You guys are handy. This is not really a conversion but a resurection. I traded into an old G38 with a bent crank. Somebody beat on it and really messed it up. After much fiddling I sprang for a new crank. I trued the steel prop hub. Thing is I do not like drilling holes in my props. I would like to make an aluminum prop hub, easy enough. Toni Clark has a good design on his web page, see attached. My only puzzlemant is how to index the holes in the hub for the two set screws. Did he use a ring on a shoulder? Unless you got it perfect the torque on the hub would not be right to align the setscrews that mate with the flywheel. Or, did he use a female thread in the prop stud that slips in a bore in the hub? The two screws then serve to hold the hub against he flywheel?

Could not see any web address for Toni Clark as you mentioned to be able to see his drawings.

Here is the G38 drawing but the hub is not dimensioned nor detailed.

http://www.toni-clark.com/ftp/zg38_3v.pdf

This one will be in stock within a couple weeks

http://www.horizonhobby.com/Products...D=ZEN260951110

Seems a good price for a piece that would take quite a bit of machining and experience to complete successfully. Have to remember the alignment has to be dead accurate and there would be at least 2 "moves" when machining which may require making a mandrel or collet to suit. All takes time.

The Horizone one looks nice. Does it work on an old style flywheel?

However I have a bar of aluminum, a good lathe, and a couple of beers that all need attention. Fortunatly my 3-jaw is within a thousandth of being dead on. It looks like the horizon hub would fit over a nut that holds the flywheel in place. The "nut" would have a cylindrical section that pilots the hub to be dead center. Foreward of the pilot bore there are threads to secure the prop bolt? The two cap screws only serve to hold it on? I have never taken a "new" style G38 apart so, I can only guess.

That seems convaluted to me. Also the flywheel face needs the be true to the axis of the line of the crank. That is a big 'IF" IMHO. So, to do this right I need to true the flywheel face, in the lathe, with the flywheel on the crank. Hopefully the two holes in the flywheel that will be treaded for the cap screws need to be in the right places.

The old flywheel is thinner so there isn't much material for the two hub bolts...
The new flywheel has a concentric extension that the new 2 bolt hub fits over..The flywheel face is trued and is perfect 90 degrees to the crank.
The old steel hub has 2 pins to keep the prop from slipping, they are not necessary...The old steel hub holds the flywheel on the crank,the new one uses a nut..
You cana't see the 2 roll pins in the new hub, they're under the prop washer...Most get pulled out so no extra holes in the prop...
Use the old steel hub if it's true enough, just cut the pins off...DO NOT try to beat the pins out with a hammer, they're really tight and the crank is easily bent...
If you use the steel hub put some Loctite on the threads so the hub won't unscrew when you crank the prop....

That is pretty much what I did.

The two pins cane out easy enough with a well fitted punch driving into a bench block with a hole a little larger than the pins. I put them back though. I'll take them back out. Did you use sticky back sandpaper on the prop driver or knurl it? Just leave it smooth?

Will the newer style thicker flywheel fit the old style G38?
I'd like to switch to the newer style aluminum prop hub but
not sure if my crank is bent or just the old steel prop hub bent.

John

The problem with the crank wobble on a G38 is usually a twisted crank. You have to buy a new crank or send your old one to Ralph Cunningham to get the crankshaft re-aligned or at least checked. The crankshaft becomes mis aligned at the crankpin.