Alignment The Big Con

[wheels-inmotion.co.uk]

Hello all. This is my first post so please be gentle. My name is Tony, i live in the UK and i have a particular interest in the Lexus.... To explain our field is chassis calibration and evolution. Here in the UK LOC approached "wheels-inmotion.co.uk" to find a solution for the members front tyre wear problems on the IS200/300/SC.

Several cars were invited for measurement... It became obvious that the static positions Lexus set were... Wrong! So we re-wrote them... These are available free on request.

One issue we have in the UK and i assume this is the same globally is how tyre centres describe their method of measurement. So in the hope a complete explanation helps i offer this...

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Various methods are described to encourage you to resolve tyre wear or handling issues, additionally members in forums are keen to advise but often fall victim to the same miss-information, read carefully and stay ahead of 'alignment the big con'

Tracking/Alignment

Is linear, this measurement shows no concern for any other angle. This form of measurement is the most common in the World and the most damaging.

Angles measured 1

Four wheel Alignment

Uses the rear wheels as a scale to centre the steering rack.... then the front toe..... this is better but is assuming the rear is centred.

Angles measured 2

Four wheel Laser Alignment

Same as above.... be wise!

Geometry/Primary

Will image the exact rear centre line to permit a centred steering wheel.. additionally the front and rear camber positions will be measured. This is the most common form of Geometry and i consider this as 'basic'

Angles measured 8

Full Geometry/primary and Secondary

Is absolute but harder to understand. Few places even with the equipment measure the Secondary angles, these include...

Castor

KPI/SJI/SAI

Scrub radius

included angle

TOOT/Ackerman

Delta curve

and so on

Most areas that involve rapid tyre wear or handling issues need to be read from the 'Secondary' data, even more important if the car has been modified or for diagnostics after an accident.

Angles measured 15+

Not easy reading indeed, millions of pounds change hands every day for 'Alignment', a need to be wise could save you £ssss

One more thing to make the 'blood boil'.. The Primary and secondary Geometry has a customer destination?

1: Primary is the 'dumb' customer version

2: Secondary is with held unless requested and named the 'Technicians version.