I have examples of that failure mode with my Mk3. I have the opinion that the thin spring clips (and the wiggly ribbon spring between the cages) succumbs to the vibration that the engine gives out. The dogbone sprag is just too delicate. Fine in stationary machines like conveyors, printing presses, machine tools and the like. Not so good in old vibratory motorbikes!
CNW e start conversion, sprag failures
- Thread starter dobba99
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Café au Lait
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I’m willing to be the Guinea Pig here. I’ve just ordered the AliExpress sprag for £15 and lets see how it lasts eh?
If on receipt it looks shite I’ll bin it of course but I wouldn’t mind betting some of the others available are just relabelled from same or similar sources.
If on receipt it looks shite I’ll bin it of course but I wouldn’t mind betting some of the others available are just relabelled from same or similar sources.
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robs ss
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Operating temp 150-160C and dropping temp 260C. Sounds okay, no?
robs ss
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I bought a couple of those from AliExpress a week or so ago (one for a mate)
$25AUD including shipping - here's what they look like:
Cheers
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robs ss
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I also ordered one of the bearings @slimslowslider mentioned on post #90 of this thread.
It's a Ringspann SFB 41-31.5 14J.
Getting it from Ringspann Australia for $155AUD.
It's coming from Germany with their usual order (to save on shipping)
I'll send photos to compare with those above when it arrives.
Cheers
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robs ss
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No - unfortunately not Mike. When I get mine I'll ask the technical bloke in Melbourne and relay his advice.
Cheers
Café au Lait
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Seriously looking like costs could get out of hand here. That grease costs as much as the sprag! Some sprags cost double that of others too all for parts with a limited life. Let’s hope the cheap Chinese lasts up to >50% of the others 
I went through the whole list and yes expesnive.
I learned a lot from this thread and from the list of greases found the below I bought and will use on my Alton Sprag.
It's made for electric motor bearings and has no EP stuff in it
I have a large grease gun tube's worth of it and if you can't get any locally at a reasonable price I am happy to mail you some!
Dennis
Mobil Polyrex EM that is non EP and under $20 for a large grease gun type tube.
www.mobil.ca
I learned a lot from this thread and from the list of greases found the below I bought and will use on my Alton Sprag.
It's made for electric motor bearings and has no EP stuff in it
I have a large grease gun tube's worth of it and if you can't get any locally at a reasonable price I am happy to mail you some!
Dennis
Mobil Polyrex EM that is non EP and under $20 for a large grease gun type tube.
Electric motor bearing grease – Mobil Polyrex™ EM | Mobil™
Mobil Polyrex™ EM electric motor bearing grease provides excellent bearing performance and protection for long electric motor life.
www.mobil.ca
Are you still using the chain primary drive with your alton? If so, you don't need to bother greasing the sprag.I went through the whole list and yes expesnive.
I learned a lot from this thread and from the list of greases found the below I bought and will use on my Alton Sprag.
It's made for electric motor bearings and has no EP stuff in it
I have a large grease gun tube's worth of it and if you can't get any locally at a reasonable price I am happy to mail you some!
Dennis
Mobil Polyrex EM that is non EP and under $20 for a large grease gun type tube.
Electric motor bearing grease – Mobil Polyrex™ EM | Mobil™
Mobil Polyrex™ EM electric motor bearing grease provides excellent bearing performance and protection for long electric motor life.
What will get in will be enough
Torontonian
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The oil bath , stock , 20 W 50 , is fine and up to the job . The sprag cage is'nt .
My MK 111 CNW kit has over 2000 starts on it with no issues ( to date ) . It runs in oil , I believe dry belt systems owners neglect periodic lubrication of the sprag . Could be wrong . Likely .
That said , I have 5 new sprags of various types ( 14 and 18 ) , that are ready to go when it does . When it does fail , the kicker will hopefully get us home for the primary sprag replacement operation . My CAA Plus has a 200 Kms. tow range . Any more has a per Km. charge .
I'll be asking for help to kick should that occur , as I've promised the wife to not kick again . I'm a man of my word .
Off in the morning to Georgian Bay . Later this month the big trip , Manitoulin area .
Enjoy .
vidar hjelm johansen
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My MK3 CNW kit has been in for 3 or 4 years now, not sure.
