Re: Question for Paul M.
That's a tough one for sure. If I get your meaning correctly, you want to thread on a new peice of metal, lock it with epoxy and then cut threads into it. What you would ideally end up with is new threads epoxied atop the old ones. <br />I'm afraid I don't think that will hold, as it gives very little surface area for the epoxy-metal interface. Once torqued, there is a close to 10,000lb load on those threads. Even with a high performance epoxy, you're going to need a minimum of around 3 square inches of contact area to meet that and you've only got 1.5 at best. You would actually have to grind down the threaded section a bit to get that best.<br /><br />One possibility would be to thread it down to 9/16 - 18 (fine) and make up a custom nut for it. But even that is pushing the limits of the crankshaft's material (or at least my assumptions about it!) since you'll be reducing the diameter of the threaded portion. <br />Another possiblity would be to completely remove the threaded part and drill & tap the end of the crank to accept a 5/8-18 threaded rod (say, cut from a high grade bolt). But that would weaken the crankshaft. You wouldn't have to go very deep (3/4" of threaded section should do it) but I don't think anyone could make any guarantees that the crank wouldn't crack during operation. That heavy flywheel has a lot of stored energy at 5000rpm.<br /> <br />I guess, the long and short of it is that the easiest and safest thing to do would be to replace the crank. Those were used on lots of different engines and should be easy enough to find.<br /><br />Well, those are my thoughts anyway.<br /><br />PS - I would avoid stainless in that sort of repair since it's going to greatly affect the torque friction coefficient. Steel would be prefereable and stronger.<br /><br />PPS - Where they once greased the taper, carefully examine the hub for any signs of cracking due to spreading.
