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Old 03-25-2020, 05:56 PM
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boy, it looks new.

Jim
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Old 03-25-2020, 07:37 PM
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Thatís what happened on my 72. Put new cheap bearings in and it was real tight and hard to turn. Threw those away and put some BocaĎs in and itís all good.
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Old 03-25-2020, 09:29 PM
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oo; looky looky see what I have found

Jim
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Old 03-26-2020, 04:10 AM
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Originally Posted by acdii
Didnít think it was possible to over tighten the prop shaft but apparently thatís what I did give it a whack with a dead blow and now itís good
In my experience over tightening the prop nut can crush your prop hub but should have NO affect on how the crank feels when turning. If you tighten the prop and the crank gets noticeably harder to turn or feels notchy one of the following has happened:

1. Rear bearing not fully seated in the case (very common)
2. Front bearing not fully seated in the case (common)
3. Tapered drive collet contacting the nose of the case (less common)
4. Bearing thickness out of spec (never seen it)
5. Crankshaft out of tolerance (never seen it)
6. Case out of tolerance (never seen it)

When new bearings are fully seated in CLEAN case there should be no problem arising from tightening props. The crankshaft is held in a fixed position within the case based on the location of the front bearing. The front bearing is captured between the front shoulder (or spacer) of the crankshaft and the tapered drive collet bushing and no amount of prop tightening will change that.

The rear bearing however is not captured by the crankshaft. The rear bearing is held in the case by its press fit of course but does not actually contact the shoulder at the rear of the crankshaft (the shoulder located at the crankshaft counterweight). There is a few thousandths of an inch of clearance there to accommodate manufacturing tolerances and thermal expansion.

Point being, the design does not allow for the bearings to be squeezed together while tightening the prop nut otherwise the bearings would overheat and last only minutes during use.

Lonnie
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Old 03-26-2020, 04:27 AM
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Being cured by a hammer tap says it all. Great fortune that the bearings didn't get notched.
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Old 03-26-2020, 04:29 AM
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Crunchy, in your case I would tighten the pea-diddly out of that prop nut again to to see if the problem comes back. If not, you may be ok; if it does come back I'd find out why the bearings are not fully seating. Remember, the case is aluminum and will grow in length more than the crankshaft as temperatures rise. If the bearings aren't FULLY seated the gap between the crankshaft counterweight and rear bearing could close down enough to side load the bearings with too much force.
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Old 03-26-2020, 04:38 AM
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Originally Posted by Hobbsy
Being cured by a hammer tap says it all. Great fortune that the bearings didn't get notched.
Tapping the crank in an attempt to seat bearings is not a good idea, ever. Likewise, attempting to seat bearings by tightening a prop is not a good idea as that process does not create the gap between the rear bearing and crank throw that is needed for thermal expansion.

If he tapped the front of the crank he could have fully seating the front bearing OR he could have just slid the crank rearward. The next prop tightening could slide it forward again and ruin the bearings.

If he tapped the rear of the crankshaft he could have fully seated the rear bearing but then that would have pushed the front bearing from its seat.


Last edited by Glowgeek; 03-26-2020 at 05:22 AM.
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Old 03-26-2020, 05:21 AM
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Default Installing Bearings

There is not more than one way to skin this cat imo.

Make sure the bearing bores are emaculately clean and use a suitable driver that contacts only the outer race of the bearing. Heat the case to approx 350į and drive the bearings in until they stop. Tighten the prop nut to your heart's content. Over.....

Last edited by Glowgeek; 03-26-2020 at 05:29 AM.
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Old 03-26-2020, 05:43 AM
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I installed Boca bearings, and everything did line up OK. I heard a pop when I cranked down on the nut. I took the prop off and gave the end of the crank a smack with a plastic dead blow, then put the prop back on and tightened it up again and it was fine, so don't know what it was, but it spins freely with the prop tightened as I normally tighten it. It almost reminds me of when I rebuilt my V8's. After torquing all the main bearing caps, took a pry bar and moved the crank back and forth a bit to check end play, and always heard a slight pop when I did. Almost as if it needed a slight alignment adjustment. The rear bearing dropped right in the case and was properly seated after it cooled since I could see it through the cam opening. It is possible I didn't get the front bearing fully seated, but it is now. I just double checked the nut, and it is as tight as I can get it, so it's good now. Spins freely.
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Old 03-26-2020, 08:52 AM
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Hi All
Hope ya'll doing well at staying well. Only been on the planet 50
trips around the sun but this is a first. Good time to reinstitute prayer if we are behind. Uploaded a short vid on a 170 R3 Saito .
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Old 03-26-2020, 09:47 AM
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Default Over the winter

Wham Bam Saitos Man! All rebuilt over the winter and 3 more are already back in planes.



45, 65, 72, 82, 91, 115. Oh, and one unspeakable in the background.

Sorry, no fancy twins or radials.

