Advice requested from those of you who have successfully checked camber at home

Practical advice (helpful hints & suggestions) requested from those of you who have successfully checked camber at home (to sufficient accuracy).
If you have never checked your automotive alignment camber at home, you probably won't be able to add much practical value to this thread; however if you have actually measured your wheel camber with sufficient accuracy at home, you almost certainly can add valuable pragmatic hints to this thread (such that we'll all learn from your experience).
I am researching whether automotive alignment camber quick checks are yet possible to a reasonable degree of accuracy using a free app on a common mobile device (either iOS or Android, both of which I own).
A search does find a variety of methods to check camber at home: https://www.google.com/search?q=check+camber+at+home where some of those articles used mobile phone apps (e.g., XXXXXX)
Here I am just asking for advice from those of you who have successfully checked your camber at home using your smartphone to measure the angles to sufficient accuracy.
To find apps which measure angles to sufficient accuracy, I have already run a variety of Google searches of the general form: 1. review best ios free app angle automotive alignment camber accurate 2. review best android free app angle automotive alignment camber accurate
Some hits from the iOS searches are as follows: A. Wheel Align for ALiSENSOR Wheel By Gloi AB https://itunes.apple.com/us/app/wheel-align-for-alisensor/id513879710 B. iHandy Level Free By iHandy Inc. https://itunes.apple.com/us/app/ihandy-level-free/id299852753 C. Clinometer + bubble level + slope finder (3 in 1) By Peter Breitling https://itunes.apple.com/us/app/clinometer-+-bubble-level/id286215117
Some hits from the Android searches are as follows: A. Clinometer + bubble level By plaincode https://play.google.com/store/apps/details?id=com.plaincode.clinometer B. iHandy Level Free By iHandy Ltd. https://play.google.com/store/apps/details?id=com.ihandysoft.carpenter.level C. Angle Meter PRO By nakhon phagdeechat https://play.google.com/store/apps/details?id=iyok.com.anglemeterpro
The amount of useless responses to this thread can be minimized simply by asking those who don't care to or who haven't ever successfully checked their camber at home to NOT respond (they're not going to be able to tell us anything we don't already know - all they're going to do is clutter up this thread to make it harder to be useful to others).
However, if you have ever attempted to check your camber at home using a smart phone angle measuring tool, your insight, hints, and advice would be greatly appreciated (and would be generally useful to many people).
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Ooooops.

I had forgotten to link to a descriptive photo of the desired task:
http://i.cubeupload.com/6CPUl7.jpg
I'm sure there are gotchas (e.g., is the garage floor really flat?), but it seems doable to measure camber at home if we can answer the main obvious questions which are (I think):
Q: What accuracy is *needed* to measure camber at home? Q: What accuracy can be *attained* with a typical mobile device? Q: Is the repeatability sufficient in a typical home measurement setup? Q: How do we compensate for typical errors (e.g., ride height, flat floor)?
What other gotchas will we need to look at to successfully measure wheel camber using a mobile device in a typical garage setup?
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John Harmon wrote:

.01 degree or better.

?????????? don't use one myself

Same way you do with the machines, Measure the floor and level the machine prior to use. Using an app you could check the floor span where you plan to do the work and zero it out.

How to attach the device to the wheel/hub.
--
Steve W.

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On Thursday, December 8, 2016 at 1:32:36 PM UTC-5, Steve W. wrote:

0.01deg ?? I don't think so...
If your car doesn't pull to one side and the tire is not wearing un-evenly, the camber is fine. I have used an ordinary carpenters bubble level to check it.
If it is within 1/4 bubble it should be OK. Most roads have crown so the camber is not as critical as you might think.
Problems with this method are:
1 ground where the car is parked needs to be both flat and level
2 ordinary tire bulges out on the bottom, need to set the level against the tire away from the buldge
Sometimes you can simply compare the reading on the front wheels to the back wheels.
Also note many cars are designed to have the front wheels tilted inward at the top slightly for stability
Unless you like this as a hobby, it probably doesn't pay to DIY.
Measuring toe in is much more fun.
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snipped-for-privacy@yahoo.com actually said:

We really must know to what accuracy we need the measurements to be becuase every measurement tool ever made has this as its basic issue.
Do you think it's less, or more accurate that we need for camber measurement?
As just one reference, page 8 of this document says that camber (and toe) measurements must be accurate to "2 angular minutes". http://www.bimmerboard.com/members/snitch740i/original/BMW_Wheel_Alignment_System%5B1%5D.pdf
The question then becomes how to translate 2 angular minutes into inch measurements.
On page 10 of that document it says the camber tolerance of another vehicle model is ? 10' (plus or minus 10 minutes).
So what is 10 minutes in inches?

I realize there are many ways to measure things, and I understand that you're using the tire wear and handling to measure camber, but I would like to try to get a bit finer in granularity (especially since lots of other things can cause both those issues).

