The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: Brian on 29.04. 2008 09:17

Title: Belt drive for generators
Post by: Brian on 29.04. 2008 09:17
I am thinking about putting a belt drive conversion on the generator of my A10. I see there are a couple of different types available and at this stage I like the look of the SRM toothed pulleys and belt type. I figure with the toothed pulleys even if they did get a bit of oil on them it shouldnt be a problem. Have any members had one of these fitted for some time now and if so how has it gone?
                                                                                      Brian.
Title: Re: Belt drive for generators
Post by: groily on 29.04. 2008 13:19
Brian, SRM toothed belt job has done well for about 2000 miles. Not the cheapest option probably, but well made and went together quite easily, although if I recall (hope I've got this right) the generator pulley has to be put on after it's been put in place on the crankcase (too large to go through the timing cover), which means it's not the easiest nut to do up tight - for the lack of means to hold everything. The 10% gearing up is helpful, as the charge rate balances demand pretty quickly, but the best thing for me is the lack of noise. I'm at 6 volt, 35 watt headlamp, by the way. Groily
Title: Re: Belt drive for generators
Post by: Brian on 29.04. 2008 14:54
Thanks for that Groily, I reckon I will go with the SRM one. The noise is the main reason I am looking to put one on, I have found if the chain is not adjusted perfectly it is noisy, it cant be too tight or too loose. Brian.
Title: Re: Belt drive for generators
Post by: LJ. on 29.04. 2008 22:28
I'm at 6 volt, 35 watt headlamp, by the way. Groily

I'm also with a 6 volt and 35 watt headlamp... but with a tweakable mechanical regulator!  *lol*
Title: Re: Belt drive for generators
Post by: groily on 06.06. 2008 23:43
Postscript to complimentary remarks made previously about toothed belt drive . . . last weekend the drive pulley on mine came loose - don't know why, it had done almost 3000 faultless miles by then and I was half way round a 200 mile run. Put it back at the roadside, with some nervousness as it didn't feel great - and it came off again miles away this afternoon (daylight, Sod's Law not operating today for a change). The slipping on the male taper wrecked the female in the soft ali pulley, to the point where there was no chance of any positive engagement, ever. Someone here said in effect 'play with the original design at your peril' in another context and I think this is an example.
The taper on the original sprocket is obviously steel and pretty tough. So I have just a few minutes ago machined the ali pulley to take the centre section of the old sprocket, complete with its steel taper, which is now attached by 6 4BA screws where the rivets in the original sprocket assembly went. It's now fine albeit a couple of ounces heavier- but a lot of fiddly turning drilling and tapping for a little thing. In a perfect world nothing ever comes undone at inconvenient moments . . . but in my world they always darn well do. So I'd say the after-market kits would be better if they had a steel insert in the pulley's centre to carry the taper, which the SRM one doesn't. Probable reason for all the hassle is that the taper on my intermediate timing gear isn't the best in the world - but I reckon that could be said for many of these things.
Title: Re: Belt drive for generators
Post by: a101960 on 07.06. 2008 08:17
I had the very same problem with the SRM belt drive kit. The problem is caused by not being able to tighten the pulley up properly if the dynamo is fitted to the bike, and  because you cannot pass the SRM pulley through the casting once it is fitted to the dynamo you cannot fit it and tighten it properly off of the bike. I have since fitted a belt drive kit from another supplier with no problems.
Title: Re: Belt drive for generators
Post by: Brian on 07.06. 2008 11:54
I'm glad I didnt rush into buying one of these belt kits. I was wondering, I have never had or heard of one of the original sprockets coming loose so maybe the belt ones being alloy expand a bit too much when hot. They shouldnt have to be that tight to stay on their taper once fitted. I have just fitted new chains to both my A10's while I was thinking about the belt conversion so maybe I will stick with them for now.   Brian.
Title: Re: Belt drive for generators
Post by: GuyboA10 on 07.06. 2008 18:41
A101960 - could you tell us what other brand u used? was it from Hawker electrical? cheers in advance, guybo.
Title: Re: Belt drive for generators
Post by: a101960 on 07.06. 2008 18:56
.....could you tell us what other brand you used? was it from Hawker electrical? cheers in advance, guybo.

