Where were 19/32", 25/32", and 31/32" wrenches and sockets used?

Orson_Yancey · Mar 10, 2012

Folks,
As I look through old wrenches and sockets, I see some 32nd sizes showing up:
19/32" which is almost 15 mm,
25/32" which is almost 20 mm,
31/32" which is almost 24.5 mm.

Does anyone know where these sizes were used in the past or are stilled used today? In seems that this sizes in wrenches and sockets were common in the first half of the 1900's to 1960 or so.
One guess might be the tools were needed to work on auto parts that domestic companies adapted from Europe on the metric system. I am just guessing, but lets suppose an American auto company found a better/low cost engine bolt-on accessory from Europe. The European bolt accessory would have metric fastener on it. Maybe that is how the 19/32 and 25/32 came about since those sizes are nearly idential to a metric size.

Do others have thoughts, ideas, or stories to share about these unusual 32nd wrench and socket sizes?

Alchymist · Mar 10, 2012

19/32 IIRC was used on some starter motor terminals, and the solenoids were 11/32. For whatever reason early electrical equipment used the X/32 sizes a lot.

junk4dummies · Mar 10, 2012

They make bolts with oversized heads. They are made for more holding power if the bolt is in tenssion.
All the over sized heads on bolts are in 32ods of an inch . Thus you have all those odd sizes. Very common in old machinery.

You can find the sizes in open end wrenches but much harder to find in combo wrenches. You will find them in old sets of double box end wrenches.

in the 50's throught the 70's they were common with Craftsman sets. Where they went I don't know. They are hard to find. There must be a 32od grave yard some place. LOL

volpster31 · Mar 10, 2012

i was wondering th same thing...i was trying to fill out my socket sets and had a spot for them,but had a hard time finding them..same with combo wrenches... did find an old craftsman rp 11/32 but i just gave up cause ill probobally never need em

JASTECH · Mar 10, 2012

I still have many of them, was going to get rid of them in yard sale but now maybe just hang onto them. Used them on bicycles and a grinder wheel ect. That makes for a large set of tools.

bgarrett · Mar 10, 2012

IIRC, 25/32 was a Ford main bearing bolt size in the 1930s or 40s

TooManyToys53 · Mar 10, 2012

I've got those in 1/2" drive sockets. Part of the socket set I took over when I was 8, 51 years ago. Still use the set, probably should be buried with me.

OccupantRJ · Mar 10, 2012

At least one size was for old Ford tie rod ends. I have a 19/32nd twelve point size in my work box, and it fits a 1/2 inch square nicely, which are used as jackbolts on conveyors, and the knee lift drives on some small milling machines. I bought my Craftsman set in the early 70's, and it was included.

Jim C. · Mar 10, 2012

I like tinkering with old Delta woodworking machinery from the 1950s. On more than one occasion, while working on such machines, I've come across original nuts and bolt heads that are sized on 32nd increments. The most common size I've encountered is 25/32". It's metric equivalent is 20mm.

Jim C.

Flyingbaldman · Mar 11, 2012

25/32 brake bolts on a boeing 727

kythri · Mar 11, 2012

volpster31 said:
i was wondering th same thing...i was trying to fill out my socket sets and had a spot for them,but had a hard time finding them..same with combo wrenches... did find an old craftsman rp 11/32 but i just gave up cause ill probobally never need em

Well, for sockets:

Craftsman 19/32 (Dual-Marked, 1/2" Drive, 12pt, Regular Depth) - 009-50745 - $4.99 List
Craftsman 21/32 (Dual-Marked, 1/2" Drive, 12pt, Regular Depth) - 009-50746 - $4.99 List
Craftsman 25/32 (Dual-Marked, 1/2" Drive, 12pt, Regular Depth) - 009-50747 - $4.99 List

They're still available, and are part of the larger "complete" sets.

Outlawmws · Mar 11, 2012

volpster31 said:
i was wondering th same thing...i was trying to fill out my socket sets and had a spot for them,but had a hard time finding them..same with combo wrenches... did find an old craftsman rp 11/32 but i just gave up cause ill probobally never need em

Henry Ford was a 32's fan T's A's and probably more...

