Help me interpret alignment numbers [image]

[Earendil]

I brought my baby back the other day from the mechanic with a fresh alignment and set of shoes. I picked it up after hours so did not get a convenient time to talk to the mechanic. I didn't even notice I received a nice alignment sheet until I went to file the paperwork today. As an engineer, I find numbers cool :)

I don't know how to interpret the numbers though :(

They did assign "red" (out of spec) and "green" (in spec) color coding, but I have no basis for knowing how good or bad any of it is. I'm also not exactly sure how to read it. So I have a few questions.

1)
I believe the Toe values in the front are the only thing that are adjustable. Now they know that the car is primarily a track car, and they are a race shop. Without me requesting anything specific, is that the reason they adjusted the toe, but not to within spec?

2)
How do we get measurements for Toe on a per wheel basis? I thought Toe was defined by how parallel two wheels in combination are. Motorcycles don't have toe, right? So how can just my front left wheel have a toe number?

3)
I would have expected to see the following fields: "After, Before, Spec", but instead I get this "Actual, Before, Spec" value. I'd be happy to map "Actual" to "After" except that it changes for things that I don't think it should.

For example, some of the "Actual" and "Before" numbers for the rear (which afaik isn't adjustable) are different. Why would that be? I could buy that in the front, adjusting toe has a moderate effect on say caster, but if nothing is adjustable in the rear...

Thanks for any help interpreting!

[jlevie]

In the stock configuration, only front toe can be adjusted. For a car that sees track time you want minimal front toe and for a track car that won't be driven on the street, toe out. Looks like they went for a compromise between a track and street car.

An alignment rack can measure the toe/camber/caster of each wheel. To keep the steering wheel centered each tie rod is adjusted as necessary to achieve the correct toe.

"Actual" in this case means "After". The differences in the rear numbers between "After" and "Before" are at the limit of the alignment rack's accuracy and don't mean anything.

[Earendil]

Great, thanks for the answers! That's good info to know the variations is due to the accuracy limits of the rack. Since that seems to be acceptable variation, I don't need to be concerned that my camber is 0.3 degrees difference between left and right? Or is that so that when I put my fat butt in the left seat it evens out? :)

What about the rear toe being out of spec? Is that a product of the car being lowered onto H&R Race?

[jlevie]

There is no adjustment for camber. Some small about of cross camber is normal, but .3deg is a bit much and could be from worn balljoints or a bent control arm or slight frame or strut damage.

[Earendil]

There is no adjustment for camber. Some small about of cross camber is normal, but .3deg is a bit much and could be from worn balljoints or a bent control arm or slight frame or strut damage.

Oh...don't say strut or frame damage :-(
It had an alignment because it has brand new control arms and tie rods. When installing the H&R springs there was no apparent damage to the struts. I guess I'll just drive her!

I thought I understood cross camber to be the absolute difference in camber between left and right. However the "specified range" gives a potential negative value, which doesn't make any sense to me if it's just the difference in values. Could you answer me this one last question: what is Cross Camber? :)

Thanks once again for the explanation!

[nickmcc92]

cross camber is the difference in camber.
i have horrible cross camber from frame damage :(
left camber:-2.6 right:-.08
cross camber :1.8 (really bad)
my handling isnt so great because of my big difference of cross camber.

[Earendil]

cross camber is the difference in camber.
i have horrible cross camber from frame damage :(
left camber:-2.6 right:-.08
cross camber :1.8 (really bad)
my handling isnt so great because of my big difference of cross camber.

So then what's the difference between a cross camber of "-0.20" and "0.20" ?
The Specification sheet says that the acceptable range is "+0.50 to -0.50", but a negative difference doesn't make any sense to me... unless you have frame damage to the point where the left tire is to the right of the right tire

[nickmcc92]

Example: If one tire is 0 degrees camber. And the other is +1.5 camber. Then it'd be 1.5 cross camber. If it was -1.5 camber. The cross camber would be -1.5. At least that's what I'm guessing.

[Earendil]

I like that guess, but what would you call cross camber if one side were -1.5 and the other were +1.5?

[Hellabad]

That is a crappy alignment.

The ONLY thing adjustable on an e30 is the front toe, and AFTER the "alignment", your front toe is still not within spec.

I would not trust a single thing on that sheet (the front toe affects the camber reading), so don't get caught up worrying about anything.

They need to redo it or give you your money back. The fact that they sent your car out the door with an unfinished alignment, indicates that someone else would be better.

Sorry about the bad news.

[Earendil]

... they know that the car is primarily a track car, and they are a race shop. Without me requesting anything specific, is that the reason they adjusted the toe, but not to within spec?

For a car that sees track time you want minimal front toe and for a track car that won't be driven on the street, toe out. Looks like they went for a compromise between a track and street car.

That is a crappy alignment.

The ONLY thing adjustable on an e30 is the front toe, and AFTER the "alignment", your front toe is still not within spec.

I would not trust a single thing on that sheet (the front toe affects the camber reading), so don't get caught up worrying about anything.

They need to redo it or give you your money back. The fact that they sent your car out the door with an unfinished alignment, indicates that someone else would be better.

Sorry about the bad news.

Did you form that opinion before reading what jlevie wrote? The place that did the alignment is a well known shop that takes care of mostly track and race cars. They know the car is a track toy, and even if I hadn't told them that the crappy exterior and stripped interior would have been a big hint that I don't use this thing to commute long distances.

Now it's possible they did a quick and dirty job because my car is worth 1/50 of some of the cars parked outside their shop, but jlevie's explanation seems reasonable.

[Hellabad]

Did you form that opinion before XXX?

The big picture you attached blows your text off the right of my monitor. I didn't see the part about "track toy".
carry on

[Earendil]

The big picture you attached blows your text off the right of my monitor. I didn't see the part about "track toy".
carry on

That's good news :)
Sorry about the confusion!