Here are some data about the threads used on Land Rovers. On Series vehicles you possibly won't find metric threads, but they have some other odd things (eg. the 4 bolts that hold the top cover of the steering relay). Coil sprung Land Rovers are a wild mixture of metric, UNF and UNC as far as I have seen on my 110.
I hope this helps anybody.
For the spanner sizes see Peter Hirsch's spanner size table

Metric and metric fine:
Thread angle: 60° 
	    pitch		dimensions metric
	metric	met.fine	i.diam.nut	out.diam.bolt
thread	mm/turn	mm/turn		(mm)		(mm)
M3      0.5     0.35		2.35    	2.68
M3.5    0.6     -		2.72    	3.11
M4      0.7     0.5		3.09    	3.545
M5      0.8     0.5		4.96    	5.48
M6      1.0     0.75		4.7     	6.35
M8      1.25    0.75/1		6.38    	7.192
M10     1.5     0.75/1		8.05    	9.024
M12     1.75    1/1.25		9.73    	10.867
M14     2.0     1.5		11.4    	12.699
M16     2.0     1/1.5		13.4    	14.699
M18     2.5     1.5		14.75   	16.374
M20     2.5     1/1.5		16.75   	18.374
M22     2.5     1.5		18.75   	20.374
UNC, UNF and BSW (Witworth):
Thread angle: BSW 55°, UNC and UNF 60° 

			pitch				UNC/BSW (no data about UNF)
size        UNC/BSW		     UNF		out.diam.bolt	i.diam.nut
(")	turns/" mm/turn		turns/" mm/turn		(mm)		(mm)
1/4	20	1.27		28	0.90		6.35		4.72
5/16	18	1.41		24	1.05		7.94		6.13
3/8	16	1.58		24	1.05		9.53		7.49
7/16	14	1.81		20	1.27		11.11		?
1/2	13/12	1.95/2.12	20	1.27		12.70		9.99
9/16	12	2.11		18	1.41		14.29		?
5/8	11	2.30		18	1.41		15.88		12.92
3/4	10	2.54		16	1.58		19.05		15.80
7/8	9	2.82		14	1.81		22.23		18.61
1	8	3.17		12	2.11		25.40		21.34
I've added the pitch in metric format, too, so one can easily see what nuts and bolts will be crossbreadable. Please note that this was Dixon Kenners idea (he even talked about ramming bolts down holes ;-) and that this is a real SPOT (stupid previous owners trick). But in an emergency it could probably get you home.

Some data I got from Mike Rooth : 
B.S.W (British Standard Whitworth)
DIA    TPI(Threads per inch)

1/16   60
3/32   48
1/8    40
5/32   32
3/16   24
7/32   24
1/4    20
5/16   18
3/8    16
7/16   14
1/2    12

B.S.F (British Standard Fine)

3/16   32
1/4    26
5/16   22
3/8    20
7/16   18
1/2    16

B.A (British Association)
(By the way,this *is* a metric thread,really wierd)
B.A.No  Dia(mm)  Pitch(mm)
0        6        1
1        5.3      .90
2        4.7      .81
3        4.1      .73
4        3.6      .66
5        3.2      .59
6        2.8      .53
7        2.5      .48
8        2.2      .43
9        1.9      .39
10       1.7      .35


If you have additional data on this subject (eg. those other odd British sizes) please let me know.
Last change: Aug. 5. 1997

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