Wheel Alignment Units?

[tiredguy]

Hello

In the USA what is the common units used on an alignment rack when performing a wheel alignment. Are the values on the printout SI (metric) or are the in US standard.

For example is toe in displayed as inches or mm?

Similar question is camber in fractions of a degree like -0.5 degree or is minutes used -30'?

 

[Gyro Gearloose]

My shop shows everything in decimal degrees. I once converted the toe error to inches and the spread on the front edge of the tires needed to be altered only a few thousandths of an inch.

 

[tiredguy]

My shop shows everything in decimal degrees. I once converted the toe error to inches and the spread on the front edge of the tires needed to be altered only a few thousandths of an inch.

thanks for the reply.

I am confused by your reply.

you mention "everything" in degrees. toe is not an angle it is a length

you converted toe to in? what was it originally in? mm?

 

[eljefino]

I am confused by your reply.

you mention "everything" in degrees. toe is not an angle it is a length

It can be either. I'm more familiar with the spec being in degrees.

 

[Nukeman7]

Here is part of the printout I got yesterday after an alignment on a Hunter machine at Firestone. As you can see, it displays the measurements in degrees.

 

[ARCOgraphite]

thanks for the reply.

I am confused by your reply.

you mention "everything" in degrees. toe is not an angle it is a length

you converted toe to in? what was it originally in? mm?

New equipment toe readout will be in degrees as Gyro and Jeff stated. I try to run total toes around 0.07 to 0.10 deg IN. if the vehicle has some neg camber and/or a caster angle over 3 deg and non worn components.

Otherwise with greater toe setting you will get outer margin wear especially if frequently driven on a crowned roadway - as most tertiary and secondary roads are - at least in N.E.

HTH

- Arco

 

[Gyro Gearloose]

My alignment printout is like the one Nukeman7 showed which automatically gives caster and camber angles as part of the effort.

If you know toe angle, which is the amount of twist the tire is making over the contact patch, you can use trignometry and 1/2 the tire diameter to calculate what distance the edge of the tire is deviated from perfectly straight. Add up the deviations for left and right sides, double it to take into account the rear side, and you should have the total difference in the spread front to rear.

In my particular case the total toe was .02 degrees out of spec in the out direction, which on a 30 inch diameter tire would translate to about 0.5 mm difference in the distance measurement front to rear.

I actually question whether with rubber suspension bushings, tie rod slop, and bearing play if that level of precision can be achieved and improved on. I took the bait though and let them try to adjust the toe since I had just put new tires on the car.

 

[DuckRyder]

Old alignment guy here.

It can be changed in the Hunter settings, but typically it is degrees in the united states. My personal preference was caster and camber in degrees and toe in fractions of an inch.

Also be warned the specs can be manipulated too, i always went for as close to the preferred as possible. If "it is in spec" crosses your alignment guys lips, find someone else.

 

[oil pan 4]

In the US most shops use imperial degrees.

 

[bdcardinal]

All the Hunter equipment I have used defaults to degrees. You can go into settings to change it on the printout, but even when I went to the Sears training with Hunter 18 years ago it was all degrees.

 

[930.engineering]

.
Always degrees (°) and minutes ('). Only idiots use inches or millimeters.
Toe is an angle.
.

 

[IndyIan]

For the DIY'r toe is measured with a tape measure, either directly or on a string and measured, then you can calculate degrees if you want. Fortunately zero degrees is also zero difference between your front and back of the tire measurements, so you know when you are close.

 

[IndyIan]

In the US most shops use imperial degrees.

I had to look up how the metric angle system works, as I forgot how radians work. Oddly enough, radians are best understood in fractions of Pi, while degrees are easily understood in decimal degrees.... 90 deg is Pi/2 radians...
I guess physicists use radians to make the math easy, and engineers use degrees to make the calculation understandable?

 

[ARCOgraphite]

.
Always degrees (°) and minutes ('). Only idiots use inches or millimeters.
Toe is an angle.
.

A bit snotty there 930

Yes. it may be an angle, but the way you translate that angle depends on your tools. Hot rodders don't bring their T bucket to the BEAR alignment shop. A fishing line will often suffice. - Arco (former M.E., Metrologist and NIASE Master from the previous century)

 

[ARCOgraphite]

My alignment printout is like the one Nukeman7 showed ...

In my particular case the total toe was .02 degrees out of spec in the out direction, which on a 30 inch diameter tire would translate to about 0.5 mm difference in the distance measurement front to rear.

I actually question whether with rubber suspension bushings, tie rod slop, and bearing play if that level of precision can be achieved and improved on. I took the bait though and let them try to adjust the toe since I had just put new tires on the car.

If you just lay your hand on the front outer sidewall, it would likely move into spec 0.05deg.

But if it was out it was likely too far out. The in / out margins are typically asymmetrical about 0.00 total toe on compact unitbody strut cars with not much allowance for toe out.
A good guy will read the tires for feathering and wear trends, and note any instability on a test drive. The rack is just a tool