I have plenty of carpenters bubble levels, one with digital output, so that's also another option.

I understand what you're saying which is that the negative camber on my rear tires can be anywhere between 0 and minus 2 degrees.
But I would like to get a bit more accurate than 1/4 bubble! :)
One of my cars specifies the following static camber range, for example: Front (non-adjustable) camber = -0.7? minimum, 0.3? maximum Rear (adjustable) camber = -2.2 ?mimimum, -2.0? maximum ( http://www.bmwdiy.info/alignment/index.html )

Some cars compensate for that by specificying cross camber specs, but mine are symmetric.
The static negative camber is "supposed" to increase lateral grip. At the same time, it certainly increases inner tire edge wear and decreases straight-line braking traction. On uneven road surfaces, you can get camber thrust (where the tire moves toward the camber).

Yup. That's a measurement and calibration issue for sure, but luckily, my garage is extremely flat (I measured it once long ago).

That's excellent advice. Since the tire bulges, I wonder if it's best to use the wheel lugs to mount a jig which is what we measure to?

This is a good hint, which is that we can just note what the *delta* is between the front and back, and measure that delta, over time, with a handy instrument.

Mine has negative camber on both front and rear, but front isn't adjustable without adding camber plates.

I disagree but I understand your point. On sheer economy, there are only 3 measurements I need for my sedan: 1. toe front 2. toe rear 3. camber rear
So all I need, to do a "pragmatic" alignment check, is to check those three. A. If they're off, then I can get the car aligned for $100 or more. B. If they're on target, then I save $100 each time I measure them.

On page 14 of the document above, it tells me that the static toe and camber accuracy needs to be: Toe measuring accuracy ?2' in measuring range ?2? in total range ?18? Camber measuring accuracy ?1' in measuring range ?3? in total range ?10?
http://i.cubeupload.com/cfaDWp.jpg
Does anyone here know how to convert the 1 and 2 minutes to inches?
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On 12/8/2016 2:12 PM, John Harmon wrote:

A jig, if you can't use the actual wheel.

No, But 30 min is equal to 0.5 degrees. Mikek
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amdx actually said:

I agree that, for our purposes, we should assume I jury rig a jig of some sort so that there is a flat completely perpendicular plate bolted onto the axle somehow (probably placed on the outside of the wheels using the lug bolts or lug nuts).

Right. And the 1 and 2 minutes are 1/60th and 1/30th of a degree respectively.
But what is 1/60th of a degree in inches?
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On 12/8/2016 3:13 PM, John Harmon wrote:

That depends on the length. Mikek

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amdx actually said:

Following that statement to the logical next step, here is a representiative track for my sedan from this thread: http://www.bimmerforums.com/forum/showthread.php?1312326-1998-BMW-528i-Complete-FRONT-Suspension-Overhaul
That photo says that the track is: - Front Track Width = 1512 mm - Rear Track Width = 1526 mm
So now what's 1/60th of a degree, in millimeters?
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On 12/8/2016 6:54 PM, John Harmon wrote:

You have a misunderstanding, to figure millimeter or inches, you need to have two lines that are connected like a below,
l****/ l / l / l / l/ The angle between l and /, we will call 1/60 of a degree, the **** is the millimeters or inches, BUT, the quantity of millimeters or inches depends on the length of l, as you can see the longer l the larger **** will be. But the angle stays the same.
Use the link below may help you see it.
http://www.carbidedepot.com/formulas-trigright.asp I put in a 1 degree angle for (angle a) and 16" for (side B) Then hit calculate to find (side a). This says you need 0.279" of tilt top to bottom on a 16" wheel. Note: this triangle is rotated 90* to your wheel. So take that into account when thinking about the calculation. Bottom line, for a 1 degree angle you need a tilt of 0.279" over 16". That's measurable, but you need a post 90* off the floor to measure from. Second note: Side (a) the tilt at the top (mm or inches), Side (b) is perpendicular to the floor, Side (c) would be the tilt of the wheel. Angle (a) is the degrees of the angle you set.
Mikek
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On 12/8/2016 7:36 PM, amdx wrote:

Just Repeating so you don't miss my post. I would like to know if my explanation made any sense to you. Be sure to use the trig calculator to help you understand. Maybe even draw out a few right triangles get the idea

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amdx actually said:

Nice graphic!
To your point, I completely agree that I'm utterly confused when it comes to "toe" angles.
It was my mistake to ever bring in the concept of "toe" to this discussion because, while measuring toe with a tape measure at home is relatively easy (once the mechanical overhang problem is solved), *converting* the damn manufacturer's spec from angles to inches is the *confusion* I have.
Here is the toe spec for a similar vehicle to mine:
http://i.cubeupload.com/RubZhV.gif
Notice that the "total toe" spec is 0 degrees 14 minutes plus or minus 10 minutes.
Also notice that the measurement accuracy for "total wheel toe" is also given in similar units of a measuring accuracy of plus or minus two minutes in a measuring range of plus or minus two degrees within a measuring range of plus or minus 18 degrees.
http://i.cubeupload.com/cfaDWp.jpg
I admit I'm confused. My dilemma is understanding how to *measure* to that spec.
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On 12/08/2016 3:13 PM, John Harmon wrote: ...

