So if I do this correctly you should see two pictures of a C1/C4 type gear out of the engine and without the view obstructed by the camshaft. You will see the gear bolts up tight against the rear of the crank. It has a small projecting ring on the back which helps align it in the crankshaft. No other attachment ot dowels etc. The -46 in the third photo is much heavier.
So here is the problem. I am unable to locate any of the original type bolts. If you have any or recognize these, or know of a source I would like to hear from you. Have already checked aircraft supply places and engine rebuilders who declined to sell parts.
So option two..given the fact that the gear is designed to use a tapered shoulder bolt, could we not use conventional tapered socket cap screws in grade 8? They are readily available. They should be just as strong. They would not have the square top and tie wire holes but why not use locktite to hold them in? That would prevent any movement or shifting of the bolts, and the only downside I can see is if the bolts were to shear off it might be a pain to get out the broken bolts. What do you the readership think of this suggestion? All opinions welcome.
Another question has to do with the cause of the failure. The owner checked the detached gearcase to see if there were any obvious bearing failures, or increased resistance to account for the breakage. Everything seemed as normal. Could it just be fatigue in 75 year old engine rebuilt 20 years ago? Aside from checking the gear case, cleaning the sump and putting in clean oil in the engine what other things need to be checked out? Again all opinions welcome.