During my preflight tests this morning I found the third failed ignition coil in the last 150 hours so I finally got serious about dropping the temps around my coils and alternator.  

 

I've been concerned about this since the under-cowl temps are as high as 180 deg F (delta T through rads is 70 - 90 deg F).  The attached photo shows the solution (hopefully).  The alternator plenum is made from a Tupperware container pirated from the kitchen with a skirt made from sheet silicone rubber.  A 5/8" ID vinyl hose routes cool air from the oil cooler plenum to it.   ( 3/8" ID hose was tried first, not quite good enough)  This was tried prior to today's scrubbed flight and a temp probe shows that air inlet temps to the alternator are only 3 - 5 degrees above ambient.  Nice.

 

I had recently added a cooling plenum around the coils (also made of tupperware) and fed by a 3/8" ID hose but it was pretty leaky and only dropped temps about 10 - 15 degrees.  After replacing the coil today I built a better fitting plenum and fed it with 5/8" ID hose.  This one is made of space-age cardboard and I'll build a more permanent one from fiberglass if it works OK.  Will test tomorrow if wx allows.

 

Input shaft

 

Buly, got your input shaft today and checked it out.  The thrust bearing rollers & races look a little stressed but the roller cage has been completely trashed.  I do not think the .005" out of flatness on your bellhousing would explain this and the odd wear pattern on the plate.  The marks and discoloration (heat) on the bearing and shaft look as if there is misalignment between the E-shaft  and the gear drive.  When you built the plate & bellhousing adapter for the drive, how did you verify concentricity?  This is much harder to do than verifying the parallelism of the bellhousing and plate but is absolutely vital.  There is no question that the drive would have soon failed if you had continued to run it.   Glad this showed up before flight.

 

Tracy  (Happy to hear that Dave L. is safe!  Good flying. )