056 AV Super hot crank

[Sammyp]

hi all,

Finally finished getting around to assembling the (cheap) box of bits I bought of another fella some years back and getting the 056AV Super up and running. Best part is i don't recall why he pulled it apart, but after putting it back to together, running and tuning it appeared to run pretty much spot on.

The saw had a new clutch side crank seal with dealer receipts from previous owner, new carb kit, couple of other bits and pieces.

After running saw for probably 10-15 mins tuning and doing a few cuts, I took it back into the shed and went to pull the bar off to put back on my Mag II, and noticed the clutch and drum were hot (really hot to touch but not plastic melting kind of hot - wouldn't sizzle a tiny bit of water but must have been very close). After touching/burning fingers for a while it appeared to be originating from the crankshaft.

Bearings appear tight with no play, chain brake was definitely off, and the bar cover/brake were no where near as hot as the clutch drum/clutch/crank.

Any ideas? Bearing on this side is NLA and around $50 for the cheapest one i can find plus postage and oil seal, so if bearing is shot i have problems that probably aren't worth fixing, pity as it's a really clean saw.

Also the bar cover has the clutch drum worn into it, nearly through the entire cover (magnesium cover and quite thick so quite a bit of wear), indicating side play in the crank? the way a chainsaw is designed i would think this nearly impossible without massive (and obvious) bearing failure. the only other thing i can think of is that guide plates weren't installed onto the cover or something and the whole cover was mounted too close to the clutch/drum.

i have also noticed that compared to my Mag II, the clutch drum overhangs the clutch by about 1mm, compared to the Mag ii being the opposite - probably has no bearing on anything but thought it would be worth mentioning.

Thoughts/ideas/solutions appreciated - how hot does your clutch get? to be honest i haven't really played with many straight off the cut before but would imagine this is past normal, or maybe i'm just being too cautious?

Thanks in advance,

Sam

 

[Thommo]

The clutch drum moves independantly from the crank so it can move out even if the crank is good. i would check to see if it has the correct clutch drum or if it needs a washer to keep it from moving outward too far.

 

[Sammyp]

The clutch drum moves independantly from the crank so it can move out even if the crank is good. i would check to see if it has the correct clutch drum or if it needs a washer to keep it from moving outward too far.

Thanks for reply thommo, yes i was considering another washer to try and pack it back in. Don't think this and the heating are related though which is my major issue (aside from buying an overpriced bar cover of course!)

thanks

 

[alexcagle]

The clutches do get pretty hot under normal use. It could even be slipping if the clutch is worn enough; and as @Thommo said; it could be an incorrect drum sprocket. I've seen 075 clutches have different spider and shoe combos that end up too small if paired up with other versions.
Careful scrutiny of used parts is a must, especially with Stihl's reputation for constantly updating designs.
They redesign when they are seeing too many failures, either as warranties, or from certain parts having higher demand.

I would pull the plug and starter off; then rotate the flywheel by hand.
Shouldn't be that hard to rotate.
If has a high initial break free point, I'd bet someone installed the bearings incorrectly, and left tension on them.

Grab the clutch drum and hold it while rotating.
Look for wobbling while rotating on the clutch side while holding the drum.

Even if it's slightly bent, it will cause it to vibrate, -but is hard to discern from the normal vibrations of a chainsaw.
This vibration will create heat.

I have ran into saws that have had trees fall on them that get parted out that have had bent cranks, and even seen an oblong cylinder that had no broken fins.
In cutoff saws, I see bent cranks quite often from tools being thrown on top of saws. The clutch covers are close to the clutch and plastic, so it's not that hard to do.
They get dropped, thrown in backhoes and bounced around.
I had one peticular saw that bounced out and then got run over by the backhoe.
I get about two saws a month from skid loaders having run over them.

Due to the fact that there was a new seal that came with the saw lends creedence that maybe there is an issue with the bearing.
If the cage is coming apart, the metal bits can tear up a seal if it goes that direction.

 

[Sammyp]

Thanks alexcagle, very comprehensive and a few things I hadnt thought of.

With break free point do you mean the initial force required to turn the crank?

Will compare both 056's and see if I get any differences.

Thanks again!

 

[alexcagle]

With break free point do you mean the initial force required to turn the crank?

