RGS sprag clutch flywheel removal

murphus

murphus

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Lost in the Midwest
Taking the sprag clutch apart on my '83 RGS. I've never serviced it and while I haven't had any issues I figured best to get in there before things go wrong. My RGS has about 75,000 miles on it, a bit over 30k put on by me. Not surprisingly, someone's been in there before, evidenced by the red loctite that had been applied to the 10mm bolt securing the flywheel/sprag clutch to the crank. Said bolt came out with a rattle gun, but the flywheel won't let go of the crank. I'm using a 10.9 16mm bolt to remove the flywheel. Initially used a 24mm box-end wrench striking it with a heavy hammer to try and remove the flywheel. No go. Then applied the rattle gun. No go. Should it be this hard to get the flywheel to let go? Suggestions for locking the crank to get better effect? Assuming I get it apart, will be interesting to see what I find as there's metal swarf evident in the flywheel, stuck to the inside edge. Also, there was no thrust washer on the outside of the idler gear. Should there always be one?IMG_4245.JPGIMG_4244.JPG
 
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I also had to use a frightening amount of force on the bolt with a rattlegun. I was sorely tempted to give the bolt a firm tap while under tension to pop it off the taper, however was warned sternly not to do that due to the potential to damage the bearings. It eventually came off with the rattlegun and I found a lot of locking compound on the taper, which can't have helped. I also had similar swarf stuck to the magnet, which may have come from the factory, as I'm fairly sure no-one has been into mine before.
Hopefully an expert will be along in a moment with proper advice ;-)
 
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Seen that idiotic notion of adhesive on the tapers of crank to ND magnetic rotor, what a nightmare, worst of all it impinges on the integrity of the taper fit. Vince will vouch for that, no doubt. The rotor itself is made of "soft" steel and also should not be side impacted, seen a few fractured ceramic magnet sections, cause unknown, rough fitting up as the rotor tends to pull itself onto the poles of the stator a possible. j
 
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They can be bloody tight, there's certainly no need for loctite on the taper. I made a copy of the factory tool which goes onto the external thread further down the alternator nose. First time I did it, it was the first time it had ever been off (1 owner bike) and it eventually let go with an almighty crack and flew across the room! Be aware of that when it does eventually let go.
Since then I always leave the bolt in place but loosened 1-2 turns and push on that. When it lets go the bolt prevents it from flying off. Of course that is not possible if using the internal thread method.
- Some carefully applied heat around the nose of the rotor when under load might help it let go.
- The factory locking tool for the alternator is basically a huge hook spanner. I improvised a ring with a pin that goes into the hole and a lever attached to it. It's hilariously awful to look at and you'd think after 25+ years I could have made a better one but it remains! :)
- Some metal in the rotor not all that uncommon, it is a bit of a magnetic oil filter of sorts. With luck it's just bits of chipped sprag roller.
- There should be hardened washers both sides of the idler, also one behind the freewheel when you get in there. Also a little tab bolted into the crankcase at 1 o'clock position guiding the freewheel. All of those items sometimes misplaced by previous mechanics.
 
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I'm a bit concerned about applying any heat to the rotor for fear of demagnetizing the flywheel. So far, everything else was in place save the outer thrust washer. However, I forgot to mention the 8mm wave washer sitting in the bottom of the cover. I don't believe there's one employed anywhere in the fixings? Perhaps dropped in if the starter was removed at some juncture? Actually, that could have been me; I removed the started when I did a top end rebuild a few years back.
 
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Even the magnets themselves can take 100+deg that the oil can reach in operation right? Hence careful application. :) So getting heat *quickly* into the nose of the rotor (in the region of the taper) while it's under load, quick enough for it to expand before the heat flows to the surrounding parts, and without getting the magnet area too hot. And be ready for it to fly off.... and then burn you... :)
 
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I'm in the shed and have one to hand, so in case Murphus wants to go that way or else someone is searching this info later, the external thread on a Series2 ND alternator is M35x1.5. Pullers are pretty widely available such as a Bikeservice BS2469 which is ~$35 in AU. Most Lav clubs will also have these sort of tools available for loan or someone in the club will have one.
Having said that the M16 bolt should also do the trick just fine. Make sure to lube the bolt thread.
 
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It's scary the first time you run into this - scary as in, "Is thing EVER going to come off?!!"

