SonexBuilders.net

So when you replace bearings, the hub needs to come off. What is the procedure?

Hit techsupport@aeroconversions.com and tell us what they tell you!

I looked and could not find anything, but my experience in 40 years of marine equipment repair suggests you will need a mix of heat, cold, and pressure.

One POSSIBLE approach.

Remove the prop bolt.

Set up the biggest hydraulic press frame you can find, and support the back of the hub firmly, with the prop bolt hole UP. If you can, DO NOT use the hub flanges for this support. Figure out how to catch the crank when it pops out of the hub.

Put the crank hub flange down into a temperature controlled oil bath (as hot as you dare given the oil you have - synthetic motor oil ? but less than 600 deg F, where steel starts to lose strength) that JUST covers the hub itself. Leave it there till it equilibrates.

Quickly pull it out, put it in the press, and drop a substantial chunk, or a cup full of flaked, dry ice into the bolt hole, and quickly start pressing the ram onto the end of the crank.

Bang, you're done.

Or no bang, and you send the whole assembly to Oshkosh and let them do it.

karmarepair wrote:Or no bang, and you send the whole assembly to Oshkosh and let them do it.

No guarantee there either. My "pre-assembled" crank came with the hub about 1/16in short of bottoming. The tell is, if the slinger rotates or moves, it ain't bottomed.

The instructions in the assembly manual work quite well. Crankshaft in the freezer overnight, hub in the oven. It all comes together quite nicely if you don't get a text or call during the process.

No distractions from my flip-phone here @Area 51%

I just did this during my engine rebuild. Sonex specifically says to use a hydraulic press and do NOT use HEAT.

Find a powerful hydraulic press the maintenance shops at BUU didn’t have enough force. I lucked out with a guy in Burlington who owns an auto repair shop and is also very well known in the experimental helicopter world. He took a large bearing splitter around the base of the hub (where the oil singer is) and hung the whole assembly from that. Remove the hub bolt and drop a couple of impact sockets in to give the press something to press on. We expected a smooth push out but it released with one large bang.

Don’t mess around with anything else. Total procedure time was less than 5 minutes. The correct tools make it a piece of cake.