Don't mix 55 and 60 degree threads on anything critical. Use them to hold on mirrors and mudflaps etc if you must. The mix does not achieve or maintain correct torque, has a self-loosening action, and crushing of the thread crests occurs.

Note also that BSF and BSW in equivalent SAE Grade 5 or 8 are almost extinct and if you find any they will almost certainly be very old stock.

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URSUSMAJOR

No, Ho. I grew up in New Farm and Winton. I live in Norman Park and used to drinlk at the Bal and VUS Juniors. My high school years were at Brisbane State High, and All Souls Charters Towers for a couple of terms whilst the oldies were on an overseas trip.

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URSUSMAJOR

I think you are mistaken - Whitworth and UNC are generally similar enough to be interchangeable in practice except for 1/2"

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JDNSW
1986 110 County 3.9 diesel
1970 2a 109 2.25 petrol

I think you are mistaken - Whitworth and UNC are generally similar enough to be interchangeable (although the thread form is different - Unified threads are 60degree, Whitworth and BSF are 55degree, and there are also other detail differences) in practice except for 1/2", but UNF and BSF are not. For example - 1/4" UNF is 28tpi, whereas BSF is 26tpi. At 3/8" the tpi are 24 and 20 respectively. Note that while you can mostly screw a Whitworth and UNC nut and bolt together (except for 1/2") it will have less than its designed strength, and is more likely to either seize or come loose or strip.

John

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JDNSW
1986 110 County 3.9 diesel
1970 2a 109 2.25 petrol

As I said in post #21 above.

NC & BSW have the same pitch from 1/4" to 1" with the exception of 1/2". I won't go into larger sizes as they are seldom encountered on the smaller vehicles. Sizes below 1/4" no longer equate to each other as since 1949 the US has used wire gauge numbers, not fractions, below 1/4". This was at the instigation of the ASME (American Society of Manufacturing Engineers) and the gauge no. reflects the wire from which small fasteners are made.

You can mix NF and BSC (Cycle Thread) as both are 60 degree thread form and the profiles are only microscopically different, mainly in the rounding of the crests.

For interest, Americans rarely use the U as a prefix to NF & NC. They didn't change anything. It was Canada and Great Britain who "unified" with the USA in 1950.

You could find any of these thread systems in a Land Rover depending on its age- BSW, BSF, BA, BSP, NC, NF, NEF, NS, ISO, ISO Specials. T'will keep you on your toes, like a tall sheila.

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URSUSMAJOR

I should add to the above, definitely do not use stainless steel fasteners in applications using or requiring high tensile bolts, SAE Grade 5 or 8, Metric 8.8 etc. Stainless fasteners have considerably less strength than high tensile heat treated fasteners.

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URSUSMAJOR

A customer came in toaday, and after chatting for a bit, we got onto the topic of restoring old british vehicles.

To cut a long story short, he has a supplier of all things BSF in Adelaide, and has promised me a copy of a price list and contact details.

I'll keep you all posted.

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1975 2-door RRC, 3.5, LT95 & Fairey OD.
112-752 88" GS 'Crusher'
REMLR no. 264