Yes it was from Hawker Electrical. It comes with a couple of extractor bolts to aid removal of the drive pinion.
Title: Re: Belt drive for generators
Post by: groily on 07.06. 2008 19:13
Just to be clear - when I said 'drive pulley' I meant the one on the timing gear. Not the equally-hard-to-do-up-for-the-reason-given small one on the dynamo. That has stayed on - but not sure quite how 'cos it's a swine - also for the reason given! Anyway, gave it 100 miles this am to see what happened, and all is well with the home-made mods - result. But a lot of hassle. Could be expansion problem with steel and ali - good thought. Won't happen again! That made nearly 1000 kilometres this week, and for 3 days I was in Angleterre! Good bike. No oil used, nothing else fell off, and I'm happy. Just need a partner that likes cleaning things.  . . probably have to wipe it over with oily rag myself . . . .

Is the Hawker one steel on steel I wonder? I made my mod so that I can use the threaded holes for extraction - in theory anyway . . . and if I make a weapon to straddle the thing . . .
Title: Re: Belt drive for generators
Post by: a101960 on 07.06. 2008 22:33
Quote
Is the Hawker one steel on steel I wonder?

No the Hawker one is not steel it is ally. What happened with my SRM drive was that both pulleys failed. That is to say within a couple of hundred miles they were loose on their respective shafts, and in the case of the dynamo pulley the wear was so great that there was not enough metal left to make a repair.I will take  a photo and post it tomorrow. In retrospect it might have been a good idea to have used loctite on the shafts on initial installation. I am wondering weather the slippage is caused by an inability to grip when the dynamo is under load because there is no woodruff key used in the belt kit like there is in the original chain set up. There are many people that have done high mileages using the SRM belt drive without trouble. Maybe I was unlucky?
Title: Re: Belt drive for generators
Post by: groily on 08.06. 2008 07:00
Not sure if anyone from SRM reads these threads, but if 2 systems have gone awol they should be told, given they are pretty serious about quality. I thought it was down to me or my taper, but likely not. And I woudn't use Loctite on the thing - why should we? Make it even harder to get off. Whatever, if someone made a system which came with a pulley pre-machined to take the unriveted centre section of the original sprocket (not hard to do for a professional shop, bit fiddly for an amateur as I discovered), drilled and tapped for a basic extractor to be applied, plus supplied a dynamo pulley that would fit through the 'ole (it would be easier to do up off the bike, although still not the simplest), life would be a lot easier!! Hawker have achieved the latter by the sound of it. A secondary problem I encountered with the SRM kit was that the side plates on the drive pulley - which stop the belt sliding off the thing - were oversize on mine. I had to pop the outer plate off and turn the outer diameter down 60 thou so that the timing case would go on. I can't remember an original sprocket ever coming off either - although I do remember them being darn hard to extract sometimes. If I'd taken a pic of the mod I've done, I'd post it . . . next time .  .
Title: Re: Belt drive for generators
Post by: bsa-bill on 08.06. 2008 10:26
No problems with my SRM kit so far although I do not get to ride as much as you gents, but due to my ignorance I do know that they function when the belt and pulleys are submerged in oil, which must say something.
Don't recall any woodruff keys in the old set up mind

All the best - Bill
Title: Re: Belt drive for generators
Post by: a101960 on 08.06. 2008 16:34
Not a very good picture but you can get an idea of the scuffing caused by the fretting of the pulley on the shaft. On my dynamo there was a key on the shaft with the original chain drive sprocket. After all these years different degrees of wear will have taken place on the shafts which might explain why some people have no trouble and others do, although I do not think that this would explain why groily experienced the trouble he did after covering so many miles. There should in theory be no problem with alloy pulleys on steel shafts. I used to own a Douglas 90+ and the camshafts were driven alloy timing gears. I encountered no problems with that set up.

Title: Re: Belt drive for generators
Post by: a10gf on 08.06. 2008 19:08
Some scenarios: if the shaft cone is worn (or too thin) the pulley may enter too far on the shaft = the nut will not be able to apply enough pressure to lock it properly onto it's shaft. Or the locking nut should have been tightened more (or retightened after a period?) to ensure a complete "bonding" between the steel and alu.

