuel pump, anti- lock brake system
(ABS) and air suspension system noises.
z Start the engine.
z CAUTION: Never probe moving parts.
Isolate the vibration/noise by carefully listening. Move around the vehicle while listening to find
the general location of the vibration/noise. Then, search for a more precise location by using a
stethoscope or EngineEAR.
z GO to Symptom Chart — Idle Noise/Vibration to assist with the diagnosis.
6: Check OASIS/TSBs/Repair History
After verifying the customer concern, check for OASIS reports, TSBs and the vehicle repair history for
related concerns. If information relating to a diagnosis/repair is found, carry out the procedure(s)
specified in that information.
If no information is available from these sources, carry out the vehicle preliminary inspection to
eliminate any obvious faults.
7: Diagnostic Procedure
Qualifying the concern by the particular sensation present can help narrow down the concern. Always
use the "symptom" to "system" to "component" to "cause" diagnosis technique. This diagnostic method
divides the problem into related areas to correct the customer concern.
zVerify the "symptom".
z Determine which "system(s)" can cause the "symptom".
„If a vibration concern is vehicle speed related, the tire and wheel rpm/frequency or
driveshaft frequency should be calculated.
„ If a vibration concern is engine speed related, the engine, engine accessory or engine
firing frequencies should be calculated. Klj . 9 ba
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„
A wobble or shudder. GO to Symptom Chart — Tire Noise/Vibration .
2. Depends more on where the vehicle is operated 1. Bump/pothole, rough road or smooth road. GO to Symptom Chart — Suspension
Noise/Vibration .
„ Noise is random or intermittent occurring from road irregularities. GO to Symptom Chart — Squeak and Rattle .
„ Noise or vibration changes from one road surface to another. Normal sound
changes.
„ Noise or vibration associated with a hard/firm ride. GO to Symptom Chart —
Suspension Noise/Vibration .
Symptom Charts Symptom Chart — Air Leak and Wind Noise Condition
Possible Sources Action
z Air leak around
door perimeter z
Loose fit seal. zPINCH the seal carrier to
improve retention on the
seal flange.
z Seal installed
incorrectly. z
REINSTALL the seal.
z Door misaligned. zREALIGN the door.
CHECK door gaps and fit
in the door opening and
ADJUST as necessary.
z Scuff plate installed
incorrectly. z
REINSTALL the scuff
plate.
z Seal or seal push pins
damaged. z
INSTALL a new seal.
z Air leak around
glass run z
Door glass misaligned. zADJUST the door glass.
z Glass run installed
incorrectly. z
ADJUST the glass run.
INSERT foam in the glass
run carrier.
z Leak path behind glass
run. z
INSTALL foam rope
behind the glass run.
z Glass run channel
spread wide. z
PINCH the glass run
channel to reduce the size
of the opening.
z Blow- out clip bent or
contacting door glass. z
ADJUST the blow- out clip
or INSTALL a new glass
run/blow- out clip molding
assembly.
z Glass run damaged. zINSTALL a new glass run.
z Air leak at inner
belt line z
Belt line seal installed
incorrectly on flange. z
ADJUST the seal. (Do not
bend the flange.)
z Belt line seal integrated
with door trim installed
incorrectly (no glass
contact). z
REINSTALL the door trim. Klj . 12 ba
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occurs on first
(morning) brake
application
pads.
Caused by humidity and
low disc brake pad
temperature.
z Squealing noise— a
continuous squeal z
Disc brake pads
or linings worn
below minimum
thickness. z
INSTALL new disc brake
pads. REFER to Section 206 - 03 for front disc brake
pads or Section 206 - 04 for
rear disc brake pads.
z Squealing noise— an
intermittent squeal
brought on by cold,
heat, water, mud or
snow z
Disc brake pad. zAcceptable condition.
z Groaning noise—
occurs at low speeds
with brake lightly
applied (creeping) z
Disc brake
pads. z
Acceptable condition.
z Grinding noise—
continuous z
Disc brake pads
or linings worn
below minimum
thickness. z
INSPECT the disc brake
pads, brake discs and
attaching hardware for
damage. REPAIR or
INSTALL new components
as necessary. REFER to
Section 206 - 03 for front
disc brakes and Section 206 - 04 for rear disc brakes.
z Moaning noise zBrake linings
contaminated
with grease or
oil. z
INSPECT the brake pads
and shoes for
contamination. REPAIR or
INSTALL new components
as necessary. REFER to
Section 206 - 03 for front
disc brakes or Section 206 -
04 for rear disc brakes.
z Brake
vibration/shudder—
occurs when brakes
are applied z
Uneven disc or
drum wear.
z Uneven disc
brake pad or
lining transfer.
z Suspension
components. z
Go To Pinpoint Test A .
z Brake
vibration/shudder—
occurs when the brake
pedal is released z
Brake drag. zINSPECT the disc brake
pads or linings for
premature wear. REPAIR
or INSTALL a new caliper
or wheel cylinder as
necessary. REFER to
Section 206 - 03 for front
disc brakes and Section 206 - 04 for rear disc brakes.
