Yep, that is the one. I should have mentioned that it was an Aerovee 2180 on a Sonex and that would have eliminated a lot of questions I got about who's engine it was. I am glad you are rebuilding this engine for Bret. He will be able to fly with confidence with a rebuilt engine from you. Happy New Year. Mark
----- Original Message ----- From: "STEVE bennett" <ifly...@msn.com> To: "krnet" <kr...@mylist.net> Sent: Friday, December 30, 2011 12:58 PM Subject: KR> VW crank failures Hi Mark, if your referring to a VW hub/crank failure from WI, the only one I am aware of this late summer is Bret T. If so, it is a 2180 from a competitor of ours that still uses a shrink fit hub on stroked engines. The engine is currently in our shop being rebuilt with an American Forged and Machined crankshaft and our Force One Prop Hub and Main Bearing Assembly. Had all of about 50 hours on it. We sent the crank out to METCO (a metal testing lab) to see what it was made of and if it was a forging or not. The material is E4340 and it is a forged crankshaft. The material had a lot of extra sulfpher in it as well as many other impurities. It was a classic break on a stroker crankshaft using a shrink fit hub. Started at back of small keyway, went around the crank until it met the back of the hole where the 20mm x 1.5 thread bottoms out. The subject crankshaft is made By/for CB Performance and this one was just a standard 8 dowel 82mm automotive crankshaft. A little 1835 or 1915 does 80 some ft lbs of torque. The 2180 generates 125 ish lbs of torque. So when using a shrink fit hub on a stroker crankshaft, the engine has to transmit that torque through the same small area on the nose of the crankshaft, just about a 50% increase in torqe!! Works some times but not always! On the stock 69mm crankshaft, the shrink fit hub or tapered short hub works very well. I don't really know of any failures unless one has a prop strike, buddy says dial the prop hub, a new prop is installed and then they go fly. And then the crankshaft breaks because the crack was already started. The other scenario of failure is if the hubs are over torqued. The big bolt 20mm x 1.5 really only needs about 40 lbs to key all in place as its in compression, working just like the prop bolts do. Sincerelyh Steve Bennett ifly...@msn.com _______________________________________ Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net please see other KRnet info at http://www.krnet.org/info.html
