See this link to
Convert Toe Degrees to Inches
Toe measurement in degrees is simply the angle
between the vehicle centerline and the tire. Toe measurements in degrees
are more accurate than measurements in inches because inch based
measurements are affected by tire size while the angle is independent of
tire size.
The Honda AP1 S2000 Shop Manual calls for 0.25 inch of
total toe-in at the rear wheels. Toe-in in inches is the
difference between measurements A and B in the diagram below. Shop Manual toe-in in
inches is measured on the tire tread at the axle level.
0.25 Inch (0.58º) of Total Toe-In
Measurement A - B = 0.25" or 1/4" total toe-in. Note 0.0625" = 1/16"
and 4/16 = 1/4
The Shop Manual 0.25 inch of total toe-in is made up of:
0.0625" measured at leading tread of the left tire +
0.0625" measured at trailing tread of the left tire +
0.0625" measured at
leading
tread of the right tire + 0.0625" measured at trailing tread of the right
tire. 0.0625" x 4 = 0.25".
When measuring toe in degrees you do not need to double the measurement
for the leading and trailing edge of the tires as you do when using
inches. If one rear wheel measures 0.29º of toe-in
and the other measures 0.29º, then total rear toe-in is 0.58º, not
1.16º.
AP1: 0.25 inch (1/4" or 6mm) of total rear toe-in is equal to 0.58º (decimal degrees) of total toe-in.
AP2: 0.14 inch (3.7mm) of total rear toe-in is equal to 0.33º (decimal degrees) of total toe-in.
If you use string to measure toe and use the wheel rim for measurements
your numbers will not match up with the Shop Manual because Shop Manual
toe is measured at the tire tread. You can get pretty close by
decreasing the tire tread measurement by 25% to approximate the correct
rim measurement.
If someone says they run 1/4 inch of toe-in you need to ask:
Is that total toe-in? (total for both wheels
on the axle, or just a single wheel?)
Where was the 1/4" measured, at the rim or tire
tread? (tire tread is the norm)
Was the 1/4" measured on one side of the tire, or
both sides (leading & trailing tread on both tires = normal total toe)
For more info on aligning the S2000 see the Alignment and Corner Balance pages.
By Rob Robinette
See my Free Android Drag Racing Calculator App in the Google Play Store
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[Convert Toe Degrees To Inches]
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