Dynamo toothed belt not lasting

[muskrat]

G'day all.
Is anyone else not getting many miles out of a belt? The cafe has just eaten her second in 3000 miles. The plunger has eaten a couple as well. There not getting oil contamination and are tensioned right (able to twist 90 degrees) and not getting hot, pulley's are in line. These are the red syncroflex AT5 10mm belts from SRM. Thinking I might have to try the 15mm belts from Mike.
Cheers

[groily]

I bet Mike's are better Muskrat, but I put an SRM one on about 5 or 6 years and a lot of miles ago, and it's still there. Not sure whether I'm lucky or you're unlucky. Probably the latter I'd say, as of course one always is fated if a long way away fom the supplier! Maybe they've changed the spec though? Dunno.
The only problems I had were with the taper on the drive pulley slipping (I fitted the centre of the discarded sprocket into the pulley to get a better solution in steel), and the retaining lip on one side of the same pulley had not been turned to finished diameter so it wouldn't allow the timing cover to go on, which involved a quick shave. Tension seems to stay put where I set it. Cheers, Bill

[muskrat]

Thanks Bill. I just noticed in Goffys A10 page he mentions belts not lasting 2000 miles. Strange to me that both mine like to chew'em. Both bikes run DVR2 to 12 volt Boyer ignition, never had the headlights on and brake light rarely comes on (brakes only slow you down  ), so the dynamo wouldn't be working too hard.
I can't find a supplier of those belts down here and it takes about 3 weeks to get one from SRM.
Cheers

[duTch]

 Funny this should come up now, as last week while doing a 'a-la-Musky-Orabanda' modification to the timing as part of my contentious cush-nut episode , I had the timing cover off to do the obvious, and spotted a few bits of swarf in the belt chamber....nothing else looked out of place, and the belt had same acceptable tension...swarf was like fine steel wool, and I think I sucked the last few bits out with a magnet.. ...  belt has done about 4500 miles, nothing neck snapping though.... dunno why they should burn out so fast

 Mine is also an SRM supplied belt, but for some reason, I had the notion they are from a US manufacturer/supplier..

[KiwiGF]

The belt conversion is on my nice to have list, mainly to see if it is the source of noise making my engine sound worse than a mates a10  ......but if the belts don't last that would put me off doing the mod as the only time the bike has let me down was when it stopped charging when I was on a night ride  (dodgy brushes was the cause)

So is there any consensus on the best kit to get and how often to replace belts to avoid a breakage?

[muskrat]

G'day duTch. Time to order a spare belt mate. sounds like its on its ay out.
KiwiGF, the jury is still out on this. I'll be contacting SRM and Gates to find a solution.
Cheers

[wilko]

I think a 1/4 inch chain conversion would be a good compromise. As in Matchy  magnetos and gennys instead of that pissy bicycle chain.

[Brian]

I've had one of Mikes belt conversions in my A10 for 12,000 miles now and the generater still charges so I guess its still going around and around. Oneday I will take the timing cover off and have a look.

[Triton Thrasher]

Is the belt being bent round a smaller radius wheel than it is meant for?

[muskrat]

I thought that too TT. Just had a look at a few sites and the minimum size pulley is 14 teeth (more than I got  ). Just put the covers back on and didn't count them but the smallest AT5 pulley on their lists is 14 teeth so assume mine would be that or bigger.
Thought I'd better check the plunger (500 mile ride coming up in a few weeks), belt looks good. I noticed that it isn't a SRM job like on the cafe. Still a 10mm belt and pulley on the dynamo but a wider 20?mm drive pulley. I can't remember where it came from  . It might be one of Mike's early ones.
Cheers
Edit: just went back to 2011 and found the plunger belt kit came from Lytedrive Australia.

[Dynamo Regulators Mike]

A little input from a seller and long term user of toothed dynamo belt drives.

The Dynamo Regulators kit has pulley sizes of 16 & 47 T, to give +20% ratio over chain drive. This incidentally restores the dynamo : crank speed ratio to the same as in a magdyno machine, and does not over-speed dynamo. The kit is supplied with a 15 mm wide Synchroflex AT5 Gen III belt. I do not have the pulley sizes of the SRM kit to hand, but overall ratio is about 10 % up on chain. The SRM belt was upgraded at some stage to the same type as we supply but only 10 mm wide, therefore far less strong of course.

