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

[clare]

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.

[clare]

Less than 1/2 degree difference between wheels CAN cause a significant pull on some vehicles.A difference of 1/4 degree can cause a noticeable pull. Accuracy to within 0.1 degree is pretty much a requirement if you wand good handling. If tire wear is your only requirement, you can be a little less precise.

You do NOT put it against the tire. You need to measure from the rim.

Except MANY cars have camber on the rear wheels too - particularly on front wheel drive cars and cars with inependent rear suspension.

You DEFINITELY need to know the manufacturer's specs. Another case where not too many of you DIY guys are smarter than the engineers that designed the car.

Definitely second that - unless you are miles from a shop and you need to verify if the vehicle is in good enough shape after damage repairs to get to a shop to have it adjusted. (like out in the "bush" and you bounce the vehicle off a stump or through a ditch and need to drive it home)

[Ben Bacarisse]

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.

[clare]

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.

[clare]

Pythagorus' theorem -, or better yet, trigonometry. Or a triangle calculator like

Solve a triangle. You know (from your measurements) the base of the triangle (distance from spindle) and the height (difference between the projected line and "straight"), or the base and 2 angles (the desired angle and 90 degrees) to calculate the height. One way tells you what angle you have, the other gives you the distance measurement you WANT.

Your biggest problem is getting your head around all the concepts.

On some vehicles it CAN be that simple -- On others it is definitely a wee bit more complex, but you have the idea.

And the length of the studs/bolts gets critical - not to mention it works best with 4 or 6 studs - not so good on odd numbers like the common 5, or the less common 3 stud wheels.

[clare]

There is a saying about Bimmers. If you have to ask how much - for anything - you can't afford to drive a bimmer.. There are enough things that can go wrong in the front end of one of those kraut-wagons that I think you are definitely being penny wise and pound foolish trying to save $100 on the maintenance of a late model Bimmer. Don't be such a cheap-ass. - or drive a Chevy.

You want to know if anything is worn or bent - and measuring CASTER is required as well to know. You really don't have your head around the concepts well enough to understand WHY an alignment check should be done properly. Your "quick check" is just that - and if you are at all in tune with your car as a driver you will know there is something wrong just as well by simply driving the car. If you are not "in tune with the car" the Bimmer is wasted on you --- (as it is on the vast majority of Bimmer owners)

[clare]

If you are going to measure the toe with a string, you may as well forget about it. You can NOT get enough accuracy or repeatability to determine if the toe is correct or not. Without pro equipment, to get that granular in your measurement you NEED to extend your measurements

5 or 10 feet and measure with a goor steel tape measure, or extend the displaced centerline accurately and measure with a steel rule. Using the simple tape measure will give you the total toe - which will be double the specified toe per wheel, and will not tell you if you are off-center.

[clare]

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.

[Ed Pawlowski]

New to USENET? I've done wheel alignment in my garage but given your arrogant attitude I prefer not potentially clutter things here.

FYI, you won't be the first to call me an asshole today so don't be so proud when you do so.

[John Harmon]

Following that statement to the logical next step, here is a representiative track for my sedan from this thread:

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]

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.

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

[tlvp]

Sheesh, you don't translate angular measurements into linear ones. An angle isn't a length. Cheers, -- tlvp

[tlvp]

You need a cataly$t, and a good front end man. Bring your vehicle to the front end man, lubricate him with your cataly$t ($100 should do nicely), and he'll perform the conversion for you, even adjusting things to the result you would desire (key word or phrase: "wheel alignment").

HTH. Cheers, -- tlvp

[John Harmon]

I agree that I'm confused (which is why I am hesitating to respond because I don't wish to muddy the technical issue further for everyone).

The problem with doing camber at home is different from the problem of doing toe at home.

For my bimmer, the camber is specified in degrees, and the measurement tools we're exploring measure in degrees.

We just have to solve the conceptually simple problem of a. Accuracy to 1 minute of angular measurement b. Creating a wheel plate that meets that accuracy c. Measuring to that accuracy with a mobile device

The problem, for my bimmer, is that the manufacturer specifies the toe in degrees, yet we measure in inches. The conversion confuses me to no end (which is obvious to all).

However, that specific translation problem may be solved if I trust this layman's chart, for a similar vehicle:

Which puts the toe-in in inch measurements of: Front toe (left): Minimum = 1/32", Maximum = 3/32" Front toe (right): Minimum = 1/32", Maximum = 3/32" Front toe (total): Minimum = 1/32", Maximum = 3/16"

As with all specs written by laypeople, I can't tell if that toe is to the centerline of the bimmer or wheel to wheel but since they specify a single-wheel toe, can I safely presume that the spec is to the *centerline* of the vehicle?

[John Harmon]

Anyone can catalyze a reaction, but the catalyst remains unchanged.

That is, if I do that, I learn absolutely nothing.

I remain as uneducated as before.

[amdx]

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

[John Harmon]

What we don't want is advice from people who would never contemplate doing a camber measurement at home.

We want advice from people who have actually checked camber at home:

All the advice from tlvp, for example, of why he would NOT to check his camber at home is and was already known before he posted anything. He added negative value to this thread.

Since he would never do it, he has never thought about how to do it, and since he not only knows not how to do it, but more importantly, he has never done it, so his advice not to do it doesn't help anyone.

He simply wasted everyone's time with his fear-filled response.

Likewise, you waste everyone's time with your I-won't-tell-you response. If you're not going to tell anyone anything, then why bother responding?

Besides, you only pretend to have done it, which is fine, but you playing make believe doesn't help anyone here. I knew all this would happen, because most people are utterly horrified at the mere thought of checking camber at home so I was trying to avoid having to respond to comments like yours and tlvp's which simply waste everyone's time.

Based on these specs (

the measurement range is plus or minus 3 degrees to an accuracy of plus or minus one minute.

If we can't achieve one minute of accuracy out of a mobile device, what

*is* the accuracy thqt we *can* achieve out of a mobile device?

[John Harmon]

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:

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.

I admit I'm confused. My dilemma is understanding how to *measure* to that spec.

[John Harmon]

Except that the manufacture specifies toe in angles but I would measure toe in distance.

Hence it's obvious to all that I am confused how to do that.

[John Harmon]

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.

Clearly I'm confused how to do the conversion.