Help with tow hitch plunger

[Joe Gopan]

Chuck, the 3 or 4 Part numbers listed in the TM 10's and SNL's are all matching and correct, it is only the thread symbol in a couple late WWII SNL's that are in error, note they are all 20 count, the post War SNL G-529 has the correct description as well as the same ORD Part Number and thread count as listed in the SNL G-747 for the M-100. All of the drawbar brackets are threaded 1/4"-20NC, why all the fuss over nothing?

[Chuck Lutz]

There is no "fuss" over the thread pitch or the head design or the length or the type of tool used to install it...the question is simply what does one look for to put in that hole or what tool is used to remove the screw? For a CORRECT FACTORY restoration a hex-head bolt isn't going to cut it....a question was asked and answered and in doing that we discovered another error in the manuals....apparently they goofed again when writing them.

A restorer might waste a lot of time and effort to find a 1/4"-20NF x 3/4" if he checked the wrong manual and might do some damage to the threads in the Drawbar Bracket if he tried to install a "modified" NF screw in that hole.

Hopefully others who are restoring G529s will now be able to do a SEARCH and find this key word "PLUNGER" if they are looking to find out about how to remove that screw or what to look for if it is missing and save a headache or two by seeing this thread.

[lucakiki]

And it is also listed in error as NF in the copy of ORD 7-8-9 G-529 Change 2 Dated 25 August 1944 Luca sent me.

Lutz does have the same , and so does Jon, Charles Pelkey,Bill H,Jeff H,Al Brass,and a few others that at the moment I cannot remember.
It is quite possible that the manuals might be wrong on the thread, but a headless screw cannot be anything different than that.
Even more evident is the fact that it cannot be an allen screw.

Of course there is no need of any expertise to decide the correct tool to use for removing a given screw,and no one needs to be taught that an allen wrench is needed for a socket head screw.
Obviously any decently skilled do-it-yourselfer can pick up a screw that can do the job,but this is not called restoring .

[Joe Gopan]

A headless screw is more likely a set screw than not, but that is why the descroption is spelled out in the SNL is accompanied by a Part Number so that it can be ordered thru the system. The SNL's were not printed with "Joe's Hardware Store" in mind, the Army was set up to service vehicles in a wartime setting with 100% coverage thru their own supply system.

[TacoDell]

muh input

[Joe Gopan]

That is Dell's M-100 set screw. Nore the coarse threads. Bet most of the trailer owners did not even realize that there was a set screw on their trailer.
It was not a high mortality item and only a handful were stocked per quantity of trailers.

[Jon]

Actually, it makes sense to have a flat tip screwdriver type set screw fitted instead of the Allen wrench type, there's no Allen wrench in the tool kit, but then again, a small screwdriver isn't there either.

Curiouser and curiouser. ....... as Alice used to say....

[Joe Gopan]

That is why the Army had support units to send items to be repaired.

[lucakiki]

...

[lucakiki]

...

[Joe Gopan]

If only the war had lasted a few weeks longer and TM9-885 on the MBT/BT3 had been put in print, perhaps the issue over the "set screw" would not have been as big an issue.

[Chuck Lutz]

Luca...over the years the sourcing of information from a post-war career in the Army and the constant referral to post-war manuals for information regarding WWII parts has shown itself to be flawed in more than on discussion on the gee....

Unfortunately when I responded to Jon's question when he posted the pic of that manual I merely repeated what I thought the description meant. My BAD...when I looked into the actual manuals for the MBT (July 1943) and the Bantam (August 1943) I discovered that the manual Jon posted was in error.

As has been explained many times.....the later manuals seem to include any changes and often include mistakes....I think the best approach is to consult all the manuals and photos and even check the actual item if possible to see what it REALLY looks like.

As far as using a 1951 manual as the "Bible" for the 1942-1945 G-529s....why ignore the TM 10-1230 and the TM-10-1281? The use of all of them would have shown the mistake was in the LATER 1951 manual and solved the problem...

Tip o' the Hat to Dell for his photo. I couldn't access my trailer due to the snow against the barn door until yesterday and then I found there was a SLOTTED headless screw in the Drawbar Bracket on my trailer....

[lucakiki]

Tell you what: just for fun, I went to check how the TM- 10-1186 lists the same screw.
It is listed as set screw 1/4"-20 x3/4" headless ( spelled out!). The kind of thread is not mentioned, nor fine nor coarse.

So yes, that SNL G-529 erroneously lists National Fine, while it should be National Coarse.
The part number, though, is correct and an army mechanic requisitioning the freaking screw by part number would anyway get the correct headless set screw, regardless of the mistake in the SNL G-529.

[Bill H.]

Luca, the thread is mentioned. 1/4"-20 x3/4" headless. 20 can only be described as course thread.

[tipdog]

I couldn't access my trailer due to the snow against the barn door until yesterday and then I found there was a SLOTTED headless screw in the Drawbar Bracket on my trailer...

Snow? in Novato? What?! too much coke get loose there in Marin County?





Unbrako keys AKA hex keys AKA Allen wrenches were available in WW2. Show me the actual parts mentioned as correct.