Advice requested from those of you who have successfully che

[John Harmon]

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).

 

[pfjw@aol.com]

Horatio Alger and/or one of his many clones is trolling again. Just check the source.

As to checking Camber "at home". When it comes to vehicular safety, when it comes to the lives of my wife, kids and grandkids, not to mention me, my advice is DO NOT TRY THIS AT HOME - as no matter how smart the phone, the operator will be an idiot.

Peter Wieck
Melrose Park, PA

 

[John Harmon]

Ooooops.

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

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?

 

[pfjw@aol.com]

On Thursday, December 8, 2016 at 1:32:37 PM UTC-5, Steve W. wrote:

> How to attach the device to the wheel/hub.

Not possible centered on the axle and neutral in two axis without additional (and expensive) tooling. Hence the "Idiot Operator" requirement.

Once again, Harmon/Alger is trolling for a Darwin Award.

Peter Wieck
Melrose Park, PA

 

[pfjw@aol.com]

On Thursday, December 8, 2016 at 1:32:37 PM UTC-5, Steve W. wrote:

> How to attach the device to the wheel/hub.

Not possible centered on the axle and neutral in two axis without additional (and expensive) tooling. Hence the "Idiot Operator" requirement.

Once again, Harmon/Alger is trolling for a Darwin Award.

NOTE: Azimuth accuracy in smart-phone devices (departure from the vertical) is typically less than 10 degrees. OK for orienting the picture on the phone, not so much for measuring tire camber. Pushing right up against the "Idiot Operator" requirement for trusting such a device for such a purpose.

It would be quite useful were the OP to actually make adjustments based on such a device - if we could only be sure when he inevitably wraps himself around a tree thereafter that he does so without any collateral damage. Yes, I am being snarky - but if ever there was a situation for such - this is one.

Peter Wieck
Melrose Park, PA

 

[John Harmon]

makolber@yahoo.com actually said:

> 0.01deg ?? I don't think so...

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?

If your car doesn't pull to one side and the tire is not wearing un-evenly,
the camber is fine.

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 used an ordinary carpenters bubble level to check it.

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

> If it is within 1/4 bubble it should be OK.
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 )

> Most roads have crown so the camber is not as critical as you might think.

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).

Problems with this method are:
1 ground where the car is parked needs to be both flat and level

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

2 ordinary tire bulges out on the bottom, need to set the level
against the tire away from the buldge

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?

Sometimes you can simply compare the reading on the front wheels
to the back wheels.

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.

Also note many cars are designed to have the front wheels tilted
inward at the top slightly for stability

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

> Unless you like this as a hobby, it probably doesn't pay to DIY.

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.

Measuring toe in is much more fun.

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?

 

[John Harmon]

Steve W. actually said:

Q: What accuracy is *needed* to measure camber at home?
.01 degree or better.

Thanks for that answer because this is a critical number we must know to do
any aligment reasonably well.

If everyone concurs that 0.01 (one hundredth) of a degree is the desired
accuracy, I can work with that.

One problem with alignment is that we have to be intelligent about
converting units because I found this document where, on page 11, it says:

Quick-acting clamp + measuring sensor + computer = 1' at a
measuring range of ? 3?
(all BMW vehicles are within that ? 3? measuring range).

http://www.bimmerboard.com/members/snitch740i/original/BMW_Wheel_Alignment_System%5B1%5D.pdf

But I don't (yet) know how to convert 1 minute to inches.
Does anyone want to take a stab at how to run that conversion?

What other gotchas will we need to look at to successfully measure wheel
camber using a mobile device in a typical garage setup?

How to attach the device to the wheel/hub.

It seems to me that a "jig" of some sort needs to be made so that there is
a plane on the wheel that is (very precicely) parallel to the wheel to the
same 0.01 inches that we need for accuracy.

My initial idea is to take this concept to that 0.01 degree:
http://i.cubeupload.com/6CPUl7.jpg

Maybe bolt a flat steel plate to the wheel lugs (luckily, one of my cars
uses lug bolts so I can just use longer bolts but my other car uses lug
nuts which may make that flat plate bolting on more difficult).

 

[John Harmon]

amdx actually said:

> I assume that is the wheel and not a hub cap.

The car I will test this out first on is a bimmer with alloy wheels and lug
bolts so both those traits make the task of bolting on a jig easier than if
it were a steel wheel with lug nuts.

