Metric Conversions

Metric conversions are making life more difficult for the mechanic. In addition to doubling the number of tools required, metric-dimensioned nuts and bolts are used alongside English components in many new vehicles. The mechanic has to decide which tool to use, slowing down the job. The tool problem can be solved by trial and error, but some metric conversions aren't so simple.

Convening temperature, lengths or volumes requires a calculator and conversion charts, or else a very nimble mind. Conversion charts are only part of the answer though, because they don't help you "think" metric, or "visualize" what you are converting. The following examples are intended to help you "see" metric sizes:

LENGTH 

Meters are the standard unit of length in the metric system. The smaller units are 10ths (decimeter), 100ths (centimeter), and 1000ths (millimeter) of a meter. These common examples might help you to visualize the metric units:

• A meter is slightly longer than a yard (about 40 inches).
• An aspirin tablet is about one centimeter across (.4 inches).
• A millimeter is about the thickness of a dime.

VOLUME 

Cubic meters and centimeters are used to measure volume, just as we normally think of cubic feet and inches. Liquid volume measurements include the liter and milliliter, like the English quarts or ounces.

• One teaspoon is about 4 cubic centimeters.
• A liter is about one quart.
• A liter is about 61 cubic inches.

WEIGHT 

The metric weight system is based on the gram, with the most common unit being the kilogram (1000 grams). Our comparable units are ounces and pounds:

• A kilogram is about 2.2 pounds.
• An ounce is about 28 grams.

TORQUE 

Torque is somewhat complicated. The term describes the amount of effort exerted to turn something. A chosen unit of weight or force is applied to a lever of standard length. The resulting leverage is called torque. In our standard system, we use the weight of one pound applied to a lever a foot long, resulting in the unit called a foot-pound. A smaller unit is the inch-pound (the lever is one inch long). Metric units include the meter kilogram (lever one meter long with a kilogram of weight applied) and the Newton-meter (lever one meter long with force of one Newton applied). Some conversions are:

• A meter kilogram is about 7.2 foot pounds.
• A Newton-meter is about 1.4 foot pounds.
• A centimeter kilogram (cmkg) is equal to 0.9 inch pounds.

PRESSURE 

Pressure is another complicated measurement. Pressure is described as a force or weight applied to a given area Our common unit is pounds per square inch. Metric units can be expressed in several ways. One is the kilogram per square centimeter (kg/cm² ). Another unit of pressure is the Pascal (force of one Newton on an area of one square meter), which equals about 4 ounces on a square yard. Since this is a very small amount of pressure, we usually see the kiloPascal, or kPa (1000 Pascals). Another common automotive term for pressure is the bar (used by German manufacturers), which equals 10 Pascals. Thoroughly confused? Try the examples below:

• Atmospheric pressure at sea level is about 14.7 psi.
• Atmospheric pressure at sea level is about 1 bar.
• Atmospheric pressure at sea level is about 1 kg/cm² .
• One pound per square inch is about 7 kPa.
  Fig 1: ASE Certification Symbol

  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

To Convert	To	Multiply By
LENGTH
Millimeters (mm)	Inches	0393***
Inches	Millimeters	25*** 4
Meters (M)	Feet	3***28084
Feet	Meters	3048
Kilometers (Km)	Miles	62137
AREA
Square Centimeters (cm2 )	Square Inches	155
Square Inches	Square Centimeters	6.45159
VOLUME
Cubic Centimeters	Cubic Inches	.06103
Cubic Inches	Cubic Centimeters	16.38703
Liters	Cubic Inches	61.025
Cubic Inches	Liters	01639
Liters	Quarts	1.05672
Quarts	Liters	94633
Liters	Pints	2.11344
Pints	Liters	47317
Liters	Ounces	33*** 81497
Ounces	Liters	02957
WEIGHT
Grams	Ounces	.03527
Ounces	Grams	28.34953
Kilograms	Pounds	2.20462
Pounds	Kilograms	.45359
WORK
Centimeters Kilograms	Inch Pounds	.8676
Pounds/Sq. Inch	Kilograms/Sq. Centimeter	07031
Bar	Pounds/Sq. Inch	14.504
Pounds/Sq. Inch	Bar	06895
Atmosphere	Pounds/Sq. Inch	14.696
Pounds/Sq. Inch	Atmosphere	06805
TEMPERATURE
Centigrade Degrees	Fahrenheit Degrees	(C°x***) *** 32
Fahrenheit Degrees	Centigrade Degrees	(F°-32)x***

Inches	Decimals	mm
1/64	.016	.397
1/32	.031	794
3/64	.047	1.191
1/16	.063	1.588
5/64	.078	1.984
3/32	094	2.381
7/64	.109	2.778
1/8	.125	3.175
9/64	.141	3.572
5/32	156	3.969
11/64	.172	4.366
3/16	.188	1.763
13/64	.203	5.159
7/32	.219	5.556
15/64	.234	5.953
1/4	.250	6.350
17/64	.266	6.747
9/32	.281	7.144
19/64	.297	***.541
5/16	.313	7.938
21/64	.328	8.334
11/32	.344	8.731
23/64	.359	9.128
3/8	.375	9.525
25/64	.391	9.992
13/32	.406	10.319
27/64	.422	10.716
7/16	.438	11.113
29/64	.453	11.509
15/32	.469	11.906
31/64	.484	12.303
1/2	.500	12.700
33/64	.516	13.097
17/32	.531	13.494
35/64	.547	13.891
9/16	.563	14.288
37/64	.578	14.684
19/32	.594	15.081
39/64	.609	15.478
5/8	.625	15.875
41/64	.641	16.272
21/32	.656	16.669
43/64	.672	17.066
11/16	.687	17.463
45/64	.703	17.859
23/32	.719	18.256
47/64	.734	18.653
3/4	.750	19.050
49/64	.766	19.447
25/32	.781	19.844
51/64	.797	20.241
13/16	.813	20.638
53/64	.828	21.034
27/32	.844	21.431
55/64	.859	21.828
7/8	.875	22.225
57/64	.891	22.622
29/32	.906	23.019
59/64	.922	23.416
15/16	.938	23.813
61/64	.953	24.209
31/32	.969	24.606
63/64	.984	25.003
1	1.000	25.400

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