Wheel balance and alignment: lets talk about how the forces on the wheels are tamed.

The entirety of our universe is based on balance. From the concept of good and the bad, the light and the darkness, Yin and Yang to the need for positive and negative electrons in an atom, to the need to balance personal life with work or relationships, even the need to balance steemit life with real life! Tell me, isn’t balance so important?

Today I wouldn’t be talking about how to balance life (I am neither a psychologist nor a motivational speaker) but I would be talking about balancing of a part of the automobile– the wheels (or tires, or tyres or whatever it is called in your part of the world).

Do I need to tell you about the wheel? Maybe I should.

The wheel is the part of the automobile that makes contact with the road. It is the final part that receives the energy delivered by the engine in the form of rotation and it helps the vehicle move smoothly on the road. They are connected to the suspension and are vital parts of the automobile. The wheels on a vehicle are ~usually~ round. ( have you ever seen a square wheel? I guess not). Wheels all over the world are black in color. If you want to know why, you can check it out in this post I wrote some time ago.

The operation of the automobile requires the wheels to rotate and maintain contact (traction) with the ground. In summary, without the wheels, any automobile is only a static engine i.e. the engine might be able to run but the vehicle cannot move.

As a circular body that rotates, the wheel needs to have an even weight in order to ensure a smooth ride. This need for an even weight of the wheel is very important to the comfort of ride and also the life span of the wheel itself. Before I go on, I would like to do some analogy.

Class in session

First, I would like us to do an experiment. It can be done in your mind or physically if possible.
You would need a rotating machine (something like a DJ turn-table). Place a circular stainless (or metallic) plate on the turn table and observe the motion of the plate. It should be rotating with the turntable evenly. (the reason why I asked us to use a plate is so as to have a part of the plate – the edges away from the surface so we can see the motion)

As usual, lets add a twist
Get a small but fairly heavy magnet and attach it to one side of the plate. You should notice a wobbling of the plate as it rotates on the turn-table. The wobbling is as a result of the uneven distribution of the weight.

One last thing.

If you attach a magnet of similar weight directly adjacent to it across the plate and examine the motion. What is expected is that the wobbling stops and the rotation of the plate is even just like without any weight.

This is because the weight you added was able to counter the effect of the first and thus balance the weight of the plate and allow the uniform rotation of the plate.

Science behind it?

When the weight is attached to one side of the plate, it disturbs the balance or equilibrium of the plate as a result of a centrifugal force F₁ = M ω² R

With M as the weight, ω, the radial velocity and R, the radius (distance from the weight to the axis of rotation).

Adding the other weight on the other side causes another centrifugal force F₂ = M . ω . ² R which counters the effect of the force F¹ and brings the rotating body to equilibrium. That way we can say it is balanced

The same principle is applied to the wheels of an automobile to ensure a balance of the weight of the wheel.

a wheel balance machine SOURCE: wikimedia commons under the Creative Commons Attribution-Share Alike 3.0 Unported license

WHEEL BALANCING

The wheels of vehicles are usually produced with precision and straight from the industry, it is usually perfect (or almost perfect) but some factors cause the weight of the wheel to be uneven when mounted to the vehicle. When assembling the wheel and rim, a small dent on the rim can knock out the weight distribution of the wheel also, of a truth, it is quite impossible achieve a perfect weight in the wheel all round and these small imperfections have an effect on the balance of the wheel.

If the wheel is rotating at high speeds, the factor of the centrifugal force due to the uneven weight comes to play and affects the rotation of the wheel causing it to wobble and would result in vibration which would be felt by the occupants of the vehicle. The vibration also has a negative effect on the wheel and causes wear. These vibrations would increase as speed increases and the effects are definitely going to be more fatal, affecting the comfort of ride and also extending to the other parts of the suspension.

That being said, I believe I have been able to explain to you why vehicle manufacturers advice balancing of wheels after a particular distance.

if you have experienced a wobbling steering or vehicle while driving and you take it to the mechanic, he would recommend you to do a wheel balance

Wheel balancing is simply a procedure of adding of (small) weights in order to compensate for the unevenness of the wheel weight. Just like in the analogy I made, addition of that second magnet canceled out the effect of the first and returned the rotation of the plate to normal, the same thing is done when doing a wheel balancing.

HOW WHEEL BALANCING IS DONE

Wheel balancing can be done in two different ways by measuring the two different types if balance associated. They are;

• STATIC BALANCE
  From the word “static” it can be decoded that this tyu[e of balance is measured with no rotation of the wheel. Static balance of a machine is measured using a static balance machine.

The commonest type of static balance machine is a device that has been calibrated with a bubble gauge. The static balance of a wheel is measured by placing the device on a level ground and mounting the wheel on it. The position of the bubble on the gauge indicates the balance of the wheel. Although these type of balancers are still in use, there are computerized static balancers that perform the same function with more precision.

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• DYNAMIC BALANCE
  If you have sone a wheel balance before and you wait to watch how it is done, you would have seen the mechanic use a dynamic balancer to balance your wheel.
  This type of machine is usually computerized and senses the forces that are effected when the wheel is spinning at a high speed. As a result of the spinning of the wheel, the centrifugal forces are sensed and the point where the forces are emerging form are recorded by the machine.

