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Post by Supercharged86 on Mar 3, 2019 21:18:40 GMT -5
Dear Friends, I’m working on a recently acquired ’78 model 360, it had good compression, seemed complete but not in running condition when I went to look at it. Likewise, the saw had a very loosey-goosey feel to it (like the anti-vibe bushings were worn out). Once back home and after a little closer look, I gave it a quick shot of prime and she fired right off, but raced right up before quitting. Ok that was a promising start. I was already figuring it needed a boot and a pulse line right off the bat. Then after some disassembly I confirmed my suspicions of needing anti-vibe bushings. I also found that one of the bushing pins was broken in two. Fast forward a week and half with new boot, lines, bushings, bumpers and pin installed. Three pulls and off she went. But almost immediately I realized this saw has a lot of vibration. A considerable amount of vibration considering it had anti-vibe mounts??? Ok, so I checked the flywheel and clutch, everything seems ok. I did notice however that the crank has some play in it, both side to side and up and down. So my first question, after that long drawn-out introduction, should there be any side to side end play, seeing that the two roller bearings are pressed into their respectable “pockets”? I measured .010” gap between the inner bearing race surface and the machined flange on the crank. Secondly, it had a hint of up and down play. Is this likely the root cause of the vibrations? Is there anything else I could be missing here? I ordered two new roller bearings and the seals, I hope this fixes the problem. Thanks. Steve
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Post by undee70ss on Mar 3, 2019 21:31:24 GMT -5
Secondly, it had a hint of up and down play. Is this likely the root cause of the vibrations? Is there anything else I could be missing here? I ordered two new roller bearings and the seals, I hope this fixes the problem. Thanks. Steve Should be no up and down play that you can feel. Also what A/V bushings did you use? They make 2 types, hard and soft. |
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Post by blythkd on Mar 3, 2019 21:46:35 GMT -5
Assuming flywheel and clutch are all still intact and not missing any pieces, anything else that could be causing a vibration will likely be something pretty major internal. These saws have historically been pretty solid but as they get older, a few major failures are popping up. Some things I've seen, mostly on rare occasion, connecting rod screws come loose or broken piston skirt. You might also check to ensure cylinder attach screws are tight although loose screws would be very rare on a 360. A loose cylinder typically causes more of a noisy operation condition than a vibration.
If you have had a crankshaft bearing failure, I'll probably be a bit surprised if the crankshaft is still in good condition.
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Post by rowdy235 on Mar 3, 2019 22:54:31 GMT -5
I am interested to see what the problem could be. I think its good to replace the bearings, that much play is definitely bad. However as blythkd mentions, you may have something amiss internally as well.
My SEZ vibrates a lot compared to other saws I own. Of course it has no anti-vibe either.
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Post by Supercharged86 on Mar 5, 2019 23:01:29 GMT -5
Gregg, the replacement bushing kit I think is the hard ones. All fastener screws were tight, cylinder head, rod cap, etc. The crankshaft looks good, nothing obvious. Any thoughts on the side to side play? I don't see any mention of acceptable or "built in clearance" in the service manual. Also, I see that the clutch side seal rides on the oiler worm gear which then slips over the crankshaft. Even though that's a relatively tight fit, how can this provide a 100% crankcase seal? Right??? Thanks guys. Steve
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Post by onlyhomelites on Mar 6, 2019 8:31:52 GMT -5
Also, I see that the clutch side seal rides on the oiler worm gear which then slips over the crankshaft. Even though that's a relatively tight fit, how can this provide a 100% crankcase seal? Right??? It really is a tight fit; the crankshaft position is fixed by the bearing and the close tolerance of the worm gear to the crankshaft results in a pretty airtight setup (maybe not 100%, but at least 95%). You can get away with something like this setup on a piston ported engine. Based on your description of the end play, I think the bearings will do the trick for you. But while the saw is apart, I'd really look at the crankshaft to make sure it isn't bent and there's no abnormal wear at the point the bearings ride. Some guys have brutalized saws removing flywheels and clutches with hammers! |
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Post by Supercharged86 on Mar 6, 2019 10:07:12 GMT -5
Also, I see that the clutch side seal rides on the oiler worm gear which then slips over the crankshaft. Even though that's a relatively tight fit, how can this provide a 100% crankcase seal? Right??? It really is a tight fit; the crankshaft position is fixed by the bearing and the close tolerance of the worm gear to the crankshaft results in a pretty airtight setup (maybe not 100%, but at least 95%). You can get away with something like this setup on a piston ported engine. Based on your description of the end play, I think the bearings will do the trick for you. But while the saw is apart, I'd really look at the crankshaft to make sure it isn't bent and there's no abnormal wear at the point the bearings ride. Some guys have brutalized saws removing flywheels and clutches with hammers! Thanks Leon, So it sounds like it should have nearly zero end play? |
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Post by rowdy235 on Mar 6, 2019 20:19:24 GMT -5
I would say pretty close to zero. .010 is definitely too much IMO. I remember I borrowed a friends dial gauge and used to measure end play on my SEZ because whoever had it before me had rigged a poulan clutch to it, without springs no less. Its hard to remember but I think I was getting about .001 or .002 depending on the direction.
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Post by blythkd on Mar 6, 2019 21:31:37 GMT -5
Also, I see that the clutch side seal rides on the oiler worm gear which then slips over the crankshaft. Even though that's a relatively tight fit, how can this provide a 100% crankcase seal? Right??? It really is a tight fit; the crankshaft position is fixed by the bearing and the close tolerance of the worm gear to the crankshaft results in a pretty airtight setup (maybe not 100%, but at least 95%). You can get away with something like this setup on a piston ported engine. Based on your description of the end play, I think the bearings will do the trick for you. But while the saw is apart, I'd really look at the crankshaft to make sure it isn't bent and there's no abnormal wear at the point the bearings ride. Some guys have brutalized saws removing flywheels and clutches with hammers! Yip, hadn’t thought as far as a bent crank yet. Haven’t seen too many of them but it’s a definite possibility. It definitely helps to have the right tools for clutch and flywheel removal! |
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