Last edited by Glowgeek; 03-26-2020 at 09:53 AM.
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Old 03-26-2020, 10:24 AM
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Nothing wrong with an OS, have two myself, but prefer the sounds of a Saito.
Old 03-26-2020, 10:29 AM
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Originally Posted by Glowgeek
Wham Bam Saitos Man! All rebuilt over the winter and 3 more are already back in planes.



45, 65, 72, 82, 91, 115. Oh, and one unspeakable in the background.

Sorry, no fancy twins or radials.
It's function is to make the Saitos look even better!
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Old 03-26-2020, 10:41 AM
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Originally Posted by FlyerInOKC
It's function is to make the Saitos look even better!
is that even possible?
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Old 03-26-2020, 10:45 AM
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OS 4 strokes are good solid engines. Perfect for planes needing nose weight.

Speaking of OS, I have a 15LA that's barely broke in if any here are interested. Doesn't hurt to ask?
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Old 03-26-2020, 10:49 AM
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People "get away" with the hammer whack often. More often the just think so. Those tight installations more often than not are a direct result of a failure to fully seat the OUTER race of one or both bearings at the bottom of their bores. Outer races should be set in place by pressure squarely applied to the outer race only. Attempts to seat outer races from forces applied to the inner race can be destructive as the forces run from single points along the inner, thru the balls then to another point on the outer race. Little dents on all parts result at the points of contact. The best way remains even pressure, heated bores. A slight tap from well fitted mandrel also works well with minimal stressing.

Also important is absolute cleanliness as a little chip or grit can hold the race from finding home.






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Old 03-26-2020, 10:50 AM
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The one LA I have is a Blue .15. Most of my 2 cycles are OS FPs, FRSs, and I think one lone AX all in the .10 to .32 range. I also have a handfull of Super Tigres 2 cycles .40 and up. In 4 cycles I have 1 Enya .46 and one Magnum .91 along with a few beloved Saitos.

Last edited by FlyerInOKC; 03-26-2020 at 10:56 AM.
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Old 03-26-2020, 10:55 AM
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Originally Posted by Glowgeek
OS 4 strokes are good solid engines. Perfect for planes needing nose weight.

Speaking of OS, I have a 15LA that's barely broke in if any here are interested. Doesn't hurt to ask?
How did you end up with the LA? It sure is a lot smaller than your other engines. I have several short kits and an Ace Staggerwing kit which take engines in that size which explains some of my collection.
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Old 03-26-2020, 10:57 AM
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Super nice bearing drivers Gary. I use various pipe sizes or sockets, whichever is handy. Once the case is heated to 350įf the bearings go in very easily, just a gentle tap or two and they find home.
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Old 03-26-2020, 11:03 AM
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Originally Posted by FlyerInOKC
How did you end up with the LA? It sure is a lot smaller than your other engines. I have several short kits and an Ace Staggerwing kit which take engines in that size which explains some of my collection.
I bought the 15LA from HH last fall to fly a 30 yr old high wing "old timer". Pretty little plane with undercambered wings and covered in silkspan. Just flipping the prop to start the engine was popping the old glue joints! Scrapped the idea and got stuck with the engine. I'm having a hard time selling it at 1/2 cost.
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Old 03-26-2020, 11:09 AM
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Originally Posted by Glowgeek
Super nice bearing drivers Gary. I use various pipe sizes or sockets, whichever is handy. Once the case is heated to 350įf the bearings go in very easily, just a gentle tap or two and they find home.
Yes, exactly. I like to maintain slight pressure during cooling just to be certain there is no creeping back as the case cools.
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Old 03-26-2020, 11:14 AM
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Originally Posted by Jesse Open
Yes, exactly. I like to maintain slight pressure during cooling just to be certain there is no creeping back as the case cools.
Ah ha, maybe creep back is what happened with the 65 I put together Sunday. I had to re-drive the rear bearing after the case cooled. First time that has ever happened.
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Old 03-26-2020, 11:24 AM
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Originally Posted by Glowgeek
I bought the 15LA from HH last fall to fly a 30 yr old high wing "old timer". Pretty little plane with undercambered wings and covered in silkspan. Just flipping the prop to start the engine was popping the old glue joints! Scrapped the idea and got stuck with the engine. I'm having a hard time selling it at 1/2 cost.
Yeah I think there are many of us interested in that size airplane. Too big for 1/2 A and 1/4 A guys and too small for everyone else. Have you thought of building one of the retro Old Timer kits like Cleveland makes or an old timer short kit from LDS?
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Old 03-26-2020, 01:33 PM
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Yep, stuck in the middle. I'll have to give it away to be rid of it.

Eyes getting older = bigger planes
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Old 03-26-2020, 02:37 PM
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My two smallest are electric powered. Would have to be beefed up to use a glow on them, everything else I have is at least 70 and larger. The smallest 4S I have is in my Citabria, a 45 Saito.
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