026/260/261/ drum

[retro]

Link to that bearing please!

Here it is on Amazon:
Koyo K10X13X10H Needle Roller Bearing and Roller, Open, Case Hardened Steel Cage, Metric, 10mm ID, 13mm OD, 10mm Width

There were some left for less than $3.00 shipped last time I looked, but they are selling out fast now... good luck!

 

[Cracker Boy]

Thanks. I have the .325-7 and 8 and 3/8 -7 for my mofo. So I'm locked in the micro for now.

Not a bad thing its oem can get rims at any stihl dealer ftw

 

[Cracker Boy]

So I'm confused does the 261 use the micro rims or the small?

Micro on stihl same drum as 026 260 but didf part numbers same oiler on adjustable oiler system go figure.i did it yesterday

 

[RI Chevy]

Just a couple of photos of the KOYO box and the numbers.

 

[Dub11]

Just a couple of photos of the KOYO box and the numbers.
View attachment 95289 View attachment 95290

Japanese bearing made in Germany! Sounds like some axis powers type *s-word.

 

[RI Chevy]

LOL. Maybe a global company? They are nice little bearings. [emoji106]

 

[Cracker Boy]

I prefer to lube mine with silicone grease.it dont melt down and make a mess like conventional grease.i use sil glyde that you do disc brake jobs with.it dont gum up either.if its good enough for brakes and can take that heat its good enough for me.

 

[retro]

I see there are two clutch drum part number versions available for swapping the adjustable oiler MS260 drum onto the MS261. Is there any difference between the 1121-160-2910A and 1121-160-2910B drums? Does one version help a needle bearing & crank stub last any longer than the other?

 

[Cracker Boy]

Not sure what diff is in the a versws b im picking up some parts this week i will find out what diff is

 

[retro]

Not sure what diff is in the a versws b im picking up some parts this week i will find out what diff is

Thanks, I ordered a new A version drum, but I will get a B version if it holds up better?

I have a friend who does non-destructive testing for various industries. I'm gonna ask him next time I see him if he can test the hardness of my 261 crank stub for me. If he can do it I'll share the result here. Regardless, maybe he'll know about some high-tech treatment process that I never heard of, that might help solve the problem.

I use Mobil 1 synthetic grease for wheel bearings in the needle bearing, do you think Silicone greases might be better lubes? Are they any stickier, or stay inside the bearing better?

 

[Cracker Boy]

Thanks, I ordered a new A version drum, but I will get a B version if it holds up better?

I have a friend who does non-destructive testing for various industries. I'm gonna ask him next time I see him if he can test the hardness of my 261 crank stub for me. If he can do it I'll share the result here. Regardless, maybe he'll know about some high-tech treatment process that I never heard of, that might help solve the problem.

I use Mobil 1 synthetic grease for wheel bearings in the needle bearing, do you think Silicone greases might be better lubes? Are they any stickier, or stay inside the bearing better?

Probably about the same mobile 1 makes good stuff i like sythetics the dont break sown and get gummy. And melt like conventionals.

 

[retro]

Yeah, so far the Mobil 1 is working OK but I'm always open to trying something better.

I'll ask my friend to test the new OEM 260 and my original 261 clutch drum races for hardness too. Any differences found in bearing race bores or finish might be helpful as well. May as well give him the OEM bearing along with the new KOYO and get the whole story...

 

[CR888]

You can use any 1121 drum/sprocket with cutout for the oilpump gear on a MS 261.
Same for 1143 and 1123.

The part dimensions are all the same and the rims for the MS260/026 and MS261.

026 / MS 260 /MS 261/270/271/280/291 = 1121 drums/sprockets with cutout for the wormgear and any 1141 drum/sprocket

017 / 018 /019 / MS 170/171/180/181/190/210/211/230/241/231/250/251 = any 1123 or 1143 drum/sprocket will fit

And all these saws have the same small rims.

Just so nobody else makes the mistake I have the info in the above post is not correct. As AM parts for ms180's are dirt cheap on eBay I ordered a ms180 clutch drum & clutch to put on my ms262. It arrived 2day & while the crank threads are the same the diameter of the OEM 261 drum is 71.2mm vs about 67mm on the ms180 drum. The clutch is thicker too on the 261 drum. But the clutch springs look the same, the washer & E-clip will work. I nearly orderd 5 drums/clutches but luck I waited for a single test one to arrive first. The needle bearing will work between both saws too. Just thought I'd add this info.

