In the third part of our Mini handling series, we look at the Mini's tracking; one of the easiest suspension changes that you can make.
Part Three of our handling series looks at tracking and how you can adjust your Mini’s suspension.
Tracking the front suspension is the easiest suspension change you can make to your Mini, and I’m sure you’ve all had the tracking set at some point in the past.
Four-wheel alignment on a standard Mini is okay, but with standard radius arm brackets or even those which let you change the camber, you can’t alter the
tracking on the rear of a Mini. You can however get camber brackets which also let you alter the tracking.
At the front, you wind the end of the steering rack in and out of the track rod ends. Winding the steering rack ends (steering rack tie-rods) into the track rod end effectively reduces the length of the
steering rack assembly, so pulling the back edge of the wheels further together.
The tracking is described as ‘toe in’ or ‘toe out’. When the back edge of the wheels is closer together than the front edge then that’s ‘toe out’. Just the same as when your heels are closer together than your big toes, your toes are pointing out. When the front edge of the wheels is
closer than the back edge, then you are ‘toe in’. Again to use the feet analogy, this is the same as if you stand with your big toes closer than your heels, as your toes are pointing inward.
The effect of tracking is something particularly noticeable. If there is no toe in or out, the wheels will be pointing
directly ahead. This is obviously best for driving in a straight line as the tyres are not fighting each other. However, it is good to have a little toe as it puts all the bushes and joints under some tension. Too much toe in either direction, however, can result in excessive tyre wear, which you don’t want.
GETTING THE BALANCE
As standard, the Mini comes with a little toe out. The setting is largely down to your preference but adding negative camber is likely to make a desirable change and a dash of toe in at the front can make a Mini a little more lively when turning in. Like everything, it’s a balance and you will need to work with how the back of the car is set up. It’s worth measuring the rear setup even if you are unable to change it as it can help you understand what is going on,
“It is good to have a little toe as it puts all the bushes and joints under some tension”
particularly if there is a difference from turning in one direction to the other, and you will then also have a reference point for when you can adjust the rear.
When you measure toe, it’s important that you do it with the car’s weight on the suspension. There is an effect called ‘ bump-steer’ which describes the way that the tracking changes with suspension drop or compression. Car designers do their best to design out bump steer but it’s inevitable, as the only way to eliminate it is to pivot the steering tie-rod so that it describes exactly the same arc as the suspension arms. As the pivot point changes when steering is applied, there will be some change when the suspension is dropped and compressed. This is also worth remembering if you adjust the ride height of a Mini.
Ideally, the same amount of steering rack tie-rod thread should be visible on both sides of the car, as this means the steering rack is centralised.
There are a couple of different methods to measure the amount of toe on your car. One is using the professional gauges, but the electronic systems and optical devices are expensive. Another is by using a plate which you roll the car on to, this deflects with the side pressure of the tyre and indicates if this pressure is due to toe in or out. A third method is by
“Car designers do their best to design out bump steer but it’s inevitable”
using a giant set of callipers to measure the difference between the front and trailing edges of the wheel, it’s this type of measurement that the Haynes manuals give measurements for. By measuring this difference in distance you can then either use that measurement or calculate an angle. Happily, the method of measuring your tracking doesn’t use expensive electronics or optics, it uses a couple of pieces of string!
What we are trying to achieve here is a measurement in degrees between the wheels. Set the steering wheel straight and then roll the car back and forth to let it settle down.
The best type of string is the nonstretchy type, but if you take care then you can use any type. We want to place the string so that when it’s tight, it just touches the front and back edges of the tyre without breaking the straight line.
If you set this up on both sides of the car, we can measure the distance between two points along each side of the string and then calculate the angle.
Start by tying the string around the back part of the wheel. Ensure the knot is around the other side of the tyre so when you stretch the string around the tread, it’s resting on the outer facing sidewall of the tyre. Then tie the other end of the string to an axle stand about 1.5 metres from the wheel.
Move the axle stand so that it is in front of the Mini and the string is taut. It should just be touching the other (front) side of the tyre but the string should remain straight.
Repeat this step on the other side of the Mini.
Now place a marker, perhaps a piece of tape, on to each piece of string (be careful not to deflect the path of the string), precisely 40cm from the point where the string touches the forward part of the tyre.
Then place a second marker one metre further away from the Mini, measured from the first piece of tape.
This gives you two points of reference. Measure the distance between the two pieces of string at the first marker and make a note of that distance. Then measure the distance between the two pieces of string which is another metre
further from the car. The first measurement should be less than the second measurement if the Mini has toe out. Every 17.5mm of difference is one degree of toe.
ADJUSTING THE TOE
When adjusting the rear toe, it’s also a good idea to extend a line forward and compare the distance between this and a point on the seam at one edge of the central crossmember, which is under the seats. These distances should be the same
on both sides to ensure that the rear wheels not only have the amount of toe you are looking for, but are also straight in relation to the Mini’s body. If they are not, then the Mini will ‘crab’ - the back end will not directly follow the front and the car will travel a little sideways.
Don’t forget that the rear of your Mini is narrower than the front, so if someone is following you, it’s easy for the inexperienced to think a Mini is ‘crabbing’ when it is not, as they will be seeing more of the side of the car than they expect.
“It’s easy for the inexperienced to think a Mini is ‘crabbing’ when it is not”
An axle stand makes a handy point to tie the string to.
Adjust the tracking by winding the track rod ends in and out.
Mini adjustable rear camber brackets.
Gently add tape markers.
Overview of the measuring system setup.
Measuring the distance between the strings.
The string should touch the tyre wall but not bend around it.