I'm guessing your looking for something between 0.5* and 2*, but I want
to know.

I later found this BMW spec which shows that I need accuracy in 1 or 2
minutes ( http://i.cubeupload.com/cfaDWp.jpg ) but how do I convert that 1
and 2 minutes to inches?

Someone said you need accuracy within .01 degrees, that's 1% of 1
degree.

I think he meant inches though.

Good luck getting the 18 year old at the tire shop to do that.
I'd be happy with 10%, being that it is an adjustable characteristic
that can depend on how you want to drive the car, comfort or cornering.

I understand that the alignment shop guy might not care all that much to
get as accurate as he can.

Right now, I think the accuracy needs to be plus or minus one minute for
toe and 2 minutes for camber.

I just don't know how to convert minutes to inches.

 

[John Harmon]

Tekkie? actually said:

Measuring toe in is much more fun.

+1 at least

According to this graphic, I need to repeatably measure toe to plus or
minus 2 minutes of accuracy and camber to plus or minus 1 minute of
accuracy:
http://i.cubeupload.com/cfaDWp.jpg

Static camber will be measured in degrees, so the plus or minus 1 minute of
accuracy is easy enough for me to understand.

But sttic toe is usually measured in inches, so a problem is how do I
convert the 2 minutes of accuracy to a plus or minus inch figure?

 

[John Harmon]

Phil Kangas actually said:

I just don't know how to convert minutes to inches.

You can't. Minutes of angle are a function of a
triangle.
Inches are simply a scalar measurement of distance.

That's bad news because both the toe and camber are specified in degrees
but when I measure toe, it will be in inches.

At least when I measure the camber it will be in degrees so I won't be
switching units back and forth.

I know how to physically measure toe in inches (e.g., with a string); but I
don't (yet) know how to measure toe in degrees with a smart phone or
digital level.

 

[John Harmon]

amdx actually said:

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

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).

Does anyone here know how to convert the 1 and 2 minutes to inches?

No, But 30 min is equal to 0.5 degrees.

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?

 

[pfjw@aol.com]

On Thursday, December 8, 2016 at 3:12:14 PM UTC-5, John Harmon wrote:

makolber@yahoo.com actually said:

0.01deg ?? I don't think so...

You are well-and-truly an idiot!

The measuring device must be accurate to one one-hundredth of a degree, or two decimal places. The measurement itself will be far less sensitive than that, probably to a single degree, no more. But if I am staring (for instance) at 90 degrees and want to get to 89.75 degrees - hence the need for that level of accuracy.

Azimuth on the typical smart-phone (how accurate is it a measuring off the vertical) is typically somewhere between 8 (at best) and 15 degrees - and that only if it has a screen-orientation function. Many do not. And many more have only a 90-degree function and only in one direction.

Put another way, the phone is smart enough not to even attempt the process. The idiot owner who insists that it is possible - with the right app/software - deserves exactly what he gets.

Minutes are a circular unit-of-measure. Not a linear unit. So, "inches" will be measured at some point on a diameter as compared to another point along that diameter using a fixed radius. If 'vertical' minutes, one endpoint of that radius will be the center of the earth. If other than vertical, the determining endpoint will be something hopefully more nearby such as the axle or some specified point. And the diameter on which the distance is measured will be specified.

But, minutes do not convert to inches other than the chord defined by the starting point and the end point of the measured distance along the total arc.

False premises lead to false conclusions. I am calling you an idiot as you seem congenitally unable to understand the most basic geometry - previously most basic physics - yet insist on some sort of false precision to draw others into your idiocy as an actual problem. It isn't. Otherwise, you are a simple (very simple) troll. Yeah, I am responding - in the same way that our grandkids enjoy Wack-A-Mole at the penny arcade. You will probably never go away, but well-turned invective can be enjoyable, even if against a helpless target.

Peter Wieck
Melrose Park, PA

 

[Steve W.]

John Harmon wrote:

Ooooops.
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

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?

..01 degree or better.

> Q: What accuracy can be *attained* with a typical mobile device?

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

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)?

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.

What other gotchas will we need to look at to successfully measure wheel
camber using a mobile device in a typical garage setup?

How to attach the device to the wheel/hub.

--
Steve W.

 

[John Harmon]

amdx actually said:

But what is 1/60th of a degree in inches?
That depends on the length.

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?

