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"Notchy" Alton

Howard

Well Known and Active Forum Website User
VOC Member
I've got a friends Comet in bits (literally, unfortunately). The original reason for opening the timing chest (or Pandora's box as I call it) was to adjust the valve timing, and to find the source of a rattle. The rattle sounded like a kickstart ratchet on the return stroke, but was evident when turning the engine with the ks. The rattle seemed to be emphasised by backlash in the pinions (don't ask why!) but it seemed to come from the Alton (about 4 years / 5000 miles old).

I've never had an Alton, so I don't know how it should be. I've taken it off and given it a quick inspection - everything seems ok, but turning it by hand it's very "notchy". It seems to be due to the poles lining up in the alternator part (I'm not an electrician) and I assume there are more notches per turn than I expected, because the gearbox increases the speed.

Is this to be expected?
Does it smooth out at speed?
Should I panic and send it to an Alton specialist?

Thanks

H
 

Pete Appleton

VOC Hon. Editor
VOC Member
VOC Forum Website Administrator
Howling gears

Howard

I bought an Alton for my Comet a few years ago. It is horribly notchy and even playing around with the backlash made little difference. The howl from the timing gear was horrendous. I have removed mine and slung it under the bench where it is now almost totally silent. If you look at the Alton website you will see that the latest ones are supplied with a Delrin gear, presumably to hide the noise. I don't believe that you can retrofit the delrin gear to older units ( I might be wrong). In any case, I would be very doubtful of the life expectancy of a plastic gear under that sort of hammering.

Peter
 

Howard

Well Known and Active Forum Website User
VOC Member
Thanks Pete.

Barry kept telling me it had always been like that, but I couldn't believe it.

H
 

Mark Fisher

Well Known and Active Forum Website User
VOC Member
I have several Altons and two newer units are in use on my shadow and my Egli. They are meant to feel notchy...this is normal! Both of these units work very well and do not whine. In the past I have had whining issues but it is not the alton itself that causes the whining, there are several reasons for this. The most common reason is that the gear/sprocket (which are usually some kind of nylon or plastic) is meshed too deeply with the chain, it seems obvious, but sometimes its quite hard to get right and on occasion I have had to reduce the diameter of the supplied spacer, if you let this persist the gear will fail but won't damage the primary. I have found that some units protude too far or not far enough into the case causing mis-alignment with the chain, the result of which is of course whining and eventual failure of the gear/sprocket. On the Egli I think I made my own spacer, but these are molnar cases.
I realise most of this does not apply to comets but hopefully it will be helpful to someone out there. Having said that, if the outer diameter is too large on the spacer part it may not be possible to get the gears to mesh correctly on the comet set up. The other thing to remember is that there are at least 4 different kinds of Alton. The early one is not notchy and feels a bit like a magneto when turned by hand, it is a direct drive and doesn't put out as much power as the later ones at lower RPM. I still have one of these and it has been perfectly reliable, but with twin plug heads, electronic ignition and electric start I wanted a bit more power for night riding. The 3 phase version was a disaster and isn't worth discussing. The next type is notchy and has an internal gear that makes the generating part spin faster thus giving more power at lower RPM to address that issue. These work very well in an electrical sense but the internal gearbox is it's achilles heel. For normal use they work well, but if you ride hard and happen to miss a gear the internal nylon gear will strip and you will have to take the unit off and replace the gear, alton are really good about sending free replacement parts, but taking the thing off and re-fitting becomes a pain if it happens often. The final type (to the best of my knowledge) is notchy also but is a direct drive and works really well...no issues at all as long as it is correctly fitted and aligned.
mark
 

Pete Appleton

VOC Hon. Editor
VOC Member
VOC Forum Website Administrator
I have several Altons and two newer units are in use on my shadow and my Egli.

I also have experience of Altons on twins and never had trouble with whining ( just the disastrous gearbox) It is on the singles that the noise occurs as the notchiness is transmitted through the geartrain. Playing around with the penetration and backlash on my Comet did nothing to alter the noise one way or the other, it was terrible even when turning the engine over by hand.
 

nkt267

Well Known and Active Forum Website User
VOC Member
The instuctions with the newer Altons warn about the clicking and state that when it is use you cannot hear it,, ho ho ho..And guess what you can't, the timing gear noise drowns it out on my Comet:D..John
 

vibrac

Well Known and Active Forum Website User
VOC Member
My alton kept its teeh but stripped all the rollers in the centre run of the primary tripple chain
But there are 2 thinks to consider first it was a Reynolds joke chain with butt welded rollers and second I was doing the lap of the IOM
I shall fit a nylon sproket if I need to have continious lights, but with a BTH mag electrickery generation is secondary, a well charged battery is normally enough
 

Tom Gaynor

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VOC Member
I've been told before that the reason they click is because the magnets inside take up the epicyclic gearbox backlash "backwards" when one is turning it forwards, but if it is spun up to speed on an electric drill the clicking stops. I haven't tried it, but have no reason to doubt it.
The instuctions with the newer Altons warn about the clicking and state that when it is use you cannot hear it,, ho ho ho..And guess what you can't, the timing gear noise drowns it out on my Comet:D..John
 

TouringComet

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VOC Member
VOC Forum Website Administrator
VOC Forum Website Moderator
My first generation Alton on the Comet made the noise only at low RPM, but I had a little too much backlash between the drive gear and the large idler. Recently installed a slightly larger half time pinion while the motor was down for other work, and was able to reduce the backlash, and it is now noticeably quieter at those low RPMs. I agree with the theory that the noise is due to crossing the polarity of the magnets, and at low RPM, there is enough time for the dynamo gear to quickly reverse direction and hit the other side of the teeth. Once the engine is turning fast enough, it stays in contact with the driving side of the teeth.
 

Howard

Well Known and Active Forum Website User
VOC Member
Thanks for all the comments. They've really been food for thought or cause for concern. The Comet in question is only ridden gently, as far as I know, so it's likely to be down in the "notchy zone" for a high proportion of the time.

The main problem in the timing chest was a broken timed breather - spindle snapped with jagged end, timing tube broken off the pinion and broken in half longitudinally, and casting around the breather has a section broken out. I've lots of theories why, but I can now add vibration to the list of possible causes.

H
 
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