CNW e start conversion, sprag failures

dobba99 said:

See my answer in post #88
Both systems use the same size sprag

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What about the apparent individual springing of elements? That's different than the normal dogbone style?

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.

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…

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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

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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: ⁠WD-40 Dirt & Dust Resistant Dry Lube Spray or dry bike chain lubricants.
  
  
  WD-40 Canada +3
  
  
• 2. High-Pressure Silicone & Tacky Greases (Best for Booted Joints/CVAs)

• Why it works: If your dog bones have protective CV boots (or if you are dealing with large-scale RC/mechanical drives), a highly viscous, "tacky" grease stays in place and prevents wear without flinging off.
• Top Products: ⁠Team Associated Black Grease (a staple in the drivetrain community), or ⁠Fast Eddy Dogbone & Transmission Grease.
  

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.
  
  
  Reddit·r/rccars
  

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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

dobba99 said:

For the Mk3, this is the kind of sprag you need

Click to expand...

Not so sure this is the Holy Grail. They might last a little longer but proved not to be fail-proof in some BMW, KTM, Huskies.

Seems to be a crap shoot. I’ve searched that # and multiple listings show at least 3 different parts going by the images