GM Service Manual Online
For 1990-2009 cars only
Table 1: 4T Strength Fasteners
Table 2: 6.8 Strength Fasteners Without a Flange
Table 3: 6.8 Strength Fasteners With a Flange
Table 4: 7T Strength Fasteners
Table 5: 8.8 Strength Fasteners Without a Flange
Table 6: 8.8 Strength Fasteners With a Flange

Fastener Strength Identification


Object Number: 728895  Size: MF

This vehicle is equipped with mostly metric fasteners. The most commonly used metric fastener strength property classes are 4T, 6.8, 7T, 8.8 and radial line. The class identification is embossed on the head of each bolt (1). The class identification numbers or marks correspond to the bolt strength. For example, increasing numbers represent increasing strength. Some metric nuts (2) are marked with a punch (3) or a single digit strength identification number on the nut face.

Replace fasteners with those of the same strength or greater. It is also important to select replacement fasteners that are of the same diameter and thread pitch as the original fastener. The correct fasteners are available through GM Service Parts Operations (SPO).

Standard Tightening Torque

Each fastener should be tightened to the specific torque value given in each section of this manual. If a specification is missing, use the tightening torque charts below in order to obtain the correct torque for the fastener. When a fastener of greater strength than the original one is used, use the torque specified for the original fastener.

The charts below are applicable only where the fastened parts are made of a steel light alloy.

4T Strength Fasteners

Thread Diameter

Specification

Metric

English

Important: Add 10% to the tightening torque given in the table below for flanged bolts, flanged nuts and self lock nuts.

  • 4 mm

1.5 N·m

12 lb in

  • 5 mm

3 N·m

30 lb in

  • 6 mm

5.5 N·m

48 lb in

  • 8 mm

13 N·m

114 lb in

  • 10 mm

29 N·m

21 lb ft

  • 12 mm

45 N·m

32 lb ft

  • 14 mm

65 N·m

47 lb ft

  • 16 mm

105 N·m

76 lb ft

  • 18 mm

160 N·m

116 lb ft

6.8 Strength Fasteners Without a Flange

Thread Diameter

Specification

Metric

English

  • 4 mm

2.4 N·m

24 lb in

  • 5 mm

4.7 N·m

42 lb in

  • 6 mm

8.4 N·m

72 lb in

  • 8 mm

20 N·m

14 lb ft

  • 10 mm

42 N·m

30 lb ft

  • 12 mm

80 N·m

58 lb ft

  • 14 mm

125 N·m

90 lb ft

  • 16 mm

193 N·m

139 lb ft

  • 18 mm

280 N·m

202 lb ft

6.8 Strength Fasteners With a Flange

Thread Diameter

Specification

Metric

English

  • 4 mm

2.4 N·m

24 lb in

  • 5 mm

4.9 N·m

42 lb in

  • 6 mm

8.8 N·m

78 lb in

  • 8 mm

21 N·m

15 lb ft

  • 10 mm

44 N·m

32 lb ft

  • 12 mm

84 N·m

61 lb ft

  • 14 mm

133 N·m

96 lb ft

  • 16 mm

203 N·m

147 lb ft

  • 18 mm

298 N·m

215 lb ft

7T Strength Fasteners

Thread Diameter

Specification

Metric

English

Important: NOTE: Add 10% to the tightening torque given in the table below for flanged bolts, flanged nuts and self lock nuts.

  • 4 mm

2.3 N·m

24 lb in

  • 5 mm

4.5 N·m

42 lb in

  • 6 mm

10 N·m

90 lb in

  • 8 mm

23 N·m

17 lb ft

  • 10 mm

50 N·m

36 lb ft

  • 12 mm

85 N·m

61 lb ft

  • 14 mm

135 N·m

98 lb ft

  • 16 mm

210 N·m

152 lb ft

  • 18 mm

240 N·m

174 lb ft

8.8 Strength Fasteners Without a Flange

Thread Diameter

Specification

Metric

English

  • 4 mm

3.1 N·m

30 lb in

  • 5 mm

6.3 N·m

54 lb in

  • 6 mm

11 N·m

96 lb in

  • 8 mm

27 N·m

19 lb ft

  • 10 mm

56 N·m

40 lb ft

  • 12 mm

105 N·m

76 lb ft

  • 14 mm

168 N·m

121 lb ft

  • 16 mm

258 N·m

187 lb ft

  • 18 mm

373 N·m

270 lb ft

8.8 Strength Fasteners With a Flange

Thread Diameter

Specification

Metric

English

  • 4 mm

3.2 N·m

30 lb in

  • 5 mm

6.5 N·m

60 lb in

  • 6 mm

12 N·m

108 lb in

  • 8 mm

29 N·m

21 lb ft

  • 10 mm

59 N·m

43 lb ft

  • 12 mm

113 N·m

82 lb ft

  • 14 mm

175 N·m

126 lb ft

  • 16 mm

270 N·m

195 lb ft

  • 18 mm

395 N·m

286 lb ft