Auto-Advance Magneto question

[flatdeck]

YIPPEE! Magneto returned Friday before Christmas. New fibre drive gear too big for the casing ??? Bizarre ... definitely the right gear. So some delicate filing inside the case and now the gear has clearance all round it. Fit the magneto and retime her and what do you know .... she runs! Got to do some carb tuning next time so she idles but it sure does sound great. Word of thanks to all those who posted on this thread. Hope I've leant some stuff that I can pass on some time.
Cheers,
Dave

[LJ.]

Great news there Dave thanks for keeping us updated on your mags progress. Now that the mag is sorted it can just about be forgotten, you wont have any more trouble with that. Let us know how things go with the carb.
Cheers.

[groily]

Many congrats! Funny how some of these new parts don't quite fit the space - well done with the pinion. Sounds as if you're almost there . . . if she starts and revs and sounds good, can't be far to go now. If the jets are right, if the throttle slide has the right cut-out and is not too floppy in the bore, if the pilot air screw is there and the slow running throttle-stop ditto, and the screw-on cap at the top does up firmly (and if there's no choke slide fitted, the hole for the cable is bunged up to keep extra air out) you should have it ticking over like a clock. And even if it's a bit temperamental, so what? It'll be great blipping the throttle to keep her alive! Groily

[groily]

And now I'm going to find out for myself exactly what the mag pinion/ATD options are, as today, in the snow (April for gawd's sake), after 275 trouble-free kilometres in the worst weather I can remember since the last time it was the worst weather I could remember . . . freezing cold, soaked to the proverbials from top to bottom . . . wham bang, stripped pinion, miles from any****where, natch. And where was my mobile dog'n bone . . . at home where I'd forgotten it. Roadside removal of timing cover proved what looking up the other end of the mag had indicated . . . and no way home. Luckily a suspicious passing native lent me his mobile - well, took a Euro off me - and the memsahib was prepared to mount a rescue operation. Shame about the 2 dogs that came with her and ran wild in the countryside - but if anyone wants to know this unlikely fact: you can get a whole A10, with both wheels still attached, bars turned down, tank off for safety's sake, in the back of a . . . . Renault Scenic. Plus wife (all squashed up at an unnatural angle in passenger seat, plus 2 dogs of medium build). Have to like the parfum of petrol and oil that comes with this idiocy, but . . . gets you home. Twill take longer to clean her car than it will to replace the pinion, is the only downside. This is all, however, a good thing - I can only get an AMC twin in a Renault Scenic if I take a wheel out. Full marks to Small Heath for thinking of this aspect of 1990s design in 1950 something. Groily

[bsa-bill]

Why is the pinion stripping cogs - that question needs to be answered before any other action takes place.
Something just goes not seem right here

All the best - Bill

[groily]

Don't know yet Bill . . . maybe some play in the drive-end mag bearing, maybe some other fault in the gear train, all will be revealed tomorrow I hope when the bits are on the bench and I can see the camshaft pinion properly. Have to say it won't be the first time a fibre gear has shed its teeth in my possession - the first A10 I ever had, a million years ago, did the same thing (same as the fibre dynamo gear, once at least, in every magdyno I ever owned when I was an Ariel single person). I recall others in the dim and distant past with the same experience, too. I do think it's i) a case of age and ii) a known point of weakness (hence length and long-lasting nature of this thread, the notion of alloy or steel pinions and manual A/R as opposed to ATD), and I think it can happen when there's nothing else wrong. New pinions, with or without ATDs, are quite hot sellers. When I had the gear train apart a few months and a few thousand miles ago, all was perfectly acceptable (in terms of slack and backlash in the whole train, even the idler pinion shaft, and the mag itself) - but the mag pinion looked good too, or I'd have replaced it then in light of previous experience. No funny noises then, and no warning of sudden loss of ignition timing when teeth went walkies today. But you wouldn't expect to hear much as steel munches fibre I suppose, until it's well-munched and you lose the timing. It's clear what has happened (just knew it had the moment it went sick and stopped - lovely backfires), possibly less clear as to why. And any way up, a lousy day for roadside maintenance here in Northern Yrup . . . I'm still cold hours later, and I'm better insulated than a high tension mains cable . . . Groily

[flatdeck]

Groily, you may find this useful, Dave
Classic Solutions (North East) Limited http://www.classicsolutionsuk.co.uk

Unit 10C
Tanfield Lea North Industrial Estate
Stanley
County Durham
DH9 9UU
Telephone
+44 (0) 1207 299 020
Mobile
+44 (0) 773 766 5570

Fibre drive gear for BSA A10/A7 auto advance unit.

