Sprag Assembly MKIII

Does anyone happen to know the measurements of the sprag assembly parts?

I need the O.D. of the starter drive gear when the sprag runs. I also need the I.D. of the sprocket where the sprag sits. I have no clue on what to measure on the sprag itself. I just rebuilt the whole assembly with new gears from AN and 18 pin Ali-Express sprag because of some issues I was having. I would like to measure up the old pieces to see if I can locate where the problem was.

Any info would be greatly appreciated.
Thanks,
Pete

Pete I can only offer a bit of advice , not measurements .
Hopefully your new A.N. sprockets are new items possibly made with harder steel than the softer original items . I would ask Andover with that query . The sprag would eventually eat away at the contact surfaces , eventually dimpling , chattering and slip being a consequence .
You already purchased the 3 items . I gave up and purchased CNW hardened steel items using a supplied 14 pin sprag . It's a kit . Plug and play with over 2000 starts on it now with no issues . Enjoy .

Torontonian said:

Pete I can only offer a bit of advice , not measurements .
Hopefully your new A.N. sprockets are new items possibly made with harder steel than the softer original items . I would ask Andover with that query . The sprag would eventually eat away at the contact surfaces , eventually dimpling , chattering and slip being a consequence .
You already purchased the 3 items . I gave up and purchased CNW hardened steel items using a supplied 14 pin sprag . It's a kit . Plug and play with over 2000 starts on it now with no issues . Enjoy .

Click to expand...

CNW's was my first choice, they were sold out. I reached out to Matt and never got a response.

I also contacted AN and never got a definitive response about the newer parts, but a recall reading something about their newer gears being better. I believe Joe himself put that info out (not 100% sure on that). When I got the new gears from AN they seemed to be a good quality, but I really have no way to actually test them, so in they went. The 18 pin AN sprag lasted about 10 starts before the long end of one of the sprags got hooked under the cage and continued to slip. Fortunately I had a couple of Ali-Express 18 pin sprags on hand. They fit in the new AN gears perfectly and I noticed an immediate difference in the way the bike started, even compared to the new AN sprag. It is a instant hook-up, just like before it started to act up. I think I'm OK now, but won't really know till next spring and I get some miles on the bike.

Can't complain about the originals. My bike has about 43K miles on them, the sprag has about 18k on it. I put it in when I rebuilt the motor in 2016-17. The one I removed was still working. I actually re-installed the original when I started to have a problem. It made a improvement, but didn't completely fix the issue. That's how I knew I was on the right track.

I would like to get my hands on the factory specs so I can measure up the originals and see what happened. They don't seem beat up at all. I'm thinking they just worn enough to increase the tolerances to a no start condition. A new sprag might have solved the problem, but I hate to keep taking everything apart 100 times, so I went to all new stuff and said a prayer.

Pete

All good . Matt was away rom CNW for a while .
The inner is a sprocket P.N. 06-4681 .
The outer is a gear , P.N. 06-4731 .
This gear is where the problems arise , the inner face where the rollers flip outwards to engage with this face is your wear point .
My notes for original softer steel items say this face can be brought back to life by 80 grit coarse Emery paper , then clean .
Also another way is to glass bead the surfaces .
Another machinist way is to machine out and press in a hard steel sleeve , secured by set screws .
My notes also say the face gets polished , or worse it can develop ridges . If ridges with 14 roller witness marks , then switch to the 18 sprag and those rollers will hopefully engage at different points .
Matt uses a thicker cage 14 .
That's it for my notes , good luck and enjoy .

Torontonian said:

All good . Matt was away rom CNW for a while .
The inner is a sprocket P.N. 06-4681 .
The outer is a gear , P.N. 06-4731 .
This gear is where the problems arise , the inner face where the rollers flip outwards to engage with this face is your wear point .
My notes for original softer steel items say this face can be brought back to life by 80 grit coarse Emery paper , then clean .
Also another way is to glass bead the surfaces .
Another machinist way is to machine out and press in a hard steel sleeve , secured by set screws .
My notes also say the face gets polished , or worse it can develop ridges . If ridges with 14 roller witness marks , then switch to the 18 sprag and those rollers will hopefully engage at different points .
Matt uses a thicker cage 14 .
That's it for my notes , good luck and enjoy .

Click to expand...

Thanks for the information, hopefully I'm in good shape now. I'll save my original stuff ( 'cause that's what we do ), just in case. I did notice that all the old components slid together pretty easily, while the new stuff was a tighter fit. So there was definitely some wear taking place. If this set last another 49 years I'll be happy