Transcript Steering Service - mPortfolios.net

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Steering Service
Tire wear diagnosis – excess toe-in
• Excessive toe-in causes the outside edges of the tire to wear
at an accelerated rate.
• When the wheels toe in the outside edge of the tires are
being dragged slightly sideways as the tires roll.
• The excess heat created by this dragging melts the tread
rubber.
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Tire wear diagnosis – excess toe-out
• Abnormal wear caused by toe-out causes the inside
edges of the tire to wear unevenly.
• If the front wheels have excessive toe-in or toe-out
rapid and uneven wear will destroy both front tires.
• Excess toe-in / toe-out does not cause pull or vibration.
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Feathered edge wear
• Uneven wear caused by excessive toe-in or toe-out
causes the tread blocks to wear unevenly.
• The wear pattern is called ‘feathered’ and appears as
rounded on one edge of the tread block and square off
at the opposite edge.
• Feathered edge wear can be felt by running your hand
across the surface – in one direction it feels smooth and
in the opposite direction it feels rough.
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Visual inspection
• Incorrect toe angle can be cause by a number of
steering and suspension problems.
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Bent or worn tie rods
Bent control arms
Worn ball joints
Worn control arm bushings
Loose steering rack / bushings
Worn idler arm
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Tie rod end inspection
Grasp the
tie rod here
• Both inner and outer tie rod ends are inspected by
grapping a hold of the tie rod and pushing up/down and
inward/outward.
• Any play in the tie rod will require replacement of the
tie rod end.
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Tie rod replacement
Exposed
threads
• If the steering arm is made of
forged steel the tie rod end can
be separated form the steering
arm using a flat side of a ball
peen hammer.
• Before loosening the jamb nut count the number of
exposed threads on the tie rod.
• When the new tie rod end is installed with the same
number of exposed threads the toe adjustment should be
close to it’s original position.
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Tie rod separator
• If the tie rod end is to be replaced a pickle fork can be
used to separate the tie rod end from the steering
knuckle.
• If the steering arm is made of aluminum or stamped
steel a screw type separator will be required.
Images courtesy OTC corp.
Replacing inner tie rod ends on rack &
pinion
• The outer tie rod end can remain attached to the
steering arm.
• Loosen the jamb nut then unscrew the tie rod from the
outer end.
• Remove jamb nut, boot clamps and boot.
• Bend the locking plate with a flat chisel
• Unscrew the tie rod end from the steering rack using a
special tie rod end removal socket.
Image courtesy OTC corp.
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Inner tie rod end removal tools
• Universal tie rod end tool sets are available with
adapters that fit a variety of vehicles.
Image courtesy OTC corp.
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Replacing inner tie rod ends
Non-reusable
boot clamp
Flats behind
inner joint
Note: portions
of the boot
have been
removed for
this photo
• Adapters are needed on this style tie rod to get to the
flats behind the inner joint.
• This style inboard boot clamp is non reusable .
Image courtesy General Motors corp.
Steering wheel off center
• Generally if there is something bent in the steering /
suspension system it will effect one side more than the
other.
• If the toe adjustment is off on just one side of the
vehicle the driver will correct for it by steering the car.
• If the steering wheel is not at 12 O’clock when driving
on a straight and level road there is unequal toe in the
steering system.
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Diagnosis – loose steering
• Most steering systems have a small amount of freeplay.
• Freeplay can be defined as movement of the steering
wheel that does not produce movement at the tires.
• Freeplay is best checked on alignment rack with the
turn plates unlocked.
• Two technicians are needed – one sitting in the car
moving the steering wheel and the other under the car
observing the steering linkage.
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Determining the location of freeplay
• Hold the steering coupler or pinion shaft with an
appropriate tool and have your assistant wiggle the
steering. If there is excessive freeplay the problem is in
the column or coupler.
• Observe the rack as your assistant wiggles the steering.
If the rack moves side to side the rack bushings or
mounts are worn.
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Determining the location of freeplay
• If the pinion shaft moves but there is no motion in the
tie rods the freeplay is inside the rack.
• If the tie rods move back and forth but the tires do not
move the problem is in the outer tie rod ends or wheel
bearings.
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Freeplay in linkage type steering
• Loose idler arm pivot bushings are a
common problem in parallelogram type
systems.
• Grab the idler arm and push up and down.
The end of the idle arm should not move up
or down more than ¼”.
• Push up and down and side to side on all the
other ball and socket joints in the system.