Fortunately, the first time I had to do mine, I had a certain Mr Keith Nairn staying. And Keithy boy certainly wasn't gonna take no messing from it ....

As IIS John said, let's hope there's no Loctite involved.

Like the idea of an external puller, Steve.
 
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murphus said:
I'll try some judicious application of heat tomorrow and see how it goes and report back. Thanks for the input.
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Tip for when you eventually get to the re-assembly stage, Murphus.

Make sure that the 3 countersunk screws that hold the freewheel cover plate on are done up well. Part number 30 382 043, piece 37 on the Albero Motore page of the parts book.

If not, they can unscrew and, in extremis, do immense damage to the starter motor - trash it, basically. DAMHIK.

Piet's advice is to give the head of the screws a wrap with a punch once you've done them up and then retighten. Tom Eatman - and I, I confess - (also) use a bit of Loctite.
Sprag clutch plate.jpg
 
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Apparently my rattle gun is worn out. Borrowed a friend's newer Ingersoll Rand and the flywheel popped right off. In my haste I neglected to remove the keeper for the gear, meaning of course the flywheel spilled some of its parts has it came off. Which brings up a question: Is it in fact necessary to remove the flywheel cover plate if it otherwise appears OK? Or is it simply stupid not to. Springs were actually OK, with mild deviation in length and one showing signs of fatigue at one end. Given the loctited holding bolt, I'm concerned that whomever was in there last also loctited the screws and they might not want to come out. There is mild scuffing evident on two of the screw heads, but I don't know how normal that is? And Ventodue, thanks for the reminder on the needle bearing, it shows signs of wear so certainly to be replaced. Pic of the components shows original on right and new on left, and a few pics of the cover plate. Otherwise, looked to still be serviceable, but obviously good to positively assess condition and renew everything. Also, what's acceptable practice for tightening the center bolt when reinstalling?Rattle gun or? Thanks for the input all.
 

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You made a good call pulling the sprag clutch. Slight scuffing of the countersunk screw heads indicates they are backing out. They should be able to be unscrewed with little effort. If you are concerned about Loctite then apply a bit of local heat but I doubt you need to do this.
I follow Piet’s advice and tap the head of the screw as you torque it up. I also use Loctite.
The design seems rather flawed as the plate is too thin to offer any undercut and contact area for the countersunk head and a backward step from the riveted back plate used without problems on the 180’s.

As an aside, when I recommission my Executive with a genuine 4000kms I found the countersunk screws on the back plate loose.

I use a locking tool and breaker bar to “as tight as” torque but others use rattle guns with success, maybe you should keep hold of the IR tool.
 
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The countersunk screws in fact came out with little effort. No signs of loctite, but will use blue when I reinstall. Thanks for the insight/advice. Just need to get the needle bearing for the gear plate and should be able to put it all back together.
 
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murphus said:
<snip>. Also, what's acceptable practice for tightening the center bolt when reinstalling?Rattle gun or?
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Nothing special. It doesn't need to go up super tight: 52-19 lb/ft is the factory spec.

Just make sure the threads aren't stretched, which might have happened if some monkey over-tightened it before. (As John- aka IIS - said, it seems some owners/mechanics don't seem to quite grasp the concept of a taper fit ...).

Me, I'd replace it.
 
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Blimey Craig, stretching a M16 bolt takes a bit of doing. Given a M16 thread can take around 185ft-lbs that takes a special kind of Monkey but we do know there’s a few out there 😁
Factory does state 52-59ft-lbs but I’ve never had a problem with an 18” breaker bar, calibrated arm and some common sense plus a dab of Loctite, just in case!
I don’t use one of those rattle guns for making up bolts, too old fashioned for that, preferring a torque wrench for the likes of the crankcase studs where precision is needed. A quick google shows many 1/2” drive rattle guns can bang out 500ft-lbs, so one of those in the hands of a Monkey could produce devastating results.
 
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It's not the M16 bolt that stretches, it's the M10x1.25 central flywheel fixing bolt that stretches, both RH and LH threads. I've had to replace quite a few, no idea how they were done up. If the concept of a taper fit is a mystery, guess proper bolt torque will be much the same. :rolleyes:

And, yes, there should be a thrust washer either side of the idle gear. Check the inside, I've often found 2 there...

piet
 
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