Craig, There are a few theories why the .45 pin is breaking. I think its basically a material or heat treatment problem and others think its a balance problem. Might be a bit of both. We had a similar problem with the EVO2/2 motors. The first series had zero problems with the crankpin but most of the later series nearly all broke crankpins within 30 minutes. There was a change of balance with the second series but I still think it was a crankpin material problem. Compared to the older EVO and GP 45's the crankpin had a softer surface. The RS was made to eliminate the problem but the crankpin size was reduced because CMB thought the thicker crankpin was causing a problem. Its possible to put the older Evo crankshafts into the EVO2/2 and into the RS and although it looks like an ugly setup because the crankweb diameter is smaller, it works and they run fine. As I said before I fitted an old GP crankpin to the RS. Its the same diameter but shorter and shouldnt work but its the longest living RS45 that I know of even surviving a conrod breakage. Unfortunately I changed the balance on that crank before Iit was used and so we really still can't be sure what's wrong. Theres a huge ongoing thread on this subject on the Prestwich Models discussion group. The mods CMB made were to change the balance by reducing the width of the crankwebs and then a new pin material but they still broke. After that a special front housing with 2 bearings. So far that seems to work but its thought that this is only extending the time before breakage occurs. I changed the balance on my motor by reducing the material around the crankpin side which is totally opposite to what CMB did. This motor has been run in my stepsons boat only because I'm a coward and I stayed with using my first series EVO2/2 motors
but now the racing season is finishing I will test it to destruction. Life's a nightmare.Dave
