FAQ’s & COMMON PROBLEMS
 There’s a strange noise coming from somewhere under my car or I think my vehicle may be unsafe?
This is a common problem that could both be due to worn components, which may need adjusting or replacement.
There is oil leaking from somewhere under my vehicle?
This could be due to your power steering or shock absorbers. Fulcrum can check these components for you.
I am getting bad tyre wear. My vehicle pulls to one side. My vehicle wanders all over the road or swerves when I change lanes. I can feel vibrations whilst driving and am generally experiencing a rough ride. When I stop quickly I lose control of my vehicle and the front end nose dives?
These are all common signs that your wheel alignment and/or balance is out, your suspension components are weak or worn, or your tyre pressure is incorrect. Your wheel alignment and tyre pressure should be checked and corrected, you may need to replace or adjust worn suspension components or tyres. Correct wheel alignment will help reduce tyre wear, improve your car’s handling and fuel economy, and make driving more enjoyable and safe.
Taking some of these simple steps can greatly improve the ride quality and steering control characteristics of your vehicle. Why not call Fulcrum today for a FREE no obligation suspension and safety check at one of our Service Centres.
Why is my wheel alignment incorrect in the first place?
Mass production vehicles are built within certain tolerances. Changes in alignment settings can be caused by hitting potholes or bumps, loose steering or suspension components, and through normal wear and tear caused by vehicle ageing.
How do I check my tyre’s wear?
These images show some of the most common types of tyres wear:
1) Feathered wear:  2) Cupped wear:
3) Both edges worn: 4) One edge worn:
Why do I need to correct camber and caster?
Correct camber and caster will provide smoother, fatigue-free, safe driving and longer tyre life.
What does a spring actually do?
The springing system is the load carrying device on a vehicle which absorbs the shocks of the road. Although suspension springs all serve the same purpose and have certain characteristics in common, actual spring designs vary widely. Four types of springs are currently in use in automotive suspensions:
- Leaf Springs
- Coil Springs
- Torsion bars
- Air Springs
Generally, the less external friction a spring creates, the more efficiently it operates. Friction interferes with spring movement, so an ideal spring should create little or no friction. However the less friction within a spring, the longer it continues to oscillate after it compresses and extends again, because nothing interferes with its movement. During their operation, leaf springs create external friction, which interferes with their movement. Coil springs create virtually no friction, while torsion bars create a small amount at their pivot point. External friction is not a problem with air springs because they do not use moving metal parts.
What is a shock absorber used for?
On a vehicle’s suspension, shock absorbers provide the friction needed to control and quickly stop oscillation caused by the spring. In Europe, shock absorbers are known as "dampers," which is actually a more accurate name, since the springs actually absorb road shocks, while shock absorbers dampen the spring action. Some Japanese manufacturers refer to shock absorbers as "dampeners".
Due to the large range of uses and applications of vehicles, dampening control in the aftermarket is a science. Aftermarket manufacturers offer a range of shock absorbers and struts designed to give greater control, altered ride conditions and longer life. Fulcrum Suspensions uses these products as part of a complete suspension system solution, whether it be for enhancement or safety purposes.
What is Bump steer? And why do you need to correct it?
Bump steer is defined as the variation in ‘toe’ that occurs when the suspension moves up or down without body roll. A significant number of technicians are not aware of the excessive tyre wear that can occur when bump steer is not considered and calculated, when performing wheel alignment.
Causes of bump steer are:
- Design of the steering linkage.
- Tie rod end positioning.
- Steering linkage that has been bent either through an accident or excessive loading.
- Toe adjusted without centralising the steering box or rack.
- An alteration to the vehicles ride height.
- Soft suspension bushes and worn front and rear independent suspension components.
A rolling toe of zero, with the thrust angle on the vehicles centre line will provide for the long tyre life and even tyre wear that customers require. Incorrect toe will destroy tyre tread quicker than any other incorrectly set alignment angle or setting and will occur on both front and rear independent suspensions. When bump steer is correct, apart from tyre wear being minimised, the vehicle will maintain stability over all terrain surfaces, provide effective braking under all conditions as well as positive tracking whilst cornering.
How does bump steer occur?
