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Heavy Oil Saw

MS261 M-Tronic Clutch Drum/Bearing/Crank

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Reading around I’ve noticed 261s have a little crank problem of wearing away. 10mm it should measure and it does, so I think I’m good there.

Two fixes I’ve come across are changing the clutch drum, but I’m at a loss to which type, the interchangeable type drum or the fixed type. Which one was fitted to alleviate the problem?

Also, greasing the clutch bearing, that ain’t a problem, but what’s the dealio with the full metal jacket type of bearing, the ones from China. I’d of thought that would increase wear. (I know the bearing only comes in to play on idle).

There’s no year on the saw, as it’s a fleabay special and definitely no warranty, so any advice is welcome, and please correct me if I’m wrong on my assumptions.

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28 minutes ago, Heavy Oil Saw said:

 

Reading around I’ve noticed 261s have a little crank problem of wearing away. 10mm it should measure and it does, so I think I’m good there.

Two fixes I’ve come across are changing the clutch drum, but I’m at a loss to which type, the interchangeable type drum or the fixed type. Which one was fitted to alleviate the problem?

Also, greasing the clutch bearing, that ain’t a problem, but what’s the dealio with the full metal jacket type of bearing, the ones from China. I’d of thought that would increase wear. (I know the bearing only comes in to play on idle).

There’s no year on the saw, as it’s a fleabay special and definitely no warranty, so any advice is welcome, and please correct me if I’m wrong on my assumptions.

 

I think the plastic cage failed because of some manufacturing error making something oval , the crank or the drum not sure which . I think the fix was to loose the floating rim and put a welded star sprocket and drum on .

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I think the plastic cage failed because of some manufacturing error making something oval , the crank or the drum not sure which . I think the fix was to loose the floating rim and put a welded star sprocket and drum on .

Thanks Stubby, I’ll get hold of a welded type clutch drum.
Hoping the newer Stihl cages are up to scratch, and non of that original stock is floating about, I buy most of my unusual/small bits from L&S.
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The Mtronic versions are OK. My theory is that the cranks in the early versions of the 261 were faulty and also reckon Stihl put out that it was a sprocket issue to avoid a huge warranty return....there's a conspiracy theory for you but am not in the position to know! I have had various 261s in and some were getting through a sprocket and bearing every six months using new OEM sprocket and bearings. I have seen MS200s and 026s on original drum bearings so what happened???

Greasing the bearing - the grease will fly out in the first few minutes use. The metal caged needle bearings last longer as the needles stay in place longer but even these grenade after a while.

Not sure how you measured the crank but you should take three readings using vernier callipers at points nearest the clutch, th emiddle of where the bearing sits and the bit closest to where the circlip sits. You can also look for pitting of the crank surface, any of this and your crank is shot.

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The Mtronic versions are OK. My theory is that the cranks in the early versions of the 261 were faulty and also reckon Stihl put out that it was a sprocket issue to avoid a huge warranty return....there's a conspiracy theory for you but am not in the position to know! I have had various 261s in and some were getting through a sprocket and bearing every six months using new OEM sprocket and bearings. I have seen MS200s and 026s on original drum bearings so what happened???
Greasing the bearing - the grease will fly out in the first few minutes use. The metal caged needle bearings last longer as the needles stay in place longer but even these grenade after a while.
Not sure how you measured the crank but you should take three readings using vernier callipers at points nearest the clutch, th emiddle of where the bearing sits and the bit closest to where the circlip sits. You can also look for pitting of the crank surface, any of this and your crank is shot.

Thanks Spud. I started to get bits for MS261, then read about the crank problems, but had started a slippery slope, so looked for remedies, and changing over the drum and to a metal caged bearing, with greasing was a possible remedy I’d try.
Ended up with a parts MS261, had the carb adjust top cover, took it off and low and behold it was a MS261c (m-tronic).
Anyway, it was all confusing, as loads of threads said the MS261 was a strong saw, no problems, all that good stuff, no one really ever mentions if it’s adjustable carb or m-tronic 261 they have, and found confusion with the suffix ‘C’, does that describe m-tronic saws only? Stihl don’t make it easy.
I measured the crank quite a few times, at different places on different planes/axis’s. My micrometer is cheap, but always tells me the measurement I want .

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6 hours ago, Stubby said:

I think the plastic cage failed because of some manufacturing error making something oval , the crank or the drum not sure which . I think the fix was to loose the floating rim and put a welded star sprocket and drum on .

Stubbs, was it not the clutch bearing failing because it was either not greased on assembly or overgreased ? As I understand, over greasing can cause the bearing to skate around the surface whilst the rollers remain stationary. Anyway, what ever it was resulted in a scored and sometimes oval crank as a result.

Edited by NFG

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Stubbs, was it not the clutch bearing failing because it was either not greased on assembly or overgreased ? As I understand, over greasing can cause the bearing to skate around the surface whilst the rollers remain stationary. Anyway, what ever it was resulted in a scored and sometimes oval crank as a result.

Another one I read was that the bearing housings weren’t cast true in the casings, causing the crank to run out of harmonic balance as such, trashing the clutch bearing and in the process the crank end.

Wish Stihl just came out with it.

I never over lube, or try not to, big waste as most lube in any application gets thrown out, and splatters everywhere.

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3 hours ago, spudulike said:

The Mtronic versions are OK. My theory is that the cranks in the early versions of the 261 were faulty and also reckon Stihl put out that it was a sprocket issue to avoid a huge warranty return....there's a conspiracy theory for you but am not in the position to know! I have had various 261s in and some were getting through a sprocket and bearing every six months using new OEM sprocket and bearings. I have seen MS200s and 026s on original drum bearings so what happened???

Greasing the bearing - the grease will fly out in the first few minutes use. The metal caged needle bearings last longer as the needles stay in place longer but even these grenade after a while.

Not sure how you measured the crank but you should take three readings using vernier callipers at points nearest the clutch, th emiddle of where the bearing sits and the bit closest to where the circlip sits. You can also look for pitting of the crank surface, any of this and your crank is shot.

Can confirm my 026 still on original drum bearing can't remember when I last greased it lol, used regularly in woodland maintenance/felling/firewood. Owned from new, has been a good saw, no issues whatsoever.

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10 hours ago, NFG said:

Stubbs, was it not the clutch bearing failing because it was either not greased on assembly or overgreased ? As I understand, over greasing can cause the bearing to skate around the surface whilst the rollers remain stationary. Anyway, what ever it was resulted in a scored and sometimes oval crank as a result.

No idea . Could be .

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8 hours ago, Heavy Oil Saw said:

Another one I read was that the bearing housings weren’t cast true in the casings, causing the crank to run out of harmonic balance as such, trashing the clutch bearing and in the process the crank end.

Wish Stihl just came out with it.

I never over lube, or try not to, big waste as most lube in any application gets thrown out, and splatters everywhere.

This sounds more feasible .  All what I said was from memory and written on hear in the past . Never had a 261 myself .

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