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Do I need to replace primary chain?

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Do i need to replace the primary chain on commando? I was about to clean the clutch plates and noticed what looks like a small crack in one of the chain links , photo included . thanks in advance for any advice. mark

Attachments primary-chain-copy-jpg
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In the picture it looks like the plate is broken. No doubt in my mind that the chain must be replaced. Imagine if that plate comes adrift while you're riding!

David

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So lucky to spot that before the chain failed completely! The new chain you are just about to fit will be so much cheaper than the chain and chaincases you would have had to buy if you had run it any longer.

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Hi,

What would concern me was how the chain became damaged. The triplex chain should be fairly bullet proof. How many miles have you got on the bike ? are there any other signs of distress on the chain or the sprockets ?

Tony

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Check sprockets for alignment. The clutch sprocket can be shimmed to get alignment close to engine sprocket in the 'plan' (top) view but this will not correct misalignment in the 'end' view i.e shafts not parallel. Having said that shafts might not be parallel in plan view also.

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A Commando triplex Primary chain run in perfect conditions should last around 30,000 miles before making noises. Always use a Reynolds. I don't know what make of chain yours is or how many miles it has covered but I've never seen that happen before.

As said, check for alignment. Either a bad chain, left to run dry or out of line. Good luck.

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A dry chain normally sheds rollers first. I suspect just a faulty chain or previous damage (a foreign object between chain and sprocket). Worth checking alignment though. I have a BSA with 45,000 miles on a duplex primary chain and no hint of stretch or wear. These things do last well if there's oil in the chaincase.

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Good points Gordon but the BSA may have an easier life than a Commando, just a guess, all things being equal.

My Mk3 was making a clunking noise I could hear when reving from tick over. I asked Les Emmery what it could be. He asked me the mileageand if the primary chain had been replaced and he said the chain was knackered.New original chain later and all was well. I have spoken to a few owners with the same problem and fix. A new Reynolds chain and here's to the next 30,000 miles! Thankfully I caught this in good time because all of the sprockets were in good order. Says something for ATF.

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With primary drive sprockets square to each other and inline I would expect more than 30,000 miles from a chain in constant tension and sitting in an oil bath. Ask a rotary owner how many times they have adjusted the final drive chain let alone have had to replace one.

I think the short life of Commando primary chains is due to shafts not parallel and mis alignment of sprockets.

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Hi,

I have nearly 70,000 on my Commando, I have owned it from new and it is still on its first chain. I too get a clunk when blipping the throttle when first starting but this is due to the hydraulic tensioner slowly losing it's oil. Once it has built up pressure it is ok. It has done this for as long as I can remember.

Tony

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Wow, and of course, after you have fitted the new chain you charge up the tensionners, hence no clunk!

Last night I was reading Mick Hemmings article on Isolastics. Classic Mechanics November /December 1987. There was also interesting stuff on clutches but what he said on primary chains was that if you snap the throttle lots on your Commando, he recommendedchanging the primary chain every 12-15,000 miles.

However, I shall revise my 30,000 miles to 70.000. I had better inform my Son!

PS: Sorry for my miss spelling previously of Renold........

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Thanks all for the advice, but does anyone know of an easy way to get the alignment correct. Would a steel rule on the top between the sprockets be sufficent? Any ideas on how to test if the shafts are parallel? I can only think of putting extentions on the shafts and then measuring close and then further back ...

Previously simon_ratcliff wrote:

Check sprockets for alignment. The clutch sprocket can be shimmed to get alignment close to engine sprocket in the 'plan' (top) view but this will not correct misalignment in the 'end' view i.e shafts not parallel. Having said that shafts might not be parallel in plan view also.

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Hi Mark,

a steel rule aross the top of the clutch plate housing circumference can be used as a datum to measure distance from edge of the rule to the sprockets. Distance to clutch chainwheel will be constant but distance to engine sprocket varies dependent on shims fitted behind chainwheel.

Your method of checking for parallel seems ok to me.

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Thx for the speedy reply, when the replacement parts arrive i will spend some time on the alignment.

Previously simon_ratcliff wrote:

Hi Mark,

a steel rule aross the top of the clutch plate housing circumference can be used as a datum to measure distance from edge of the rule to the sprockets. Distance to clutch chainwheel will be constant but distance to engine sprocket varies dependent on shims fitted behind chainwheel.

Your method of checking for parallel seems ok to me.