When this kit went in, I removed the kick,and I haven't missed it .
Vidar
When this kit went in, I removed the kick,and I haven't missed it .
Vidar
Café au Lait
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My Chinese sprag arrived today and looks decent enough to these untrained eyes at least. A few grams heavier than Matt’s probably due to being 18 dog rather than 14. Dressed in a very light oil presumably as an anti-corrosion measure rather than a lubricant for use.
Mounted in a dry (belt drive) primary the one question I do have is what lube to use if any? In a chain drive primary it would be 20W50 I assume. Seeing as the shaft is constantly spinning at high rpms I’d imagine centrifugal force will fling whatever is applied?
AFAIK the existing one has been dry all the time as that’s what I noticed on the occasions I’ve pull the primary apart (quite often as it happens)
I emailed Matt 2 weeks ago about this and uncharacteristically heard nothing from him. My fear is this thread has pissed him off
According to my callipers each dog on my old one is .004” smaller than the new one measured from each contact surface.
Mounted in a dry (belt drive) primary the one question I do have is what lube to use if any? In a chain drive primary it would be 20W50 I assume. Seeing as the shaft is constantly spinning at high rpms I’d imagine centrifugal force will fling whatever is applied?
AFAIK the existing one has been dry all the time as that’s what I noticed on the occasions I’ve pull the primary apart (quite often as it happens)
I emailed Matt 2 weeks ago about this and uncharacteristically heard nothing from him. My fear is this thread has pissed him off
According to my callipers each dog on my old one is .004” smaller than the new one measured from each contact surface.
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HouTexNorton
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When my replacement sprag came from Matt it was in a plastic bag and marked "pre-lubricated" so I just installed it as is.
If you go back a few years (2017, i believe)you will see that I installed a $17 Chinese sprag in my MK3. This was done on a lark to see if the estart could be made operational again. The previous expensive Norvil sprag had only lasted a couple of days, so I had been kick starting the bike for years.Seriously looking like costs could get out of hand here. That grease costs as much as the sprag! Some sprags cost double that of others too all for parts with a limited life. Let’s hope the cheap Chinese lasts up to >50% of the others
I kept track of the starts with the Chinese sprag up to 700 or so in the first 3 years, then I stopped counting. That $17 Chinese sprag is still in there and working fine. It's been in there for nine years around two thousand starts now.
I posted about this success at the time and quite a number of other cheapie Commando owners followed suit.
From time to time I have asked if there have been any failures of these sprags.
Now would be a good time to ask again.
Last time I checked, there was only one Chinese sprag failure reported here vs. many happy users.
Glen
With the cnw sprag living between two sealed bearings it is effectively sat in its own sealed chamber so what ever lube you use is in there until you have it apart again, That said, throw into the mix the heat generated by the dragging dogbones, any lube has to resist this heat and not dry out. Or else you might as well fit the sprag dry.My Chinese sprag arrived today and looks decent enough to these untrained eyes at least. A few grams heavier than Matt’s probably due to being 18 dog rather than 14. Dressed in a very light oil presumably as an anti-corrosion measure rather than a lubricant for use.
Mounted in a dry (belt drive) primary the one question I do have is what lube to use if any? In a chain drive primary it would be 20W50 I assume. Seeing as the shaft is constantly spinning at high rpms I’d imagine centrifugal force will fling whatever is applied?
AFAIK the existing one has been dry all the time as that’s what I noticed on the occasions I’ve pull the primary apart (quite often as it happens)
I emailed Matt 2 weeks ago about this and uncharacteristically heard nothing from him. My fear is this thread has pissed him off
According to my callipers each dog on my old one is .004” smaller than the new one measured from each contact surface.
Doesn't surprise me that Matt hasn't replied to your email. I bet his inbox is full of Cnw e start kit owners (he has sold over 600 of them) now asking how and what he is doing to alleviate this misuse of the sprag. Looking at the cnw sprocket/sprag and drive gear , i don't think that Matt can redesign the sprocket and drive gear to use the sprag the correct way. There just isn't enough space (and still use the lucas alternator)
Fast Eddie
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Why not take the inner seal off of each and pack the entire centre with grease, thus lubricating both bearings and the sprag at the same time ?
