Commando primary chain rubbing on bottom of inner chain case Alton Electric Starter Kit.

I have recently fitted an Alton starter motor kit to my 850 1973/4 Commando and I am having problems. The primary triple chain is rubbing on the bottom of the inner chain case no matter how tight I adjust the chain. When the machine is ticking over all looks good but when you rev the motor you can see a blur as the chain seems to have excessive up and down movement. When the engine is switched off you cannot press the chain under tension down onto the chain case. I did not have this problem with the standard inner chain case. Also the sprag clutch assembly rotor has seized onto the end of the crankshaft and we are going to have to use an angle grinder to cut it off because we have tried everything to remove it with no movement. The last time I removed this assembly it came off easily.

Any advice would be greatly appreciated please!

Are you sure your primary chain isn't stretched in one spot ?
That's what it sounds like
If you can't get the sprag off it sounds like it's sheered or partially sheered the woodruff key

If you have recently fitted it then its likely there is an assembly error, remove and start again checking every step especially anything that could affect chain tension.

sounds to me, you have a sheared woodruff key. question, is your primary chain the original OE, or a aftermarket replacement? IF the cause is a failed wookruff key, i have a theory that it stems around the crank nut and the alton spacer. the crank nut has a step flange - that step flange corresponds to a mating step on the crank. IF those mating surfaces make contact BEFORE full clamping torque is achieved on the nut to sprag clutch surface, you'll get a false torque reading on the crank nut. i'm thinking this is all caused by a tolerance stackup issue between the alton spacer and various norton OE parts. the whole alton design relies on the clamping force of the crank nut, and i'm thinking the problem only affects a very small number of bikes. i personally have had two failed woodruff keys. the first failure, i literally had to destroy the alternator rotor during removal. dodged the bullet on the second failure. i then opted to incorporate the famous "yves" fix. since then, no further issues and problem solved. good luck with the repair. keep us posted as you dig into this - post some pics if possible. an easy fix requires adding a serrated belleville spring washer, thread locker, and upping the torque on the crank nut to 70 ft.lbs.

had to search for that famous Yves fix:

YukoNorton said:

had to search for that famous Yves fix:

final fix - alton starter/yves mod-upgrade

got back the last of the machining from my friend for the Yves fix for the alton starter/woodruff key failure. everything worked out perfectly, considering he's 1K miles away and we did this via snail-mail and the phone. the scary part was transferring the location for the spacer holes from...

www.accessnorton.com

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folks can read all about my alton srarter snafu - everything from install to final fix by going to "advance search", searching "alton" and posted by my forum ID name - https://www.accessnorton.com/search/72242/?q=alton&c[users]=joe+czech&o=relevance

i might add, a year or two now, all fixes in, and to date, all is good and working perfectly.

I fitted the Yves fix (Very expensive)after we had angle grind the sprag clutch off where it had sheared the woodruff key. That cured that problem. Then the shaft on the end of the starter motor rounded off along with the intermediate gear. So new starter motor and intermediate gear......that cured that. Now I am on my second starter chain as they stretch in just a few starts and they must snatch because the rubber inserts in the gear shear off. Wish I had left it a kick start only been an awful experience and still not over. Just ordered a length of Reynolds chain to make up for the starter chain hoping this will be less likely to stretch.

Speak to Andy now Jason the chainman for an Iwis chain which copes better than the Alton supplied chain. Doubt Reynolds chain will be any improvement.

kommando said:

Speak to Andy now Jason the chainman for an Iwis chain which copes better than the Alton supplied chain. Doubt Reynolds chain will be any improvement.

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I agree
The Reynolds chain won't be any better
Get the iwis conversion from Jason chain
I've had one on my Alton for many years many starts

How do I find Jason Chain please?

Phone him on 07564 870313 or jason@the-chain-man.co.uk

Peter Waller said:

I have recently fitted an Alton starter motor kit to my 850 1973/4 Commando and I am having problems. The primary triple chain is rubbing on the bottom of the inner chain case no matter how tight I adjust the chain. When the machine is ticking over all looks good but when you rev the motor you can see a blur as the chain seems to have excessive up and down movement. When the engine is switched off you cannot press the chain under tension down onto the chain case. I did not have this problem with the standard inner chain case. Also the sprag clutch assembly rotor has seized onto the end of the crankshaft and we are going to have to use an angle grinder to cut it off because we have tried everything to remove it with no movement. The last time I removed this assembly it came off easily.

Any advice would be greatly appreciated please!

Click to expand...

I don't know whether they have changed inner cover casting over the years (mine is an early one) but the inner cover bottom face has more of a slope up from seal face to inside of the inner cover than the original factory covers had. So less chain clearance at the back of the cover. Mine had worn as in the pic below.

Last time i had all apart i took to it with a small angle grinder and made more clearance but i dont think that has totally fixed the issue.
Even with the chain on the tight side it does dance around a lot at idle.