Only one metric bolt

Ok, not all mixed up.  But let me tell you how it went.  This weekends subject, a 1991 F240 4wd 7.3l Diesel.  It was time to change the 3 of the 4 belts.  I grab all the standard sockets, wrenches, extensions that you need to work a Ford from that era.  The belt install goes as expected until past me took short cuts that present me had to re-do.  But more on that later if anyone is interested.  The 4th belt on this truck is for the vacuum pump.  It is a rather short belt that runs off of the alternator.  I loosened the alternator to remove the belts and is pivoted far enough to remove the vacuum pump belt.  With the new alternator belt in place I have to loosen the vacuum pump pivot to put the belt back on.   And that is where I found it.  The lone metric headed fastener involved in this job.  The lock down bolt for the vacuum pump had a 10mm head on it.  Everything else to do this job was standard.  Yes, there i was for a moment, "Arrgh!  3/8th is too small and 7/16ths is too big!  Wait..."

Dodge excels at this issue.

GM tried it for a little while in the 80s too.

ShawnG said:

Dodge excels at this issue.

GM tried it for a little while in the 80s too.

We had a 78 Chevy Malibu that we road Raced.

When working on it, you had to have some insight into how and where it was put together.

A fastener was metric if it was part of the chassis assembly.  It would be (most likely) SAE if it was part of the drivetrain.  

Fun times.

F-bodies were the start of metrification for GM. They put one 15mm bolt in the transmission mount and it spread.

G-bodies were next. Chassis parts all became metric on those models.

After that, it was game-on.

For a very long time, if it screwed into the cylinder block or head  it was imperial.  Into the alternator, power steering pump, metric.  Chassis was a bit of a wild guess.  A guy got to where 9/16 and 15mm were different enough to tell at a glance.

I remember hearing there was a generation of Range Rover that had metric, imperial and Whitworth. I know that my Rover has two of the three, and one ain't metric.

Try working in a Fox Body Mustang

DAHIK

Metric threads as well, or was it just a weird-sized head?

My '82 RX-7 has one SAE bolt, the seat belt anchors are 7/16-20 thread. I'm guessing it was a federal standard.

Ducati 860s are metric everywhere except passenger footpegs which are SAE thread because Ducati was floundering, couldn't pay their suppliers and got a good deal on some pegs from Triumph.

They also come with either Veglia or Smiths gauges, depending on who they owed money to that week.

j_tso said:

My '82 RX-7 has one SAE bolt, the seat belt anchors are 7/16-20 thread. I'm guessing it was a federal standard.

Same with Miatas. I believe you are correct.

Keith Tanner said:

j_tso said:

My '82 RX-7 has one SAE bolt, the seat belt anchors are 7/16-20 thread. I'm guessing it was a federal standard.

Same with Miatas. I believe you are correct.

Yup, I came in here to point this one out.

Deleting the rear seat and belts on my 968, I was looking for some basic bolts just to plug the holes as they open up to unibody cavities. "7/16-20 SAE? What the berkeley?"

wvumtnbkr said:

ShawnG said:

Dodge excels at this issue.

GM tried it for a little while in the 80s too.

We had a 78 Chevy Malibu that we road Raced.

When working on it, you had to have some insight into how and where it was put together.

A fastener was metric if it was part of the chassis assembly.  It would be (most likely) SAE if it was part of the drivetrain.  

 

Fun times.

Everything GM designed 1981 and later was metric.

Everything that was built before that (in the US) was not.

So Buick 3.8s had SAE fasteners everywhere because they were made with legacy tooling from before 1981, but the modern accessories were metric.

Keith Tanner said:

j_tso said:

My '82 RX-7 has one SAE bolt, the seat belt anchors are 7/16-20 thread. I'm guessing it was a federal standard.

Same with Miatas. I believe you are correct.

I am fairly sure that it's an international standard.  You'll find cars made on all three continents to use 7/16NF hardware.  Presumably because it isn't use anywhere else on the car so you can't use the wrong fastener for this critical component.

Somewhere I vaguely remember seeing one of those guys who buys and restores old (but not "vintage") Formula One cars, noting that their harnesses were attached with 7/16NF hardware.  (Specifically "it isn't 10mm and it isn't 12mm, what is going on here?")

In reply to Pete. (l33t FS) :

Real 289 Cobra was in the shop for restoration. 

The seat belt anchor eye bolts were 7/16 fine.