Understanding Metric Hardware

Even though many of us spend our time messing around with cars built on the metric system, we live in a world where the motorsports aftermarket seems to only focus on Imperial hardware. What are we to do with our 14mm strut bolts, 8mm flywheel bolts and the odd 3mm screw when Carroll Smith concentrates on the world of ^{1 …}

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This is the article that I'd been hunting for from my magazine archive!

Knowing the difference between ISO and JIS and everything else, makes working on a car much easier, since once you know what language the car speaks, it all makes sense.

Even things like my dear S40... engine was Swedish and brakes were Lucas, so they all used one species of fastener.  Chassis was Japanese, so everything that bolted to the chassis was a different species.  Once you knew that, everything was easy.  Even though you did need every wrench in the drawer.

Can we make a list of places to find *quality* metric fasteners in small quantities? 
 

I just bought a light bar for our Subaru and the chassis mounting bolts are metric and the bolts holding it to itself are sae and it bothers me. All of my vehicles are metric and those are the tools I keep around. 

Screw you and your Metric and Imperial sizes.

Signed: Torx 

ebonyandivory said:

Screw you and your Metric and Imperial sizes.

Signed: Torx 

Torx is available in standard and metric.

(Want to find a standard Torx?  Look at Ford seatbelts from the 70s.  Seatbelt fasteners are always 7/16-NF, and Ford used Torx)

Knurled. said:

ebonyandivory said:

Screw you and your Metric and Imperial sizes.

Signed: Torx 

Torx is available in standard and metric.

 

(Want to find a standard Torx?  Look at Ford seatbelts from the 70s.  Seatbelt fasteners are always 7/16-NF, and Ford used Torx)

I knew someone would write that.

I was obviously referring to Torx head sizes using the T1 to T100 designations.

In reply to ebonyandivory :

The head sizes are not really as important (and usually immaterial around here anyway) as knowing what to expect thread-wise.  A lot of hardware stores do not carry JIS thread pitches, for instance.  One gets to be able to recognize them and hoard them as necessary.

In reply to Knurled. :

Understood. All I ever need to know is what size bit I need to get the thing out of my way.

I hate to be that guy but....

They can come in any head form and finish, but the most common are hex-head cap screws (think Allen bolts), and usually they are black finished rather than shiny zinc or chromate-plated.

 

A Hex head cap screw is what it sounds like, a hex head. A socket head cap screw (SHCS) is the allen head variety.

Trent says, "A hex-head cap screw is what it sounds like, a hex head. A socket head cap screw (SHCS) is the Allen-head variety."

Thank you! Thank you! It is so nice to find another anal-retentive gearhead in the crowd! (I don't have OCD, I have CDO—it's the same thing, but the letters are in alphabetical order, as they damn well should be.)

In reply to Satch_Carlson :

I second that. Is that in the correct order ?

In reply to Jumper K Balls (Trent) :

Also, there is a difference between a Hex Head Cap Screw and a bolt...

In reply to spandak :

Check for "Bolt & fastener Suppliers" in you're area.  I have a store here, https://sarjo.com/ that I can walk in and get pretty much anything on the spot or in a day or two and I don't even have to figure what thread it is. 

spandak said:

Can we make a list of places to find *quality* metric fasteners in small quantities? 

The only place you really need to know is McMaster-Carr. Maybe Fastenal for a few *really* oddball sizes.

ebonyandivory said:

Screw you and your Metric and Imperial sizes.

Signed: Torx 

TORX can berk right off.

spandak said:

Can we make a list of places to find *quality* metric fasteners in small quantities? 
 

I just bought a light bar for our Subaru and the chassis mounting bolts are metric and the bolts holding it to itself are sae and it bothers me. All of my vehicles are metric and those are the tools I keep around. 

I typically order my metric stuff from Boltdepot.com. They have JIS flange bolts that match the type Mazda uses. I got a handful of different sizes and it has gotten me out of a bind a few times. 

BA5 said:

spandak said:

Can we make a list of places to find *quality* metric fasteners in small quantities? 

The only place you really need to know is McMaster-Carr. Maybe Fastenal for a few *really* oddball sizes.

Bel Metric deserves a mention too.

Appleseed said:

ebonyandivory said:

Screw you and your Metric and Imperial sizes.

Signed: Torx 

TORX can berk right off.

When it comes to automotive fasteners, I agree, but for wood, Spax construction screws with Torx heads are the truth.

In reply to obsolete :

Reluctantly agree. Spax are really good.

Reformatted: Anywhere rust, corrosion,  and general gunk can become involved TORX can berk off.

ebonyandivory said:

Screw you and your Metric and Imperial sizes.

Signed: Torx 

Screw your fancy computer designed for maximum torque and resistance to slipping. Coulda just made a square with a slight taper. 

Signed, your Canadian cousin Robert. 

BA5 said:

spandak said:

Can we make a list of places to find *quality* metric fasteners in small quantities? 

The only place you really need to know is McMaster-Carr. Maybe Fastenal for a few *really* oddball sizes.

Get their (M-C) app as well. It's well organized and simple. 

bearmtnmartin (Forum Supporter) said:

ebonyandivory said:

Screw you and your Metric and Imperial sizes.

Signed: Torx 

Screw your fancy computer designed for maximum torque and resistance to slipping. Coulda just made a square with a slight taper. 

Signed, your Canadian cousin Robert. 

Why would I want 4 points when I could have twelve?

XZN FTW.

Signed,

 Probably the only person in the Western Hemisphere who appreciates XZN aka triple-square

I second bel metric. My Simca and my Renault both use m7s everywhere. I'd be scared to add up how much I've spent on odd metric hardware for French cars

Quick additions/corrections:

JIS uses M7x1.0 rarely, it will be a 10mm hex or 12pt.

JIS uses M12 fine for most stuff, M12x1.75 coarse for heavy dumb things like BH & engine mount bolts.

M12x1.5 is commonly used for lugnuts.

JIS uses M10x1.25 fine for most stuff, M10x1.5 coarse for dumb things like waterpumps & accy brackets.

M10x1.0 is the JIS & DIN standard thread for brake line fittings. Of course they have different flares to trip you up.

JIS uses M8x1.25 almost exclusively. Have only seen M8x1.0 on bespoke plumbing fittings.

In reply to FJ40Jim :

I have a Japanese car that uses a lot of 10x1.5 for a lot of things, and 10x1.25 hydraulic threads.

I have only seen 12x1.75 once on a Japanese car: the threads in the diff cover of a Hitachi R160 rearend.