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wheel alignment the big con

4K views 10 replies 7 participants last post by  wheelsinmotion 
#1 ·
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
 
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#3 ·
Heh, this whole subject gets on my nerves. With my previous car I had cause to visit three different tyre centres within the space of a single month (one to have my alloys refurbished, one to have some new front tyres and one to have some new rear tyres). There were various reasons why I went to three different places, but the long the tall and the short of it is that each and every one of them came to me and said "your wheel alignment is out mate, it'll be £xx for us to put it right".

Hmm, so I need three wheel alignments in one month do I??? Funny that isn't it, unless each one of you is doing a very bad job of aligning my wheels then I rather think you are all bulls*****g me to get some extra £££.

Oh, and no I hadn't hit any potholes in between
 
#4 ·
Rant Alert!!

DARK ARTS spring to mind!!!! Like how do you know anything is 'out' until the tyres are scrubbed out and when you go back they say that you must of kerbed it! well if where I live is anything to go by then it seems that most people these days can't park their car unless they put two wheels on the kerb/pavement so this might class as kerbing it, even though there is enough room to park on the road properly no problem, I just wonder how they manage to DRIVE along the road if when it comes to stopping and leaving it they think its too big for the road ( must swell up when you put the handbrake on or something!) or is it a 'I'm only going to be a short time parked' or it could be a 'I'm at work' thing white vans especially)

Rant Over....

Cheers Paul M (flapless)
(all 4 wheels on the road!!!)
 
#10 ·
Hmm there could do with a little more explanation to some of those secondary angles.
I would challenge the view that the secondary angle contribute to the most tyre wear, Toe and Camber will produce some serious issues if outside manufacturers data.
It is unlikely that castor will contribute to tyre excessively, what it will do though, if the castors are uneven is to cause the vehicle to drift to the side with the least amount of castor.
SAI and scrub radius kind of go hand in hand and they will cause the car to tramline, pull under braking etc but they are unlikely to wear tyres.
TOOT could cause tyre wear but it is generally considered as a non adjustable angle and if the toes are correct and TOOT is out of spec, something is usually bent.
Delta or Toe curve change is rarely adjustable unless you own a couple of vw/audi vehicles and could possibly cause tyre wear but more likely poor handling would be observed.

The most important thing with wheel alignment is to ensure that the angles that can be adjusted, are adjusted by a competent techy who is interested in the subject and is using calibrated equipment to manufactures specs.
Rear toes have a massive effect on how the car feels and if yours are adjustable you should be using proper 4 wheel alignment kit to do the job.
 
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