 

[amdx]

On 12/8/2016 11:23 AM, John Harmon wrote:

Ooooops.
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

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?

I assume that is the wheel and not a hub cap.
I'm guessing your looking for something between 0.5* and 2*, but I want
to know.
Someone said you need accuracy within .01 degrees, that's 1% of 1
degree. Good luck getting the 18 year old at the tire shop to do that.
I'd be happy with 10%, being that it is an adjustable characteristic
that can depend on how you want to drive the car, comfort or cornering.
I don't have a clue about phone app accuracy, but you can check it.
But hey, I've never done it, so don't read my response.


Mikek

 

[Phil Kangas]

"John Harmon"

I just don't know how to convert minutes to inches.

You can't. Minutes of angle are a function of a
triangle.
Inches are simply a scalar measurement of distance.

 

[amdx]

On 12/8/2016 2:12 PM, John Harmon wrote:

makolber@yahoo.com actually said:

0.01deg ?? I don't think so...

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?

If your car doesn't pull to one side and the tire is not wearing un-evenly,
the camber is fine.

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 used an ordinary carpenters bubble level to check it.

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

If it is within 1/4 bubble it should be OK.
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 )

Most roads have crown so the camber is not as critical as you might think.

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).

Problems with this method are:
1 ground where the car is parked needs to be both flat and level

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

2 ordinary tire bulges out on the bottom, need to set the level
against the tire away from the buldge

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?

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

Sometimes you can simply compare the reading on the front wheels
to the back wheels.

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.

Also note many cars are designed to have the front wheels tilted
inward at the top slightly for stability

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

Unless you like this as a hobby, it probably doesn't pay to DIY.

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.

Measuring toe in is much more fun.

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?

No, But 30 min is equal to 0.5 degrees.
Mikek

 

[amdx]

On 12/8/2016 2:17 PM, John Harmon wrote:

amdx actually said:

I assume that is the wheel and not a hub cap.

The car I will test this out first on is a bimmer with alloy wheels and lug
bolts so both those traits make the task of bolting on a jig easier than if
it were a steel wheel with lug nuts.

I'm guessing your looking for something between 0.5* and 2*, but I want
to know.

I later found this BMW spec which shows that I need accuracy in 1 or 2
minutes ( http://i.cubeupload.com/cfaDWp.jpg ) but how do I convert that 1
and 2 minutes to inches?

Someone said you need accuracy within .01 degrees, that's 1% of 1
degree.

I think he meant inches though.

Good luck getting the 18 year old at the tire shop to do that.
I'd be happy with 10%, being that it is an adjustable characteristic
that can depend on how you want to drive the car, comfort or cornering.

I understand that the alignment shop guy might not care all that much to
get as accurate as he can.

Right now, I think the accuracy needs to be plus or minus one minute for
toe and 2 minutes for camber.

I just don't know how to convert minutes to inches.

Something wrong, 30 minutes is equal to 0.5 degrees.
1 minute is 0.0167 degrees, I don't think that's what you are after.

You might play with a trig calculator.
> 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.

Mikek

 

[amdx]

On 12/8/2016 3:13 PM, John Harmon wrote:

amdx actually said:

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

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).

Does anyone here know how to convert the 1 and 2 minutes to inches?

No, But 30 min is equal to 0.5 degrees.

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?

That depends on the length.
Mikek
>

 

[AMuzi]

On 12/8/2016 2:12 PM, John Harmon wrote:

makolber@yahoo.com actually said:

0.01deg ?? I don't think so...

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?

If your car doesn't pull to one side and the tire is not wearing un-evenly,
the camber is fine.

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 used an ordinary carpenters bubble level to check it.

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

If it is within 1/4 bubble it should be OK.
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 )

Most roads have crown so the camber is not as critical as you might think.

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).

Problems with this method are:
1 ground where the car is parked needs to be both flat and level

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

2 ordinary tire bulges out on the bottom, need to set the level
against the tire away from the buldge

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?

Sometimes you can simply compare the reading on the front wheels
to the back wheels.

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.

Also note many cars are designed to have the front wheels tilted
inward at the top slightly for stability

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

Unless you like this as a hobby, it probably doesn't pay to DIY.

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.

Measuring toe in is much more fun.

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?

Sort of mixed units.

For a circle with radius about 286.5 feet your circumference
will be about 21,600 inches so each minute of arc will be
one inch. I don't think that helps you here.

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971