OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Chainsaws and Concrete Cutters McCulloch Chainsaws McCulloch 10-10 chainsaw chain tension problem

Hi All,
I have just bought this chainsaw from a flea market. It had a start up problem which I have fixed so I now have what I need - a decent reliable saw for rare/emergency use on my plot.

However there is a chain tension issue with which I would welcome some assistance.The distance from edge of saw body to tip of bar is just under 16''. The chain has 60 links which is all in accord with the specs I see on the websites. But the chain is so slack that there is no adjustment left in the tensioner screw - so the chain is being held at the extra (at least one link) and correct tension by means of the two cover retention bolts which clamp the cover on to the bar.Please see photos - you can see that even before the chain is tensioned with the cover on, the bar is a long way extended, leaving little adjustment for the tensioner screw.

The bar looks in decent condition. I am happy to buy a new chain (hopefully I can still buy one) - the existing has little sharpening left in it - but I don't want to be back to the same problem. My understanding is that chains don't stretch to this degree.
The tang which is on the chain tensioner screw and which locates in the bar is a bit chewed but non the less does locate in the bar slot ok.

So, help please.

May I close by thanking Bruce and the team for the Forum - previous experience gained from Forum guidence and parts lists for mowers gave me the confidence to have a go at this chainsaw and the engine disassembly proved to be straightforward. I paid my extra sub for chainsaw manuals and there straightaway was a pretty close match to my 30 year plus model!

Uploading another picture showing the chain cover bolted on.

Hi Brian You dont have aproblem really .Just a normal thin with achainsaw chain It just needs alitaken out. Bit hard to do unless you have an anvil to supprt the chain while you punch out therivets Your chain may have equal number of cutters on each side. It does not matter at all but when you have shortened it it will have one cutter short one on side. . Best take the chain off and take to a chainsaw shop as it will need a new joining ink to join it back up. IF the shop does not have the correct size pre set tie strap for the chain then ask them to punch out the link ans give you back the 2 tie straps etc and the plain links . You can join the chain up again using the old tie straps etc but you will not have a great deal of metal to rivet over but it will get you going again till you can buy the right new tie strap. . Will look in here again . BTW I have the gear to shorten chain etc which I can give to you Cheers Joe Brown

Joe,
Many thanks for your reply - I didn't know this was a normal situation. Is it that the chain stretches/loosens with age.

I will call in at the chainsaw shop early next week when they are quiet and will let you know how I get on.

In the meantime, thanks again for reassuring me.

Hi Brian Good to get a reply from you. Only ask for 1 link to be taken out. Someti,es it looks like a chain would stand 2 links being taken out but from long experience I know this is a bit of a rtap.
The chain itself does not stretch but the rivet and the holes they sit in wear . if you get 10thousands of an inch wear on the rivet and 1o,thousandsth wear in the hole that makes up to 20 thou per rivet .On a 60 link chain in 3/6th pitch there are 120 rivets so if you multiply 12o by 20 thousands of an inch well that how much the chain has got longer. Chains dont stretch they just get wear Cheers Joe

Joe,
Went to my nearest Mower Superstore today. In a nutshell, because of the wear on my chain they refused to shorten it for safety reasons. They showed me the Stihl replacement and, especially in my ignorance I had no option but to accept. So I bought the new one but argued a discount, - came out at $38. I attach a photo.
My woes are not over though - as I spin the chain I have a tight spot. So I have the chain as slack as I dare - the chain hangs about 1/2 inch so that the tips of teeth (that engage in the drive sprocket), are just still in the bar groove - and then when I hit the tight spot i can just about pull the chain by hsnd.
I can only think this can be worn drive sprocket. I attach photo.

If you have any suggestions I shall be very grateful. I would like to think that the chain as it is won't fly off and the tight spot will stretch/wear - or am I fantasising.

regards

Brian Y,

I need you to check the drive sprocket for a groove. If you have one then you need to replace it.

Hi Bruce,
Thanks for joining in - please have a look at the pic of the drive sprocket that I uploaded. It has grooves/notches in all the teeth - they look like the sprocket was formed that way but some notches show wear/chipping. Can I get a replacemnt sprocket from you.
regards

Those grooves in the center of each sprocket tooth are wear - they were not part of the sprocket.
While people often talk about chains stretching, they do not actually stretch, they wear, often due to inadequate lubrication, but also due to abrasion associated with exposure to dirt (including dirt embedded in the wood you cut). Some of the wear is to the rollers, but most is in the pivot pins and side plate pivot holes. This causes the chain to become longer, but much more importantly, it has more length for the same number of links, so each link has increased in pitch. Unfortunately the sprocket still has its original pitch, so the chain and sprocket pitches no longer match. This causes serious damage to the sprocket teeth, such as yours show. Putting a new chain on old sprockets is just about always a false economy, since the damaged sprockets then apply uneven loads to the chain links, and cause premature wear to the new chain. To summarise, you need a new sprocket as well as a new chain, and then you need to keep the chain and sprockets clean and properly lubricated by chainsaw bar oil, not by another kind of oil. The bar oil contains an additive that makes it super-sticky, and this is essential. You should remove the chain, clean it in solvent, re-oil it, and reinstall it, at frequent intervals - especially if you ever cut fallen trees or other deadwood. Contact with dirt doesn't just blunt the chain and strip the chrome off it - it also sticks to the chain and gets into the pivots.

