CNW e start conversion, sprag failures

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Well, I just ordered the one shown by @gortnipper in post # 67 and what I actually received was what is shown by @dobba99 in post 100 !

I’ve contacted the seller to see if they can exchange it as what was received is not what was shown.

The spherical leaf spring type arrangement in the one gortnipper showed looks fairly robust to me, but as dobba says, the one with a tiny spring attached to each dog does look rather on the feeble side…

Unfortunately, according to the seller, the small spring design is the new ‘upgraded’ design that replaces the old one.
 
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Fast Eddie said:
Well, I just ordered the one shown by @gortnipper in post # 67 and what I actually received was what is shown by @dobba99 in post 100 !

I’ve contacted the seller to see if they can exchange it as what was received is not what was shown.

The spherical leaf spring type arrangement in the one gortnipper showed looks fairly robust to me, but as dobba says, the one with a tiny spring attached to each dog does look rather on the feeble side…
Click to expand...

For the Mk3, this is the kind of sprag you need
 
robs ss said:
It also appears that each of the "elements" (not dogbones) is separately sprung. Looks promising given what @dobba99 has outlined as a shortcoming of the cNw starter!
Can't really tell but it appears the elements are activated by torque inertia, but sprung out of the way otherwise.
Cheers
Click to expand...
Other way round, the elements, or dogbones if you like, are sprung into contact with the inside (drive gear in the Mk3 or engine sprocket in the CNW conversion kit) and when the starter button is pressed and the engine starts the elements are thrown outwards and disengage (in the Mk3)
This doesn't happen in the cnw conversion kit, the elements are held against the engine sprocket snout (by the little springs) and so wear out in short order.
 
below are excerpts from a search I just did

For dog bones or constant-contact joints, use dry lubricants (like graphite or PTFE/Teflon) or high-viscosity, dirt-resistant synthetic greases. Because dog bones operate in highly exposed environments, wet spray greases will attract abrasive debris and accelerate wear.


Top Lubricant Recommendations
1. Dry Graphite or PTFE Sprays (Best for Dry Running)
  • Why it works: These sprays go on wet but quickly evaporate, leaving a slick, dry film that repels dirt and resists friction under constant metal-on-metal contact.
  • Top Products: CNW e start conversion, sprag failures⁠WD-40 Dirt & Dust Resistant Dry Lube Spray or dry bike chain lubricants.
    CNW e start conversion, sprag failures
    WD-40 Canada +3

  • 2. High-Pressure Silicone & Tacky Greases (Best for Booted Joints/CVAs)
Best Practices for Application
  • Replace When Worn: Constant-contact dog bones are essentially sacrificial wear items. If the joints become deeply grooved or sloppy, the most effective remedy is replacing the dog bones and drive cups.
    CNW e start conversion, sprag failures
    Reddit·r/rccars

I
 

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Sounds like accepting a replacement from Matt is adding another failure to one’s calendar. Very interested in the best remedy as although pulling the primary apart is easy enough I’m actually starting to get a bid bored with it now🤣🤣🤣
 
Seems to be a crap shoot. I’ve searched that # and multiple listings show at least 3 different parts going by the images
 
dobba99 said:
See my answer in post #88
Both systems use the same size sprag
I have one of the ringspann sprags, lent to me as an example (came in a Cross and Morse box) and my impression is that it is too delicate for use in the Mk3 system, given that the engine vibrates i wouldn't install this type of sprag in a Mk3.

Click to expand...

Yes , the cage itself is too delicate and eventually gives grief .
How can I buy one of your stronger cage roller sprags after all is said and done ? Peter .
 
gortnipper said:
Yeah, that is what I have heard. I am in the odd (2x) phase. So watching closely before I order a part.

I do know that a few here in NZ have used the "RGM Norton sprag unit. (This is the original sprag that they came out from the factory when new), this being a 14 ‘bone’, this sprag looked a lot stronger. RGM Norton, item 1310145, Sprag cage part number 761316145, 14 rollers, sph Cross and Morse (C.M)."

And our local NOCNZ Prez @MurrayNZ says, "When several customers had sprag trouble with the 6 or so CNW kits I sold, initially CNW replaced the sprags, but they inevitably all failed, so I took it upon myself to find a solution. After trying 18, 16 and 14 bone sprags, the 14 bone sprags were the only reliable replacement, which I replaced free of charge to my customers."

