The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: wortluck on 04.08. 2018 21:56

Title: Bugga, bugga, bugga (broken dynamo chain)
Post by: wortluck on 04.08. 2018 21:56
Look guys, I know there may be topics on this already, but I need a bit of convo as I'm a bit p****d off.  Returned from my usual jaunt to find no charge on the ammeter.  Checked the wires, which were the culprit last time, then into gear to double check the drive - no *&^%^& movement  *angry* *angry* *angry*  Whipped off timing cover and, sure enough, broken dynamo chain link.

So, I've rescued the chain and broken link, presumably nothing will have entered the engine as it's sealed within the timing chest.  I've noticed some deepish grooves in parts of the inner timing case where the chain had previously been neglected and chewed into it.  Chain was checked a short time ago when I had to replace the mag fibre wheel and was fine.

Question - should I go for belt drive kit or just put another chain on?  If I go for the chain, do I remove the dynamo or engine sprocket to fit?  Finally, without looking at my manual, what's the procedure for adjusting the chain?  I know it has to do with some kind of cam operation (I think).  How often should tension be checked?

Humour me on this folks, I hate being put off the road and want to fix asap - and it's going to be a nice couple of days. *pull hair out* *pull hair out* *pull hair out* *angry* *angry* *angry* *problem* *problem* *problem* *bash* *bash* *bash* *bash*

Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: muskrat on 04.08. 2018 22:15
G'day wortluck.
I put belts on both of mine. At first I snapped a few till I got the tension (or lack of it) right. I found that the screw boss had been eaten by the chain and had sharp grooves so I cut it off and used a countersunk screw in there. I was worried the belts were rubbing on it causing their failure. On the + side the ratio of the belt system increases the dynamo speed bring the charging on lower in the rev range.
To adjust you loosen the strap and turn (spin) the dynamo to get the desired tension. Set it a bit loose as when you tighten the strap it will turn the dynamo a little tightening the chain/belt. So you have to guesstamate the amount.
Cheers
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: wortluck on 04.08. 2018 22:28
Cheers musky.  I like the sound of belts if only because they cause no damage if they break.  Chains in an ally case are always a cause for concern.  I guess it's a toss up between a 100 GBP kit and an 11.00 GBP chain.  Either way, I need to get back on the road asap (also have a broken front mudguard stay - vibration fracture).

This is just after I got her running well after a misfire.  That time it was the HT lead on the L/H pot that just pulled straight out of the pickup - only had one small wire remaining.  Brushes were a bit oily though, is that another problem.  The slipring wasn't oily?
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: berger on 04.08. 2018 22:37
I have not been to the pub , private msg sent wortluck
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: duTch on 04.08. 2018 23:26

 If you have the pennies for a belt drive, well worth the investment. Like Musko, I stretched the first one having it too tight (SRM/Syncroflex), but have now done 6 or 7 Kmiles since intstalling the new one. Seems the kits recently discussed have the nod of choice (wider belt and Mike is a member here).
 I run my belt quite loose now and it doesn't seem to bother it, adjusted so the loose side, (opposite the drive side) is clear of the boss that Musky mentioned, though they'll both be tight/loose at some stage, keeping in mind that it rotates in a anti-clock direction.
 **Not fit and forget, still need to check periodically, like when doing oil changes and want to drain the oil in the pump cavity....
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: berger on 05.08. 2018 00:41
unless your riding a long way at night bang the case on and enjoy, I use meths on a cotton bud {carefully} to clean inside maggy with plugs out and in 4th gear turning back wheel. what type of chain do you want? continuous or one with a split link.?{let me know before Monday dinner time please} if continuous you undo dyno clamp and spin it towards engine when you've fed it over drive sprocket, I carnt remember now if you have to drop drive sprocket  off its taper, someone will know..then adjust to a 1/4 inch play on the top run. as musky says you may well find dyno will tend to tighten the chain as you tighten the clamp, you might have to play about a bit to get it correct. I fitted one of the v belt drives a few years ago and for 60 quid its working well considering the heat the v belt gets,,,, *idea*thinking again I recon drive pully has to be dropped off to fit continuous chain. and finally don't panic mr mainwareing they don't like it up em!! *whistle*
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: duTch on 05.08. 2018 04:35

 I was going to say a chain would be a quick easy fix, but forgot....

 and I was thinking this too...if it's endless..

