Stihl 070/090 pulling clutch...Houston we have a problem

Arborist Forum

Help Support Arborist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

TYoungKY

New Member
Joined
Feb 12, 2019
Messages
3
Reaction score
2
Location
Saint Charles, KY
I recently bought a "complete repair kit" Stihl 070 from the Farmer Tec/Huztl website with 090 piston/cylinder kit and put it together using the1chainsawguy's You Tube series. It was extremely easy to do, I actually built it in my kitchen with no vice or anything at my disposal just basic tools (my shop doesn't have internet to follow along with You Tube videos).

Anyway on to the problem. The first time I cranked the saw it ran great right off the bat, I was ecstatic, couldn't believe it. My joy was short-lived however because when I killed the saw the nut that holds the fan/flywheel on the crankshaft spun off, letting the fan and flywheel slide down the crank shaft and into my pull rope. Luckily the woodruff key didn't deform or sheer so I could put the flywheel back on along with the fan with no major visible issues. This is where I made my mistake, in order to ensure this didn't happen again I decided to tighten the crank nut with my 1/4" Dewalt impact driver ( I also went to the other side and did the same to the left handed nut on the clutch side).

Upon reassembly I then attempted to crank the saw and found that when I pulled the starter rope the clutch/chain- sprocket/chain all try to turn together. Needless to say it made an already high compression/hard to pull saw 10x harder to start when your turning the whole chain with every pull (bar is 5ft long, 172 link chain going to be milling huge oak for fun). Believe it or not it still cranks if you pull hard enough, but the chain turns like crazy the whole time even on idle which is clearly not the right thing for it to be doing.

Obviously, the answer is to pull the clutch/chain sprocket off and re-torque using a piston stop and torque wrench to the 32/33 ft lbs recommended by Stihl. But the question is how in heck to do this? I have a 3 pronged gear puller which I've attempted to use but the chain sprocket is rounded on the edges so it doesn't grip well. Also what's making it even worse is this little tapered adapter sleeve that wedges between the inside of the clutch and outside of the crank, when you pull on the clutch it just makes it tighter on this sleeve. I've tried heating, penetrating fluid, but not sure what to try next. I've seen people recommend re-greasing chain sprocket bearing every 3 months of use (which involves pulling it off) so I know some people do this task regularly but I can't find a single video showing how.

TL/DR: I over-tightened crank nut on clutch side causing clutch and chain sprocket to be fused together so the chain tries to turn at all times such as during cranking/at idle and now I can't get it off.

PS: I know chain is loose and spark plug isn't hooked up in pic, that was right after I got done assembling saw and putting bar on.
 

Attachments

  • image1.jpeg
    image1.jpeg
    427.6 KB · Views: 33
I'd give the clutch itself afew lite taps with a hammer to loosen the speith adapter on the shaft. If your puller has reversible jaws put a few wraps of wire around them to keep them on the clutch drum.
 
I'd give the clutch itself afew lite taps with a hammer to loosen the speith adapter on the shaft. If your puller has reversible jaws put a few wraps of wire around them to keep them on the clutch drum.


My puller isn't quite as big as what this guy has, it looks like the jaws on his has a longer shank at the bottom that will reach around the curved part and grab where it starts to flatten out. I guess I'll run by harbor freight and see if I can pick up a bigger puller. I tried wrapping a rachet strap around and around mine to hold it on but even that wouldn't hold it when I really put the torque to it. Thanks for the video.
 
its common to undo 1106 clutch in the woods with 2 piece of stick, put them opposite way and rock it back and forth prying the drum. thats how its done in 3rd world countries, this model is designed to be fixed with minimal tools
 
The reason the clutch is binding up is likely from the washers being too far out of spec. I had to change both out with the one I was working on. To the best of my memory the little one is too thick, and the outer one was too large in diameter. I believe the parts I used in place of those came from an 076.

The flywheel nut spacer sleeve is also a problem with the kit saws. There is no bevel on the inside edge to clear the shoulder on the taper and will tighten up against the end of the stub instead of the flywheel. I had a couple flywheels spin loose and both were destroyed by the key.
 
Well after quite a few attempts to pull the clutch off, I've managed to move the clutch farther up onto that sleeve adapter creating the few mm of space the chain sprocket needs to freely turn. Saw cranks good again, have her running really nice. Worst part about it is the clutch is slid up on that adapter sleeve harder than ever (so deep that barely any of it shows), I guess someday when the chain sprocket bearing goes out I'll have to give it another go, not looking forward to that but I think it'll work long enough to do what I need it to.
 
Back
Top