39 replies to this topic

[68+86auto]

I thought it was obvious but apparently not. Fasteners on minis are imperial (SAE) apart from a few exceptions. In fact some are even Whitworth.

Elsewhere on the internet, there is currently a few people trying to say that their classic minis are mostly or entirely metric.



This is far from the first time I've read this but never with so many people.

 

 

 

Metric tools should NEVER be used on imperial fasteners or the other way round. It is always important to ensure that the correct size tool is used, not one size up or down. Failure to use the correct tool results in damage/wear to both the tool and fastener. Don't get me started on screwdrivers...

[beardylondon]

“Minis are not Metric” would make a good t-shirt!

[Steam]

Mine is metric when the only rule I have is in mm.

[Spider]

What I feel is unhelpful here is the later Factory Workshop manuals were metricated. They'll give a measurement in metric first, then if you're lucky, Imperial as the second column. Same with fastener torque settings. It drives me around the bend. They are for the most part, an Imperial car, and never deviated from that to the very end.

 

There are a couple of metric threads and some metric bearings in the cars, but by and large, they are imperial.

As a side note, I find it amusing though that 90%+ of Seat Belt Bolts fitted to nearly all cars to this day are 7/16" UNF.

 

https://www.theminif...er-information/

 

[r.tec]

Well,nothing special. Wheels and tyre diameters are generally measured and indicated in inches. And even some tubes especieally for plumbing are sometimes measured in fractions of inches. On some Escorts that were sold on the Continent the bodies were in metric sizes while the engines in SAE. Very confusing for the mechanics in the workshops.

 

But everybody must admit that calculating in metric sizes is much easier. Simply, 1000 m makes 1 km, and 10mm makes 1 cm. And that goes through all other measuremts, too, be it mass, speed..... And as an engineer you have it in your blood that gravitational acceleration is 9.81 m/s² or 100km/h is 27.7m/s due to 3600 s for one hour. Your very own Newton as a measure for force is much easier to handle than pounds. I often see kgf for kilogramm-force which is obsolete for more than 60 years now. kg is mass (number of particles of substance) and Newton (N) is force. So 1kg of mass has a force of 9.81 N on earth. On the moon the number of particles are the same, namely 1kg but the weight-force is only one sixth because the gravitational force is only one sixth of the earth. 

[PoolGuy]

Wheels and tyre diameters are generally measured and indicated in inches. 

 

But everybody must admit that calculating in metric sizes is much easier. 

 

I like that tyres combine metric and proper measurements just to confuse the hard of thinking.

 

As for metric being easier, only if you're a youngster, I'll stick with proper English measurements thank you.

[DeadSquare]

Well,nothing special. Wheels and tyre diameters are generally measured and indicated in inches. And even some tubes especieally for plumbing are sometimes measured in fractions of inches. On some Escorts that were sold on the Continent the bodies were in metric sizes while the engines in SAE. Very confusing for the mechanics in the workshops.

 

But everybody must admit that calculating in metric sizes is much easier. Simply, 1000 m makes 1 km, and 10mm makes 1 cm. And that goes through all other measuremts, too, be it mass, speed..... And as an engineer you have it in your blood that gravitational acceleration is 9.81 m/s² or 100km/h is 27.7m/s due to 3600 s for one hour. Your very own Newton as a measure for force is much easier to handle than pounds. I often see kgf for kilogramm-force which is obsolete for more than 60 years now. kg is mass (number of particles of substance) and Newton (N) is force. So 1kg of mass has a force of 9.81 N on earth. On the moon the number of particles are the same, namely 1kg but the weight-force is only one sixth because the gravitational force is only one sixth of the earth. 

"It was Greek to me"  (Casca, Shakespeare’s Julius Caesarr )

[r.tec]

...I'll stick with proper English measurements thank you.

 

Oh, in this case you shouldn't accept Unified either! It's american  MAGA!

[PoolGuy]

I thought unified was a post war initiative between us and the Yanks, well before the orange baboon took ‘charge’?

[r.tec]

Yes, your are right, it replaced the American National Standard in 1949. USA, UK and Canada. But Canada has gone to metric since then, at least it was the case when I was there. Petrol in litres and speeds in km/h. I have never been to Autralia but afaik they have gone to metric sizes, too. But there are members who surely know better...

[DeadSquare]

The threads stem from the military.  (As explained at Imperial College)

 

In  Gt Britain, Lord Armstrong standardised coarse threads, to his satisfaction, making guns and his subcontractors fell in with his Whitworth threads.  As the British Empire and its army spread, Imperial threads, spread, but the head and nut sizes were smaller in USA.

 

In Victorian Britain,Two  committees standardised the fine threads, hence British Association and British Standard Fine, but they had far less impact on the world.

 

To complicate things, BSF had smaller head and nut sizes than Whitworth, and, when mass production started "Rolling" threads, because impressing a thread is much faster than cutting one, BSF was found to be too fine and in WW1, the USA  standardised a Rollable National Fine thread for war contracts.

 

As mentioned above, it was after WW2 that the imperial world standardised head and nut sizes, "Across the Flats", hence A.F., adopting a modified Whitworth thread for coarse and the USA N.F.

[Spider]

'On Car', including engines, gearboxes etc, I work in Imperial, but most new brackets and other parts, I mostly work in Metric. I generally Machine in Metric but occasionally in Imperial (though, becoming more so). For clearance measurements, I can only work in Imperial, I know what a thou is, but be buggered what that translates to in French.

 

Figure that out !

[r.tec]

A thou is a thousands of an inch: 25.4mm/1000 = 0.0254mm

[stuart bowes]

which is only useful if you can actually manufacture to that level of tolerance..  (i know a lot of you here actually can)

 

I design things in solidworks and often end up with fractions of mm's but when it comes to cutting and positioning, welding, drilling, can I actually place that point in the right place or does it get rounded to the nearst mm (or 2mm lol) fortunately for the sorts of things I do it mostly doesn't matter

Edited by stuart bowes, 19 June 2025 - 08:57 AM.

[stoneface]

I'm the same Spider.

I did my apprentiseship in imperial and we had to learn all the decimals for fractions from 1/64th to and inch in 64ths.

I now design mostly in metric and machine in both, but when it comes to small gaps like spark plugs or limits and fits, I prefer imperial thou. I can picture a thou but 0.0254mm, I've no idea what that looks like..