 
Quote
.....*idea*thinking again I recon drive pully has to be dropped off to fit continuous chain. and finally don't panic mr mainwareing they don't like it up em!! *whistle* 
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: Black Sheep on 05.08. 2018 07:07
A properly adjusted and lubricated chain will last indefinitely. I would stick with a chain. The large sprocket is fixed by shear rivets to protect the cases in event of a broken chain jamming the sprocket. BSA did think it through. 
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: bsa-bill on 05.08. 2018 09:17
both my bikes - belt drive
First one was SRM - still fine no problems, the second was very similar but not SRM it's still going fine as well,
First thing I do on any future project .
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: wortluck on 05.08. 2018 09:31
Thanks guys, with a special thanks to berger.  I've no idea how old the chain was or what quality it was.  With hindsight, I would have asked for the chain to be replaced when the engine was rebuilt, but it was deemed to be serviceable.  It was adjusted correctly when I checked it about 1k ago.  Interestingly, it seems no damage was done by the event with the chain coiled up just above the drive and not in contact with it!  Nothing appears mangled apart from some grooves in a couple of places which were a result of neglect over the past 50 years or so.  Thankfully, the shear rivets weren't needed.
Someone said getting an endless on is possible without removing sprockets.  The trick is to manoeuvre the dynamo and persuade the chain on.  What do you think?
Berger's right, of course, I could just bang the cover back on and ride - if I had a serviceable gasket of course.  Actually, I could manage without a gasket as I discovered it only has a mild leak metal to metal - hmmm.
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: JulianS on 05.08. 2018 10:13
Belt drive is quieter and the drive pinions easy to remove and slightly gears up the dynamo speed. Would not want to go back to a chain driven dynamo.

Mine is from DVR;

http://dynamoregulators.com/drive-belt-kit.php
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: RogerSB on 05.08. 2018 12:49
This is SRM version. Already on there when I bought my current GF but if I ever needed to replace it my choice would be the version from Dynamo Regulators.
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: wortluck on 05.08. 2018 19:18
Cheers guys.  Slapped cover on (without gasket) and went for a 120m run - just a couple of spots of oil!!!  Leaks less oil without the gasket. *eek*  Found some bits of one the rollers but not the tiny bits for the broken link.  Cleaned out all the grease and checked oil, but no sign *????*  Bike was noticeably quieter (ran beautifully) without the chain and I was intending on a 200m run.  Unfortunately I had to return with a couple of cable ties (courtesy of a random tradesman in a small North Yorks village) holding the front mudguard on because one of the side brackets broke in half (this was in addition to the lower stay breaking yesterday). 

There are words to describe the quality of materials BSA used but I cannot, in good conscience, use them here.  I guess they may be half a century old.  By the way, my side stand also crumbled, that's why I only use a the centre stand.

Think I'll do a diary of all the breakages/breakdowns and post them.
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: RichardL on 05.08. 2018 19:32
Think I'll do a diary of all the breakages/breakdowns and post them.

Sorry, but all post limited to under one terabyte.

Richard L.
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: RogerSB on 05.08. 2018 20:33
Could change your name to Worstluck?  *bright idea*.

But here's hoping you don't have any more probs  *beer*.
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: wortluck on 05.08. 2018 22:02
Fanks Rog, may have to  *sad*
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: kiwipom on 05.08. 2018 23:07
hi guys, Wortluck says, (There are words to describe the quality of materials BSA used but I cannot, in good conscience, use them here.  I guess they may be half a century old.  By the way, my side stand also crumbled, that's why I only use a the center stand,
Think I'll do a diary of all the breakages/breakdowns and post them)

...These machines were made to last for certain time BSA certainly did not envisage that our models would be around some 60 yrs on, its a credit to them that n.o.s. is still around plus all the bits stored by owners. Its not impossible to have good parts made if you want to pay today's prices, cheers
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: RichardL on 05.08. 2018 23:11
BSA certainly did not envisage that our models would be around some 60 yrs on,

...or that there would be enthusiasts like us. Now, leaving the pub ((16 oz., only) and riding her home.

