Excessive Shaft End Play
Posted: Fri May 10, 2024 10:25 am
by Raluttio
Hello everyone - I am a new Sonex legacy owner as of 3 weeks ago. It has an Aerovee 2.1 (non-turbo) with 40 hours since new - the previous owner had this new engine built by an A&P. There have been a few minor issues that I have worked through but I believe I have come upon a larger one that I would appreciate some guidance on.
Last week I noticed some play in the drive shaft when I was repositioning the plane. I took a video https://youtube.com/shorts/yJZBBHb3Fj0?si=xlhzZVbRmB4PEpBH and sent it to tech support at Sonex. The response was this:
The link below is a video that deals with setting crankshaft end play along with page 17 in the manual. What I see in your video appears to be excessive.
The AeroVee manual calls out .006" as the maximum end play.
Normal end play is within .003 to .006 inches. End play is set by the number and thickness
of shims that are placed between the thrust bearing and flywheel. Three shims maximum.
I assume he meant three shims minimum.
I did find this thread on the forum https://sonexbuilders.net/viewtopic.php?f=7&t=1556&hilit=shaft+end+play&start=30 from several years ago but none of the links are working any longer.
The engine has 40 hours on it. From what I have read in the above link and what I have been told from Sonex I believe my plan of action will be as follows.
- Use a dial gauge to measure the current end play. Subtract .003" from that to determine how much more thickness in shims I will need to add.
- Pull the engine off of the accessory plate.
- Remove the gland nut. It sounds like this will take a considerable about of force. Should I remove the prop and attach a 2x4 so that I will have the leverage I need?
- Measure the shims that are currently installed. Swap them for the correct combination of 3-5 shims for what I need.
- Reverse the process.
Is there anything that I should watch out for that isn’t in the installation manual?
How much time would you expect this to take a novice to complete? I do have decent mechanical sense and was able to successfully rebuild the font suspension of my 1980 MGB after watching numerous Youtube videos. That said - working on engines is all new to me.
Thank you for any help!
Re: Excessive Shaft End Play
Posted: Fri May 10, 2024 11:31 am
by Bryan Cotton
Hey Rodger,
Welcome to the forum! KBUU is really close to C77.
Check out my thread on torquing the gland nut:
viewtopic.php?f=7&t=7577
I would recommend a 2x4 in place of the prop, and a setup similar to what we used. You will need a 250 ft-lb torque wrench from somewhere, either borrow or go to Harbor freight. Leave the accessory plate on the engine mount and remove the 4 bolts that hold the case to the mount. The worst part of the job will be the R&R of the engine.
Re: Excessive Shaft End Play
Posted: Fri May 10, 2024 11:55 am
by pappas
You don’t need to take the prop off. Secure the motor to your bench in any way that you like and use this tool,
https://www.amazon.com/Universal-Flywhe … hdGY&psc=1
to immobilize the flywheel while removing the gland nut. It only fits one way on our flywheels. I always used an impact driver to remove the gland nut and it came off with no problem. But you do need a BIG torque wrench to get the required install spec. I never removed the prop for this job. You will use the same technique if you replace the main seal in the future. (I hear they leak sometimes)
Re: Excessive Shaft End Play
Posted: Fri May 10, 2024 3:55 pm
by kmacht
You will need to pull the flywheel off after removing the gland nut. When you go to put it back on make sure you use the absolute minimum amount of sealant you can. Too much and it will screw up your endplay again. Now that I think of it the rear main seal has to come out as well to put the new shims in. You will want a new one as they are cheap and difficult to remove without damaging.
Keith
#554
Re: Excessive Shaft End Play
Posted: Sat May 11, 2024 12:38 pm
by Raluttio
I measured the end play between the engine and prop with a dial gauge: .0188" so I’ll need .015-.012" more in shims. I’m going to strive for .014" in additional shims. Too bad the shim pack doesn’t come with that thin of shim - I’ll have to measure what is currently in there once I pull the engine off.
I’ll have the torque wrench and nut tomorrow so today I’ll just be taking everything apart.
Thanks for the tips so far. I ordered the flywheel immobilizer that Pappas suggested.
Bryan - what do you mean by R&R? I like the 2x4 on the fly wheel to counter the force - being able to keep the engine on the hoist instead of setting it on the ground solves one problem.
Re: Excessive Shaft End Play
Posted: Sat May 11, 2024 2:42 pm
by Bryan Cotton
Remove and replace. We had one 2x4 bolted to the case and one on the prop hub. With 2 people easy to do on the hoist that way.
Re: Excessive Shaft End Play
Posted: Sun May 12, 2024 6:08 am
by SNX1508
Hi Rodger,
I am at 57C, I have a 250 LB torque wrench that you can borrow. I also recall using a 2X4 on the prop hub when tightening the gland nut. I am on the road quite often for work but I can assist when I am available if you desire.
Re: Excessive Shaft End Play
Posted: Tue May 14, 2024 8:55 pm
by Raluttio
Update
I was able to get everything taken apart and discovered there were four shims in place - just as builder’s assembly notes had stated.
Shockingly, two of the shims were deformed and mangled. The shim closest to the flywheel looks as if it has been crushed in a hydraulic press and worn to be egg-shaped. The fourth shim looks like a hydraulic hammer came down on it multiple times. The middle two shms were stuck together (I thought it was just one shim until closer inspection) but mostly in good condition.