Hi Brian, What Grumpy has said is all very true. Dirt is the arc enemy of Chain saw chains and bars.
I feel that you have been conned though by the chainsaw shop that sold you the new chain without offering to sell you a new sprocket.
From the worn condition of the chain you took in to get a link taken out of, they would certainly have known that the sprocket would be worn to an extent that it would need replacing
For them to refuse to shorten the chain on safety grounds I find very strange, as it it quite a normal thing to do.
With the tight spot in your new chain,it may well be that it is riding up on the worn sprocket, but also, have a look and see if you can find where the chain has been joined up.
Most shops keep the chain in bulk on a roll and cut off new chains and join them up.
It may well be that someone has tightened up the chain at the join by being too heavy handed with the pressure on the rivet spinner, and the chain is not free in the join up link.
You can pick out the joining section if you look carefully at how the rivet heads appear all around the chain, then pick out the difference in the appearance of the rivet.

You will need to look at both sides of the chain though as the new rivet rolled over, will only be one one side. Cheers Joe

Good advice there, Joe, it certainly does appear that the chainsaw shop is lacking in both expertise and of good workshop practice. Fitting a brand new chain on a badly worn drive sprocket can be very dangerous for the operator.

I,too, believe Brian has been conned by them,they should have supplied him with a new sprocket.

Hi again All,

Again, many thanks for your contributions - especially Joe.

Well, I continue to live and learn - hopefully other readers of the Forum will also benefit.
As I touched on earlier, the markings on the drive sprocket are so well sculptered, I had taken it that they were deliberately manufactured to contain the chain and stop it sliding sideways. Yes it would have been nice if the mower shop had looked at the sprocket - in fairness to them they were not mad about supplying bits for a 30 year old saw and told me up front that they were unable to do any work on it as it is not braked.

Joe, I have found the joining link and it is free. I have talked to the mower shop again and they dont have a replacement sprocket. I could run the new chain so it cuts its way into the worn sprocket but (not surprisingly) I want to replace the sprocket, which is welded to/part of the clutch drum on the McCull 10-10. Already got the old part off.

I have asked Bruce if he can supply this part but if he cant and anyone can help please let me know.

Kind regards

Brian,

This is the type of sprocket that I would recommend that you get as you will only have to replace the spur rather than the whole unit. I will need to know the chain that you are running either 3/8 or 404 pitch.

Hi to all Firstly Bruce refers to spur in his reply but I think he meant rim The type of sprocket he shows in the diagram is a rim sprocket and they are very good as you can change them over very quickly Of course you have to buy the drum as well and if Bruce has a drum and rim kit for the Mac 10-10 then you are very lucky indeed .
I see in your early posts the pics of the bar aet that you sent in had image numbers given and I was able to view the pics easily by clicking on the link but later post where you say you are sending pics of the sprocket did not have image numbers and I cannot see how to find those pics . Serves me right for not keeping up with the updates to this site.
No doubt you will set me right on how to find the pics.
I was thinking about the rim and drum set up and although it may not be required in this case ,as it looks like Bruce may have a new one,how much trouble would it be to unbraze the spur sprocket off and replace it with a hub taken off say a new drum aor even a used drum . P
Perhaps this would be a new topic in another forum..
Anyway I would be pleased if someone will tell me how to access the pics that Brian sent on the sprocke.............. Maybe I should say :Thanks Bruce : in anticpation Cheers to all Joe Brown

Joe,

Thanks for letting me know about the error. I have now corrected it.

It's great when moderators pickup errors because it really helps the members with correct information.

Bruce,
I attach pics of my drum/sprocket assembly (part no. 95165). My spec. sheet says 3/8 pitch, 0.50 guage. Thanks for looking.
Regards

Hi Bruce since my post No.18464 I have had look at the postings again and see that the image numbers are there now and I have had alook at them Good Pics too . . It certainly makes it easy when you can get some good pics . I must look into how to send pics . I use Piaccas and they have an up date It may be quite easy to use . Cheers Joe

Hi Bruce and Joe,

Pleased to be able to post that I have been able to source a drum and sprocket set (separate pieces as shown in Bruce's diagram) so all is now well. I note that these would have been supplied with the saw originally, so if the situation re-arises I need only replace the sprocket. However I shall be carrying out careful maintenence as indicated by Grumpy (unlike the previous owner).

Thank you again.