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:

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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

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B. iHandy Level Free By iHandy Inc.
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C. Clinometer + bubble level + slope finder (3 in 1) By Peter Breitling
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Some hits from the Android searches are as follows: A. Clinometer + bubble level By plaincode
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B. iHandy Level Free By iHandy Ltd.
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C. Angle Meter PRO By nakhon phagdeechat
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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).

Reply to
John Harmon
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I had forgotten to link to a descriptive photo of the desired task:

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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?

Reply to
John Harmon

.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.

Reply to
Steve W.

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".

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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 (

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)

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?

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

Reply to
John Harmon

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

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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?

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:

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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).

Reply to
John Harmon

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

Reply to
amdx

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 later found this BMW spec which shows that I need accuracy in 1 or 2 minutes (

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) but how do I convert that 1 and 2 minutes to inches?

I think he meant inches though.

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.

Reply to
John Harmon

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:

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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?

Reply to
John Harmon

"John Harmon"

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

Reply to
Phil Kangas

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

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

Reply to
amdx

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.

Reply to
John Harmon

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?

Reply to
John Harmon

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.

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

Reply to
amdx

That depends on the length. Mikek

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Reply to
amdx

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.

Reply to
dpb

Inches depends on the outside diameter of the tire:

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Minutes to degrees can be found here:
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Regarding the needed accuracy, it depends on exactly what you are trying to achieve. There is a wide range in camber that will not cause any meaningful tire wear. Toe is much more critical, including for overall feel at higher speeds, but you are also dealing with runout, and there really isn't any good way to adjust for that at home.

The overall point is that even if you are off with the camber, the tires are not going to be worn out all that much earlier, so close can be good enough, especially if you bother with rotation. Toe is much more important, and if you want that exactly right, pay someone to do it right. You can get it close at home, but it's just luck if it's exactly right.

You also have to keep in mind that a rear drive car's toe out will increase with speed, and a front drive car will do the opposite. There is plenty of slop in steering & suspension, and you will get varied readings, especially if you are not using turntables. Sometimes trying to save money is not such a good idea.

At the same time, finding someone to do the job right can be a challenge, too. There's plenty of hacks out there.

If all you care about is getting things close enough that there won't be ridiculously excessive tire wear, then have at it. But if you are trying to get things just right, both for handling and tire wear purposes, pay someone.

Reply to
Bill Vanek

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.

Reply to
AMuzi

The accuracy of the level application on my one phone is out bt over

7 degrees. That is a simple "level" app.. The "rigid" level application on my Blackberry PlayBook is very accurate - How you reference it to the wheel will be the biggest variable that can through your accuracy off. A trammel type setup made from a straight bar of metal (or "straight" hardwood) with 2 screws protruding to reach the edge of the rim, adjusted to be identical in protrusion, will transfer the wheel angle accurately to the "level". You can determine if the rim is true to the spindle by checking the level with the bar upright with the wheel turned 180 degrees to make sure the reading is the same with the wheel turned.

WITH CARE you can check your camber to a reasonably high level of accuracy. To get the camber "normalized" you need to roll the car back and forth a few feet so the car "settles" on it's suspension. A professional setup uses a "slip plate" that allows the wheels to slide in and out with little resistance. Normal procedure is to bounce the car on the slip plates to "normalize" the suspension.

I've done it long pre-smart-phone using a simple bubble level to verify the alignment was "close enough" afterr an accident in central Africa severely damaged the front of my Peugeot. I've also done hundreds of alignments with "pro" equipment.

Reply to
clare

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.
Reply to
Ben Bacarisse

Well, 2 angular minutes is 1/30 degree, 03 0.03 degrees.

It is .01 degrees

And the caster has an offset instead.

Like I said in an earlier post - make a "jig" - a kind of trammel device - that contacts the lip of the rim and transfers the measurement out to a straightedge that spans the rim fiving a flat surface parallel with the wheel centerline. Best to use this for toe adjustments as well.

minutes are 1/60th of a degree.. Converting that to inches requires offset and trig. The farther you can extend the "offset" the more accurate you can be. I use a laser level on the trammel jig to extend the line out about 10 feet from the spindle. Then do the calcs to find out how much toe-in you want at 10 feet for the angle specified. If the toe is specified in inches it is the difference between the front and back of the tire circumference. Again, some calculations will allow you to measure farther out for more accuracy.

Reply to
clare

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