TOPIC:

I assume they reduced the diameter of the shaft before they pressed the repair sleeve on? If that gear is through hardened they had to grind the shaft to size.

Please get a file and see if you can make a small cut anywhere on the gear. If the file can make a small cut in it, then it's not hardened, if the file does nothing, or leaves a tiny scratch, then it's hardened.

Zukdave, you are correct in that it is a sprag clutch, and should have left out the part about "sun, ring, and planets", because it bears no resemblance at all to a planetary gearset.

A straight answer to your question.

The starter clutch boss should be hardened.
Not mild steel.
If you repair with mild steel i'd be surprised if it worked more than once or twice before failing.
To repair the existing boss it will need to be ground undersize and a hardened ring shrunk on and then that ground to the correct size.

I been here now and then steell, I just noticed the forum on tapatalk hence my current visit means I can sit in bed on a sunday on a tablet browsing.

Like you say its a simple sprag cluch, the friction isnt to bite the roller into the gear to stop it skidding (you dont want that), the roller is supposed to get just enough friction to roll up the ramp in the sprag and jam. Its the wedge action that locks it, also why the original gear is deformed, over the years its been pushed into by the roller so much its got deformed by it. It's supposed to be round and uniform like the rollers that come out squashed into funny shapes by years of use too. Thats generally why you replace the clutch, because this surface gets too deformed and beat up.
Maybe I'm being anal about how hard it needs to be, but they were factory hardened. Take a file and scratch the original gear, if the file just skips over it, that'll give you an indication it was hardened. Remember also, its only doing anything when the motor is starting, after its cranked its thrown back out of mesh and centrafugal force is enough to overcome the springs wanting to push the rollers coming back down the ramps into contact again.

Les, was it something I said? Repair sleeves are intentionally thinner than bearing inner races, this is what I was referencing but in the shaft version.
www.bartlettbearing.com/products/em-quik-sleeves/

The original gear was definitely hardened steel. The machinist mentioned it after working on it. And a file won't do anything to it.

From a little reading on case hardening, it seems like i should be able to find someone who can do that. In fact, the machine shop I used ought to be able to do it.

There seems to be enough doubt about this working as is that I'm hesitant to install it on the bike. I'm going to see if I can at least get it case hardened first.

Spoke to the guy at the machine shop. He says he didn't case harden it because he was worried about warping the sprocket. I asked what it would cost if I wanted to do it and just take that risk. He said about $100. YIKES!

That seems pretty high to me. He said it'd take about an hour or so. With a shop rate of $75 I guess that's what it's going to cost.

I'm about $100 into this already between the used gear and the machining so far. I'm not sure it's worth dropping another $100 into this.

No, mrFluffy, it wasn't you.

Les

The heat treat place can do different levels of hardness. My guess is that this boss is softer than the rollers but hard enough to hold up to normal use. A heat treat shop should be able to do a "prick" test on the sprocket to let you know how hard it is.

I would have made a sleeve ID about .001-.002 smaller than the boss, had it hardened and shrunk the sprocket in liquid nitrogen and slightly heat the sleeve and dropped it on the sprocket.

My .02 worth

Hope this helps.

Steell I was just using that to ref. the part's I know it's
not a plant gear.

les holt wrote: Sorry, taking my response down. I'd go to another site and ask what to do.

Les

how does sending someone to another "site" help our site grow?

leon

Go to an engineering site or a Mechanics site that has grounded information, not opinion so the unsuspecting, uneducated person that reads this doesn't spread the BS/bad ideas as fact next time this same question is asked. Like many other unfounded bits of info that are still keep popping up on this site year after year.

I'd rather not see this grow farther into a city of fools!

This isn't aimed at any one! it's just FACT!!!

Les

les holt wrote: Go to an engineering site or a Mechanics site that has grounded information, not opinion so the unsuspecting, uneducated person that reads this doesn't spread the BS/bad ideas as fact next time this same question is asked. Like many other unfounded bits of info that are still keep popping up on this site year after year.

I'd rather not see this grow farther into a city of fools!

This isn't aimed at any one! it's just FACT!!!

Les

A long time back, when I was a Mod, I kept getting PM's from some dude that insisted that I must edit posts because so much inaccurate info was being presented. And of course he knew all the correct answers and would tell me what to edit.

Was that you?

No, it wasn't me, I just prefer to not muddy the waters. I made a suggestion and decided it may not be the correct one and decided to remove it. That's all

Les