There should be nothing loose.
• Grab the steering coupler and rock the
worm shaft back and forth. If there is
motion in the worm shaft but the pitman
arm does not move there is freeplay in the
steering box.
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Adjusting the steering box
Jamb nut
Adjuster
screw [Allen]
• Freeplay can be adjusted on a
recirculating ball steering box.
• First separate the pitman arm from
the center link.
• Center the steering wheel.
• Loosen the lock nut.
• Turn the Allen screw inward ¼ turn.
• Turn the steering wheel from 9
O’clock to 3 O’clock .
• The adjustment is correct when a
very slight resistance is felt as the
steering passes through 12 O’clock.
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Diagnosis – fluid leaks
• There should no lose of power steering
fluid over time. If fluid needs to be added
to the reservoir there is a leak somewhere
in the system.
• Leakage in one of the rack seals may be
contained in the rack boot. In normal
operation the rack boots should be dry.
• Because of liability issues leaking racks,
steering boxes and pumps are normally
replaced rather than installing new seals.
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Replacing hydraulic lines
• Flair nut wrenches are needed to
remove and replace P/S hoses.
• Flair type ‘crows feet’ adapters are normally required in
the tight confines surrounding the steering rack.
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Why flare nut wrenches are needed
• The hose connector nuts are made of a soft metal.
• When conventional wrenches are used the flats on the
nuts are damaged.
Replacing hydraulic lines
• Plastic looms are located between the sub-frame/body
and metal hydraulic lines to prevent abrasion.
• Rubber cushions are wrapped around rubber hydraulic
lines where there may be contact with the unibody.
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Hard steering - diagnosis
• Possible causes
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Loose power steering belt
Low fluid / fluid leak
Faulty power steering pump
Seized ball joints – strut bearings – tie rod ends
Faulty control valve
Blocked or restricted P/S hose – pinched metal line
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Fluid level
• Power steering should be checked with the
fluid at 80o F.
• Most reservoirs have a dipstick in the cap
with a hot and cold mark.
• To bring the fluid up to temperature turn
the steering lock to lock several times
with the engine running.
• Place a drop of fluid on a clean shop
towel. The fluid should be clear and not
appear burnt.
• The fluid in the reservoir should be free of
air bubbles and foam.
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Hard steering - diagnosis
• With the vehicle raised off of the ground and the engine
off turn the steering.
– If the steering is harder to turn than normal disconnect the tie
rod ends from the steering arms.
– Turn the steering knuckle by hand – if it doesn’t move freely
the ball joints or strut bushing are frozen.
• If the steering turns normally with the engine off but is
hard to steer when driving on the road the problem is
probably in the power assist system.
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Hard steering - diagnosis
• If the belt]s] is OK and tensioned properly and the fluid
level is normal a pressure test may be needed to further
diagnose the problem.
• A P/S system tester combines a 0 – 3000 psi hydraulic
gauge and a shutoff valve.
• The tester is connected between the pump and high
pressure hose.
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P/S pressure test
• With the tester
connected the
pressure should be
around 100 to 150
psi with no steering
input and rise to
about 1000 psi when
the steering is turned
to full lock.
0 – 3000 psi
gauge
Shutoff Valve
High
pressure
hose
Control
valve
Accessory hose
– part of
pressure tester
set
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P/S pressure test
Gauge end
connects to
pump
Valve end
connects to
High pressure
hose
Shutoff Valve
• With the tester
connected the pressure
should be around 100 to
150 psi with no steering
input and rise to about
1000 psi when the
steering is turned to full
lock.
• With the shutoff valve closed the pressure should rise
to about 1000 psi.
• If the pressure does not rise when the shutoff valve is
closed the pump is faulty.
Image courtesy OTC corp.
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P/S pressure test
• If the pressure rises to about 1000 psi when the valve is
closed but does not rise as much when the valve is open
and the steering is turned to full lock the fault lies
inside the rack/steering box.
• If there is higher than specified pressure when the valve
is open and there is
Pull to either side – self steering
• Generally a pull to the right or left is caused by an
alignment or brake problem.
• A bad control valve however can cause a steering
system to self steer.
• To check for a possible self steer raise the vehicle on a
lift so the tires are off the ground.
• Center the steering a 12 O’clock.
• Start the engine and watch the steering wheel.
• If the steering wheel turns to either side the control
valve is faulty and the rack/box will have to be
replaced.
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Replacing the power steering pump
• A new or remanufactured power steering pump does
not usually come with a pulley.
