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Checking toe-n and other DIY alignment issues

I have an '89 Cressida and I've been looking into DIY wheel alignment, rather than tithe $80 to the local tire place and just for the enjoyment of doing it.

It seems crucial that you have the ability to compare things to the centerline of the vehicle, but the things I've seen are a bit vague on this. For doing toe-in, for example, all the things I've seen talk about comparing the difference between the the front and rear of the wheel/tire. Okay, but how do you know which wheel is "right" to begin with? Let's say you see a difference of .5" inches (strictly for illustration) either way between front and rear. That could mean one wheel is exactly parallel to the centerline of the car and the other is skewed. Or they could both be toed in/out a bit. What do you use as your starting reference point, and how do you get all 4 wheels lined up with this centerline and further allow for the fact that the wheels are presumed to not be in perfect alignment to begin with?

-How do you find the exact centerline of the car and mark a line parallel to it?

-What about doing a car that has adjustable rear alignment such as this Cressida?

What's a great, clearly explained, idiot-proof website or reference for someone who wants to try this themselves without spending a fortune on tire shop equipment?

Thanks for all input

Reply to
Doc
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A proper wheel alignment on a modern vehicle involves all 4 wheels, which pretty much requires a 4 wheel alignment machine. An alignment machine finds the centerline of the vehicle by having a sensor head attached to each wheel. You've probably seen the results of a DIY alignment when you see a vehicle dog-walking down the road, where it looks like it is going down the road at an angle.

The difficulty in performing an alignment with a toe gauge or a tape measure is that making an adjustment on one axis can change another axis at the same time. For example, adjusting camber will affect toe and vice versa, and it is possible to have proper toe while at the same time having improper caster. The Cressida has quite a bit of positive caster, and as you turn the steering, you will notice that the camber on the front wheels changes noticeably.

The other tricky part is due to wheel offset, where the physical centerline of the wheel is not the same as the pivot point of the wheel when turned left-right so you have to calculate the centerline of the wheel and the centerline of the movement.

Finding the centerline of the car entails measuring diagonally in an "X" from wheel centerline to wheel centerline and then measuring left-right and front-rear.

I do most of the work on our vehicles myself, but I take them to a shop with a 4 wheel alignment machine when it is time for an alignment.

Reply to
Ray O

Very true, but the folks doing alignments with string lines are much more knowledgeable about alignments than your average DIY-er.

No argument from me there!

The point is that one should know the cause and effect of each change in setting to avoid unsatisfactory results.

Yup, poor choice of words on my part.

I know what I don't know...

Reply to
Ray O

As coyoteboy mentioned, my point was that doing an alignment with a measuring tape and strings is not something that a do-it-yourselfer is likely to have success with and was not meant to be instructional on how to do an alignment.

I have no problem when people catch my errors and correct them because that is one of the ways I learn or am reminded of stuff I've learned in the past and have forgotten.

OTOH, I do have a problem when people who don't know what they're talking about argue with the facts!

Thanks,

Reply to
Ray O

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