13 replies to this topic

[mighty mini jack]

are most of the bolts on minis imperial or metric as i want to get a tool kit for when i get a mini to work on

[Bungle]

imperial

it is a British car designed in the 50's

[Ethel]

imperial

it is a British car designed in the 50's

Using American specification nuts 'n bolts

[mighty mini jack]

so are they imperial or metric ? american or british bolts?

[dklawson]

Using American specification nuts 'n bolts

Well... yes and no. It's my understanding from the little bit of reading I've done on the subject that the UNF and UNC bolt classes arose during WWII from the need for common tools and hardware between allied forces. While most of the sizes and pitches were in the U.S. at the start of the war, a few really were derived jointly in response to the needs at the time. History lesson over.

Back to the subject... you'll need imperial tool as stated above.

EDIT: It's not "American" or "British", it's Imperial or Metric. The uniquely British fasteners that are still in use are primarily the BA series found on gauges, clocks, and things like the electric SU fuel pumps. There are unique exceptions like... the weld nuts holding the center binnacle to the bulkhead on early cars are BA threads.

Edited by dklawson, 01 December 2007 - 03:14 PM.

[Dan]

And metric. The Mini was in production for a long time, later in production lots of Metric fixings started to appear on the car. You will need both metric and imperial tools and a few BA sizes (actually you can do without those for the most part).

[Jammy]

Halfords have a FANTASTIC deal on their socket and spanner set at the moment:

Link

Can't remember if they are metric or imperial, but something tells me there is a bit of both in that set.

[Monkeh]

wonder what the trade discount will be on that set

[Ethel]

So in the interests of a pointless discussion to while away a wet afternoon...

Which is the best thread pattern, Metric, Whitworth, UNF/UNC....?

UNF must be the strongest in shear? - excluding metric fine as they're few 'n far between.

Which would be best in tension?

[Dan]

Whitworth is strong and is now used mainly for assembling lifting equipment, lifting threads in the top of large pieces of machinery for example remain as whitworth. It's not just the thread pitch but the seat angle and other aspects of the thread that give it strength. That's why I don't like the American tradition of naming a thread purely for its thread count, Whitworth has the same thread count as UNF but is not truly compatible because of the different seat angles. This annoys me when I buy some parts because the cameras I use all have 3/8 Whit threads in them and people are always trying to sell me UNF bolts to fit to them when I ask for Whitworth, the thing is I don't really want to break a 1/2 million pound camera because someone is too lazy to get me the right thread off the shelf!

[dklawson]

Dan, the deal with the pitch is not an American thing. Most modern fasteners specify the diameter and pitch or lead of the thread. Look at metric. You may get by walking into a store and saying you need an 8mm bolt, but you run the risk of getting the wrong bolt. The correct method is to say that you need an M8x1.25 or M8x1.0 bolt. The metric standard is to specify the major diameter and the lead of the screw which is a virtually identical method as used with imperial fasteners that specify the diameter and pitch. It seems that your biggest concern is that the the Whitworth fasteners have a different thread angle but can have the same pitch as the comparable size imperial fastener. That will cause serious binding if you try to thread the two together... but please don't blame this on us Americans.

[Dan]

Dan, the deal with the pitch is not an American thing.

It really does seem to be Doug, over here you would order a Metric course, fine or superfine rather than describing the thread pitch. And you would order imperial as 3/8 Whit or 3/8 UNF for example, but these are both called 3/8-16 in America. We would never say M8x1.25, we'd say Metric course. We refer to threads by the name of the threadform. How would you describe the difference between Whit and UNF over there if you needed to order something specific?

[dklawson]

Interesting points Dan. I can also use expressions like metric standard, fine, or extra-fine but that isn't the way I've seen such parts listed by my suppliers. As for how I'd specify Whitworth, that in itself is a unique situation. On the industrial level there are only about two sources who could supply them. Beyond those two suppliers, my best chance of finding Whitworth fasteners would be to inquire at motorcycle shops... old motorcycle shops. Finding BA fasteners is even more difficult. I recently had to mail order about $70 worth of BA taps and dies for some repair work. None of my usual suppliers had any idea what I was looking for.

[Sleepy Stu]

Dan, the deal with the pitch is not an American thing.

It really does seem to be Doug, over here you would order a Metric course, fine or superfine rather than describing the thread pitch. And you would order imperial as 3/8 Whit or 3/8 UNF for example, but these are both called 3/8-16 in America. We would never say M8x1.25, we'd say Metric course. We refer to threads by the name of the threadform. How would you describe the difference between Whit and UNF over there if you needed to order something specific?

Wooooosh (ducks as that conversation went stright over his head)