e.
Title: Re: Belt drive for generators
Post by: groily on 08.06. 2008 22:34
Agree there should be no prob with steel-alloy - I've just put alloy mag pinion on per previous threads and that HAS to stay put! Fingers crossed. Don't know why the dynamo drive gear fell off, but could well be because it wasn't far enough up the taper, or the nut should have been checked. It was tight when it was put on, is all I know. I'll check the revised arrangement with the old steel centre in a few more miles - but am pretty confident it can't budge. Famous last words. It'll probably last until it's dark and raining, which is when I usually find myself groping for the tools in some unfriendly ditch. Amazing how one becomes acquainted with ditches over time . . .
Title: Re: Belt drive for generators
Post by: a10gf on 08.06. 2008 23:13
Thinking about it, I'd believe the mag with it's large dia is much easier to turn than a charging dynamo's small sprocket. The alu sprocket on the mag has an easy job and should not slip unless one forgets to tighten the nut at all, not so on the dynamo side, I'd say there is a good reason why there is a key on the original design.
Title: Re: Belt drive for generators
Post by: Dynamo Regulators Mike on 10.06. 2008 09:04
I have had A Hawker belt drive fitted for a couple of thousand now. Only problem has been the need to tighten belt perhaps every 500 miles or it will slip. But I did take up the option from Hawker of fitting the seal to keep the belt completely dry. This only after it had slipped in a trace of oil and worn the belt somewhat. A bit of a hassle but perhaps best done during next winter fettling. A new belt will probably help to cure my remaining 'stretch' now its all perfectly dry running.
Perhaps the puuleys should be fitted with a suitable grade of loctite. It also seems to me that if the aluminium were anodised the harder surface would grip more tightly on the tapers as well as the belt running surface being less prone to abrasion.
Should say that I run a 55/60W headlamp and Boyer ignition so dynamo is doing a fair bit of work. Belt drive ratio is 3:1 on my setup.
Cheers
Mike
Title: Re: Belt drive for generators
Post by: GuyboA10 on 10.06. 2008 10:10
G'day. Hey Mike, did you fit the special seal or did Hawker do it? just wondering as it sounds like a good option. Also, what is the ratio for the SRM beltdrive??I think they say it offers 10%-15% more charge.Hawker...3:1 ,cheers Guybo.
Title: Re: Belt drive for generators
Post by: Dynamo Regulators Mike on 10.06. 2008 11:08
And g'day to you cobber.
Hawker fitted the seal into the timing cover by return. It's a small V seal and has worked a treat. The belt drive is supplied with a cork seal as originally fitted apparently. You may be lucky and this will do the trick. It did not fit behind the drive pulley on mine - too thick.
There are I believe at least two dynamo drive ratio fitted to our twins. Don't recall the sprocket teeth nos, but I think mine worked out at about 2.2:1. Sean Hawker said his belt kit offered about a 30% speed increase over standard, and a bit more than SRM.
Incidentally read yesterday on Yahoo board about a problem with a tooth belt drive shedding teeth after over stressing whilst tightening. Something else to watch for.
But belts are quieter, cleaner and offer more speed. Nothing ever seems clearcut when it comes to 'improvements' does it?
Mike
Title: Re: Belt drive for generators
Post by: RichardL on 10.06. 2008 16:09
a101960,

I have had a very good supplier/customer (I'm the customer, of course) relationship with SRM. They have never denied me help, even when it did not lead directly to their profit. SRM is very receptive to telephone and email communications. Having had trouble with their product, you should definitely give them a call or send them a note, as I'm certain they would like to know about it.

Richard

Title: Re: Belt drive for generators
Post by: a101960 on 10.06. 2008 22:34
Quote
Having had trouble with their product, you should definitely give them a call or send them a note, as I'm certain they would like to know about it.

You are right of course, and I have bought other products from SRM that have proven to be very good. However, having had that product fail (both pulleys working loose) I rather lost confidence in the product. Even if I had be given a replacement I would have been constantly worrying about if and when it was going to let me down again. The Hawker system is a much better engineered product (in my opinion) it certainly does not look as fragile (especially the dynamo pulley). The only down side to the Hawker belt drive kit is that due to initial belt stretch it does require adjusting a couple of times until the belt has settled. The belt is a a toothed 'V' belt by the way. I know that others have used the SRM system without trouble, and it is equally likely that some people have had problems with the Hawker belt drive. From my own personal point of view there is no point pursuing something that you have lost confidence in. For the sake of balance I should say that I had a Hawker electronic regulator fitted, which although I cannot truthfully say that it did not work, it could be a bit eccentric in the way that it did work. I subsequently changed to a V2 regulator which I am much happier with. It is I suppose all a matter of continual experimentation until you find a solution to a task that suits you as an individual.
Title: Re: Belt drive for generators
Post by: RichardL on 11.06. 2008 00:47
a101960,

Well, perhaps you have a different view of money than I. Were it I, and I was unconsolably dissatisfied, I would have asked if I might have my money back. I imagine that the kit was more than a few "quid," as you would say. Knowing SRM a bit, I suppose they would rather refund your money than have you unhappy. Nevertheless, some folks don't like to bother with such things and being one of them may be your way.

