Areas not directly related to the brake system should be inspected as
they may indirectly cause noise or pull when the brakes are applied.
Tire condition and inflation pressure should be considered.
The pressure and tire size should be equal from side to side
on the same axle. Tire condition may indicate front suspension
problems.
Shimmy: A condition where the front wheels oscillate laterally resulting in rotational movement at the steering wheel.
• Dynamic wheel imbalance
• Excess tire/wheel run out
• Radial force variation
• Excess positive caster
• Excess front toe-in
• Worn/bent steering components
• Worn/bent suspension components
• Wheel bearings
• Excess steering gear lash
• Steering damper
• Structural damage
Loose wheel bearings may allow the disc to wobble on disc brake
systems. This moves the piston farther back into the bore (large
brake clearance) so that additional brake pedal travel is required
to apply brakes. On drum brake systems, the drum cocks which
can cause grabbing and pulling; shoes may drag when properly
adjusted.
Worn suspension bushings or ball joints change front-end
geometry and may cause a pull or drift when the brakes are
applied.
When excessive wheel and tire run-out is present, a vibration may
be felt on brake application. Check the vehicle Repair Manual
for the specific run-out specification. Vibration may also be felt
at cruise speeds. For example, it may come in at 55 mph and be
gone at 60 mph.
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