Those ones you can't find are probably hiding in My tool box. They keep appearing; I think it's a conspiracy... :ninja:

Charles (in GA) · Mar 11, 2012

Many items before WWII used these 32'ed sizes, but the war created a need for simplification and spelled the end of most of the /32 sizes.

Charles

DrkMtnDew · Mar 11, 2012

I think the only 2 thirty-second sizes I've use have been 11/32'' and 25/32''. But I don't know for what.

Outlawmws · Mar 11, 2012

DrkMtnDew said:
I think the only 2 thirty-second sizes I've use have been 11/32'' and 25/32''. But I don't know for what.

#8 machine screw nuts are usually 11/32, so likely wire contact lugs.

mattygee · Mar 11, 2012

25/32 were indeed used on early ford engines... Model A/T flathead 4 comes to mind

M

Orson_Yancey · Mar 15, 2012

Outlawmws said:
#8 machine screw nuts are usually 11/32, so likely wire contact lugs.

Yes, I have run into 11/32" on hex nuts of #8 screws. For example, on the Tecumseh small engine nut that holds the wire connectors to the points, in the older point ignition small engines.

I see that 11/32" is part of Craftsman combination wrench sets and GearWrench gearbox wrench sets today.

I have used 9/32" on the rare square nuts on #4 screws.

NC-Fordguy · Mar 15, 2012

The interior door handle nuts on first generation Ford Broncos are 11/32

xfrk · Mar 15, 2012

19/32" oil pan plug on my '03 Silverado. rk

jjjrmx5 · Mar 15, 2012

Orson_Yancey said:
Folks,

One guess might be the tools were needed to work on auto parts that domestic companies adapted from Europe on the metric system. I am just guessing, but lets suppose an American auto company found a better/low cost engine bolt-on accessory from Europe. The European bolt accessory would have metric fastener on it. Maybe that is how the 19/32 and 25/32 came about since those sizes are nearly idential to a metric size.

Do others have thoughts, ideas, or stories to share about these unusual 32nd wrench and socket sizes?

LOL.

Not EVERYTHING tool and fastener related is based upon the automobile and the automobile assembly and repair process.

Lots and lots of other things being assembled out there with nuts and bolts from bridges to machine tools to manufacturing assembly lines, to durable goods.

IIRC, someone mentioned that the odd sizes came as a result of a lack of standardization or quality contol of bolt head sizes where they could vary as much as a 64th or 32nd of an inch by batch or run. Obviously not a problem today, but teh early 20th century was still the teething point of assembly mfg.

rsanter · Mar 15, 2012

During war time they used to purposely use bolt sizes that were different than the enemy used to make it harder for them to repair captured equipment

Then surplus stuff went to the public so they needed the tools to maintain the stuff

Bob

Canadian Cowboy · Mar 15, 2012

They were used on British motorcycles and cars till about 1970 when Britain starting switching to US sizes and thread form.
The British had their own measuring system (British Standard Whitworth) Their wrenches and sockets are sized by the fastener diameter not across the flats of the nut or bolt like US and Metric fasteners,the thread pitch(angle) is also 55 degree where the US is 60 degree.
17/32 is 5/16 British standard Whitworth
19/32 is 3/8 British standard Whitworth,ETC
Britain now uses the metric measuring system.

CC

metaleltr · Mar 15, 2012

xfrk said:
19/32" oil pan plug on my '03 Silverado. rk

Should be 15mm.

gorilla · Mar 15, 2012

19/32' fits thr connecting rod bolts on Cadillac flathead V-8's, must be a thin wall though.

TOOLS4WORK · Mar 15, 2012

I believe that the oil pressure senders on early cars (mopars anyway) was something/32.
Maybe 25/32

bluebolt · Mar 16, 2012

Ford 428CJ rod bolts were 13/32 and used a 19/32 nut.

bts · Mar 17, 2012

Had the 19/32 out this morning repairing a Lincoln grease pump.
Lincoln still use a lot of 32 sizes on their grease pump legs.

mikew13 · Mar 17, 2012

25/32 for the bottom depth stop rod found on the Delta 17" drill press made between the late 30s and the late 50s.

byoungblood · Mar 17, 2012

metaleltr said:
Should be 15mm.

