Author Topic: Belt drive for generators  (Read 4271 times)

Online Brian

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Belt drive for generators
« 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.

Online groily

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Re: Belt drive for generators
« Reply #1 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
Bill

Online Brian

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Re: Belt drive for generators
« Reply #2 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.

Offline LJ.

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Re: Belt drive for generators
« Reply #3 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*
Ride Safely Lads! LJ.
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Online groily

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Re: Belt drive for generators
« Reply #4 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.
Bill

Offline a101960

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Re: Belt drive for generators
« Reply #5 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.

Online Brian

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Re: Belt drive for generators
« Reply #6 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.

Offline GuyboA10

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Re: Belt drive for generators
« Reply #7 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.

Offline a101960

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Re: Belt drive for generators
« Reply #8 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.

Online groily

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Re: Belt drive for generators
« Reply #9 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 . . .
Bill

Offline a101960

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Re: Belt drive for generators
« Reply #10 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?

Online groily

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Re: Belt drive for generators
« Reply #11 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 .  .
Bill

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Re: Belt drive for generators
« Reply #12 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
All the best - Bill
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Offline a101960

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Re: Belt drive for generators
« Reply #13 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.


Offline a10gf

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Re: Belt drive for generators
« Reply #14 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.

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