 

[retro]

I should update... I got a new 1121-160-2910A clutch drum in an OEM MS260 rim sprocket kit last week. The new 260 drum fits my new 261 perfectly. I really like the build quality of it compared to the OE 261 drum, because it has a stronger looking sintered steel hub, the drum & hub joint has a stronger (and better looking, thicker) welded/brazed joint and the 13mm bearing bore has an excellent random-directional ground finish.

I also met my friend for crankshaft stub hardness tests and learned a lot from him. He was limited by equipment for the tests because the device he uses for radiation analysis of the types of alloys (and content percentages) present in the crankshaft steel were out of state in use at a jobsite. So, basically all we could investigate were hardness & surface durability characteristics of the crank, which really didn't tell us much more than we already suspected just from looking at it. We need to test for alloy content percentages for a fair and complete appraisal. I'm not sure when/if that can be done.... but it won't be anytime soon.

In the meantime, I am continuing to limit the 261 to 2 tanks of fuel runtime max (just one tank where its not a major inconvenience to quit working) between every drum bearing cleaning & regreasing. I am measuring during each teardown and looking for increases in wear rates between parts and breakdown of the journal surfaces. I'm still using Mobil 1 synthetic grease and so far it is doing a good job... until it all gets slung out of the bearing... thats why the saw goes back to the truck after 2 tanks max.

I did drill a 1/16" hole in the washer so I can grease the bearing with a needle greaser during every refueling if I get any more paranoid...

EDIT:
Forgot to mention that I am looking into a permanent repair option for the crank stub. I need to discuss this idea with my machinist first, then I intend to buy & install a needle roller bearing inner ring raceway from a major bearing manufacturer. The crankshaft will be turned down a bit, then the new inner ring journal raceway will be press-fit and bonded to the crank with a special high temp adhesive made for that purpose. After the new bearing inner raceway is in place on the crank, the OD will need to be ground down to fit a new needle bearing, possibly on a crankshaft grinder... the clutch drum bearing bore may also require a resizing so thats what I need to discuss with my machinist first. I'll update as it happens over the next month or so..?

 

[Cracker Boy]

Isnt that crazy they have 2 diff pat numbers but will take same drum.ihave th 026 and 261 no one could answer or dealer so i pulled one and put it on and it worked.i rwad so much about cranks and drums wearing on 261. But never heard of it on 026

 

[nohoff]

Just so nobody else makes the mistake I have the info in the above post is not correct. As AM parts for ms180's are dirt cheap on eBay I ordered a ms180 clutch drum & clutch to put on my ms262. It arrived 2day & while the crank threads are the same the diameter of the OEM 261 drum is 71.2mm vs about 67mm on the ms180 drum. The clutch is thicker too on the 261 drum. But the clutch springs look the same, the washer & E-clip will work. I nearly orderd 5 drums/clutches but luck I waited for a single test one to arrive first. The needle bearing will work between both saws too. Just thought I'd add this info.

just read my post.
they only share the same rims not drums


Put a MS 260 drum on your MS 261 and it will work.
or a MS 180 drum on a MS 241 and it will work

Yesterday i found out that you can put a MS 201 Drum on a MS 200 without any problems.
So 1129 = 1145

 

[retro]

Isnt that crazy they have 2 diff pat numbers but will take same drum.ihave th 026 and 261 no one could answer or dealer so i pulled one and put it on and it worked.i rwad so much about cranks and drums wearing on 261. But never heard of it on 026

I agree 110%! The 260 drum I bought fits the crank and new bearing better too. With the OE 261 drum there is considerable slop in the bearing, but with the 260 drum and the same bearing there is a lot less slop. The drum doesn't rock on the bearing and shaft (putting it in an obvious bind) when tripping the brake on the 260 drum like it does with the OE drum.

I recommend that every 261 owner swap a new 260/026 drum and a new bearing from a major manufacturer (Koyo or other brand) ASAP and clean & grease them often.

The only two issues left for me to fix now are the soft china-like crankshaft stub and those childish, chintzy, china-like flippy caps. Then I might own the professional grade work saw that I bought and paid for. Shame on those sorry bastids... tricks are for kids.

 

[Cracker Boy]

I hate flippy caps.i had heard that the 261 had a recall or had issues with those drums they knew about or something there of