Fixings - Metric vs Imperial

[JohnD]

Thank you for all the reply's, as i expected it was a mixed bag of varying opinion. Going forward i will probably use all metric on the bodywork where it is less likely to be removed at the roadside and leave all mechanical and running gear as intended.

[Rogerfrench]

Here in Texas I can get Metric or Imperial very readily, but the Imperial is, of course UNF / UNC, or "standard" as it's labelled here.
Fortunately I don't have any BS threaded cars, though my Lotuses ensure I use both the others. I guess from the answers that UN isn't readily available in UK nowadays? I must say that from an appearance viewpoint, UN fasteners are more attractive as BS substitutes than are Metric.

[Dave Wortley]

The unf screws have a dimple in the centre of the head which is a good way of distinguishing them from bsf/bsw.

[Parazine]

I guess from the answers that UN isn't readily available in UK nowadays? I must say that from an appearance viewpoint, UN fasteners are more attractive as  BS substitutes than are Metric.

UNF and UNC (basically American ANF and ANC) are very much still available here. They just don't tend to get a lot of exposure on "Our" cars due to the vehicles age.

[Ian Dunford]

For the smaller sizes at least,BSW and UNC are virtually the same.
Not BSF and UNF though

[Chris KC]

Metric I can understand but UNF/UNC?
I concede there is 1 UNF thread on my car, but it is so Loctited as to never again be undone.

[Ivor Hawkins]

I’ve been able to buy UNF/UNC for my Plymouth Road Runner here in the UK easier than BSW/BSF!

[Rogerfrench]

Metric I can understand but UNF/UNC?
I concede there is 1 UNF thread on my car, but it is so Loctited as to never again be undone.

A 6mm bolt head looks like 6mm. A 1/4" head, whether BS or U.N., looks like 1/4". If appearance is important, and BS unavailable, then UN is a better substitute surely?

[Chris KC]

Don't disagree Roger but the whole UNF/UNC venture seems like a wrong turn with hindsight. Funny how each successive attempt at standardisation has merely resulted in another layer of confusion.

[Tony Griffiths]

What really bugs me is to see modern bolt heads with raised letters. These should be machined off. Oh for the days of the Williams Brothers fasteners factory in Sheffield. You could ask at the counter for some obscure fitting that needed to be, say, fully machined and chemically blacked. On one occasion the sales chap said that I'd better come with him to check, as he didn't want to traipse around the building putting stuff back. Off we went down a long corridor, taking the second set of stairs on the right; up two floors, another corridor, a flight of stairs to the left and stopped half-way down a set of shelving packed with boxes. He reached up, selected a carton and said, "Are these right?" They were. I asked if the location of everything was logged in a book; He replied in the negative and tapping his head said, "It's mostly in here."