pto drive shaft to winch drive

i am having problems with an old koenig 100. the bolt securing the drive shaft to the winch came off and the small shim which pits into the winch input shaft
was lost (Alan bolt). I made a new shim out of old spring and it fits perfectly, however the 3/8 inset hex head bolt is not providing enough pressure and the winch still fails under a heavy load. I tried drilling a bit into that shim and also ground the bolt to fit into the depression and got a fair pull before the winch again failed. the rotation is starting to score the input shaft.
I appreciate any ideas....any one ever just drill through the input shaft so the securing bolt fully penetrates the drive shaft.? I am amazed with the strength of the winch when operating normally and it is crazy that there is only a pressure hold and not a bolt all the way through the shaft....thanks for any ideas....
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I'm not familiar with your specific winch, but I've come across other systems using a similar drive set up.
The design has a purpose: to keep the winch from being overloaded ... a slip clutch setup, as it were, for your safety.
I would suggest having the bolt hole drilled and tapped to the next larger thread size in a fine pitch (7/16" S.A.E. fine thread) and use that size Allen head ( your "inset hex head") or a Grade 8 Aircraft grade bolt.
Do not let anyone sell you a stainless steel bolt as they will gall and stick in the threaded hole without anti-sieze and that would mean drilling and tapping out for an even larger bolt.
Hope this healps.
Budd "zane 79 landcruiser long body"

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replying to Budd Cochran, zane 79 landcruiser long body wrote: thanks budd, got a good pull earlier, dragging a coconut tree out of the creek at my place here on the west coast of sumatra....i run a surf camp here....our motto is to protect and surf.....or surf and rescue when the beast, my 79 cruiser, is in a good mood. having the winch is essential i have pulled a lot of small truck out of dangerous situations.....btw I just ground down the 3/8 inch bolt to a flat face, my idea of drilling a small divot into the shim and tapering the end of the bolt was a bad idea. your suggestion helped me solve the problem.....thanks again....take care, zane
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"zane 79 landcruiser long body"

Glad to help.
I was a heavy equipment mechanic and journeyman millwright for ten years in an automotive muffler factory here in the States but I also served with the Indiana National Guard Combat Engineers in the 1970's.
US Army 6X6 trucks used a similar overload unit on some winches and I remembered how were set up.
Surf Safe!!!!
Budd
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065b0505594b06f549b8b6640ba408f1 snipped-for-privacy@example.com says...

I believe that that part is a key, not a shim, and there should be a matching groove on the mating part.
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