034 Crankshaft - to split or not to split?

[danw]

Short version: free 034AV runs great after I put a few parts in it. Now I notice that needle cage and clutch drum have aton of slop and it turns out it's the crankshaft itself worn down where the needle cage runs. Anybody know why this might happen? Is there a fix short of splitting the lower end and replacing the crankshaft?

Anyone want a parts saw?

 

[Hddnis]

You did you try a new bearing and clutch drum?

I don't know of fix other than a new crankshaft. You might be able to turn down the crankshaft and sleeve it, but I've never heard of that being done on a chainsaw. I've never heard of an oversize bearing either.


Mr. HE

 

[danw]

yeah, I thought about a sleeve or an oversized bearing which I'm sure I could find, but the problem is the worn crankshaft itself. I can't even turn it down and put a new snap ring groove in it without taking it off the saw, and if I do that I'm not putting back on!

...or maybe I could start the saw, and turn in down on the saw!!! kidding, kidding...

oh, yes it's a new drum and bearing. I put them both on a 10mm shoulder screw and they're nice and tight, maybe a couple mils of slop.

So, how hard is it to split it? If I do that I would probably end up replacing bearings and oil seals right? Anything else?

 

[wigglesworth]

oh, yes it's a new drum and bearing.

Is it possible you got the wrong bearing/drum? How did the old one fit? I highly doubt the crankshaft is worn down, not saying it's not possible, but very, very unlikely.

 

[sefh3]

Anyone want a parts saw?[/QUOTE]

Yep I'll take it off your hands......

 

[sefh3]

Short version: free 034AV runs great after I put a few parts in it. Now I notice that needle cage and clutch drum have aton of slop and it turns out it's the crankshaft itself worn down where the needle cage runs. Anybody know why this might happen? Is there a fix short of splitting the lower end and replacing the crankshaft?

Anyone want a parts saw?

Spliting cases isn't that bad. Sometimes you just have to. Bearings are cheap and not hard to do.

 

[blsnelling]

Is the crank obviously out of shape? I've never heard of one doing this. That's not to say it doesn't happen though.

 

[striperswaper]

the bearing is really only turning at idle
how does the slop compare to your 361?

 

[Grande Dog]

Howdy,
The thing that usually starts the wear process is rust, dry bearing, and a lot of idling. The bearing is only moving when the saw is idling. If it was my personal saw, I would run it and limit the idling as much as possible. If you decide to replace it, and can't find a deal on a used one, we sell an aftermarket replacement for $100.00.
Regards
Gregg

 

[danw]

I can't really figure out why it would do that, but it was like that when I got it. It's definitely worn down - I think the guy that gave it to did something major and then kept running it. If there is a bit of slop and the clutch grabs the drum at an angle, the drum would alternate back and forth relative to the shaft as it turns. Maybe that's where the excessive wear came from??? I'll take a picture of it tonight, it's pretty strange.

Are the crankshafts hardened? Maybe just nitrided or case hardened?

Oh, and it's WAY sloppy, like 5-10 degrees each way sloppy.

 

[Hddnis]

That really sounds like wrong bearing and/or clutch, not questioning you, I know it could be that worn, I've just never seen it.


Mr. HE

 

[danw]

OK, so if I'm going to split this thing, what should I replace? Both bearings, seals, and then see what condition the piston and rings are in?

 

[andrethegiant70]

That's just downright weird. Crankshaft material is hard as hell. If that's really what's going on, I'd replace the bearing and seal while you're in there. Doing any piston work i think would be optional if the saw is running good. That's easy stuff to do anytime. I'd mic the piston (top and bottom) and take a hard look at the piston skirts for wear. If they are thin, buy a piston. If it all checks out though, slap it back in there. If you just want to freshen up your compression, you could do rings. I agree it would be nice to "feel" a difference after putting the work into it.

 

[Saw Dr.]

There are two different bearings for that series. They came up with a big bearing kit for longer service. Hopefuly Thall will be by to straighten this out. Sounds to me like you have a mix of parts there.

 

[danw]

SOunds good - you're right I could do the P&C work later if needed. Not sure if I can ask here, but where should I buy the CS, bearings, and seals? Should I buy OEM?

 

[sefh3]

For piece of mind, I would throw some rings in it. They are too bad price wise and you already have the cylinder off.