My mechanic son and I attempted to replace the stop collar, mounting hardware, and the gear mounting bolt and associated hardware today, as per the SB. Didn't go very well. First, the bolt holes in the new collar were significantly smaller than the hole through the bottom of the gear leg and smaller than the bolt diameter. Unfortunately I didn't have my drill and bits at the hangar today; didn't think they'd be needed for this job. Wrong. In the process of trying to thread the bolt through the slightly undersized holes, the threads on the new AN5-17A bolt were ruined. Strike 1. Somewhere in there, prior to removing the gear mounting bolt, we tested for play in the mount; there was absolutely none. Good! Removed the gear mounting bolt, which was pristine. Since we were replacing that bolt and nut anyway, we decided we would throw an extra washer on the old gear mounting bolt and use it temporarily in the stop collar. Managed to wreck the threads on that one too. Strike 2. Okay, we knew we wouldn't be able to complete the job today and would have to order a new bolt for the collar, and take the collar home to drill the holes out, but we could put the new gear mount bolt in up top, put the cowlings back on and just come back with the new stop collar bolt and finish the gear reassembly later. Unfortunately, the new AN5-20A bolt would absolutely, positively NOT fit; the shank was too big. We removed the strut and checked the fit of the bolt in the strut hole itself, taking the engine mount out of the equation; would NOT go through that hole. The old bolt was a nice snug fit, the new one simply will not fit; it stops cold at the shoulder of the shank. It might be possible to pound it through, but there is no way to generate any swing in there with the strut in the engine mount, and I believe that the amount of pounding that would be necessary, if it is even possible, would damage either the strut or the bolt. Strike 3 and we're out. Just as a little icing on the cake, by the time we were done messing with all of that, I was no longer sure of the reassembly order for the washers, gear yoke and spring disc. I had tried to keep everything in order as I disassembled the gear, but one extra washer seemed to materialize after disassembly, and I haven't figure out if it goes between the stop collar and the top of the gear yoke, or between the bottom of the yoke and the spring disc (which would mean a washer both above and below the spring disc). The drawing only clearly identifies one washer, so I'm still scratching my head on that one.
So, I have to order a new AN5-17A and drill out the stop collar. No big deal. However, I am a bit puzzled about what to do about the upper gear mount bolt; the new bolt is undamaged and is the correct bolt (I assume), but it flat out doesn't fit. The old bolt, which on visual inspection was in perfect condition, fit perfectly and allowed no play whatsoever in the strut. My fear is I will order another AN5-20A hoping for one with a slightly smaller shank (I know there is some variability in bolt diameter) and the next one won't fit either. I really wish we hadn't wrecked the threads on the old bolt; I would have re-used it and would have been quite confident that it was safe. I guess perhaps I should get a micrometer, measure the old and new bolts, and provide Vans with those measurements when I order a new one; hopefully they can provide a bolt that fits if they have enough information. Any other ideas?
As noted, there seemed to be absolutely no damage done to the upper bolt, hardware, or holes despite the stop collar having been mounted backwards. There was significant damage, however to the stop collar (it looked exactly like the ones in the pictures from az gila above) and the bolt was bent right at the base of the threads. My belief is that the deformation that occurred there absorbed the excess loads from the incorrect collar mounting and may have prevented damage at the top end. Could be wrong, but that's how it looks to me.
At any rate, the plane will be grounded until I can get new bolts (again) that hopefully fit it the prescribed holes. Not a good day at the hangar.