I'm sure it is probably just another case of grabbing something in the box because it looks close, and being a US made car some folks expect it to be SAE, even though you'd be hard pressed to find many SAE fasteners on anything built in the last 10-15 years.

junk4dummies · Mar 17, 2012

xfrk said:
19/32" oil pan plug on my '03 Silverado. rk

Instead of a 19/32" it might be a metric size. The head on an oil pan would be larger to take a gasket. That would make sense.

RRmech · Mar 17, 2012

I used 11/32 constantly on #8 nuts.

Steve

Milton Shaw · Mar 17, 2012

I have used 9/32 on zerk grease fittings. Actually to remove the plug is the 9/32 the fitting is usually a 5/16. These were on 70 and 80's Gm cars that came with plugs instead of fittings on the front suspension. 11/32 is what fit the starter solenoid nuts for the wires on the same cars. Older cars with point ign. the coil was also 11/32. The bigger sizes I have seen the wrenches and sockets but have never found anything they fit.

Nichoveski · Apr 7, 2014

English Automobiles (Royce, Bently, Rover, MG, etc.) standard for mechanical wrench, die bolts nuts etc., sizes was the "Whitworth."

They switched from the Whitworth to the Metric system somewhere around mid 60's.

An example, the Whitworth 5/16W is 11/32 wrench, 3/4W is a 25/32 wrench, a 15/16W is a 31/32 wrench etc.

Advantage of knowing this, ONE 3/4 X 7/8W open end wrench is $74.75 in the current Moss Motors MG T series catalog. Where as a 25/32 and 29/32 open end at Autozone or O'Riley for about $10.00.

Rust · Apr 7, 2014

mikew13 said:
25/32 for the bottom depth stop rod found on the Delta 17" drill press made between the late 30s and the late 50s.

Same for Walker Turner. But I found the bolt on a table saw.
Its the only 25/32" bolt I've ever seen...and I was glad to have the wrench.

Jim C. · Apr 7, 2014

mikew13 said:
25/32 for the bottom depth stop rod found on the Delta 17" drill press made between the late 30s and the late 50s.

If it's the nut I'm thinking it is, it appears on that drill press as well as several old Delta machines to include the heavy duty and light duty shaper fences and on a few lathes too. Restoring old Delta machines was the reason I started buying tools sized on 32nd increments. If you work on old stuff, you gotta have them.

Jim C.

toolmaven · Aug 13, 2014

Its a kind of old thread, but I get asked this often enough. Of all the 32nd sizes, only 11/32" for No. 8 machine screws is still popular and standard. It is common in electrical work and non-car assemblies today. I do run into the others on occasion in old machinery of various kinds. 13/32" used to be for USS 3/16" (#10) bolts. If you can find an old Williams or Armstrong catalog on line, you can see what the mysterious 32nds used to fit.
I added a clip, it doesn't show 21/32, so that was a manufacturer spec, not standard.

squeakz28 · Aug 13, 2014

I just finished rebuilding an old electric motor that powers a shop fan. This fan is at least 30 years old as it was rebuilt once before I was born. The nuts that held the wires on the studs were 11/32". To my knowledge, that is only time I have ran into having to use a x/32" on something.

creativecars · Aug 13, 2014

As my dad would say... "Where or Why"..."To make you ask questions" :thumbup:

Mohawk Dave · Aug 13, 2014

I just disassembled a JH William Vulcan 54" chain wrench last night, and the thing has 25/32" nuts on it.

Luckily, I have a little drawer full of 32nds" sockets. I was a little dumbfounded when 3/4" was too small and 13/16" was too big...

ttpete · Aug 13, 2014

11/32 was common on Delco distributors and coils. Xcelite made a combination nut driver with 11/32 on one end, and a special screwdriver for loosening the terminal post on the distributor on the other end. It was needed to replace points on the old Chevy 6 distributors.

Where were 19/32", 25/32", and 31/32" wrenches and sockets used?

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