Foreign standard?

[ChristianReske]

That´s a good one!

Some tool Makers labled the Sockets as "21 mm (20,7mm)" or "21mm (13/16)"
Thats uncommon today. The Spark Plugs and sockets are now just labeld "21mm" here.
Giving the correct size confused "metric" people, maybe?

However...

Out of curiosity i meassured my 21mm Spark Plug socket: Its in fact 21,23 mm, well build in acceptable tolerance.
The DENSO spark plug meassured.... 20,57 mm. Also well build in tight tolerance.

So, there really emerges a noticebale gap between the spark plug and the socket. I can twist the spark plug a little bit to the left and right after i inserted it in the socket.

In reality, it dont bother. Spark plugs dont need much torque and new sockets have "Flank Drive" hex profiles, so it work well despite the unusual wide gap in between.

 

[Leo99]

Originally Posted By: bdcardinal
Royale with cheese.

 

[artificialist]

I'm not sure what they call it in Japan, but Toyota likes to use drain plugs that take a 3/8 or 1/2 inch ratchet. It surprised me when I first saw it.

 

[Silk]

A lot of those are 10mm and 13mm, particually on Nissans...but I have seen those 3/8 ones, my 10mm square won't fit.