DSG-423 METRICS
09 -2
INTRODUCTION
Most threaded fasteners are covered by specifications that define required mechanical properties, such as tensile
strength, yield strength, proof load and hardness. These specifications are carefully considered in initial selection of
fasteners for a given application. To ensure continued satisfactory vehicle performance, replacement fasteners used
should be of the correct strength, as well as the correct nominal diameter, thread pitch, length, and finish.
Most original equipment fasteners (English or Metric system) are identified with markings or numbers indicating the
strength of the fastener. These markings are described in the pages that follow. Attention to these markings is
important to ensure that the proper replacement fasteners are used.
Further, some metric fasteners, especially nuts, are colored blue. This metric blue identification is in most cases a
temporary aid for production start-up, and color will generally revert to normal black or bright after start-up.
English or Metric system fasteners are available through your Ford Parts and Service operation.
NOMENCLATURE FOR BOLTS
* The Property class is an Arabic numeral distinguishable from the slash SAE English grade system.
** The length of all bolts is measured from the underside of the head to the end.
English System Bolt, 1/2 - 13 x 1 Metric System Bolt, M12 - 1.75 x 25
G = Grade Marking (bolt strength)
L = Length (inches) **
T = Thread Pitch (thread/inch)
D = Nominal Diameter (inches)
P = Property Class (bolt strength) *
L = Length (millimeters) **
T = Thread Pitch (thread width crest to crest mm)
D = Nominal Diameter (millimeters)
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