• The pulley on the old P/S pump is transferred to the
new P/S pump
• The P/S pump pulley is press fit to the pump shaft.
• A special tool set is needed to remove and replace the
P/S pulley.
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Removing the pump pulley
Pulley
Installer
tool
Pulley
removal
tool
Thrust
bearing
Threads connect
tool to pump shaft
Sleeve presses
against pump
shaft
Internal flange grips
groove in hub
Images courtesy OTC corp.
Removing the pump pulley
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Groove for
removal tool
• The pulley has a groove in it’s hub that the pulley
removal tool engages.
Image courtesy General Motors corp.
Installing the pump pulley
• Before removing the pulley from the old hub
look to see how far the pump shaft extends
outside the hub.
• Install the pulley on the new pump with the
same amount of shaft protruding.
• Press fit pulleys can be repositioned to bring
a misaligned belt back into pro
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Correcting excess toe-in
• To correct the toe-in
problem here both tie rods
need to be made shorter.
Clamp
Jamb nut
Inner tie rod
• Toe is adjusted by loosening the
jamb nut then turning the inner tie
rod until toe is correct.
• The outer boot clamp may need to
be loosened to prevent boot
twisting.
Correcting excess toe-out
• To correct the toe-out problem
here both tie rods need to be
lengthened.
• If the steering rack is located
ahead of the axle centerline
the tie rods need to be
shortened.
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Rack and pinion
replacement
procedure
Lock the steering
• With the steering in a straight ahead position wrap the
seatbelts through the steering wheel.
• Disconnect the battery.
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Disconnect the tie rod ends
• If the rack is being replaced a pickle fork can be used to
separate the tie rod end from the steering arm.
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Remove outer tie rod ends
Another way is to count
the number of threads
outboard of the jamb nut
after the tie rod is
removed
• After disconnecting
the tie rod from the
steering arm unscrew
the tie rod end from
the inner tie rod.
• Count the number of
turns so that the tie
rod ends can be
installed on the new
rack in the same
position.
Disconnect steering coupler
• Lift the rubber boot that
protects the steering coupler
to gain access to the pinch
bolt.
• The coupler pinch bolt is a
special bolt that should be
labeled so that it is
reinstalled in its original
location.
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Remove the hydraulic lines
Return line
Supply line
• Disconnect the supply and return lines.
• The two smaller lines can stay attached to the rack.
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Remove the rack mount bolts
Rack
mount bolt
• The rack mount bolts are special bolts that should be
labeled and reinstalled in their original position.
Remove rack
• The rack can
now be
withdrawn
through the
wheel well.
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Remove tie rod end lock nuts
• With the rack removed from the vehicle the lock nuts
can be removed easily.
Pinion shaft notch
• The pinion shaft is
notched to insure that
the coupler is
installed at the
correct depth and
orientation.
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Center the rack prior to installation.
• Turn the pinion shaft all the way to the right and then
turn to the left while counting how many turns.
• Turn the shaft to bask the right half that number and the
rack should be centered.
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Reinstall the rack
Note: Return line on
this rack uses a
conventional hose
connection with a
worm clamp.
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Connect the steering coupler
Notch in
pinion shaft
• The notch in the pinion shaft
must align with the hole for
the pinch bolt.
• When the coupler is
installed correctly the pinch
bolt can be easily installed
with your fingers.
• Do not hammer the pinch
bolt into the coupler.
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Install new O-rings on the hydraulic
lines
• A set of new o-rings are included in the remanufactured
steering rack box.
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Connect tie rod ends
• The tie rods ends should be
threaded onto the inner tie
rod end with the same
number of turns that were
recorded when they were
removed from the old rack.
• The number of turns on the
left and right side should be
roughly equal.
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Install copper pin and trim to length
• After trimming the cotter pin end is bent upward.
Top off PS fluid
• Before starting the engine fill the PS
fluid reservoir.
• With the engine running top off the
fluid level.
• With the engine running turn the
steering all the way left and then all
the way right to bleed the air out of
the system.
• Shut the engine off and wait 15 to
20 minutes for the remaining air
trapped in the system to rise to work
it’s way out then repeat this process
to purge any remaining air bubbles.
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Alignment
• Any time the rack or tie rods are replaced the toe angles
must be readjusted on an alignment machine.
• Besides correcting the toe angle the alignment will
insure that the steering wheel is at 12 O’clock when the
vehicle is driven straight.
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