Jonsered 70e chain tightens and loosens while moving by hand.

[Rocket350]

Hello, great info on this site! I just replaced the old worn-out 16 inch bar and chain with a jonsered 24 inch bar and chain. The original chain was 3/8. The sprocket is stamped 3/8. The new bar and chain has a pitch of 3/8 with a gauge of .058. While sliding The Chain by hand the chain gets tight and then gets loose enough to where its sagging off the bottom of the bar. Everything looks to be ok. The bar is tight and flush. The sprocket looks a little worn but nothing out of the ordinary. Is it possible that the sprocket just needs to wear a little bit with the new chain? The clutch and bearing is fine as well. This is the bar & chain: http://www.tractorsupply.com/tsc/pr...-combination-for-cs-2172-cs-2166?cm_vc=-10005

 

[HarleyT]

Put up a pic of your sprocket.

 

[Cantdog]

Put up a pic of your sprocket.

Yes...we will need this.....I am assuming it's a rim drive sprocket......a worn sprocket's symptom is alternately tightening and loosening of a chain......whether on a saw or bike or piece of industrial equipment....

Furthermore than bar should not fit on that saw.....you must have filed the bar slot in order to even get in on there. That saw should have a Carlton 71, an Oregon DO24 or Windsor JR mount......these are hard to come by. If you have in fact altered the bar to fit the studs make very certain that to oil hole also aligns with the feed properly

 

[Rocket350]

Hmm. I guess it's worn?? Let's see if I can post a pic..

[/URL][/IMG]

[/URL][/IMG]

 

[Rocket350]

Did my pictures post? Sorry, 1st time posting pictures. Great point about the oil hole. It looks spot on. Thanks.

 

[old guy]

That sprocket looks completely wore out on the inside. I have never seen one like that before, it looks like it was too big to fit the splines. Also it is wore out on the outside.
You may want to consider replacing it with a 3/8-7 rather than 3/8-8.

 

[Cantdog]

Yes......definitely replace the rim drive.....that is a cheap version......the Oregon ones cost a few cents more but have wear bars like an automobile tire so you know when it worn beyond spec.....

 

[Rocket350]

Awesome thanks. Is this something I can get from the local stihl/echo dealer? Or look online? And do I replace it with the 8 tooth like the original? Thanks for all help. Here us one more picture

 

[heimannm]

I have never seen a rim sprocket as bad as that on the I.D. That is certainly the cause of the chain tension changing, just watch it as you pull it around and you will be able to see the problem.



Sprockets are available everywhere, I think those older Jonsereds saws were the large (7/8" I.D.) spline but one of the more knowledgeable will confirm.

Mark

 

[Rocket350]

One more question (not sure if I need to start a new thread), what is this and what does it do?

 

[calebng15]

Looks like your chain catcher. Stops the chain if it throws one.

 

[Cantdog]

Looks like your chain catcher. Stops the chain if it throws one.

Yes that is one feature.....however it is also the oil pump strainer access. You pull the three screws and behind that is a white-ish plastic screen that filters the bar oil before it goes to the oil pump and it also gives access to the oil tank and line within.

 

[albert]

That sprocket looks completely wore out on the inside. I have never seen one like that before, it looks like it was too big to fit the splines. Also it is wore out on the outside.
You may want to consider replacing it with a 3/8-7 rather than 3/8-8.

8 tooth is stock for that saw.

 

[Cantdog]

Awesome thanks. Is this something I can get from the local stihl/echo dealer? Or look online? And do I replace it with the 8 tooth like the original? Thanks for all help. Here us one more picture

Yes an 8 pin is good.........this rim is worn but in this pic I'm not looking at wear......there is nothing that would wear this rim by the splines in such a way. This was poorly made to start with .....the splines are actually fairly tight on the clutch drum.......if rim wear is causing this problem you describe it is where the chain links are worn deeply into the surface of the rim......if you replace the rim with a good quality one and the problem persists you have a crankshaft issue......crankshafts do not bend but they can, however, slip out of phase through an impact......when this happens one counter weight (almost always the PTO side) slips on the crank pin and the shaft goes out of alignment with itself.....you would check this by using a dial indicator on the crank where the clutch bearing runs.....or if it is real bad you can see the shaft travel in an eccentric by eye when turning the crankshaft. I have replace two or three crankshafts because of this. Again just buy a new rim and see if that helps.....way easier fix!!