Steering Angles and Alignment Flashcards
steering geometry refers to what specific wheel alignment angles
. toe . caster . camber .king pin inclination . turning radius . thrust and scrub
what are the two classifications of tire angles
tire wearing and directional control
a wheel alignment angle whose primary purpose is to reduce tire wear is classified as a
tire wearing angle
what are the tire wearing angles that if adjusted away from manufacturers spec will cause premature tire wear
camber
turning radius
toe
a wheel alignment angle whose primary purpose is to add steering stability is classified as a
directional control angle
what are the angles that fall into the directional control angle category
caster and kingpin inclination
what must happen before attempting a wheel alignment
all steering components must be within allowable limits
what is toe
toe is the difference in distance between the front and the rear of the wheels on the same axle
what is toe in
when the wheels are closer together at the front then the back
what will happen if toe in is excessive
the tires will scuff as it moves down the road and a feathered edge will develop
what will happen if toe out is excessive
the tires will scuff and a feathered edge will develop
what is the purpose of the toe setting
to compensate for any deflection (wear) in the steering linkage
what would create optimum tire life
zero toe
what is caster
forward or backward tilt of the kingpin
what type of angle is caster
a directional control angle
what is the steering axis
the steering axis is the invisible line drawn through the center of the kingpin about witch the wheel can be turned
what are the three possible castor conditions
. positive castor
. negative castor
. zero castor
what is the purpose of castor
castor tends to make the vehicle to want to go straight
and helps to return the steering to the straight ahead position after making a turn
what is the center of the tire footprint called
point of contact
where will positive castor project the load
ahead of the point of contact
what is the spot where the weight of the load is being projected called in a castor position called
point of load
whenever the point of load is projected ahead of the point of contact what will the wheel want to do
it will have a tendency to follow this projected point
what will happen with excessive positive castor
. road shock
. heavy steering
. shimmy
what type of excessive castor will reduce road shock
negative castor
what type of excessive castor will result in more heavy steering
positive castor
what type of excessive castor will result in shimmy
positive castor
what type of castor will create easier steering
negative castor
what type of castor will cause instability at high speeds
negative castor
good directional control can only be obtained if
the point of contact follows the point of load
what type of castor will produce wander a weave
negative castor
what is camber
camber is the outward or inward tilt of the wheel at the top
what type angle is camber
wear angle
what are the two main purpose of camber
. brings the point of contact more directly under the load
. provides easier steering by allowing the weight of the vehicle to be carried closer to the steering axis
what are the effects of incorrect camber
abnormal and premature tire wear
steering and stability issues
where will to much positive camber cause a tire to wear
on the outside edge of the tire
where will to much negative camber cause a tire to wear
on the inside edge of the tire
what will happen to the camber if the axle is overloaded
it will become more of a negative camber
what will having the camber equal on both sides assist in
the vehicle will be less subjected to outside forces such as cross winds because of the opposing forces holding the vehicle on a straight path
what will result if the axle is bent and the camber is not equal on both sides
camber pull
if a vehicle has camber pull what side will the vehicle pull to
to the side with the most positive camber
what can also happen if you have excessive camber
the wheel bearing will be abnormally loaded causing premature wear
what is the kingpin inclination angle
it is the inward tilt of the steering axis at the top
what type of angle is kingpin inclination angle
directional control witch is established by the vehicle manufacture
is the KPI angle adjustable on I beam front axles
no it is set by the manufacturer but will still have to be measured when doing wheel alignment
what are some of the purposes of the KPI angle
. it reduces the need for high camber
. it brings the point of contact more directly under the point of load
. it provides a pivot point for wheel to turn around producing ease of steering
. it provides steering stability
. it reduces road shock
. it reduces brake pull
what must you consider when measuring KPI angle
you must also consider camber angle
what is the included angle
the combined reading of the KPI and the camber
if the camber angle is zero
then the KPI and the included angle are the same
what is the scrub radius
is the distance between the projected steering axis and the center of the tire contact area measured at the road surface
how could the scrub radius be altered
by installing rims with a different offset
what is turning radius
turning radius is toe out on turns
what type of angle is turning radius
tire wearing angle
what is the number one tire wear angle
toe
what is the purpose of tire turning radius
to reduce tire scuffing during cornering
what determines the angle of the turning radius
the shape of the steering arms
can the turning radius be adjusted
no
what angle helps reduce tire skidding during cornering
toe out on turns angle
what is the vehicle center line
it is the invisible line that runs longitudinally down the middle of the vehicle
. it is determined by measuring equally on both sides
what is the geometric centerline
a line that is determined by the midpoints of the front and rear wheels
. if the wheels are not offset the VCL and GCL are identical
what is the thrust line
it is a line that is determined by the total toe of the rear wheels
. the thrust line divides the toe in half and runs up the center of the vehicle
what line will determine the direction the vehicle will travel
the thrust line
if the thrust line is off what will the vehicle do
dog track in the direction of the thrust line
what is the thrust angle
it is the angle that results from any difference between the GCL and the thrust line
when a vehicle is tracking to the right or left what direction will be the easier way to turn during this condition
if its tracking right it will turn easier to the left
if it is tracking to the left it will turn easier to the right
what is the scrub angle
its the angle formed by the intersecting lines drawn through the rear axle when total toe and offset is zero
what will happen if you have any scrub angle greater than zero
it will cause the two rear axles to work against each other pushing the front of the vehicle to one side or the other
what is positive scrub
when the axles are closer on the right side of the vehicle . this will push the vehicle to the right
what is negative scrub
when the axles are closer on the left side of the vehicle . this will push the vehicle to the left
what should be done if you feel you have steering looseness in your steering gear
adjust the internal play
will lateral runout of a rim affect the toe check and adjustment
no . but it will affect drivability
what can worn and loose wheel bearings affect
toe measurement and camber angle
what problem can affect castor angles when measuring
broken or sagging spring ( air bags ,rubber block ,leaf and torsion bar )
why is accuracy important when measuring toe
because the toe setting is quite small 0-1/8”
what would a special spring loaded marking scribe be used for
making a accurate thin line in the tire centerline to measure toe
how can you get the most accurate reading when measuring toe using the toe setting gauge
by placing the gauge pointers as close as possible to the centerline of the spindles
if the tie rod is moved so the back of the tires are 1/16 further apart and the front of the tires are 1/16 closer together how much have you changed the toe setting
by 1/8”
how is the toe setting on a rack and pinion steering system set
by using a computerized multi-wheel alignment rack
when setting the toe on a rack and pinion style steering it is ok to center the steering wheel by adjusting the tie rod ends
NO this will change the toe setting . in order to center the steering wheel you must remove the steering wheel it and reposition it to the center position
what is used when adjusting the castor angle
one tapered shim placed between the axle and the leafspring
what might a high camber reading indicate
a kingpin inclination problem due to a damaged axle or steering knuckle
before checking rear axle alignment what must be within specification
frame and suspension
what tool could be used when measuring rear axle scrub
a trammel bar
what two angles can be checked but not adjusted
KPI and turning radius
