Clutch Removal - Well that didn't go according to plan....

[John Lyngdal]

I picked up a used Husqvarna 351 a few weeks ago and decided to replace the spur clutch drum to a rim drive.
With ill founded confidence based on doing the exact same thing to other saws I proceeded with the task.
I pulled the spark plug and stuffed rope in the top of the cylinder for a piston stop.
Grabbed a 16 oz hammer and small chisel and proceeded to place blows in an attempt to rotate the inner assembly clockwise for removal( just like the arrows indicate).
After several whacks with no results, I increased the power of the hammer blows. I should have stopped right hear and applied Kroil to the threaded area and let it sit overnight.
But no.... I just grabbed a bigger hammer and proceeded to break both clutch arms without even budging the clutch loose.
So now I applied some heat and Kroil to the area and see if after a couple days I can but the clutch loose so it can be replaced.

 

[ballisticdoughnut]

Mite wanna make sure the crank isn’t bent before proceeding. Hammer and chisel plus chainsaw, not a good combination.

 

[huskihl]

Mite wanna make sure the crank isn’t bent before proceeding. Hammer and chisel plus chainsaw, not a good combination.

That’s how they’re made. Same as many older clutches

 

[muddy42]

I find a deep socket spanner and breaker bar (which effectively extends the spanner handle to gain more leverage) works well. Watch out the rope doesn't get into the transfer or exhaust ports.

 

[Dellirium]

This type of clutch can be easily taken off by using a piston lock device. What happened to you was because of the rope that absorbed the inertial momentum. Because the shock was absorbed by the piston, the clutch didn’t got enough torque in that specific area to break loose, instead it kept squishing the rope and coming back due to rope squish elasticity

 

[muddy42]

This type of clutch can be easily taken off by using a piston lock device. What happened to you was because of the rope that absorbed the inertial momentum. Because the shock was absorbed by the piston, the clutch didn’t got enough torque in that specific area to break loose, instead it kept squishing the rope and coming back due to rope squish elasticity

For me, I think what you describe is a good thing. You don't want to shock the crank with a hammer or impact wrench and risk damaging it, you just need lots of slow turning power. This is the kind that I use (turning by hand) reverse thread:



I don't like piston locking devices as they concentrate a lot of pressure on one part of the piston head which can fracture it. You want to fill the space above the piston with rope which spreads the force over a large area.

 

[Dellirium]

Well what you have there is the best possible scenario, in which you have almost zero risks, maybe some bruised knuckles, but for these type of clutches which can be taken off with a hammer and a flathead screwdriver, if you stop the piston with a stopper, and you make sure first that the piston is firmly in contact with said device, you also have minimal chances of wrecking something. If the piston is not seated against the stopper, then that is another can of worms

 

[muddy42]

Apologies, I just realised you were talking about a different type of clutch which doesn't have a section that can be turned by a spanner.

I see what you mean now. You either buy/make a special tool or hit it.

 

[Dellirium]

Yeah, we both talked about different stuff. You have to be crazy to strike a clutch which can be easily taken out by a socket or a spanner, those usually are tighter torqued than the rest

 

[Vintage Engine Repairs]

Place rope in the cylinder and carefully hold the clutch in the jaws of a vice (don’t over tighten) and rotate the engine, it will come off without any damage. Use soft ally jaws in your vice.

 

[cookies]

air hammer...

 

[HarleyT]

I take those off with a hammer and pin punch, but nothing locking the engine. Same action as when I use an impact. Light quick blows, and it usually lets go.

 

[huskihl]

Place rope in the cylinder and carefully hold the clutch in the jaws of a vice (don’t over tighten) and rotate the engine, it will come off without any damage. Use soft ally jaws in your vice.

Tough to do with an external clutch with the drum in the way.

He probably has room to get in there now tho with the vise lol

 

[Kenlip]

Righty loosey, Lefty tighty.

 

[Captain Bruce]

I picked up a used Husqvarna 351 a few weeks ago and decided to replace the spur clutch drum to a rim drive.
With ill founded confidence based on doing the exact same thing to other saws I proceeded with the task.
I pulled the spark plug and stuffed rope in the top of the cylinder for a piston stop.
Grabbed a 16 oz hammer and small chisel and proceeded to place blows in an attempt to rotate the inner assembly clockwise for removal( just like the arrows indicate).
After several whacks with no results, I increased the power of the hammer blows. I should have stopped right hear and applied Kroil to the threaded area and let it sit overnight.
But no.... I just grabbed a bigger hammer and proceeded to break both clutch arms without even budging the clutch loose.
So now I applied some heat and Kroil to the area and see if after a couple days I can but the clutch loose so it can be replaced.

Go easy on that Kroil! I retired from Marathon and its tough to find????

 

[xraydaniel]

Hmm. You guys ever try a rusted washer tub nut removal? Now that requires the dead blow hammer and more. Chainsaw clutches? Be tender.

 

[Vintage Engine Repairs]

Tough to do with an external clutch with the drum in the way.

He probably has room to get in there now tho with the vise lol

I have been working on too many other pieces of equipment other than chainsaws recently, very good point!

 

[singinwoodwackr]

This type of clutch can be easily taken off by using a piston lock device. What happened to you was because of the rope that absorbed the inertial momentum. Because the shock was absorbed by the piston, the clutch didn’t got enough torque in that specific area to break loose, instead it kept squishing the rope and coming back due to rope squish elasticity

Works great…until it doesn’t and you punch a hole in a piston
I’ve been using a 1/4” drive Makita impact for years. It has 4 pads, 4 torque setting and those can be adjusted in combination.
never busted a piston again.

 

[steele_109]

I've worked on a lot of 350s that was the first saw I ever rebuilt. Anyway I took several clutchs of the same way you tried to. Till I ran into one that wouldn't budge.I then cut down a socket, that would fit under the springs and used a impact and they come right off.No damage nothing breaks they just come off.

 

[angelo c]

Go easy on that Kroil! I retired from Marathon and its tough to find????

While I've prayed to the "AeroKroil" gods a few times at the hangar...and watched quite a few AP/IAs prone themselves on a aircraft turbo and exhaust system...
I've also had great results with 50:50 acetone and ATF(with some diesel for aromatics-wife loves it when I come home smelling like a "heavy duty" mechanic)...
Let the clutches set overnight in the ATF/Acetone and they usually give up. Had one take three days..
But my stubborn headedness eventually won.