Hi Net I started the day investigating my prop hub installation. Again I laid the type 2 crank and My type 4 crank side by side. Here are the numbers: #4 bearing Journal T2 = 1.569 T4 = 1.569; #4 bearing OD vs. Hub OD 1.971 and 1.969; #4 bearing ID vs. Hub ID 1.573 and 1.570. I measured the bearing recesses in both cases and they were the same even though the T4 hub had been riding inside of that recess. Next I removed the fan support hub and the prop hub for a comparison of the tapered ends on the two cranks. The external appearance of both cranks is the same at the taper with the exception of the key slot. The T4 key slot was double the size of the T2 slot. The bolt hole on the T4 had been enlarged to accept a 1/2 in fine threaded bolt and was deep drilled. As for the prop hub, the size of it is designed to fit over an original crank which only needs to be modified by cutting a larger keyway and drill/tapping for the bolt. Orma L. Robbins Southfield MI 19 Years flying KR-2 N110LR http://www.aviation-mechanics.com
