fun with 661's

[angelo c]

So I haven't split too many 661's to date...but the two I have done were similar in the clutches were the hardest to remove Ive ever removed. and the bearings were a biatch to remove off the crank as well. both were reasonably low time saws and around here a 661 is not the first saw off the truck for tree service guys...anyway...in removing the case bolts and many other bolts I noticed how lightly "torqued" on they are and they all now have some sort of a "loc tight" that is grey and thick and ads a good amount of resistance to the bolts all the way out. also the bolts are some new cheap kinda metal that aint too tough....


Questions:
What is the factory putting on these chit screws that are so lightly torqued that they stay on ?
What is the metallurgy of these "new" screws that my weak as chit hands snapped one on assembly ? ( Chinese bat wings maybe ? )
What are the factory torque specs for the new bolts ( case in specific)

@DND 9000

 

[jacob j.]

Here be the service manual with the torque settings from 2013. I don't know if it has been updated. It also has some comments about Loctite.

 

[angelo c]

I feel like they may put loctite on them.

its the thickness and texture of "never seize" but not as much of a PIA to wipe off. I looked at the SM and no mention of its use during "replacement" of the cases.

 

[angelo c]

Here be the service manual with the torque settings from 2013. I don't know if it has been updated. It also has some comments about Loctite.

thanks JJ
I see it in the "Special" tools section but missed it in the "assembly" section.

 

[Creaky limb tree care]

So I haven't split too many 661's to date...but the two I have done were similar in the clutches were the hardest to remove Ive ever removed. and the bearings were a biatch to remove off the crank as well. both were reasonably low time saws and around here a 661 is not the first saw off the truck for tree service guys...anyway...in removing the case bolts and many other bolts I noticed how lightly "torqued" on they are and they all now have some sort of a "loc tight" that is grey and thick and ads a good amount of resistance to the bolts all the way out. also the bolts are some new cheap kinda metal that aint too tough....


Questions:
What is the factory putting on these chit screws that are so lightly torqued that they stay on ?
What is the metallurgy of these "new" screws that my weak as chit hands snapped one on assembly ? ( Chinese bat wings maybe ? )
What are the factory torque specs for the new bolts ( case in specific)

@DND 9000

I know what you mean, seems like they are made from a kind of alloy, very light almost like aluminium!

 

[DND 9000]

It`s possible that these are aluminium screws. They are often used on newer models and the screw connection is more stable in magnesium cranckcases, due to termical reaction. There is also not so much corrosion due to these 2 metals and if such a screw is overtightened it will break off above where the threads start. The aluminium is also softer as the magnesium and therefore normally no damage on the case.

 

[huskyboy]

My 064 is 30 years old and none of the case screws ever had a problem. Seems like another over engineered solution to a problem that never existed in the first place. Lol

 

[angelo c]

It`s possible that these are aluminium screws. They are often used on newer models and the screw connection is more stable in magnesium cranckcases, due to termical reaction. There is also not so much corrosion due to these 2 metals and if such a screw is overtightened it will break off above where the threads start. The aluminium is also softer as the magnesium and therefore normally no damage on the case.

Any idea as to what the grey goopie "loc tite" is ? Stuff works well

 

[DND 9000]

I think it is something like locktite 243 (blue) medium hard. Screws coated with that can be loosened again with a screwdriver. Fixture time around 5-10min. Stihl mentiones locktite 242 medium.

 

[angelo c]

I think it is something like locktite 243 (blue) medium hard. Screws coated with that can be loosened again with a screwdriver. Fixture time around 5-10min. Stihl mentiones locktite 242 medium.

oh Im certain the "Manual" states 242, 270 and 272....doesn't specify where/when and im also certain neither of those three are "grey" and that "thick" they just feel different then any Loctite ive ever seen/removed. Usually Loctite holds hard and lets loose once a certain amount of force is applied....this goop seems to hold all the way out with a resistance to removal. Maybe its just me. But I swear the bolts are cheaper, less torqued and the goop is much better.