Regards,

Richard

Title: Re: Belt drive for generators
Post by: groily on 11.06. 2008 15:51
Next time I talk to them (SRM) - they're always v helpful as everyone seems to agree - I shall certainly be mentioning the hassle with mine. Not to say it's their 'fault' but just to explain the circs and why I think the design is less than ideal. As I've now remade mine I can't complain too loudly. But I shall certainly whine if the fragile dynamo pulley also comes a cropper and I have to make a new centre for that out of something from the farmyard (or old lawnmowers, my favourite source). A few quid indeed - I think about 60 UK beer vouchers Richard, which these days equates to quite a stash of your beleaguered monopoly-money unfortunately!
Title: Re: Belt drive for generators
Post by: groily on 12.06. 2008 00:34
Doesn't bear thinking about Richard - all the years I was out there on your side working - '94 - '00 -, a quid was worth about a dollar fifty. Lucky you guys make most of what you consume . . . apart from the vexed question of oil and I'm not going there here! I guess it only matters if you want to go somewhere - those I met who came over to France for the D Day remembrance ceremonies last week were all pretty shocked at the relative cost of everything . . . hope it's just a cycle and things will get back to sensible in due course.
Title: Re: Belt drive for generators
Post by: groily on 12.06. 2008 22:28
It's me that's thick. Wasn't sure whether you meant 15 comma whatever or 15 full stop whatever . . . if the former, I missed the point, if the latter I thought maybe the exchange rate Chicago side had plummeted even further from the abysmal 2 to the pound to some horrible new level encouraged by usurious persons unknown. Must now check how much money there is in a standard British Monopoly Set (if the kids haven't lost half of it over the years). In any event, the lament for your devalued money holds good . . . have some old friends from Ohio staying with us this week, and am embarrassed to let them buy me so much as a beer for fear of what it's costing them . . .
Title: Re: Belt drive for generators
Post by: RichardL on 13.06. 2008 05:32
Absolutely. I just filed my expenses for my trip to London 1-1/2 weeks ago and it is a bit shocking when I look at it in dollars. It seems everything in the UK is at just about the right price, but it happens to be in pounds. I guess I am not a good economist, as it makes me think the dollar is quite strong, as long as it is spent here.

Just curious, are your Ohio friends into BSAs. Ohio appears to have one of the more active clubs in the US.

Richard
Title: Re: Belt drive for generators
Post by: fido on 13.06. 2008 08:14
For many years the dollar was worth about 7 shillings and sixpence (37.5 pence) and indeed my father sometimes used to say something cost him a dollar if that had been the price of the item.
Title: Re: Belt drive for generators
Post by: octane on 14.07. 2008 18:31
Hi folks!

...stumbled across this thread,
and accidentally I am right now in the process
of re-installing the SRM-belt system as part of re-assembling the engine.
I've had it for a couple of years (no idea how many km/miles) and so far no real problems.

..the generator pulley has to be put on after it's been put in place on the crankcase (too large to go through the timing cover), which means it's not the easiest nut to do up tight - for the lack of means to hold everything..
The trick (although time consuming) is to remove both timing-side covers
...install dynamo (with suitably tightened up pulley)
...then the inner and outer covers

I just did it an hour ago BTW

(http://i184.photobucket.com/albums/x214/octane98/belt.jpg)

.. The slipping on the male taper wrecked the female in the soft ali pulley, to the point where there was no chance of any positive engagement, ever. ...
I agree: the ali pulley does seam to be made of some rather soft'ish material.
I always worry if it will stay put.

Another thing is; be very careful to line up the dynamo
so that the two pulley's are in perfect alignment.
On my engine it means that I can't use the cork-seal.
It's too thick and will move the dynamo back too far.
Title: Re: Belt drive for generators
Post by: groily on 15.07. 2008 12:45
Did think about taking off the inner case Octane, but too darn lazy! Got the dynamo pulley on OK in the end - well, it's still there despite the disaster with the drive pulley! Good luck with yours, looks a nice job