F15A Cab Rope Lashing Points

[Jacques Reed]

Hi Eric,

Just to add the attached photo showing the aforementioned plates that are spot welded to the rear of the cabin. I had an earlier cabin where there was no plate but the cleats were just attached via the screws and nuts.

Have noticed often that WW2 fastener head sizes are substantially larger than those on currently made fasteners. Case in point is those screws. Compared to a modern screw with the same threads, the countersunk head is substantially larger on WW2 screws so if you can scrounge a couple from and old floorboard you will find they fit the cleat perfectly.

Cheers,

Jacques

[Tony Smith]

Originally Posted by Jacques Reed

Hi Eric,

Going by mine, they should be 1/4-20 UNC Flat head countersunk slotted screws about 3/4" long.

Have noticed often that WW2 fastener head sizes are substantially larger than those on currently made fasteners. Case in point is those screws.

Cheers,

Jacques

I have noticed that many Australian-built cabs feature Whitworth fittings, oddly often right alongside SAE threads. 1/4" UNC and 1/4" BSW are both 20tpi, but the UNC hex is 7/16" and the 1/4"W is 0.525".

Whitworth Hex sizes were oversized in relation to the thread diameter by current trends, but in 1940 an austerity measure was introduced with War Emergency B.S. 916 : 1940 to conserve steel. This had the effect of reducing bolt hex sizes by one smaller spanner size for the same thread. For 1/4" BSW, the old hex of 0.525" became 0.445", which is very close to 1/4" UNC (7/16" = 0.438"). Wartime BSW threads are very easy to mistake for UNC due to this close similarity of Hex sizes. While these measurements relate to Hex headed bolts, the same applies to countersunk screws.

[Jacques Reed]

Hi Tony,

Yes, I noticed the various Whitworth screws as used on my truck also, mainly on the Holden built body and Australian cab but perhaps I was not clear in my comment.
I was referring to the actual head height of many of the SAE screws and nuts used on the truck. Most are much higher than the currently manufactured ones. See the attached example of two 3/8 UNC screws a commonly used fastener on the truck. New one on the top. Both use 9/16 AF spanners but the height from the bottom of the head to the top of it is higher on the original WW2 manufactured one.

Cheers,

Jacques

[Grant Bowker]

I think the thick headed SAE bolts you are describing are also known as "heavy hex head bolts", described at http://www.mcmaster.com/#standard-cap-screws/=13bs90h and drawn at http://www.mcmaster.com/#92655a331/=13bs912
They aren't cheap, but they seem to exist if you need them.