PRESENTATION TO UNDERSTAND CAUSES OF STEERING PULL ON VEHICLES AND ITS POSSIBLE CHECK.

1. Presentation on
Steering Pull on Vehicles
Yogesh Prasad

2. What is steering Pull ?
It as phenomenon that causes the vehicle to follow a path other than a straight one.
And the driver has to maintain constant pressure on the steering wheel can very
tiring, not to mention hard on the tires.

3. Steering Pull can be classified into various categories:
1) Steady pull
2) Memory steer
3) Off-center steering wheel
4) Steering wander
5) Bump steer
6) Torque steer
Types of steering Pull ?

4.  Steady Pull
This is a condition where the vehicle continually pulls or drifts to one side while
traveling straight. The driver typically has to maintain steady pressure on the
steering wheel to keep the vehicle on the road
Need for correction to drive in straight line

5.  Steady Pull-Possible causes include
Uneven camber side-to-side. Too much cross-camber can make a vehicle pull
or lead towards the side that has the most (positive) camber or away from the
side that has the least (negative) camber.
The underlying cause may be:-
• Bent strut.
• Mislocated strut tower,
• Bent spindle,
• collapsed control arm bushing
• weak or broken spring,
• shifted cross member.
• Check included angle to see if these
are in or out of specs to diagnose the
• Check ride height. Correct by replacing
worn or damaged parts, correcting
location of strut tower, repositioning
engine cradle, and/or reducing cross-
camber to half a degree or less by
readjusting camber to specifications.

6.  Steady Pull-Possible causes include
The underlying cause may be:-
• Bent strut,
• Bent spindle
• Mislocated strut tower.
Uneven caster side-to-side. Too much cross-caster can make a vehicle pull
or lead towards the side that has the least (negative) caster.
• Correct by replacing damaged
part,
• correcting location of strut
tower, and/or reducing cross-
caster to half a degree or less by
resetting caster to
specifications.

7. Rear axle steer. The front wheels are with alignment specifications but the
vehicle pulls to one side.
 Steady Pull-Possible causes include
• Measure and compare the
wheelbase on both sides
• Check for the presence of a
thrust angle, and/or measure
individual rear toe.
• Correct by realigning the rear
axle or rear toe, or by
performing a thrust angle
alignment.
The underlying cause may be:-
• Rear toe out of specifications
• A bent rear axle,
• Chassis misalignment or a stack
up of assembly tolerances in the
chassis causing rear axle
misalignment.

8. Brake drag. The pull is constant to one side and may get worse with the
application of the brakes. Raise the vehicle and spin each wheel by hand to
check for excessive drag.
 Steady Pull-Possible causes include
Possible causes include :-
• caliper sticking,
• frozen or sticking piston in caliper,
overfilled fluid reservoir in master
cylinder (does not allow caliper pistons
to retract when brakes are released)
• weak drum brake return springs,
• Misadjusted drum brakes,
• Misadjusted parking brake,
• Misadjusted parking brake pedal switch
(creates residual pressure in the master
cylinder to cause drag). Readjust or
repair brakes as required.

9. Low tire pressure. The vehicle will lead towards the side with low pressure
in the front tire. Correct by inflating tires to recommended pressure.
 Steady Pull-Possible causes include

10. Mismatched tires side-to-side. The vehicle will pull or lead towards the side
that offers the greatest rolling resistance.
• Compare tire sizes,
• tread wear,
• tread styles and patterns,
• also brands.
 Steady Pull-Possible causes include

11. Uneven tire wear. If one side of the tread is worn more than the other, the tire
develops Conicity. The effect is much the same as camber, causing the tire to
roll towards the side which is worn most.
 Steady Pull-Possible causes include
The uneven wear may be the
result of
• incorrect camber,
• toe and/or failure to rotate
the tires periodically to
even out wear.
• If rotating the tires side-to-
side reverses the direction
of the pull, the tires need
to be replaced.

12. Ply steer. A manufacturing defect in the way the belts are positioned inside the
tire causes the tire to generate a lateral (sideways) force as the tire rolls.
 Steady Pull-Possible causes include
To test for this condition, drive the
vehicle forward, then in reverse.
• If the direction of the drift or pull
changes, one or more tires at
fault.
• Rotating the tires front-to-rear or
crosswise may help cancel out the
ply steer, otherwise tire
replacement is necessary to
correct the condition.

13. Unbalanced power assist. Seal leaks in the control valve or off-center steering
may route hydraulic pressure into one side or the other of the boost cylinder
piston causing the steering to want to turn itself to one side.
 Steady Pull-Possible causes include
This can be checked by:-
• Raising the wheels with the
engine running to see if the
wheels turn to one side by
themselves.
No change would indicate
another
cause, but if the pull suddenly
vanishes an imbalance in the
power steering system is to
blame.
• The control valve assembly or
steering gear needs to be
replaced.

14. Excessive road crown. Roads are raised or crowned in the middle so rain water
will run off to the outside for proper drainage. But the slight slope to the
pavement can often make a vehicle drift to the outside. This can be countered
by adding a little positive camber and/or negative caster to the left front
wheel , but this should only be done if the vehicle spends most of its time on
crowned roads and you have a noticeable pull.
 Steady Pull-Possible causes include

15.  MEMORY STEER
The steering wheel and wheels want to return to some position other than
center. This may cause a steering pull or drift to one side after turning.