Richard L.
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: wortluck on 05.08. 2018 23:30
Good points!  Thinking about it through the haze of beer and cider, we just don't know what these machines have been through.  Tearaways using them as field bikes, crashed and smashed, left out in all weathers, abused, etc.  I do know for a fact mine was used as a donor machine by a previous owner who may have taken off the good bits.  No doubt they'll also have been painted, repainted, sandblasted and enamelled.  When I was restoring the bike, I was insistent that anything serviceable be kept and used/refurbished rather than buying new.  I wanted to keep the machine as it was, but with everything 'tidied' up.  This may partly be responsible for some of the failures I'm having now.  At least this way, when I replace, I know I've got everything I can out of that particular component.
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: Black Sheep on 06.08. 2018 06:28
One old gentleman was heard to mutter whilst looking a Rudge at a bike show "If I knew it was going to last this long I would have specified cheaper materials". Yup, they were all intended to be scrapped years ago, in which case survivors are all examples of bad engineering practice. The ideal machine, on reaching its design life, should simultaneously disintegrate into a pile of dust.
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: cyclobutch on 06.08. 2018 08:42
Off topic here but you guys drifted it this way; I'm using an RGS type front mudguard on mine - given up using std supplied stays for that. I've got flat aluminium strip front and back and a chunky bit of steel flat stock running up form the forks to the bridge. Seems to have sorted it.
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: bsa-bill on 06.08. 2018 08:49
Quote
BSA certainly did not envisage that our models would be around some 60 yrs on

And which if any of today's bikes or cars or whatever are designed to be any different, excluding of course the Bentley's, Rollers and other's costing several arms and legs
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: muskrat on 06.08. 2018 09:08
"Tearaways using them as field bikes, crashed and smashed, left out in all weathers, abused, etc. "
At least I kept her and cleaned her up later.
Cheers
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: wortluck on 06.08. 2018 09:13
The bike, I take it, musky *smile*
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: muskrat on 06.08. 2018 09:45
Yep, the A7 was my bush basher for a while. Even towed a mate and his girl on a TT600 a few miles through the bush to get home.
Cheers
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: wortluck on 10.08. 2018 22:37
Quick update.  Although a kind member of this forum sent me a split link dyno chain, I had to see if I could get the engine sprocket off for future reference.  Someone suggested knocking a wooden wedge down the back and tapping the shaft.  I found an old wooden door wedge and did this, then tapped round the sprocket gently with a hammer - popped off a treat!!  Snag one was having to make a lock washer out of a bit of galvanised steel as one of the tabs instantly broke as I tried to bend it back. *sad2*  Cleaned everything up (and found the bits of the link that had broken), regreased and put back together with new gasket and no leaks. *smile*  Gasket did protrude quite a bit round the casings, but a sharp razor blade took care of that.  All fired up with dyno working again but, no headlight? *angry*  Discovered that another wire had broken in the headlamp cowl so that was next fix. *problem*  Once I have the broken front mudguard bracket painted and fitted, it's back to the road.  Wonder what'll break next time? *pull hair out* *bash* *pull hair out* *bash*
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: duTch on 10.08. 2018 23:23
 
Quote
Wonder what'll break next time? *pull hair out* *bash* *pull hair out* *bash*

 yahoo...fun and games   *smile*
Title: Re: Bugga, bugga, bugga (broken dynamo chain)
Post by: wortluck on 11.08. 2018 08:59
You are not kidding, my friend.  Beer was invented specifically and exclusively for BSA riders *beer* *countdown* ;D