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Previously mark_oliver wrote:

Do i need to replace the primary chain on commando? I was about to clean the clutch plates and noticed what looks like a small crack in one of the chain links , photo included . thanks in advance for any advice. mark i would change primery chain [for a belt ]just over £200 and all will be ok...no need to line up the chain and no oil to worry about and no clutch slip.i,m still on the same belt 15yrs later and a new belt is cheaper than a chain

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Thx, but chain already ordered and in post. Although i would have thought that with a belt it would be even more critical to get the alignment correct and any wear in the mainshaft bushing would be instant belt destruction. I have no engineering skill and very little knowledge of belt drive systems but i am very impressed that your belt drive has lasted 15 years and am tempted if it is that good. Who supplied your parts?

Previously mark_oliver wrote:

Do i need to replace the primary chain on commando? I was about to clean the clutch plates and noticed what looks like a small crack in one of the chain links , photo included . thanks in advance for any advice. mark i would change primery chain [for a belt ]just over £200 and all will be ok...no need to line up the chain and no oil to worry about and no clutch slip.i,m still on the same belt 15yrs later and a new belt is cheaper than a chain

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Previously anthony_williams wrote:

mark i would change primery chain [for a belt ]just over £200 and all will be ok...no need to line up the chain and no oil to worry about and no clutch slip.i,m still on the same belt 15yrs later and a new belt is cheaper than a chain

Please see 'Commando Crank Run Out Issue' to see what can happen if the belt pulley's are not parallel in two planes.

Mark is correct in thinking that it is more important to align a belts pulleys than a chains sprockets. This is because there is a larger acceptable tolerance between sprocket alignment with a chain than a belt simply because of chain flex 90 Deg. to the rollers, or side play if you like. If you are checking anything for alignment may as well get it as close as possible.

A flippant attitude to assembly and maintenance is asking for trouble. see 'Commando clutch bearing'.

Anthony, if you've had no problems then it's possible the bikes crank drive shaft and gearbox mainshaft are acceptably square to each other, but where's the harm in checking on assembly? I do wonder how many miles the bike has done in 15 years. May be you could tell us.

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Simon, you are baiting the wrong bloke this time.

Tonys commando, dommy and ES2 are thoughfully modified, well maintained and used hard.

Theres very few people who do more miles in all weather on their Nortons than he does. He is always up for a ride out and his bikes never let him down

And he is a bloody good bloke always ready to open his house, workshop and toolbox to help any other Norton owner in need.

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I'm not baiting anybody Peter.

Knowing how many miles a component has done can tell you the suitability of the component and give an indication of how the engine has been assembled. The more miles the better. Whereas only knowing how long it's been fitted says very little.

I'm not questioning wether he's 'a bloody good bloke' or how many miles he does in the wet. I've only questioned his assembly logic and justification of why he advocates not checking shafts for square in this case.

So how many miles has the bike done in 15 years?

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Previously simon_ratcliff wrote:

I'm not baiting anybody Peter.

Knowing how many miles a component has done can tell you the suitability of the component and give an indication of how the engine has been assembled. The more miles the better. Whereas only knowing how long it's been fitted says very little.

I'm not questioning wether he's 'a bloody good bloke' or how many miles he does in the wet. I've only questioned his assembly logic and justification of why he advocates not checking shafts for square in this case.

So how many miles has the bike done in 15 years? simon i,ve done about 30.000 mls on the belt.not a lot to some but i have other bikes i try to use as well,i,ve placed a gearbox adjuster block on the engine plate just behind the inner chaincase with a bolt adjusted upto the gearbox spindle nut i,ve been told the factory did this on the early racers ?.its worked for me so far. i know lots who use belt drives and are happy to..i have friends who stick to the chain.its a personal choice

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Why has this thread dragged on for so long? The question was "Does the chain need replacing?". The correct answer was in the first reply "Yes". Why so much irrelevant waffle?

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Thanks for the reply Anthony,

Not conclusive, but 30,000 is a significant mileage to establish wether a component works or not. As I said, it's possible your shafts are square enough to each other, and the fact you've done additional work to secure the gearbox means it's far from a standard set-up. So not just simply fitting a belt as you suggested initially.

Wether people prefer a belt or chain is secondary. The important thing to do is check that the shafts are square to each other. Otherwise there will be problems, especially with a belt as many owners have found out.

