talken from another forum but posted by wheels in motion. im sure they will confirm this. i think it should be a sticky as its very useful
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
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