Symptom Chart—
Driveline Noise/Vibration Condition
Possible Sources Action
z Axle howling or
whine— front or rear
axle z
Axle lubricant
low. z
CHECK the lubricant level.
FILL the axle to
specification.
z Axle housing zINSPECT the axle housing Klj . 17 ba
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damage.
for damage. REPAIR or
INSTALL a new axle as
necessary. REFER to
Section 205 - 02A for Ford
7.5 rear axles or Section 205 - 02B for Ford 8.8
integral axles.
z Damaged or
worn wheel
bearings or axle
bearings. z
CHECK for abnormal wheel
bearing play or roughness.
REFER to Wheel Bearing Check in this section.
ADJUST or INSTALL new
wheel bearings as
necessary.
z Damaged or
worn differential
ring and pinion. z
INSPECT the ring and
pinion ring for abnormal
wear patterns or broken
teeth. INSTALL a new ring
and pinion as necessary.
REFER to Section 205 - 02A
for Ford 7.5 rear axles or
Section 205
- 02B for Ford
8.8 integral axles.
z Damaged or
worn differential
side or pinion
bearings. z
CHECK for abnormal
bearing play or roughness.
INSTALL new bearings as
necessary.
z Damaged or
worn differential
side gears and
pinion gears. z
DISASSEMBLE the
differential carrier. INSPECT
the side and pinion gears for
abnormal wear patterns or
broken teeth. INSTALL new
gears as necessary. REFER
to Section 205 - 02A for Ford
7.5 rear axles or Section 205 - 02B for Ford 8.8
integral axles.
z Driveline clunk— loud
clunk when shifting
from reverse to drive z
Incorrect axle
lubricant level. z
CHECK the lubricant level.
FILL the axle to
specification.
z Excessive
backlash in the
axle or
transmission. z
CARRY OUT a total
backlash check. REFER to
Section 205 - 00 .
z Damaged or
worn pinion
bearings. z
CHECK for abnormal
bearing play or roughness.
INSTALL new bearings as
necessary. REFER to
Section 205 - 02A for Ford
7.5 rear axles or Section 205 - 02B for Ford 8.8
integral axles.
z Damaged or
worn universal
joints (U- joints). z
INSPECT the U- joints for
wear or damage. INSTALL
new U- joints as necessary.
REFER to Section 205 - 01 .
z Loose
suspension
components. z
INSPECT the suspension
for damage or wear.
REPAIR or INSTALL new Klj . 18 ba
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components as necessary.
z Broken
powertrain
mounts. z
INSPECT the powertrain
mounts. INSTALL new
mounts as necessary.
REFER to Section 303 - 01A
for 3.8L engines or
Section 303 - 01B for 4.6L (2V)
engines.
z Idle speed too
high. z
CHECK for the correct idle
speed.
z Driveline clunk—
occurs as the vehicle
starts to move
forward following a
stop z
Worn or galled
driveshaft slip-
yoke splines. z
CLEAN and INSPECT the
splines of the yoke for a
worn or galled condition.
INSTALL a new yoke as
necessary. REFER to
Section 205 - 01 .
z Worn or galled
driveshaft and
coupling shaft
splines. z
CLEAN and INSPECT the
splines of the driveshaft and
coupling shaft for a worn or
galled condition. INSTALL a
new driveshaft assembly as
necessary. REFER to
Section 205 - 01 .
z Loose rear leaf
spring U- bolts. z
CHECK the U- bolts for
loose nuts. TIGHTEN to
specification. REFER to
Section 204 - 02 .
z Driveline clunk (FWD
vehicles)—occurs
during acceleration or
from cruise to
coast/deceleration z
Damaged or
worn inboard
constant velocity
(CV) joint. z
INSPECT the inboard CV
joint and boot. REPAIR or
INSTALL a new CV joint as
necessary.
z Driveline clunk (4WD
vehicles)—occurs
during shift- on-the- fly
engagement z
Clutch relay.
z Shift motor.
z Transfer case.
z GEM. z
CHECK the 4WD
engagement system.
REPAIR or INSTALL new
components as necessary.
z Clicking, popping or
grinding— occurs
while vehicle is
turning z
Inadequate or
contaminated
lubrication in the
(CV) joints. z
CHECK the CV boots and
joints for wear or damage.
REPAIR or INSTALL new
components as necessary.
z Another
component
contacting the
halfshaft. z
CHECK the halfshafts and
the area around the
halfshafts. REPAIR as
necessary.
z Brake
components. z
INSPECT the front brakes
for wear or damage.
REPAIR as necessary.
REFER to Section 206 - 03 .
z Steering
components. z
INSPECT the drag link,
inner and outer tie- rods or
idler arm for wear or
damage. REPAIR as
necessary. REFER to
Section 211 - 02 .
z Suspension
components. z
INSPECT the upper and
lower ball joints for wear or
damage. REPAIR as
necessary. REFER to Klj . 19 ba
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