John, I would say the irrelevant waffle has been minimal. Majority of contributions have been constructive in helping to find a solution to a problem.

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John, a simple 'Yes' isn't always an adequate answer. For instance, you ask a doctor 'Will I die?' The answer is Yes. A bit of additional waffle should help to reassure - as in 'but all things being equal, not until you reach a ripeold age'. Hopefully anyway! Gordon.

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Previously Gordon Johnston wrote:

John, a simple 'Yes' isn't always an adequate answer. For instance, you ask a doctor 'Will I die?' The answer is Yes. A bit of additional waffle should help to reassure - as in 'but all things being equal, not until you reach a ripeold age'. Hopefully anyway! Gordon.

OK Gordon, I take your point, but, I don't have much faith in doctors either. My GP did not refer me to a specialist, untlil my cancer was so far advanced that the bladder, and several other bits had to be removed. This was over nine years ago, and, fortunately I made a full recovery. Still feel bitter about it though.

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Looking at your photo of the broken chain, I notice that it does not have any makers name on the plates. I have recently replaced my primary chain after owning my bike since 1975 and covering about 65,000 miles. The chain I took off has reynold on every plate and whilst there are other manufacturers, at least Reynold has a pedigree of some sort. The chain I removed looks in better condition than your broken one. Chains running in an oil bath should suffer minimum wear and contrary to some peoples beliefs they do not stretch but the pins and holes wear. As Simon says, even triplex chains can accept some element of mis-alignment, belts are not so tolerant. One rotary owner has covered 85,000 miles on his enclosed rear chain.

Mark, good spot on the broken side plate. It must be replaced for safety and peace of mind IMHO

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I've just looked at the photo again and magnified it to the limits of resolution. The link doesn't look broken to me, it looks cut. Any one agree?

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John, I'm sorry to hear of your medical problems and glad you made a recovery. That said, I have to agree with Gordon and Simon. For example; if it were not for this thread I would, at least at this time have assumed 30,000 miles to be the time / distance limitto replace my Mk 3 primary chain yet again.Other owners as well have a different different takes on this. I think what also comes out of this that the standard Renold chain is a safe bet.Then there is all the advice on alignment.

The simple advice of course is of course to replace the chain but then with what and what might have caused the problem and how long can a chain last, runnning in perfect conditions? This is all related,Alternative views should be discussed of course, especially based on experience but not discussing the wider topic is a bit off. Sorry John.

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Previously neil_wyatt wrote:

John, I'm sorry to hear of your medical problems and glad you made a recovery. That said, I have to agree with Gordon and Simon. For example; if it were not for this thread I would, at least at this time have assumed 30,000 miles to be the time / distance limitto replace my Mk 3 primary chain yet again.Other owners as well have a different different takes on this. I think what also comes out of this that the standard Renold chain is a safe bet.Then there is all the advice on alignment.

The simple advice of course is of course to replace the chain but then with what and what might have caused the problem and how long can a chain last, runnning in perfect conditions? This is all related,Alternative views should be discussed of course, especially based on experience but not discussing the wider topic is a bit off. Sorry John.

OK, Neil, grovel, grovel, perhaps I was a bit harsh. However, some threads seem to go on and on, with the same advice, or opinions, being repeated. Nothing lasts for ever, and, eventually most moving parts have to be replaced.

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"Do i need to replace the primary chain on commando? I was about to clean the clutch plates and noticed what looks like a small crack in one of the chain links , photo included . thanks in advance for any advice. mark"

This was the first post on this subject!

The answer is ÃES' any doubt of the serviceability ofa critical component, such as an internal part, should be replaced!

That looks like it is possibly a fatigue crack, and where there is one, there is surely going to be another soon, if not already. Also, that black mark on the corresponding rear plate may already be another?

Paul.

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Just as a matter of interest, I got my figures wrong on the Commander rear chain life, should read 188,000 miles, and an Interpol 2 owner has 450,000 miles on the original chain. A triplex chain running in an oil bath should last forever.

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Thanks to all, the replacement parts have arrived and fitting has begun. Just for the record the chain has been in service for over 10 years with no issues and covered lots of miles (speedo is a bit hit and miss so cannot be accurate) , in fact i may have only had to adjust the chain once in this time although i have had to clean the clutch plates once or twice a year.

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Mark, Use ATF and change it on a regular basis and it should be years before you need to clean your clutch plates.

Hope you bought the original spec Renold?

 

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