by sonex1374 » Wed May 20, 2020 12:55 pm
Carlos,
Sticking with the bolts called out in the plans is probably the best plan. The upper gear leg bolts (that pass through the engine mount) have been known to break, but the factors leading to the breaks are still not well understood. It seems each case is a little different (burs on the inside of the gear leg, imbalanced tires, loose fitting leg in the engine mount socket, worn/wobbly axles on the bottom of the gear leg, and possibly over-tightening of the nuts securing the upper bolt). As these factors came to light, the factory revised the bolt specs in the plans (first changing to an AN bolt for higher strength, then changing to a castle nut so as to not overtighten the nut). While these bolt changes are a good idea, a bolt alone won't make up for an underlying problem such as a wobbly axle or out of balanced tires. My advice is to be precise with your alignment process, drill the gear leg using only a NEW cobalt drill bit using frequent applications of drill lube, and balance your entire wheel assemblies before installing them. If you find that anything is wobbly after doing all this, you'll need to correct that first. If you still can't get a good fit on your upper bolts, then maybe consider trying to source a close tolerance bolt or up-sizing to an AN5 bolt.
As for the tail spring, I don't think there has ever been any problems with the bolts holding the tail rod at either the fuselage socket or the tailwheel caster. The plans bolts work fine and don't need anything. If the rod fits loosely inside the socket you might consider something to improve the fit (thin shims, structural adhesive, etc), but this won't affect the bolts. However, even a loose fit of the rod isn't really a problem....the rod's not going anywhere.
Jeff