Final drive chain replacement

I think the final drive chain on my 750 is closing in on its wear limit - I can pull it off the rear cog a bit and there are obvious tight and loose spots along its length. Having no experience with traditional type chains - would it be usual to replace the chain and sprockets as a set at the same time or just replace the chain alone ? I notice the reynolds chain on there has a split link so I'm thinking it might be a fairly regular (and easy) thing to take off / soak in an oil bath / generally tinker with etc without having to pull off the primary and change over sprockets too ? Condition of the sprocket teeth on the rear wheel look good btw.

If the sprocket teeth are still in reasonably good condition then you could just fit a new chain, but a new chain running on worn sprockets is likely wear out at a slightly faster rate than the old one so it can be something of a false economy.

The rear sprocket is cast with the brake drum and is pretty hard material. The front sprocket has only about half as many teeth (from 19 to 22 on most Commandos, dependent on year, motor and choice) and is more prone to wear. If the sprocket teeth look symmetric, its good. If the tip of the tooth is missing the little bit of bevel near the tip, its worn and should be replaced. Here's an extreme example of good v worn :



This is what an extreme rear sprocket would look like. The front sprocket would be a mirror image. The actual sprockets on Nortons have and additional slight bevel at the tip which isn't shown on this bicycle sprocket.

Ya don't have to replace sprockets as long as the chain can still turn the things, but peaked teeth can quickly wear all the way off to rounded off lumps and interesting whirling ringing noise while going no never fast. Worn teeth can wear chain links quicker too. If I don't lube my plain chain in our gritty conditions, which includes staying oil tight in stuff ahead of it, then I get about 10K miles per chain, with about half dozen re-tension adjusting. How ever far you can pull links out of valleys that's where links bare on teeth. I get pension and easy on throttle at 1/3 lift out point and star planning on another chain. If lube gets on my plain chain, like Trixie did last season with ring gap head and case blow by, then each ride needs adjusting chain.
If properly flooded with oil as Norton properly set up their chain oiler so whole back of bike grimed by the sling off, then chain lasts longer as expected. 99 links up to 20T sprocket and 100 links for 21 T. Don't know link count above that tooth count size. Chain change is done like you mention, use old one to pull new one around. Next chain on plain Trixie will be 530 X ring and let it eat its own clear path dry as a bone on the outside if I can help it. Most labor intensive for economy is one chain running while other cleaned chain soaked in graphited melted grease. Too tight is way worse than too loose. BTW wheel alignment is mainly to get straight chain run more that straight tire run.

It is also possible in some cases to replace just the smaller front sprocket along with the chain if it has more wear, often the case on many bikes and standard practice on bicycles (though the small cogs are in back)

stu said:

I notice the reynolds chain on there has a split link so I'm thinking it might be a fairly regular (and easy) thing to take off / soak in an oil bath / generally tinker with etc without having to pull off the primary and change over sprockets too ?

Click to expand...

Beware - if you remove the old chain, it can be a bugger to refit as the front sprocket is hard to get at to wrap the leading links over. If you have a new replacement chain, link it to the tail of the old and pull it through.

Mick

ML said:

stu said:

I notice the reynolds chain on there has a split link so I'm thinking it might be a fairly regular (and easy) thing to take off / soak in an oil bath / generally tinker with etc without having to pull off the primary and change over sprockets too ?

Click to expand...

Beware - if you remove the old chain, it can be a bugger to refit as the front sprocket is hard to get at to wrap the leading links over. If you have a new replacement chain, link it to the tail of the old and pull it through.

Mick

Click to expand...

The trick is to locate the master link on the bottom of the loop. With the bike on the center stand and the trans in neutral, take the link apart, attach the new chain to the link, and roll the tire BACKWARDS. The old chain will pull the new into place. Once you've got the new chain pulled in, unhook the old, join the new chain and close the masterlink. Remember, if you're replacing the chain, you'll need to move the axle forward again, as the new chain will be tighter. Turn each adjusting bolt an equal number of turns to keep the axle true (take a scratch pad and keep count of the number of flats the bolt is turned and pay no attention to the number of turns on the locknut - it just needs to be backed off all the way, then re-tightened once you've set the slack). If you turn the bolts in all the way equally and move the axle all the way forward, it'll be easier to close the link. Then turn the bolts out equally to get the proper slack in the chain. It's amazing how much the chain will move by turning the bolt one full revolution. I move the axle before breaking the old chain apart - it's nearly idiot proof that way.
Also, as long as you are replacing the chain, check the slack on the primary chain - this needs to be done BEFORE setting the slack on the drive chain, as it's adjusted by moving the transmission, which moves that little sprocket you're wrapping the new chain around. You don't have to take the cover off the primary to adjust the chain, but its a good idea if you haven't done it before.

Recap:
Bike on center stand
Primary cover off
Adjust primary slack
Move axle forward by turning adjusting bolts EQUALLY and slackening axle nuts 1-2 turns
Locate master link on center bottom, split link
Pull new chain in by linking to old and rotating rear tire backwards (clockwise)
When new chain is pulled in, remove old, join new
Set slack by turning bolts out EQUALLY, making sure bolts are in contact with axle spacers.
When slack is set, tighten axle nuts and tighten adjuster lock nuts
Close up primary, adding oil.
Test ride, check slack on primary and final drive, adjust as necessary.
Usually a drive chain will need to be adjusted after 100 miles or so, then just check occasionally. Remember, a little loose is better than a little tight.

Now you've done it. He'll never learn anything that way. It's always good to figure out how to get that blinking chain over the front sprocket. I was expecting a new thread on that.

Dave
69S

Sorry!

Bill the thread killer

How about the easy way to do it if you just have one chain?

Well the tricks and tools to deal with types of master links was left out for the learning curves to enjoy.

hankmarx said:

How about the easy way to do it if you just have one chain?

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It takes two people.
First pull the clutch lever and zip tie it to the bar.
Put the trans in 2nd or 3rd gear.
Have your buddy slowly push the kickstarter down with his hand while you feed the chain in from above the swingarm. When the sprocket catches the end of the chain it will pull it through so you can grab it from below. Jim

Thank You! Now dealing with a stripped primary drain bolt hole. Then the chain. Thanks for the Shine, Hobot!

Say What hankmarx! I'm pretty alert who I share Ozark Dogpatch KIck-a-Poo Joy-Juice with so assume you got a snort out of glass flash in Texas LOP. Comnoz did too. I of course hardly touch the stuff but like to share the spirit.

Just grind the primary drain plug to stuff in with permanent sealant like even JBW if required and never ever touch it again and inform next owner not to either. Its total useless like tits on bog hogs, ain't the right level and don't really drain fully and as you see its prone to wallowing out by prior unknowing owner. Do align the plug flats for nice alignment on close inspections. Fill with favorite lube just so cold chain slack is 1/2 way in oil w/o bouncing it.

Back to the original topic - I usually go through two, maybe three chains per set of sprockets (drum). A worn chain is hard on the sprockets. If the teeth aren't hooked, just put a chain on it.

Greg