Metrics on old cars

[enjenjo]

It might surprise you to know that metric measurements have been used on cars for a long time. For instance 18mm, 14mm and 10mm spark plugs were virtually the only ones used after the 1920s. Many of the wheel bearings on old cars are actually metric measurement. That's where we get some of the odd sizes that don't reflect on anything Imperial. Spark plug wires are metric, as are the threads on many dash switches. Spicer U joints are metric and have been from the start. We just never noticed it.

When Volkswagen built the bug, it was designed that metric or imperial tools could be used to repair it. If you look at things in that light the XX/32" wrenches start to make more sense.

Your thoughts?

[chimp koose]

If god wanted the world metric ..Jesus would have had 10 desciples . Seriously though it is a great system for science because the units are easy to convert.  I think it takes 1 calorie of energy to heat 1cc of water by 1 degree celsius . That makes for some easy conversions in science . In machining , most everything is in imperial and what i have done in the past is convert metric sizes into imperial when it comes time to make a part . I guess its an easier point of reference for me , I know about how long to polish something to take away a small amount of material when I think of it in thousandths of an inch , not so much when looking at hundredths of a mm . Back when I was working in a repair based machine shop we would get mangled pieces to reconstruct or duplicate new . A metric size was a hint of that size being for a bearing  with its required accuracy on the size.

[chimp koose]

I still think of fuel economy in miles per gallon . I buy meat by the pound , even if i have to convert the weight myself . Canada started going metric in the 70s . We still buy/sell homes based on square feet , most people will tell you the birth weight of their children in pounds . My moms homestead farm was 640 acres....I cannot convert to hectaires without looking it up . I am fine with temperature in celsius or fahrenheight , that was the first thing to go metric here . It also helps that you can FEEL temperature so an extra sense helps you convert.

[idrivejunk]

What irks me is having to keep a 10mm wrench in the inches box just because that alternator stud is now metric only.

Aside from that, the transitional GM products are something I have just avoided. Two toolboxes, nonsense.

I think in inches. But, all of every bit of the collision repair and most of the paint mixing work I did was metric and frankly it makes a whole lot more sense for body measurement and would for fab as well its just they don't have metric tape measures and rulers on the shelf here.

[phat46]

When I went to work in China a few years ago, I had to learn metric measurements real fast. I worked 32 years for a Canadian company where I ended up doing QC on the product before it left the shop so there was lots of metrics in use already. Our tolerances were metric, but I knew what they were in SAE too. I found the Metric system simple and more accurate for what we were doing, but haven't used it much since.

[GPster]

What irks me is having to keep a 10mm wrench in the inches box just because that alternator stud is now metric only. .

Try riding a Harley down the road in the early '90 with no more than a small roll of tools and finding out on the side of the road that your American made motorcycle that you needs a (box end)10mm wrench too disconnect it's American made battery. GPster

[purplepickup]

If you look at things in that light the XX/32" wrenches start to make more sense.

Your thoughts?

Interesting. I always wondered what the 19/32" wrenches in my box were for. They've never fit on anything right. I didn't think to see what the metric conversion was...close enough to a 15mm I guess. I'll have to etch them and put them in the metric drawer.

[jaybee]

I'll sure agree when it comes to transitional cars which have a mix of metric and SAE fasteners. A good argument for rolling the toolbox right next to the car, I'd say.

[chimp koose]

I think the funky 32nds wrenches were  for british whitworth stuff . 55degree angled threads reportedly to thwart germans from pillaging fasteners from wrecked equipment to use for repairing their own during the war . Or so the story goes  :?

[enjenjo]

I think the funky 32nds wrenches were  for british whitworth stuff . 55degree angled threads reportedly to thwart germans from pillaging fasteners from wrecked equipment to use for repairing their own during the war . Or so the story goes  :?

Whitworth bolts were around from 1841 with the wrenches marked with the size of the bolt shank rather than the wrench opening. So a BSW 1/4" wrench had a .525" opening. Then there was the case of Morris and MG that had metric bolts with Whitworth heads, then switched to Imperial bolts, and finally to true Metric bolts.

[kb426]

I always thought the British had too many pints before naming the sizes. I think I can safely say that in my corner of the state, I'm the only person with Whitworth tools. British cycles in my past. I have some strange sockets also.