To use a dynamic balancer to balance a wheel, the wheel is mounted on the machine and locked to position. Switching on the machine, it spins the wheel to a speed of about 100RPM or higher and locates the points where the centrifugal forces are emanating and the amount of weight needed to cancel it out. The machine then guides the operator to the point where he would attach the correction weights.

When a static or dynamic balance is done, correction weights are attached to the wheel to counter balance the centrifugal forces due to the uneven weight and a equilibrium of forces is achieved. Counter weights come in various sizes and are easily attachable to the inner or outer rim of the wheel either by glue or by knocking them on with a rubber mallet.
so, when next you see those small pieces of metal attached to the rim of your wheel, you should know what they are for and you shouldn't remove them as that could knock off the balance of your wheel.

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Balancing of wheel is usually done alongside a process called wheel alignment but they are not the same things. As a matter of fact, wheel alignment and wheel balancing are two different things. However, I would like to say a few things about wheel alignment.

A vehicle mounted on an alignment machine. NOTE the sensors mounted on the wheels (image taken by me)

WHEEL ALIGNMENT

As the name implies, wheel alignment is a process of adjusting (or aligning) the wheel position as specified by the manufacturers or to suit personal preferences. Generally, wheel alignment is aimed at making the wheels at right angles with the ground and parallel to one another. This ensures that the wheel has enough traction and handling of the vehicle is perfect.

A car with a wheel that is out of alignment would experience some or all of the following symptoms;

• Vehicle pulling to one side even when driving straight
• Vibration at the steering wheel
• Wear of the tread of the wheels unevenly and rapidly

If any or all of these symptoms are experienced, it is an indicator that the vehicle is out of alignment and should be fixed as soon as possible.

Unlike the wheel balancing, the wheel alignment operation is not done on the wheels directly and there is no need to detach the wheel from the vehicle rather the parts that connect the wheel to the vehicle.

In the case of alignment, there are three angles that are checked and corrected to ensure proper alignment. They are the toe, camber and caster. Lets take them one after the other.

• TOE
  Well this is not the toe on your feet but the inward or outward tilt of the wheels if they are viewed from above. Simply, to explain the toe, let’s do another simple exercise.
  Stand on a level ground and look down at your feet. If you position your feet inward and you have demonstrated a toe-in situation of vehicle. If they are positioned outward, away from each other, that is called a toe-out alignment. Simple isn’t it? In any case, the toe-in or the toe-out alignment need to be corrected for proper alignment.

• CAMBER
  Just like the toe, the camber is the angle of tilt inward or outward but this time around it is when the wheels are viewed from the front of the vehicle. When the vehicle is tilt inward, it is called a negative camber, if outward, it is a positive camber any of which affects the alignment if too much.

• CASTER
  A caster is the angle of tilt of the steering axis. This is usually when viewed from the side. If the tilt is toward the front of the vehicle, it is called a positive caster. If away from the front, it is a negative camber.

The caster is quite important as it has effect on the straight line driving, negotiating corners and stability of the vehicle.
The three angles are very important in ensuring the proper alignment of the vehicle to ensure a smooth and comfortable ride. No one would be happy to have his vehicle pulling to one side on its own. It could lead to an accident or could cost the owner some money due to the uneven and rapid wear of the wheels.

A vehicle can be out of alignment due to a lot of reasons such as worn bearings or ball joints or expansion or contraction of other parts of the suspension such as the tie rod. Alignment is done on an alignment machine where probes are mounted on the wheels and calibrated using a computer. The computer then measures the toe, camber and caster angles respectively indicating whether it is positive or negative thereby guiding the technician on how to adjust the angles.

There are some other angles that can be checked in the case of extreme alignment issues. These angles are called secondary angles and they include; Steering Axis Inclination (SAI), Included Angle, Scrub radius, Riding Height, Set Back, Thrust Angle, Steering Center and Toe Out on Turns

The wheel alignment and balancing processes are not complete without a test drive as the technician is required to drive the vehicle to see the effect of the adjustments made. When next you take your vehicle for an alignment and balancing, it would be nice for the technician to do a test drive to ascertain that the correction made are effected and on the right plane (in the case where you do not trust the technician, maybe you should do the test drive yourself).

CONCLUSION
Wheel alignment and balancing are two independent operations done on a vehicle to ensure the correct quality of ride and cancel out irregularities. Usually, experts recommend having a wheel balance and alignment done every 5000 or 6000 miles to ensure optimum performance of the vehicle and also increase the life span.

When next you notice any of the indications I mentioned above, I think it is time to visit your mechanic. Although the symptoms are not perfect pointers to a balancing or alignment problem, making the decision to visit the mechanic for diagnosis the first and the best decision. As I would say, it is not advisable to perform a repair or any operation on your vehicle if you are not trained to do so.

The feedback I get on my content is always amazing and I hope I get some more on this one. Please endeavor to drop comments as they are appreciated. Do have a nice day.

REFERENCES
1 Wheel alignment
2 What you need to know about tire alignment
3 Wheel alignment and wheel balancing
4 Tire balance
5 The what, why and how of wheel balancing

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