I believe the engine was constructed properly but something happened to define the shims after installation. I’ve sent photos and video to Sonex if they have seen something like this before. I met a guy at my airport that had constructed an aerovee and worked on several others before - he was gobsmacked to see the condition of the shims. The contact area of both the flywheel and case look normal to both of us.
I would much rather figure out what caused this rather than replacing the shims and hoping it all turns out ok!
Pictures and videos didn’t truly show the extent of the deformation but here they are.
Shim 1- closest to flywheel
https://youtu.be/-dx72TUndXE?si=fdjC2qAF3K2nInWh
Shim 2 - closest to case
https://youtu.be/P50_7W7QnWU?si=gX-2qk_iOr6CmQMW
Re: Excessive Shaft End Play
Posted: Tue May 14, 2024 9:31 pm
by Bryan Cotton
Wow, interested to hear what Sonex says. Thanks for posting.
Re: Excessive Shaft End Play
Posted: Wed May 15, 2024 8:42 pm
by Raluttio
The tech at Sonex has no idea how this could have happened to the shims. Not really the kind of thing I want to hear.
I was given the contact for Joe Norris a while ago so I reached out to him (the guy in the assembly videos for anyone who doesn’t recognize the name). Really nice and helpful guy by the way. He has never seen this situation before. His best guess was that there was oil starvation early on which led to high friction → heat → deformation. Emphasis on guess as he doesn’t know the history of the engine.
I don’t see how a bearing inside the case could cause this.
My only other plausible hypothesis is that there is some runout on the bearing surface of the flywheel. I’m going to have the metals teacher at my school (where I work) stick the flywheel on a lathe and check with a dial indicator on Friday.
When it’s said and done I might replace the shims and watch very closely to see what happens. Possibly to the extent of pulling the engine and pulling off the flywheel in 10 more hours to visually inspect the new shim’s condition. Too bad I can’t get a borescope in there!
Re: Excessive Shaft End Play
Posted: Thu May 16, 2024 2:36 am
by 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…
Re: Excessive Shaft End Play
Posted: Mon May 20, 2024 4:31 pm
by Bryan Cotton
Rodger posted this video:
Re: Excessive Shaft End Play
Posted: Wed May 22, 2024 10:38 am
by 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.
Re: Excessive Shaft End Play
Posted: Wed May 22, 2024 5:32 pm
by 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.
Re: Excessive Shaft End Play
Posted: Wed May 22, 2024 8:05 pm
by Bryan Cotton
Area 51% wrote:If the oil pressure was adequate before teardown, I suspect a “dry” first start to be the culprit.
That seems plausible!
Re: Excessive Shaft End Play
Posted: Thu Jun 27, 2024 10:49 pm
by Raluttio
For those who may come across this in the future I have a wrap up.
I conducted a major overhaul which included a new crank, all new bearings, new cylinders, new pistons, new gaskets. All of this was necessary due to the metal shavings that were created by the end play shims being ground up and sent through the engine in the oil. I still do not have a confirmed cause of the shims being ripped apart other than what I previously speculated.
One more piece to the puzzle came into play - and may be what caused all of this - after reassembling the case and calibrating the oil level. The full mark that the previous owner had set on the dipstick was just above the 2 quart mark - maybe 2.2 quarts. I am confident now that this engine had been run with too little oil.
I had first run of the rebuilt engine two days ago and first flight was yesterday. The engine runs much smoother, is able to idle lower, and I am able to run lean of peak - something I could not do before.
I still need to:
-Adjust the timing of the secondary ignition.
-Cover up my oil cooler more - oil temperature is still only getting to 140 even on a 90 degree day during first flight!
-Investigate further my #1 EGT running 150+ degrees hotter than the other 3 - had to manage the mixture to keep it below 1400 while the others were 1300 or below. This is something that was occurring before the rebuild. It is a new probe at rebuild and I can see discoloration of the metal at the 1hour oil change so I am confident that it is not an instrumentation problem. I cleaned up all of the mating surfaces between the head and the exhaust. I lapped every single valve while the heads were off so I can’t imagine it’s a leaky valve.
-investigate a faint oil smell in the cabin. I only saw slight weeping from the oil cover after an hour (didn’t tighten the nuts enough) so I’m not sure of this source.
I feel as though I will continually be tinkering. HOWEVER - I am ecstatic to be flying again!
Re: Excessive Shaft End Play
Posted: Thu Jun 27, 2024 11:28 pm
by Bryan Cotton
Great news Rodger! Our #1 EGT is always a lot hotter than the other 3. Nature of the beast. Hard to get a good balance. And yeah we always smell oil inside. Actually anywhere within 30 feet of the airplane, especially when hot.
Re: Excessive Shaft End Play
Posted: Fri Jun 28, 2024 8:35 pm
by Raluttio
Thanks for the insight Bryan. I flew again today and for a while #1 egt was 300 degrees hotter than 4 which was the coolest. The #1 Egt is always the coolest so I assume it’s running rich. I’ve seen a bit of the discussions around trying to balance out temps. Sounds like making it a turbo is the only real fix!
I’m still leaking oil from the sump cover and I noticed a small drop on the bottom of the pump cover. Hopefully it’s from the cover and not the pump to case interface. I didn’t use the gasket between the pump and cover plate like the manual shows but maybe that’s a mistake.
I also adjusted my secondary the wrong way - had a noticeable decrease in performance today.
I’m just happy to be flying though.