Part No: CS50277 Price: 8.51 pounds

[groily]

Thanks Flatdeck - I saw that and have duly added to 'Favourites'. Sadly, cause of the problem, I think, is very excessive wear on the centre bush of the ATD device - makes Richard's rod wobble look like nothing, and over a much shorter length. 8 teeth ground down to the point of missing the camshaft gear teeth (which are just fine) as are the rest of the train. Clearly there'll be some grunge in the system, but I suspect the teeth ground over a period - there are no lumps of much anywhere I can see without serious additional dismantling . . . so it'll have to be an oil change and general clean-up and fingers crossed. SRM are awaiting an order of new ATD units complete with pinion this week, so I've ordered one to come with a K2FC mag I already have with them for the full works. Not cheap compared to the bare pinion (144 quid I think) but it'll last. Mate with a Velo had the same prob recently with the pinion for either a mag or dynamo (not sure what drives what in Velocettes myself). I shall attempt - see previous comments in this thread as to do-ability - to strip the ATD without damaging it and use a morsel of phosphor bronze or something to make a new bush, then fit to new bare pinion to have as a spare (that I'll never probably need now!). Problem is getting the collar off the back (mag-side) of the thing without a press, so might have to wait till I have access to one. . . . Groily

[RichardL]

Sorry to hear of your ill-fated pinion and frozen ride. I am, though, a little confused as to why you were out in that weather. One might say that it was a sign of love for riding, or, punishment. You might know a better source, but I just found www.weatheronline.fe. Surprisingly, this weekend was beautiful and 60F+ here in Chicago, but I was in Los Angeles for most of it visiting my "dear old mum." 96 is old, right? Doesn't really matter, I wasn't going to riding, as you know.

Hearing of your purchase from SRM, and given flatdeck's link, and given that you may already know about these guys, it may be moot to mention www.magneto.co.uk. I am curious what caused the bushing wear. Just time and miles? I guess we should assume that the mag is spinning freely or you would have mentioned it.

Happy reassembling!

Richard

[groily]

Ah well, the joys of club life Richard - we always go out for an organised run the first Sunday of the month, come what may! But yesterday was a tough one, starting well over 65 miles from home and ending about 60 miles from home, after a 50 mile trundle round - well, roughly, I've gone all kilometric lately!

Re the pinion. Yep, wear is the main culprit here. Got it apart this afternoon without a press, and apart from the springs and the bobweights, it's scrap and not worth trying to fix. The central shaft is pitted and horrible, as is the 'bushing' - really just a hole in the middle of the thing. Not enough meat to do a really good job with a bushing, although I suppose one could remake most of it from scratch etc etc - but loads of work, not all of it easy.
Shame, but I'll be pleased to have a new one and know that that particular point of failure won't strike again.

As to dismantling the thing, if anyone's keen to be similarly mad (SRM will, given time, recon one's own unit for less ££ than a new one), it's a Q of 'get the collar off the magneto-facing side'. Somehow. This allows you to pull the 2 halves apart. The rivets that hold the ATD in the pinion can then be tapped out from the mag-side - they can't from the other side. With them out, the big washers that hold the fibre pinion in a solid sandwich are free and the pinion can be pulled from the inner half of the ATD to which it's very firmly attached - light taps with small hammer using suitable sized socket spanner as distance piece. The central fixing hollow bolt comes out of the outer half of the ATD on a coarse LH thread which might or might not be a left handed 9/16 ww, mine's too messed up to tell for sure. Apply pulling pressure to the bolt head - pair of self-locking pliers or similar, and turn clockwise.
If the state of the thing had been better, I'd have bought Fido's £8 pinion and done it myself, but life's never that pleasingly simple it seems! And I'd have been wondering why the teeth got so messed up. At least I can see why, per Bill's query. Ah well, end of day and time to go and get clean. Groily

