We offer a crank service as a courtesy to our 5th bearing customers. We have, in the past, had requests to have builders’ cranks serviced minus the 5th bearing installation. We do not support this process and here is why:
We do believe a Corvair flight engine should have a 5th bearing installed – this is why we designed it. Different types of Corvair flight engines have suffered a crank failure without a 5th bearing installed. Whether it be low and slow or fast and aerobatic – there isn’t a difference – no type of aircraft has been immune to crankshaft failures.
The total weight addition in the current configuration adds a total of 3.56 lb. to the engine. It is our opinion that 3.56 lb. should not sway a safety decision.
We do realize that adding a 5th bearing to your engine conversion project does add a considerable amount to the overall cost of the project. However – if you have a crankshaft failure then the cost or weight of it matters none. Please remember we have personally broken a crankshaft and had numerous friends experience the same.
Regarding crankshaft servicing – having a crankshaft serviced properly by quality shops is costly and we don’t make a profit on this process. We simply sourced a quality shop to service our 5th bearing customers’ crankshafts as a courtesy. If you decide you do not need a 5th bearing on your engine then you may want to consider having Moldex service your crankshaft. Although they do not stress relieve the crank they do a good crankshaft service.
