Stihl Contra Info Sharing Thread

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Pulling the clutch drum

Frank...Here is a link to photos of how I had to do it on my Sand Cast (1st year) contra.

http://www.arboristsite.com/chainsaw/185425-4.htm




Stihldriver: realy nice saws, makes me jelaous in the best way they can. Thank You for pointing out the different carb number, still I didn´t found it on the castings.


So some more dumb questions regarding Contra disassembly, since I don´t wanna do any oops:

How to get the clutch shoe and drum off the crankshaft?
The clutch looks like this (the center nut can be unscrewed with no problem):

Seems to me it´s factory original, but it leaves no way how to get the cover down. Do I need to drill the rivets off? How it´s now, I don´t see anything to get it off.
The clutch drum is for the rim sprocket. I´m not so familiar with this saw, but doesn´t the drum look too thin (worn)?


From initial measurement, the thread for pulling down the flywheel seem as a M 36x1,5, resp. 36 mm outer diameter and 1,5 mm pitch. Any proof I´m right?
Also, since it will take some time for me to acces a lathe, is the pull force reasonably low to use a piece of bar with pulling screw in the middle and two studs threaded into two opposite holes for fan screws? Or is the force so high it´s likely going to strip them?

Fuel line "plug":
that plastic boss/plug, which leads fuel through the tank is of the snap-in kind, or is fastened there somehow? Just pry out with some alike screwdriver, or some other procedure needed?

Thaks for help
 
Frank...Here is a link to photos of how I had to do it on my Sand Cast (1st year) contra.

http://www.arboristsite.com/chainsaw/185425-4.htm




RIMG0031.jpg


Remove from dismantling the clutch sprocket with this completely.

Caution good spray with oil before disassembly
 
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Probably I shall start my own thread for disassembly questions, but it´s might better all info in one thread, I´m not sure.

OK, the clutch was sitting overnight under WD 40, so it took about 20 minutes of tappind the crankshatf with a hammer and some grey hair from keeping in place a pad to protect the threads.
It seems to me that there´s less than 1/4 of the lining left, about 1,3 mm, while newer clutches seems to have about 4-5 mm of lining on the shoes:




The clutch is down. Now how about the spieth sleeve, which didn´t move any bit. It seems I need a two-part gadget, bored and turned to match all the grooves on the sleeve-again, need for a lathe.
Any other hints and tips how to get the spieth sleeve down?
 
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CCF29012012_00000-1.jpg


If the Spieht adapter sleeve is stuck on the crankshaft stub, use two screewdrivers to pry it off the shaft as shown.

Screwdriver hold the left thumb with the left and right with your right thumb hold. Sprocket to move left and right while pulling from the crankshaft
 
Probably I shall start my own thread for disassembly questions, but it´s might better all info in one thread, I´m not sure.

OK, the clutch was sitting overnight under WD 40, so it took about 20 minutes of tappind the crankshatf with a hammer and some grey hair from keeping in place a pad to protect the threads.
It seems to me that there´s less than 1/4 of the lining left, about 1,3 mm, while newer clutches seems to have about 4-5 mm of lining on the shoes:




The clutch is down. Now how about the spieth sleeve, which didn´t move any bit. It seems I need a two-part gadget, bored and turned to match all the grooves on the sleeve-again, need for a lathe.
Any other hints and tips how to get the spieth sleeve down?




Did you get my information?
 
These are awesome scans, Stihldriver! I wish I had the whole booklet. Plus now I know the purpose of the thread in front of the crankcase-a build-in crankshaft blocking device. I used the rope through the sparkplug hole trick...
I will have to mfg some tool to pull the sleeve down, no matter if with the clutch drum (major damage probable) or alone, because the retaining nut (sicherung nut) was fastened by anything, but not 45-50 Nm. Rather about 80, I had to clamp whole saw to the bench (well, at least for better stability) and I was happy to have a 1 ft ratchet in hand.
 
OK, so after six weeks of soaking the spieth sleeve in WD 40, brake fluid, petroleum, trying and prying everything from screwdrivers to vice and back in few meantimes, I get to make a little crude gadget to try the most force possible to apply and voilá:

After clamping the puller´s jaws closed, hitting the sleeve with quick shot from small propane gun and wondering if the puller withstands what was loaded (about 100 Nm of torque on the wrench), decent audible "crack" and it moves:





There´s a visible "colar" with a bit eroded and burred material, just about in the middle of the sleeve, which holded it so tight. I suppose it´s a result of overtightening the sleeve by means of 1,25 mm high washer (in fact, nut from the stop switch) between the sleeve and clutch nut:






The gadget partialy disassembled. Just two short position bars of 7x10 mm and two plates of Bohler K720 tool steel 2 mm thick, with a 13 mm hole crudely drilled and filed in. Edges of the hole must be rounded, not left sharp, to fit into groove of the sleeve. The spieth sleeve is 17 mm dia, so about 17,5 mm between the bars is needed. I would suggest not even try to use some cold roled construction or mild steel for the plates, since the forces may be realy high and deforming plates will damage the spieth sleeve easily. High carbon construction steel will do the job probably even without heat treatment, but mild steel not.
Position bars and pulling plates are held together by M5 bolts, 1/8" will do also.
I will make a second version of this gadget for casual use and post it here with basic measures, if someone wiould need it.