Incompatible...one is an angle, the other a distance.
As _amdx_ points out in another subthread, you've got to convert an angle to a distance via trig relationship of the angle you're measuring to the corresponding length of the appropriate side of a right triangle.
He posted some values there, but 1 minute subtended over 16" length of diameter of a rim is an offset of only 0.005" difference from vertical of the top/bottom edges. That does seem to be absurd precision to expect.
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On Thursday, December 8, 2016 at 4:48:57 PM UTC-5, dpb wrote:

one of the links you provided above shows a guy using a sting with a weight to define vertical and then a ruler to measure the distance to the wheel.
He also showed the math to convert distance to angle.
It depends on the height of the tire.
Its basic trigonometry sine = opposite / hypotenus. which is close enough for small angles
so using a calculator if the top of a tire is 20" off the ground and over that distance it tilts in by 1"
using a calculator inv tan(1/20)= 2.9 deg
thats inverse tan or arctan of 0.05 = 2.9 degrees
be sure the calculator is in degrees mode, not radians.
arcsin instead of arctan is opposite / adjacent which for small angles is almost exactly the same.
or we can work it the other way round
lets use 1 degree
tangent of 1 deg
tan(1) = 0.017.
So for every 10 inches of tire height, the tilt inward will be 0.17"
get it? m
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dpb actually said:

Except that the manufacture specifies toe in angles but I would measure toe in distance.
http://i.cubeupload.com/RubZhV.gif
http://i.cubeupload.com/cfaDWp.jpg
Hence it's obvious to all that I am confused how to do that.
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For small angles sin(A) = A (provided A is in radians) and d times sin(A) (hence d times A) is the displacement at a distance d caused by an angle a. To convert to radians, multiply degrees by .0174532925199 (pi/180).
For example, 2 minutes = 1/30 deg = .0005817764173 radians so 8 inches from the hub that corresponds to a displacement of 8 * .0005817764173 .00465 inches or 4.65 thousandths of an inch (0.118 mm). I image that's hard to measure.
The suggested accuracy of 0.01 degrees corresponds to a displacement of 3.5 micrometres at 8 inches. That's less the typical width of a human head hair.
--
Ben.

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On Thu, 8 Dec 2016 21:13:33 -0000 (UTC), John Harmon

That depends whether it is at 12.5 inches, 12.5 feet, or 12.5 miles....... You REALLY need to study your high-school math.
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snipped-for-privacy@snyder.on.ca actually said:

This off-topic confusion is all my fault.
I should never have brought toe into this discussion because toe is easily done at home when you have specs that are in linear dimensions such as inches but not so easily understood when you have toe specs in angles.
http://i.cubeupload.com/RubZhV.gif
http://i.cubeupload.com/cfaDWp.jpg
Clearly I'm confused how to do the conversion.
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On 12/9/2016 11:20 AM, John Harmon wrote:

Ya, I am to. But first let me say this, The first spec you posted, 0* 14' plus or minus 10', seems this isn't as critical as some posters are making it. For toe, it is still a trig problem, but the problem is defining, side b (a reference point).
> http://www.carbidedepot.com/formulas-trigright.asp
I wonder do the shops attach a laser and measure on a wall scale a defined distance away?
I don't know this, is it a single adjustment that moves both wheels or do you adjust both wheels separately? (makes a reference even more important) Sorry just thinking on the keypad.
You have a trig problem and a measurement problem. The measurement problem is more difficult.
It is not be hard to convert the 14 minutes to inches using the wheel diameter as one line. The angle is how much more is the front of the wheel turned in more than the rear of the wheel. I'll call the wheel 16" from front to rear. (just realized this almost the same trig problem for camber, just rotated 90*)
I'm using the trig calculator above, this time the orientation is correct. Put the following numbers in, (side c) = 16, (angle A) = .233. The angle is .233 because 14min/60min = .233. Your answer is (side a) which is 0.065". So, you want the rear of a 16" wheel stick out 0.065" more than the front. Not real easy to measure, But, if you could extend the 16" to 12 ft (192") with a laser pointer, then (side a) is 0.781". The laser must be perfectly square with the wheel. Just some thinking. Hope it makes some sense. Mikek
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to the OP
consider using mirrors and a laser pointer.
The hard part is a fixture that can attach a small mirror to the wheel accurately.
have fun
Mark
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