Sprocket cover screws 34890-52

[hennesse]

It looks like the sprocket cover screws started out as slotted heads, and then later changed to countersunk hex heads.
Any idea when this changed?
Dave

34890-52

34890-52.jpg (14.91 KiB) Viewed 8059 times

[starcain]

Dave, pretty sure the hex head countersunk dcrews came in 1954

[Jim Garrett]

My original 1954 KH has hex head bolts.

[fiftysevenXL]

The 1954 Museum KH also has the hex-head screws ( with the early sprocket cover )

[sportsterpaul]

Do you guys use loctite on these tapered sprocket cover and generator bolts? I hate gluing my bikes together so I avoid loctite if I can. I love when the bolts free-run after you crack them loose. I do use loctite on the four bolts holding the trap door, and the engine sprocket nut. Everything else gets anti-seize. Bonneville racer Vance Breese told me anti-seize actually helped keep fastener tight, but then again, he used a lot of safety wire and took his bikes apart frequently.

I worked with a brilliant maintenance tech that had worked at GE electric motor plant in San Jose. He explained that countersunk screws never perfectly line up with the holes. So there will be more pressure on one side of the countersink. He said depending on where the thread started on the screw, you had a 50-50 chance they would either tighten under vibration or loosen. This finally explained to me why the military hardware I worked on had loose captive nuts for countersunk panel screws. The nuts would self-align and the screw would not back out under vibration.