DIYbanter - View Single Post - Advice requested from those of you who have successfully checked camber at home

Tekkie®

posted for all of us...

On Fri, 9 Dec 2016 15:14:34 -0000 (UTC), John Harmon
wrote:

tlvp actually said:

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

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:
http://www.bmwdiy.info/alignment/index.html

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?
No you can not. Total toe iis the difference between the track at the
front of the tire and the track at the rear of the tire. devided by 2.
The specification on the Bimmer and most cars today is given as the
toe PER SIDE, which theoretically is 1/2 of the total toe.. The toe
per wheel is measured to the parallel longitudinal axis of the vehicle
and is given per wheel to enable centering of the steering linkage so
the car goes straight when the wheel is centered.

The reason the measurements are given as an angle is because that is
essentially what you are setting. You are setting the angular
relationship between the wheel and the longitudinal axis of the car. A
linear measurement is not an accurate specification because differen
diameter wheels can be used on vehicles, and the displacement of the
neasurement from the rolling axis of the tire affects the linear
measurement, but not the angular measurement.
If you are not using professional equipment and you are depending on
calculated linear measurements the ONLY way to aproach the accuracy
BMW is specifying is by extending the measurement to at least 3 feet,
prefferably 6 to 10, and calculatinf the offset at that point.

But I'm wasting my breath - You've been told this several times and it
has not gortten through to you. Stop being a cheap-assed wannabee,
find a good mechanic - and TRUST HIM. Pay him what the job is worth.
If you can't afford to proain a bimmer, drive a bloody Chevy!!

Letz see up to +127 ?

--
Tekkie