Chevrolet 1977 Monte Carlo, Repair Manual, Page: 417 / 428

M ETR IC A N D FASTENER IN F O R M A T IO N 10-3
M E T R IC B O L T A N D N U T ID E N T IF IC A T IO N
Common metric fastener strength property classes are 9 .8 and 10.9 w ith the class identification
embossed on the head of each bolt. Customary (inch) strength classes range from grade 2 to 8 w ith
line identification embossed on each bolt head. Markings correspond to tw o lines less than the
actual grade (i.e. grade 7 bolt w ill exhibit 5 embossed lines on the bolt head). Some metric nuts will
be marked w ith single digit strength identification numbers on the nut face. The following figure
illustrates the different strength markings.
G R A D E 2
(G M 2 0 0 -M )
G R A D E 5
(G M 2 8 0 -M )
G R A D E 7
(G M 2 9 0 -M )
G R A D E 8
(G M 3 0 0 -M )
Customary (inch) bolts - Identification marks correspond to bolt
strength - Increasing numbers represent increasing strength.
Metric Bolts - Identification class numbers correspond to bolt
strength - Increasing numbers represent increasing strength.
M A N U F A C T U R E R S
ID E N T IF IC A T IO N
N U T S T R E N G T H
ID E N T IF IC A T IO N
P O S ID R IV
SCR EW H E A D
ID E N T IF IC A T IO N M A R K S (4)