16.  MEMORY STEER-Possible causes include:
Misalignment or improper installation of Rubber bonded socket (RBS) tie rod
ends. RBS tie rod ends do not swivel freely like conventional tie rod ends. When
installed, the steering linkage must be centered and straight ahead before the
tie rod studs are tightened. Inspect and readjust as needed.

17.  MEMORY STEER-Possible causes include:
Binding in upper strut mounts. Raise wheels and turn the steering from side to
side. If effort is high, disconnect tie rod ends from steering arms and turn each
wheel by hand to check for resistance. If upper strut mount is binding or loose,
the strut will have to removed or rebuilt to replace the upper bearing plate
assembly.

18.  MEMORY STEER-Possible causes include:
Binding in ball joints. Unload the ball joints by raising the suspension. Let the
suspension hang free with MacPherson struts. Support the lower control arm on
an SLA, modified strut or wishbone suspension if the spring is on the lower arm,
or the upper arm if the spring is over the upper arm). Turn the wheels from side
to side to check steering effort. If high, disconnect the tie rod ends and try
again. If a ball joint is binding, replacement is required.

19. Unbalanced power assist. Seal leaks in the control valve or off-center steering
may route hydraulic pressure into one side or the other of the boost cylinder
piston causing the steering to want to turn itself to one side.
This can be checked by:-
• Raising the wheels with the
engine running to see if the
wheels turn to one side by
themselves.
No change would indicate
another
cause, but if the pull suddenly
vanishes an imbalance in the
power steering system is to
blame.
• The control valve assembly or
steering gear needs to be
replaced.
 MEMORY STEER-Possible causes include:

20.  OFF-CENTER STEERING WHEEL
This condition may accompany a steady pull or memory steer. But if the
steering wheel is off-center (crooked)
Steering linkage not centered when toe was adjusted. Correct by
recentering steering wheel and equalizing lengths of both tie rods, then
readjusting toe to specifications.
Bent steering arm or linkage. Check turning angle both ways. If arm is bent,
knuckle (or strut if arm is attached to strut) will have to be replaced.

21.  STEERING WANDER
The vehicle lacks directional stability and wanders or drifts from side to side.
Loose or worn steering components. Inspect the
tie rod ends, inner tie rod sockets on rack &
pinion steering units, and the idler arm and center
link on parallelogram steering. Check the steering
column couplings. Also check for loose or broken
rack mounts. Check the amount of play in the
steering rack or steering gear. Lateral play at the
edge of the steering wheel should usually be less
than 1/4 inch (always refer to manufacturer
specifications). Replace worn parts and/or adjust
rack yoke or adjustment screw on steering box to
reduce play.
Loose or improperly adjusted wheel bearings.
Check and adjust wheel bearings to specifications

22.  STEERING WANDER
The vehicle lacks directional stability and wanders or drifts from side to side.
• Insufficient caster. This may be due to
increased ride height at the rear of the vehicle
(raising the rear end with air shocks or air
springs) or lowered ride height at the front of
the vehicle (weak springs or shorter than stock
springs). Increase caster and/or reset to
specifications.
• Extremely low tire pressure. Inflate to
recommended pressure.
• Extreme toe misalignment. Check the steering
linkage and adjust or repair as needed.

23.  Bump steer
The steering suddenly jerks or veers to one side or the other when the vehicle
passes over a bump. The condition is caused by unequal toe changes that occur
as the suspension travels through jounce and rebound. The condition can be
confirmed by checking individual front toe with the suspension loaded
(compressed), then checking toe again with the suspension raised slightly. If the
amount of toe change is not equal on both front wheels, it can cause a
momentary pull to one side. The direction of the pull will depend on which end
is high or low, and whether the steering linkage is ahead or behind the knuckle.
Possible causes include:
Parallelogram steering linkage not level. Check the idler arm
height, and adjust as required.
Steering rack not level. Check rack height and rack mounts.
Repair, adjust or replace as needed.
Bent steering arms. Check to see that both are the same
height. Replace knuckle (or strut if arms are mounted on strut)
if bent to correct.
Structural damage such as frame twist, mislocated or twisted
crossmember or engine cradle.

24.  Torque Steer
Equal outer steering joint angles produces equal steering Torque
If one side receives more engine torque that side creates more tow
in and result is pull on one side
Specially during Acceleration.

25.  Torque Steer
The steering veers or pulls to one side during hard acceleration. This is a common
condition in front-wheel drive cars with unequal length driveshafts, and is caused
by unequal toe changes as the suspension is loaded.
Compliance allows the wheel with the longer driveshaft to experience less toe-in
change than the wheel with the shorter driveshaft. This causes the vehicle to veer
towards the side with the longer driveshaft. FWD cars with equal length drive
shafts usually do not experience this condition.
Torque steer cannot be eliminated but possible to minimize, but certain
conditions may make it worse:
• Loose or collapsed control arm bushings.
• Loose or worn tie rod ends.
• Loose or worn inner tie rod sockets.
• Loose or broken engine/transaxle mounts.
Vehicle manufacturers have offered various repairs to reduce the severity of
torque steer in some FWD cars. The corrective measures include using stiffer
control arm bushings, shimming motor mounts, realigning the engine cradle,
replacing the motor mounts with stiffer mounts, or increasing cross-camber.