How to Balance a wheel correctly!
In our last wheel balancing article we discussed the difference of dynamic and static wheel balancing, this time however we are explaining how to balance a wheel correctly.
So before we start please keep in mind that this article has been written using very basic terminology in order to make it as easy to follow as possible.
Trust us when we say we are aware that there is a far higher degree of technicality involved (god knows we get bombarded with keyboard warriors wanting to point out specifics) but we do have to get the point across to everyone and all abilities.
Setting up the wheel balancer.
This may sound like an obvious place to start but you would be amazed at how often this gets overlooked and even ignored, and is the most common reason for us getting called out to look at a “Malfunctioning” wheel balancers.
And for this article we will be using the Teco 710 as our demonstration model but all balancers work the same, albeit with variations on display and data acquisition and entry.
There are THREE!!! …. Yes three dimensions that wheel balancers require in order to measure the wheel imbalance correctly. These are:-
- The DISTANCE (d) from the wheel balancer cabinet to the inside edge of the wheel
- The DIAMETER (di) of the wheel itself
- The WIDTH (Lr) of the wheel (often known as the J size of the wheel)
Note… the unit measurements of d, di and Lr are the normal units found on Italian manufacturers.
These measurements are important for wheel balancer computer to know where the inside and outside edges of the wheel are in relation the wheel balancer face plate, but also the height of the rim lip or rim edge from the shaft where the weights will be positioned.
If you do not put all three measurements into the wheel balancer then the wheel will NOT be balanced correctly, and may cause you problems with “chasing weights” or “comebacks”.
All machines will have the ability to enter the data manually either with buttons or dials (generally found on much older models).
Most newer automatic wheel balancers have a measuring arm that you pull out to measure the distance and diameter of the wheels.
Then for the third wheel data entry which is the wheel rim width (or J size) of the wheel you would either use a set of wheel rim callipers to manually measure the rim or use an optional measuring system of the wheel balancer.
Some machines will have an “outside measuring arm” which you would pull into contact with the outside rim edge. Others may use a sonic measuring device which is normally connected the wheel balancer hood.
Mounting the wheel.
Now I know what you’re thinking ….. How hard can this bit be right? …. Well you would be surprised.
Back in the days of all wheels being steel wheels the general setup would be to “Front Cone” the wheel. This is where you place the wheel onto the shaft, then slide on the centring cone, followed by the lock nut.
Ultimately this is not really the best way to balance a wheel as the cone is centring on the outside face of the wheel hub mount, but due to steel wheels being fairly thin in material thickness it has very little effect on the “Run Out” of the wheel.
With the onset of alloys wheels (which has generally become the norm for most cars) it becomes more important to use the “Back Cone” mounting method. This involves fitting the correct cone onto the shaft first (the reverse of front cone setups) followed by the wheel, then locked in place with the locknut fitted with a clamping hood with protective rubber ring. This minimises the amount of run out created when balancing wheels, due to the wheel being centralised on the wheel hub mount as opposed to the centre cap hole.
On larger alloy wheels the profile of the mounting hub (from front to back) can be as much as six to eight inches thick. If the alloy wheel is mounted using the front cone method it can result in an increased amount of runout causing the wheel to be incorrectly balanced.
There are also Pin or Finger plates that can be used for absolute positioning but we will cover these at a later date.
Wheel Balancing Procedure
At this point your wheel should be mounted correctly and all three dimensions had be input into the wheel balancer.
The last step would be to choose the wheel balancing program i.e… “Knock on” or “stick on” weights (or a combination of both) to suit the wheel you are balancing.
There are several different weight balancing programs but for simplicity in this article we will just use the “knock on” method. The “stick on” method works exactly the same.
Ensure you have remove all previous wheel balance weights, then start the measuring run and let the machine spin the wheel up.
Once the measuring run has completed, your wheel balancer will calculate how much imbalance there is in the wheel and display the weight required to balance it up correctly.
In this instance you can see that the machine is asking for 5 grams to be fitted on the inside and 15 grams to be fitted on the outside. So rotate your wheel until the wheel balancer indicates you have reached the point in which the weight is to be applied.
Each manufacturer and model is different and will use either an LCD panel which will use LED’s indicators, an LCD Screen (as seen with the Teco 710 we are using) or a TV / Monitor display.
But either way there will be a centre point which will be obvious regardless of which system it uses, this is where you would fit the weight indicated on the display.
Note:- For 90% of wheel balancers this will be in the 12’ o’clock position or Top Dead Centre. Some other balancers can use the 6 o’clock and 3 o’clock positions but this will usually be indicted on the display.
Then once you have fitted the weights required on both plains (if required) finish off the balancing procedure by starting another measuring run. If all is good then your wheel balancer should indicate zero in both weight planes.
This means that the wheel is balanced.
But it’s got weight reading still?
Ahhh the joys of wheel balancing…. now this is where good fitters prove their craft and poor training becomes evident.
In the event of the wheel balancer indicating anything other than zero zero on both balance plains, you now need to either add weight, remove weight or move the weight!
For this next bit you have to imagine you have rotated the wheel to the point in which the machine indicates the imbalance.
When to ADD weight.
So the weight reading is locked into position and the wheel weight fitted in the previous balancing run is located at either top dead centre (12 o’clock position) or as near as. This is when you add the desired amount of weight by removing the weight and fitting another to suit the amount required.
- So in this instance the previous weight was 20 grams
- The new indicted weight is 5 grams
- 20g + 5g = 25g
- Remove the 20g weight and replace with 25g
When to Remove weight.
So the weight reading is locked into position and the wheel weight fitted in the previous balancing run is located opposite of top dead centre (6 o’clock position) or as near as. This is when you remove the desired amount of weight by removing the weight and fitting another to suit the amount required.
- So in this instance the previous weight was 20 grams
- The new indicted weight is 5 grams
- 20g – 5g = 15g
- Remove the 20g weight and replace with 15g
When to move the weight.
So the weight reading is locked into position and the wheel weight fitted in the previous balancing run is located anywhere other than top (12 o’clock position) or bottom (6 o’clock position) this is when to move the weight.
The direction to move the weight will depend on which side of the shaft the previous weight is sitting, but will always be moved towards top dead centre. So if your previous weight sits between the 7 and 11 o’clock positions you would move the weight clockwise (as in the image above). And if your previous weight sits between the 1 and 5 o’clock positions you would move the weight anti-clockwise.
How much do you move the weight? … Well there is no hard or fast rule and everyone has their own methods but me personally, I would generally move the weight about an inch for every 10 grams difference.
Re-spin the wheel and check the imbalance reading.
Note:- If you are consistently getting the same imbalance no matter how much you add, remove or move the weight and just cannot get a zero reading regardless of how precise you are being, then you are most likely in need of having your wheel balancer calibrated.
You should only ever have one small area on a balancing plain with wheel weights. If you have multiple wheel weights spread around the wheel this is called “COUNTER BALANCING” and means the wheel is NOT balanced!
This is where an operator does not know how to correctly balance a wheel and simply just keeps adding more and more weights to a wheel in an effort to achieve a zero reading.
The amount of times I have seen this is just painful, and just shows how many people out there are balancing wheels incorrectly.
If you or your staff require training on wheel balancing please get in contact with us where we can organise one of our engineers to visit your place of business and provide on-site training. Certification of training can also be provided.