These belts are designed for durability will tolerate oil and grease or run dry and good up to 100 C. The sole manufacturer is Conti in Germany. The way these things are distributed means limited outlets and minimum quantities apply, not a simple off the shelf item, and not cheap, just the best for the job.

DRL has sold roughly 200 kits to date with very few problems. Some customers will buy a spare belt from the outset, others come back for a spare before a long trip. Only a handful of spare belts sold have been replacements for broken belts. The few problems we have heard of are mostly traced to over tension of belt when cold. What seems reasonable cold becomes a twangingly tight belt hot, which will obviously cause wear problems. It is important that the pulleys are correctly aligned so the belt does not rub excessively on one side.

The noise reduction benefit of these drives needs to be heard to be appreciated. The chain is noisy; this appears fussy perhaps until you realise the difference. Take a look when next at an auto-jumble at the witness marks on the timing cover where the chain rubs. Very few do not have the tell-tale pair of grooves.

The dynamo belt drive on my A10 has done well over 10,000 miles and showed no sign of any degradation last time I looked. Quite a few users have told me similar after greater mileages. 30,000 miles lifetime is the best estimated obtained for belt life. It is working well below maximum load figures in our application. How often do you chaps reckon to adjust or replace a dynamo chain?

Cheers
Mike Hutchings

[duTch]

 

G'day duTch. Time to order a spare belt mate. sounds like its on its ay out.

 Yo, that was first on my mind, at least to have on hand...I didn't scrutinize it too close as everything else looked ok- needed to finish task at hand first, but have a feeling it's 15mm but can't be sure.will have better look soon.

[muskrat]

G'day Mike.
 Thanks for your input, it's great to have a member in the industry for knowledge on such issues. I wonder how long before they (SRM) follow your lead in going 15mm.
To be fair Gary at SRM was very quick to respond to my email.
 
G’day.
I have one of your kits on my ’57 A10 Café. The belts aren’t lasting very long at all. Two have gone in 3000 miles! Belts are not oil contaminated, pulleys run true and in line, tensioned so the belt can be twisted 90 degrees with fingers, dynamo in top condition. Any ideas? How much to send another two out to Australia? Link to my post on the BSA A7 & A10 Forum.
http://www.a7a10.net/forum/index.php?topic=9131.msg65949#new
Cheers

This is Gary's reply.
Hi Jim,
we have sold literally hundreds of these kits, and only to my knowledge two people including you have this issue, both cases are in a country where temperatures can run high and both cases belt has been run "dry" , these belts are suitable for running in grease or oil, we do suggest to run with grease, it will keep it a little cooler and help keep belt lubed to pulleys.
 
Also if you run a dedicated 12v wound dynamo, instead of converted 6v by regulator, this armature has thinner wires, and if a high wattage halogen bulb say a 45 to 50w is used, dynamos running this and rear tail will overheat and cuase excessive load on the drive and sometimes even seize the dynamo up., There are low wattage 35w halogen BPF bulbs availbale to help keep the load requirement from the max 60watts output of the old dyanmo down to a minimum, also some ignition kits if replacing the magento run at 28 to 30 watts, so with a headlamp bulb dynamo is definately overloaded.
I can send couple belts out to you with some discount and free post to help you out, but if possible can you give any info or input about the information i have given above, to see if you have any of these issues that may have contributed to the belt failures ?
Thanks Gary

So the only cause I can see would be heat. The pipe on the cafe run over the top of the cover and may contribute. I'll wrap them to see if this improves the situation.
Cheers

[Triton Thrasher]

They recommend greasing the belt?

[orabanda]

Grease on a toothed belt? Not this little vegemite!

I have fitted the SRM kit to half a dozen bikes, and was dismayed to have one belt shred itself after 2,000 miles.

It was also adjusted correctly.

Hoping it doesn't happen again. the others; so far, so good.

I tap two 1/4"BSW holes in the main pulley, so it can be pulled off the idler pinion.

Richard from a hot Kalgoorlie (45C).