Maybe there are special applications for (a) and ( c) methodology - but not for automotive con-rod bolts. The head sits securely sideways within the slotted-nut or castellated-nuts slot, and the slots and splin pin head sizes are specified accordingly, and the bending of the feet ensure tight fitting, and no movement of the split-pin.Ī split pin fitted as per (a) or especially ( c) will move so in an engine running at 5000rpm, can easily fatigue fracture thus the used engines found with split-pins missing. Having said that, my understanding is there is only one correct way of installing a split-pin in any critical applications, and that is as per Robs illustration (b). The BROWN BROS catalogue referring to Split Cotter Pins suggests a compromise amalgamated name, and you have to wonder about Nettlefolds using Cotter Pin - maybe some patent or licensing origin of the special ‘Drivopen’ version, which I really cannot imagine would have had much acceptance in the auto industry, for critical applications such as con-rod bolts. In 1942 these three standards were withdrawn, due to the US/British confusion regarding SAE versus Whitworth, with an interim new wartime emergency BS1083-1942 Standard was introduced for BSW and BSF Bolts, Nuts and Setscrews only, now deleting coverage of washers, studs and Split Pins - with later updates of standard still not covering. No reference to Cotter Pins, solely Split Pins, with a line drawing illustrating and a full table of the ‘standard’ sizes. We learn from the XK120 parts catalogue that the L.103.5/8U cotter pin was size 7/64" diameter and 1" long and called the “Drivopen” type, which was a brand name from Nettlefolds of Birmingham.įor what its worth, there were originally three different British Standards - BS190-1924, BS191-1924 and BS193-1924 for BSW, BSF and BSWS respectively that as well as bolts, setscrews, nuts, washers and studs, also covered/specified SPLIT PINS. The 3.4 3.8 S-Type catalogues list both and mentions that the one supersedes the other. Not sure about the side valve cars because the parts aren’t listed separately.Ĭounting up yearly production figures in Clausager’s Jaguar, a Living Legend, leaving out pre-'38 and post-'67, this adds up to a little over 316,300 engines, mostly six cylinders with some fours, or about 3,700,000 cotter pins.įor pushrod engines the slotted nut was part C.358 size 3/8"-20 BSF, and the split cotter pin was part L.103.5/8U for all 4 and 6 cylinder engines.įor the XK engines, the slotted nut was part C.2361 size 3/8"-24 UNF and the same L.103.5/8U cotter pin was used up until the change to self-locking nuts beginning with the Series 2 E-Type and XJ6. Studying parts catalogues, I find that SS and Jaguar used slotted nuts and split cotter pins in connecting rod bolts from before 1938 to about 1968, when they changed to a different bolt with a self-locking nut. Another Arctic cold snap in Chicago so I’m inside doing some research just to satisfy curiosity.
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