WORK­SHOP

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.

Mini Magazine - - Contents - Words and Pho­tog­ra­phy Neil Burgess

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.

MEA­SUR­ING TOE

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.

Track­ing ex­plained.

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