Excessive Shaft End Play

[Murray Parr]

The shim closest to the flywheel looks like it was installed not on center. It has been a few years since I built one of these, so I don't recall if that is possible or not.
Maybe it sheared part of the shim off when forced onto the wrong position. This doesn't however explain how the shim closest to the case got deformed without effecting the 2 in between but maybe it took the builder a couple of tries and deformed the other before putting it on.

Just a thought...

[Bryan Cotton]

Rodger posted this video:

[Raluttio]

I have become quite frustrated with my engine. I decided to crack open the case on Nathan at Sonex's advice to look around. I still have not discovered the cause of the mangles shims but the consequences are quite apparent. Every single bearing face is beaten up from all the metal shavings that were created.

I have put photos and videos of the internals in this Google Drive folder including the video that Bryan linked: https://drive.google.com/drive/folders/ ... drive_link

I consulted with the metals and automotive teachers that I work with. I made some v blocks and checked the flywheel and crank with calipers and a dial indicator that is accurate to .00005" and have not found anything that is out of spec. Just a few of the measurements I've done that I can remember off the top of my head: Measuring from front bearing to the thrust bearing longitudinally there is less than .001" of play. The main journal and front journal both measure an amazing .00000" - essentially both are perfectly round. All of the connecting rods are .018" or less in side to side clearance with no detectable up and down movement. The thrust bearing itself measures less than .0007" in runout on the internal diameter and less than .001" variance from the lip that the shims run on and the lip inside the case. I measured this thing in every way possible - very methodically multiple times on 3 different days. I repeated all measurements multiple times to ensure reproducibility so I am confident in my measurements.

I might still take it to a machine shop and have them check but I can not find anything wrong with the internals.

New question and new problem now that I know about the damage caused by the shredded shims - is the crank salvageable given the scoring that has been caused by the metal shavings? When I run my finger nail over the journals I can just ever so slightly feel the ridges. My finger nail doesn't catch - I can just barely feel the roughness. If I polish up all of the journals and replace all of the bearings will everything be ok or does polishing take off enough material that I would need undersized bearings? How would I deal with the two single piece bearings on either side of the timing gear - I'm not sure the prop hub and timing gear will come off given they are interference fit.

I have looked all around on forums - including The Samba - and I can't find a single case of someone having their shims shredded. This is particularly frustrating given this engine has less than 50 hours on it. Engine logs do show all oil changes during break-in were performed at the proper times.

[Area 51%]

If the oil pressure was adequate before teardown, I suspect a "dry" first start to be the culprit.

Common wisdom would have you remove the spark plugs and crank the motor till the oil pressure comes up to fill the galleys and provide enough lubrication for the first start.
Better than nothing, but an outside pressure source, and slowly rotating the engine till oil emerges from the rocker arms is a safer bet.

Remove the hub and replace the one piece bearings if you're comfortable with the condition of the crank. Probably cheaper to replace the crankshaft than have a shop rework it though.

[Bryan Cotton]

If the oil pressure was adequate before teardown, I suspect a "dry" first start to be the culprit.

That seems plausible!