H-D Big Twin round-tube swingarms 1958–72

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Speeding Big Twin
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Re: H-D Big Twin round-tube swingarms 1958–72


Post by Speeding Big Twin »

Forging number 47614-58A officially first appeared for 1963 models but I think your swingarm is about a 67 model, partly because it was around then that the forging die number became 10. Notice the axle clip appears to have two holes for the brake hose clamp screw. Some die-10 axle clips have only one hole for the screw but some have an extra hole further to the rear and that appears to be what yours has. Also notice there is no boss for the additional hole. It may be that early-67s only had the hole in the rectangular boss first introduced for 63 and my guess is most swingarms for 67 had that hole tapped ready for use. But at some stage during the 67 model year it seems the factory wanted the hose clamp mounted further to the rear and that may be why some swingarms have two holes. I expect very late 67s only have the rearmost hole, as do 68–72 models. For those swingarms the rectangular boss remained in place but it did not have a hole. Outside the left clip you may find a run number, maybe around H12? The R-H axle clip appears to have die number 37 upside down.

Forging number 47614-58B was introduced around 1968? Die number 16 suggests about a 72 model and that would be roughly consistent with run number H38. Outside the R-H axle clip I’d expect a die number in the 70s, perhaps about 72 or 73? The pivot bolt housing is marked 4 which may be a die number but I’ve also seen these later housings with 1, 2 and 3 and the housings don’t seem to have been used in any particular order. Letters may be FE or FF but I don’t know what they represent. Sometimes you’ll even see HH but I don’t know what that indicates either.
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