Wheel Alignment - 101 questions!

Hi Guys!

Looking at doing wheel alignment for my A6 myself. Looked on YouTube and dozens of useful videos there covering this subject in-depth, BUT three questions!!!

  1. For toe in and out, whether using string method, or laser etc the theory seems to be the same. The Toe In and Out can be checked by checking the alignment against the rear wheel on the same side. This seems to be VERY common in the videos. But how do you know that the rear wheel will be straight? It is simply because it does not steer and so, in theory, should always be straight??? And if so, does this also apply to four wheel drive cars?

  2. For toe in and out (again) another method is to use two plates against the front wheel and measure the gap between them at the front and rear of the wheel. So this would show toe in/out if the measurements are different, but how on earth would you know which side the in/out is happening on as there is no other point of reference, so you could set it with the toe in on one wheel, and toe out on the other and the measurements would be the same, but both wheels would not be straight!!??!!

  3. My last question relates to Camber. I’ve seen a lot of the spirit level type of tools which have a magnet on the bottom and stick on to the brake rotor (disc) and measure the camber that way. BUT this is done with the wheel removed and car jacked up - but how do you know that when the suspension is drooping (i.e. jacked up) that the rotor angle is the same as when the wheel is on and weight on the suspension?? I would guess that the angle would be very different, or is my logic off?

Any help with these three questions much appreciated!!!

Your Audi has independent rear suspension. So a four wheel alignment is required for a proper wheel alignment.


Why not just take to a shop that has the proper equipment and knowledge or you can leave it go and spend $$ one tires sooner or have it done now and spend $$ on tires much later.


Do you have a problem with tire wear or is this something you just want to do ?

I’d prefer to do the alignment myself ideally, most shops only adjust toe in/out as anything beyond that (camber etc) is time consuming and adds up to big money quickly. Plus we have three cars, so would be nice to do myself as 3x the savings!!

I’ve change the front struts recently, and want to get things set back up correctly.

I’d prefer to do the alignment myself ideally, most shops only adjust toe in/out as anything beyond that (camber etc) is time consuming and adds up to big money quickly. Plus we have three cars, so would be nice to do myself as 3x the savings!!

To me that would be false savings as you don’t have the equipment or knowledge or you would not be asking the questions you have.


So, don’t bother learning anything, just pay someone else to do everything in life for you?

Very helpful advice, thanks for that :frowning:

Did not say that there are a lot of things worth learning but when it comes to needing expensive equipment unless you are planning on going into the buisiness for yourself it is much cheaper in the long run to pay some one else to do it for you.

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So it’s impossible to do four wheel alignment in a more DIY orientated way?

Unless you have a machine that costs thousands, it’s simply not doable?

There must be a way?

In the old days when cars were body on frame you could get a decent alignment with the string and level method but now with the unibody and four wheel alignment needed things are much different.


Just about, if you’re just talking strings and carpenters levels. I’d spend my time learning about maintenance items well suited to the home garage: fluid changes, brake jobs, filters. Get the alignment wrong and you’ll be buying tires.

And if your shop only does the toe adjustment because it’s easy, then you need a new shop. Some cars have limited adjustments without buying camber plates, that kind of thing, but a good shop will check everything and recommend that if needed.


I won’t say the string method will work or not work. But if you have the proper tires ( not cheap ) on this A6 why not let a good shop set things as they should be . At least that way you will have some kind of warranty and many places have lifetime alighnments .

Most likely only the front needs anything. So you can try that and leave the rear alone.

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Yes, I was thinking on looking at adjusting just the fronts as that’s where the work was done.

Would I be correct to assume that the rear wheel alignment (thrust angle) is usually checked first on a ‘proper’ wheel alignment, and then the fronts are checked for toe in/out using the rears as the point of reference?

The rear toe is adjusted first and it often requires adjustment.

The front and rear track width are not equal on all cars so you can’t directly eye-ball the front to rear tires for straightness.


Interesting! So on a professional laser machine, once those rear wheels are checked and set with the correct track on each side, how then does the machine align the fronts - I am assuming it must reference against the rears which get set first?

You would imagine that the laser (much like a piece of string, i.e. a straight line) will not be accurate to use to reference the fronts, unless the rears have a dead centre 0 track on them (i.e. perfectly straight). Does a machine somehow allow for the angle change of the rear wheel track to allow you to still cross reference the rear to the fronts for your front toe adjustments?

The machine measures the alignment of each wheel independently.

But how? What is it referencing from? It’s can’t be gravity for toe and that is linear, not vertical (unlike camber).

How does it reference the wheel angle aginst the chassis/car angle? What’s it measuring from and to?

Put 4 wheel alighnment video in your search engine and you will find many Youtube videos showing just how it is done.

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Good idea! I’ll take a look. The only ones I have seen so far just show how the targets attach, but not actually what’s being read/referenced, but I’ll take a look to see if anyone out there is explaining what’s actually happening when the lasers are firing.