660 case split

[Sawdustmaker]

I had to change the clutch side of the case on my 660. Now i have it back together and everything seems fine until I tighten the screws. Then i can hardly turn the crank by hand. Is there anything I can do besides doing it all over again?

 

[Lakeside53]

When you say "change the clutch side of the case"... I assume you realise you cannot just replace one half of the case pairs.... they are machined as pairs relative to the three indexing dowel pins.


If that's not what you meant...

You either did not set the bearing to the specified depth, or, you need to adjust the crank position in the crankcase...


They bearings are deep groove radial type and need to be in the center of their races. Biasing them to one side or the other will create a "preload" condition that is detrimental to bearing life. I assume you used OEM (stihl) bearings?

Tighten up the screws to the correct torque. Then.. tap the end of the crank with brass or poly hammer until the crank is BOTH centered in the crankcase (measure the lobes inside) AND it spins very freely. You might need to do this a few times. I find that if you tap to the side requiring less lobe clearence, center it, and give it a tiny bit more... one or two taps from the other direction will release the bearings and get you to the centered crank.

 

[Sawdustmaker]

I could not find what the specified depth is in my service man.
What is it?

 

[Sawdustmaker]

Yes i was trying to change one half of the case. Why cant i? I do not understand. The halves went together fine and now that I tapped them like you said everything seems alright.

 

[Lakeside53]

You MIGHT get lucky. The problem is that even a few ten thousanths of an inch difference in bore alignment preloads the crank/bearings - you're basically "bending the crank".

Check your cylinder base for matching height. The steel gaskt is not very forgiving.


The 361 and 441 are the only current Stihl saws that allow individual side replacements.

 

[Lakeside53]

I could not find what the specified depth is in my service man.
What is it?

It's in the manual.

The clutch side is pressed in aganst the oil pump -that registers it to the correct depth. I do it a little differently but end up at the same result. The flywheel side is just bottomed into the case.

 

[Sawdustmaker]

Thanks. is there anything else to check?

Hey brad. Where is the other half of this case? Does that guy in in TN that you are working with have it. I might want it.

 

[bcorradi]

Thanks. is there anything else to check?

Hey brad. Where is the other half of this case? Does that guy in in TN that you are working with have it. I might want it.

I'll ask, but I have a feeling he doesn't have it. I have a complete like new 660 crankcase...but its going to cost ya . The crank is even installed for ya lol.

 

[Sawdustmaker]

I guess so. I think i'll take my chance on this. These aren't new bearings so if they burn its no big loss. We'll see. I'll run her some friday and see how it goes