[groily]

Ah, good question Richard and not touchy at all. Had I ground to a halt an hour earlier in the course of our club run, no problem . . . trailer follows us round to pick up the pieces and get them back to, at least, neutral ground (as in someone's garage). . . thing was, I'd done all the organised bit, had a great run round, and was on my own on the homeward run . . . parted company with a couple of similarly frost-bitten people about 20 minutes before coming to a halt. Had there been a few others around, the old camaraderie thing would have kicked in and we'd have ended up celebrating the joys of breaking down in some bar, with a trailer on the way to collect the oily remains . . .  Perversely, I don't mind the odd breakdown too much, although I suppose I ought to subscribe to some recovery service to avoid reliance on Her Indoors. I do carry a lot of tools, inner tube, pump, fuses, bulbs, cables etc in an effort to cover the likely hassles but sometimes there's nothing to be done - luckily rarely. In 7 years of trundling round hereabouts I've only had to trouble Herself twice, although I can't say I haven't struggled home late once or twice after having to do running repairs . . .  All part of the fun, I guess . . .

[LJ.]

Spot on Groily! aint that just what classic motorcycling's all about? The 'will it or won't it'? and when it does... The warming satisfaction of it having done so... 

[groily]

There's nothing like a few days reflection when things go wrong . . . I wasn't happy at the thought of shelling out a lot of english money to buy a new ATD and fibre pinion for the beast . . . and I'm not going to.

For a fraction of the cost I've found a 2nd hand manual advance and retard end housing for a K2F, I've modified (as in drilled and tapped a couple of new 2BA holes) in the mag body to take account of the different locations of the fixing screws on a manual as opposed to fixed-cam-ring mag, made a wotsit to engage with the slot in the manual cam ring, dug an old handlebar lever out of box of bits, re-worked an old throttle cable, and have got an inexpensive aluminium fixed pinion on its way. So should be up and running soon.
 
Now I know I have said a few times that the ATD is a better proposition, given that the advance and retard doesn't affect the optimum sparking position of the armature, but heck, the lever is fully advanced most of the time - at which point the mag ought to be at its most efficient. So goodbye to edible pinion, welcome all metal gear train, and quite a few ££ saved.

Having made those choices and done those things, thoughts returned to the ATD device which I described as scrap and which was staring balefully at me on the bench. However, amazing what can be done with a bit of dead sit-on lawn mower rear axle shaft . . . when it's a finish-ground bit of 3/4 inch stock, it's obviously crying out to be machined up to make a new centre shaft for a knackered ATD . . . With a gentle ream - more a touch than a scrape - of the 'other half' of the ATD to make good the bushing, it's as good as new with the various important bits pressed or brazed on, a new self-extracting home-made sleeve nut, and it just awaits the arrival of a 2nd aluminium pinion which I'll machine up to fit and have as a spare if I feel like swapping mag parts round again or get bored with the cable.
 
Very pleasing, 'warming satisfaction' LJ!, or will be when I have some pinions to play with. As the registration document - it's probably a liar - says that the beast was once a Super Rocket, the manual ignition is, I suppose, 'original'. Suppose I'll have to find an alloy head next, if this silliness carries on . . . . Groily

[flatdeck]

Hi,
When I had the fibre drive gear replaced I sent the whole ATD + new drive gear to John at British Spares, Silverstream, Wellington, New Zealand. The new fibre drive gear was fitted and the springs replaced and the whole thing cleaned and checked and couriered back to me for the equivalent of about 30 quid .... v happy.
Dave

[groily]

Well, new pinion in alloy installed (35 pounds or so from SRM) and back on the road. Very happy. ATD to Manual mag mods done and OK and so far so good. A/R cable routing not as comfortable as I'd like owing to carb and drip tray getting somewhat in the way (?whether there are other versions of the K2F manual end housing that would suit an A10 better), but works OK for now after some trouble finding a suitably strong spring for the cable at the mag end. Am nearly there with machining up a 2nd alloy pinion to go on remade ATD unit, fingers crossed it all goes together and works as planned . . .. if it does it will be tougher than original, if it doesn't, it'll sit there as a monument to my incompetence and another 35 quid wasted. Groily