I think these will work in both the Mk2 and Mk3 cNw kits?

Click to expand...
@fasti had a conversation with our NOCNZ VP last night (who i also got the lube info from) and he clarified a couple of things for me that u was unaware of when I made this post:
1. The comment from Murray was re the MK3 conversion kits, not the full cNw kits.
2. He (our VP) dealt directly with C.M and they recommended a slightly different part no. than the one i listed above once he described the actual application of the sprag, and failures being seen in detail.
3. He bought 3 of the CM recommended parts, and got a discount, so there are opportunities for a group buy.

I am awaiting specific part number detail, along with his email correspondence with CM that document the recommendation. I will share that here when I receive it.
 
Fast Eddie said:
Well, I just ordered the one shown by @gortnipper in post # 67 and what I actually received was what is shown by @dobba99 in post 100 !

I’ve contacted the seller to see if they can exchange it as what was received is not what was shown.

The spherical leaf spring type arrangement in the one gortnipper showed looks fairly robust to me, but as dobba says, the one with a tiny spring attached to each dog does look rather on the feeble side…

Unfortunately, according to the seller, the small spring design is the new ‘upgraded’ design that replaces the old one.
Click to expand...
My VP told me last night that the sprag recommended by CM has individual dog springs, and not a single wrap around spring. He said CM told him this would be a better spring return and prevent drag in our application.

Again, will post when I get details.
 
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I been taking a bit of notice with this subject as I got to fit the CWN starter kit, seems to be a lube problem on the sprag bearing, what about the old fashion STP on that sprag, not much just a few drops and worked in as it will stick and not flick everywhere and will lube for a long time.
Many years ago I ran an old Joe Hunt magneto on my Triumph that had a unsealed bearing and every major oil change I pulled the cover off the JH and put a few drops of STP on the front bearing and kept the bearing lubricated and never flick off the bearing, I had no failure from the bearing in 9 years of doing this and the rest of the magneto didn't have oil splashed all over the internals.
Just a thought, but can you get to the sprag with the ES kit altogether as I haven't even opened the box that GP sent me yet.

Ashley
 
ashman said:
I been taking a bit of notice with this subject as I got to fit the CWN starter kit, seems to be a lube problem on the sprag bearing, what about the old fashion STP on that sprag, not much just a few drops and worked in as it will stick and not flick everywhere and will lube for a long time.
Many years ago I ran an old Joe Hunt magneto on my Triumph that had a unsealed bearing and every major oil change I pulled the cover off the JH and put a few drops of STP on the front bearing and kept the bearing lubricated and never flick off the bearing, I had no failure from the bearing in 9 years of doing this and the rest of the magneto didn't have oil splashed all over the internals.
Just a thought, but can you get to the sprag with the ES kit altogether as I haven't even opened the box that GP sent me yet.

Ashley
Click to expand...
You've got to be careful with what lube you use Ash. Some additives stop them working properly.
Have a gander at my post #17 in this thread - tells you a bit.
Cheers
 
ashman said:
I been taking a bit of notice with this subject as I got to fit the CWN starter kit, seems to be a lube problem on the sprag bearing, what about the old fashion STP on that sprag, not much just a few drops and worked in as it will stick and not flick everywhere and will lube for a long time.
Many years ago I ran an old Joe Hunt magneto on my Triumph that had a unsealed bearing and every major oil change I pulled the cover off the JH and put a few drops of STP on the front bearing and kept the bearing lubricated and never flick off the bearing, I had no failure from the bearing in 9 years of doing this and the rest of the magneto didn't have oil splashed all over the internals.
Just a thought, but can you get to the sprag with the ES kit altogether as I haven't even opened the box that GP sent me yet.

Ashley
Click to expand...
No EP, no graphite - nothing too slippery. The lube that the mfgr (C.M.) recommends is $$$$ per tube. An aero mechanic did some research and found the ingredients in that are the same spec as SKF LGMT 2/0.2 - which is ~$30 for all the sprags you will ever need.

Apply sparingly to the dogs pivot/spring mechanism - "like a light smear of vaseline" is what I heard.

CNW e start conversion, sprag failures
 
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