In the following example a Technician has adjusted the toe-in on a vehicle to 4mm (2mm per side) and has positioned the rack correctly. (Fig. 1) As the rear wheel drive vehicle starts to move, rolling resistance will cause the wheels to be pushed backwards and provide a rolling toe of zero mm (Fig.2). Any movement of the suspension components on compression or rebound will cause further changes to toe and this variation is termed ‘Bump Steer’. Application of the vehicles brakes will also cause suspension movement and change rolling toe, if this toe change is excessive and outside specified parameters, tyre wear will occur at a rapid rate (Fig. 3)
Manufacturers design also causes “Bump Steer”, through the tie rod ends not traversing the same arc relative to the rise and fall of the suspension support arms (Fig. 4). In this diagram, the path taken by the control arms varies from the tie rod end. This quite clearly indicates that as the deflection increases, so does the amount of toe change. Technicians can reduce toe change tyre wear by observing a few simple procedures.
How is bump steer correction calculated?
Firstly the Technician must familiarise themselves with the normal load and operating conditions of the vehicle. Manufacturers also in some instances specify alignment settings with a loaded height, so always check your specification charts for any loading requirements.
Secondly ensure the steering is centred and adjust the toe setting to zero. Next compress the suspension 25 to 30 mm and observe the toe reading, then extend the suspension by the same amount and observe the reading. This then will provide the operator with that vehicles “Bump Steer” over average suspension travel. If the operator notices a greater change in one side to the other checks must be made to determine if any suspension components are damaged, worn or bent. The average change should then be used in conjunction with the manufacturers specification to provide a rolling toe of zero. Remember other factors that will affect bump steer are spring and shock absorber rates as well as the fitment of low compliance bushes or modified idler arms, etc.
SUSPENSION TERMINOLOGY
Toe in/Toe out
The Toe measurement is the difference between the front of the tyres and the back of the tyres. Toe in means the front of the tyres is closer than the rear and toe out is the opposite. Excess toe in, on a vehicle’s axel will usually wear the outside edges of each tyre and too much toe out will generally wear the inside edges of the tyres. Fulcrum’s Alignment Technicians take into consideration the amount of bump steer, camber, tyre offset, tyre size and the type of general driving you use the vehicle for, to arrive at the correct toe settings on your vehicle.
Camber
The inward or outward tilt of the top of the tyre as viewed from the top of the vehicle. A vehicle’s camber can be negative or positive depending on the vehicle manufacturer’s suspension design. Positive camber is when the wheels lean outwards (from a vertical line) at the top, when looking from the front or rear of the vehicle. Negative camber is when the wheel leans inwards at the top.
Too much positive camber will generally wear the outside of the tyre tread and too much negative camber will generally wear inside of the tyre tread. Negative camber provides a full footprint of the tyre during cornering or weight change on the vehicle’s suspension, with the settings being a compromise between design, handling and good tyre wear. Excessive variation from side to side can cause the vehicle to veer to one side.
Caster
The forward or rearward tilt angle of the steering axis, calculated by the line that runs through the upper and lower pivot. Caster can be negative or positive pending on the vehicle manufacturer’s suspension design. The caster angle provides straight line stability and assists in the self centering action of the steering.
Positive caster is when the upper pivot in relation to the lower pivot is to the rear of the vehicle. Negative caster is the opposite. Excessive variation from side to side on the vehicle will make the vehicle pull to the side with the least positive caster.
ABOUT SUSPENSION
Normal wear and tear on suspension and steering systems happens gradually, which means as a driver you will adapt to the changing driving condition of your vehicle and be mostly unaware of that your vehicle may be becoming unsafe. Worn suspension components will increase your vehicle’s breaking distance and body roll, and in general make your vehicle more difficult to control, especially at high speeds.
Look for the tell tale signs:
- Uneven tyre wear
- Your vehicle ‘wanders’ across the road or swerves when changing lanes
- Squeals or clunks from the front or rear
- When breaking your vehicle nose dives or you lose control
- You are generally experiencing a rough ride.
Did you know the correct wheel alignment can help SAVE on your car’s FUEL USAGE?
Vehicle misalignment can cause poor fuel economy. If the rear axle is incorrectly aligned it can cause tyre drag that will result in lower fuel economy and increased tyre wear. Keeping your car’s tyres at the correct tyre pressure will also help improve fuel economy.
Regular suspension checks
Regular suspension checks will help keep you safe and enhance your vehicle’s performance and handling. Ask one of Fulcrum’s Suspension Specialists how we can help make your suspension perform better for you.
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