The clutch drum is not original, it´s Oregon 10612. May I ask someone to measure the wall thickness of this drum when new? This one has 2 mm (2/25"), lining on clutch shoes is about the same.
What is the listed gap between clutch shoes and drum here? My saw has 3 mm (73 mm dia clutch, 79 mm dia drum), which seems to me quite alot difference.
Thanks
 
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OK, so after six weeks of soaking the spieth sleeve in WD 40, brake fluid, petroleum, trying and prying everything from screwdrivers to vice and back in few meantimes, I get to make a little crude gadget to try the most force possible to apply and voilá:

After clamping the puller´s jaws closed, hitting the sleeve with quick shot from small propane gun and wondering if the puller withstands what was loaded (about 100 Nm of torque on the wrench), decent audible "crack" and it moves:





There´s a visible "colar" with a bit eroded and burred material, just about in the middle of the sleeve, which holded it so tight. I suppose it´s a result of overtightening the sleeve by means of 1,25 mm high washer (in fact, nut from the stop switch) between the sleeve and clutch nut:






The gadget partialy disassembled. Just two short position bars of 7x10 mm and two plates of Bohler K720 tool steel 2,4 mm thick, with a 13 mm hole crudely drilled and filed in. Edges of the hole must be rounded, not left sharp, to fit into groove of the sleeve. The spieth sleeve is 17 mm dia, so about 17,5 mm between the bars is needed. I would suggest not even try to use some cold roled construction or mild steel for the plates, since the forces may be realy high and deforming plates will damage the spieth sleeve easily. High carbon construction steel will do the job probably even without heat treatment, but mild steel not.
Position bars and pulling plates are held together by M5 bolts, 1/8" will do also.
I will make a second version of this gadget for casual use and post it here with basic measures, if someone wiould need it.

The clutch drum is not original, it´s Oregon 10612. May I ask someone to measure the wall thickness of this drum when new? This one has 2 mm (2/25"), lining on clutch shoes is about the same.
What is the listed gap between clutch shoes and drum here? My saw has 3 mm (73 mm dia clutch, 79 mm dia drum), which seems to me quite alot difference.
Thanks

WOW Frank...

Neat jig and excellent documentation. Looks like you had the same binding problem that I had on mine. You get credit for a very creative/inventive solution. I only wish I had the metal working knowledge and equipment to do like projects. Thanks for posting the info and excellent photos. I'm away from my saws for a couple weeks or I would post the measurements but expect others can post them.

Are you going to try to save the crank?
 
Thank for compliment. Neat-uhh, it was last try-pull it or break it, I was accounting some possibility that the sleeve will be pulled in half. So all parts were left as they fall off the cuting wheel, after eyeballing the measures just enought not to cut my foot (errr, vice :) ). I´m still thinking about two part block with a hole drilled to acomodate the sleeve, with webs matching the grooves, to be able to grip all three. But reconstruction of a lathe I´m doing for a friend didn´t go fast enought.
The only machinery needed for this setup is a drill press with something to clamp things reasonably tight. I´m happy I could contribute a bit, after gainig so much tips and deepening knowledge here.

As to saving the crank-it´s partialy "saved" now, just a bit more elbow grease and finesandpaper (600+ grit) needed. The hard surface case from heat treating is torn to about 0,15 mm depth, but the ring is only about 0,9 mm wide, so there´s alot of gripping surface around. I didn´t ever though about replacing it, the damage is realy not severe. And the sleeve is OK completely, which realy surprised me. (Once again, thanks to Stihldriver-knowing that spare sleeve is possible to get realy whoops up the comfort of doing things in "now or never, glory or death" matter).

It seems to me that the inner grooves in the sleeve shall be filled with a hi-temp gear vaseline, to prevent this. There were rests of a small amount, dry as hell. I´m sure it helped to the sticking problem. Even the brake fluid didn´t penetrate between the crankshaft and the sleeve, it was that tight. This speaks damn high about the surface qualities. Today, where can be seen comparable?
 
Had to put aside my hobbies for a few months, but the bits of evenings adds together and I´m slowly aproaching to final assembly.

I found out that the angle iron mount of the front left silentblock of the AV handle is held in place by lower front bolt of the starter assembly. As well, there´s a boss on the lower front side of the fan casing, which has a steel peg protruding out about 3 mm, which fits into a hole in the angle iron. (Sorry, no photo now-later if needed).
The question:
Is the peg just a peg, or is it supposed to be a bolt there (into the boss)? If the later, I have some major pain ahead during drilling the headless bolt out and recuting the threads.
Thank you
 
OK, such questions are worthless without an ilustration.
Here it is. The peg I´m asking about if it is just a peg or if it should be a bolt under normal conditions is pointed at by the arrow. A hole in the mount of a silentblock of the AV handle fits perfectly over this peg, but then it´s being held only by one bolt of the fan cover, which seems to me as a bit weak and non-logical, concerning presence of the boss.

Thanks for response.

 
OK, such questions are worthless without an ilustration.
Here it is. The peg I´m asking about if it is just a peg or if it should be a bolt under normal conditions is pointed at by the arrow. A hole in the mount of a silentblock of the AV handle fits perfectly over this peg, but then it´s being held only by one bolt of the fan cover, which seems to me as a bit weak and non-logical, concerning presence of the boss.

Thanks for response.

you have a broken bolt. might try a little heat and vise grips or maybe take a very thin die grinder blade and cut a screwdriver slot to turn it out.

or just drill it and easy out.

I have seen several of those that were larger threads already from damage.
 
I was afraid of it, thanks for making it sure.
Heat does not help, as well as anything except driling out and recuting the thread. The head was missing a long time even in the hands of the former owner, so the stud is worn round. Tried, but no way to get a secure grip.
 
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