*
Yes, that's exactly what I meant.
Remember, the flywheel magnet will create resistance as it passes the coil.

 

[Sammyp]

Beauty thanks for that, will try out hopefully tomorrow night and let you know

Also, i have another 056 in bits (not complete), I've never done it but have read heat is the best way to remove an old bearing, would it be possible to remove the bearing and use it in the current saw? Or am i better off swapping over the whole casing to avoid damage? (Think it's a mag II casing, assuming they're the same?)

Thanks

 

[Sammyp]

ok so I tested out the break free point, no resistance that I can feel or more than I would expect, and also on turning the flywheel round I couldn't notice any out of roundness holding onto the clutch drum.

I also cut roughly half a tonne with my mag II tonight and the clutch on that one was pretty hot too, so maybe I'm just being too cautious with a new (old) saw?

thanks for info anyway, I'll post back up if one of them explodes a bearing!

would still love to know anyones thoughts on the bearing question above too?

thanks

 

[hotshot]

QUOTE="Sammyp, post: 6042285, member: 120170"]would still love to know anyones thoughts on the bearing question above too?

thanks[/QUOTE]

Even though the 056 PTO bearings are the same, the Mag crankcase half is different on the cylinder base bolt spacing, with some other minor differences in the dawg mount webbing.

You, or a machine shop buddy, should be able to pull that bearing off just fine with a bearing splitter though. Go slow at the start, then shift the jaws to the inner race when you get enough room.

 

[Sammyp]

thanks for that, will try it out when i get time!

 

[alexcagle]

QUOTE="Sammyp, post: 6042285, member: 120170"]would still love to know anyones thoughts on the bearing question above too?

thanks

I whack the bearing separator with a hammer to start, then tighten it up. Then I use a shop press to finish.
That puller setup you have there looks like a pain...... lol

 

[Sammyp]

since we're on the subject, I've been looking at buying a bearing puller (now i have a use for one!), do the bearing pullers work if the bearing is left in the crankcase? is there a different attachment that comes with them or something?

the one's I've seen all look like your photo hotshot?

i'm too aggressive for hammers so will leave that to the people that can use controlled force!

 

[alexcagle]

since we're on the subject, I've been looking at buying a bearing puller (now i have a use for one!), do the bearing pullers work if the bearing is left in the crankcase? is there a different attachment that comes with them or something?

the one's I've seen all look like your photo hotshot?

i'm too aggressive for hammers so will leave that to the people that can use controlled force!

*
This is what Stihl invented for crankcase separation. They have at least two round plates that are indexed for each saw. I even use them on Husqvarnas too sometimes. Lol
*
Sometimes I use a hammer and whack it with one of these flywheel removers, which is basically just a long threaded nut that's solid on one end. If you whack it apart though, discard the bearings.
It's important to wedge something between the crank counterweights, or you risk bending the crank. I don't think manuals of any kind endorse this, but it's something I do for insurance. These have been heated up to install the new bearings, but when it's together and bolted up, if it's not nice and smooth, a moderate whack will release the tension one side or the other.

 

[hotshot]

do the bearing pullers work if the bearing is left in the crankcase

Use heat from an electric heat gun or a torch to go around the case half where the bearing is stuck in the case. They usually just fall out when given a light tap.

Your mileage may vary on the final case temp when applying heat, LOL, but 275F does it for me.

There is a blind type collet & slide hammer set up for pulling the outside races when a bearing separates, but I've fortunately never had to use one. That would almost take a second person to heat & hold the case half, while you pop the slide hammer....a real pain there.

 

[alexcagle]

Use heat from an electric heat gun or a torch to go around the case half where the bearing is stuck in the case. They usually just fall out when given a light tap.

Your mileage may vary on the final case temp when applying heat, LOL, but 275F does it for me.

There is a blind type collet & slide hammer set up for pulling the outside races when a bearing separates, but I've fortunately never had to use one. That would almost take a second person to heat & hold the case half, while you pop the slide hammer....a real pain there.

*
Just watch burning rubber things.....lol

 

[Sammyp]

Sweet thanks, very helpful!

Will try it out on a spare case which I'm sure i can find floating around in the shed somewhere.... just in case theburning rubber bit happens first time round!