Alternative Motorcycle Repair

PO Box 820
Sahuarita, AZ  85629

E-mail: mail@amr-tucson.com

British Thread Standards


British Associated British Standard Whitworth British Standard Fine
B.A.
No.
Dia. of Bolt
No of thds. per inch
0 .2362
25.4
1 .2087
28.2
2 .1850
31.4
3 .1614
34.8
4 .1417
38.5
5 .1260
43.0
6 .1102
47.9
7 .0984
52.9
8 .0866
59.1
9 .0748
65.1
10 .0669
72.6
11 .0591
81.9
12 .0511
90.9
13 .0472
102.0
14 .0394
109.9
15 .0354
120.5
16 .0311
133.3
B.S.W.
Dia.
No of thds
per inch.
1/4 in.
20
5/16 in.
18
3/8 in.
16
7/16 in.
14
1/2 in.
12
9/16 in.
12
5/8 in.
11
11/16 in.
11
3/4 in.
10
13/16
10
7/8
9
15/16
9
1 in.
8
B.S.F.
Dia.
No of thds. per inch
7/32 in.
28
1/4 in.
26
9/32 in.
26
5/16 in.
22
3/8 in.
20
7/16 in.
18
1/2 in.
16
9/16 in.
16
5/8 in.
14
11/16 in.
14
3/4 in.
12
13/16 in.
12
7/8 in.
11
1 in.
10
1-1/8 in.
9
1-1/4 in.
9
1-3/8 in.
8
1-1/2 in.
8
1-5/8 in.
8