I contacted the supplier of tsubaki chains in Germany asking about an automotive prestretched 3 row chain. I was told they were no longer supplied in length only OEM for manufacturers. He also told me that he hast sold 3 row for a long time as car manufacturers now only use single strand chains
You don´t neeed no Tsubaki chain, get any three row chain, split rollers or not - BUT you weld up that dreaded ESA, latest or earlier type no matter, they don´t work all of them. The cam shape is still not effective for protecting the dynamo and chain rollers. Am I right in my thinking that when a split rollers type chain starts to fail it is in all cases at the central row of rollers due to the mass of the rotor/armature acting on the dynamo sprocket and overloaded by the shocks from the useless ESA ?? So my suggestion alternatively get an Alton with its lower mass of rotor and the chain rollers will survive no problem .
The big Laverdas got same triplex chains, Commandos too, and Laverdas today change chains for two single chains, no middle row anymore as triplex chain supply is a problem. Cheap enough then for binning them in periods.
The postwar Horexes with up to 400 cc and 22 hp - half of a Rapide - got duplex chains with split rollers, no ESA at all on them , see photo below middle chain. I never heared about troubles with chains on them, so engine power will not be the matter with Vincents and their triplex type, just the hopeless ESA effects on the middle row of rollers. So there is the root of the problem that you better address .
Vic
duplex chain Horex surrounded by Vincent triplex types:
Horex 400, no ESA :
two brushless magnet rotors, one Miller armature, a Bosch 3ph alternator rotor:
The big Laverdas got same triplex chains, Commandos too, and Laverdas today change chains for two single chains, no middle row anymore as triplex chain supply is a problem. Cheap enough then for binning them in periods.
The postwar Horexes with up to 400 cc and 22 hp - half of a Rapide - got duplex chains with split rollers, no ESA at all on them , see photo below middle chain. I never heared about troubles with chains on them, so engine power will not be the matter with Vincents and their triplex type, just the hopeless ESA effects on the middle row of rollers. So there is the root of the problem that you better address .
Vic
duplex chain Horex surrounded by Vincent triplex types:
Horex 400, no ESA :
two brushless magnet rotors, one Miller armature, a Bosch 3ph alternator rotor:
Well, on the one hand mine failed in exactly that manner - the rollers in the center row cracked and fell off. But, that row doesn't share any engine load, given no teeth in the center of the clutch sprocket. Is the load of rotating a 980g armature really sufficient to destroy a properly-made chain?
Harley Sportsters use a triplex chain. It is reliable. There is no ESA. I think these chains must still be available. I will compare the Harley one to the Vincent one in the next few days. I think they might be pretty close to the same lenght.
On my Vincent I use a McDougalator. The rotating magnet weighs 488 grams but it has a lot of inertia because it is about 3 1/2" diameter. The McDougalator uses a slip clutch in the drive and as long as this is properly adjusted it prevents damage to the center row of teeth on the primary chain. I have managed to put 20,000 miles on this system so far with no damage to the primary chain.
On my Vincent I use a McDougalator. The rotating magnet weighs 488 grams but it has a lot of inertia because it is about 3 1/2" diameter. The McDougalator uses a slip clutch in the drive and as long as this is properly adjusted it prevents damage to the center row of teeth on the primary chain. I have managed to put 20,000 miles on this system so far with no damage to the primary chain.
The triplex primary chain on an 883 Sportster has 94 links. I think this is the same as the Vincent. Will this chain not fit right on the Vincent with no modification? These are very easy to buy. The 1200 uses the same chain but with 96 links. I think the 1200 uses a larger engine sprocket.
I think you have answered your question yourself, the center row does not transmit much of the engine power - or maybe does as the clutch sprocket still got teeth at half size. But indeed the power requirement of the Miller is nothing , like 1/8 of one hp - 60 or 90 W or so. It is only the mass of the armature , 980 gr, that puts high loads on the split rollers when the shocks generated in the ESA when it hits the stops in both directions, arrive at the dynamo sprocket and want to accelerate or decelerate the rotor in a moment. That is why I´d bin the ESA for saving the chain and Alton or Miller from these shocks. On a Comet noone ever had a geared Alton fail from shredded Delrin teeth as it is driven from the timing gears, not by the triplex chain plus ESA ?? But on the twins there were a number of reports about failed plastic gears from ESA induced shocks, not by simple electric power overloads. Altons are installed on lots of classics without troubles when no ineffective ESAs try to wreck them.
The Spares Co is not interested in having a new design of ESA in supply like I made up , studying the well-proven BMW type for Vincent use. They only tidied up the curves so as the edges do not chip off like on original poor ESAs.
And yes, you could think about some limited-slip clutch in the dynamo sprocket for protecting the dynamo plus the chain rollers while you keep the ESA. I did two sets of friction clutches on my 3ph (servo motor) alternators, not because I believe in a real need for them when having my types of progressive ESAs on the crank. But it was sort of exercise to find an idea about slip clutches on the sprocket for Vincenteers to copy or at least some inspiration . So there are two phenolic paper friction plates plus preload from wave washers that can be set for just short of slipping at max. electric loads. My servo motors do at least 200 W and 14 V by having a converter plus rectifier hooked on them. They would do more than 40 V unregulated so I went for the converters and not for typical motorbike regulators. Some of the common mc regulators produce a lot of heat by shorts in one phase to keep voltage in limits, not acceptable.
Vic
BMW design type ESA for Vincents, three lobes :
friction clutch on sprocket:
The Spares Co is not interested in having a new design of ESA in supply like I made up , studying the well-proven BMW type for Vincent use. They only tidied up the curves so as the edges do not chip off like on original poor ESAs.
And yes, you could think about some limited-slip clutch in the dynamo sprocket for protecting the dynamo plus the chain rollers while you keep the ESA. I did two sets of friction clutches on my 3ph (servo motor) alternators, not because I believe in a real need for them when having my types of progressive ESAs on the crank. But it was sort of exercise to find an idea about slip clutches on the sprocket for Vincenteers to copy or at least some inspiration . So there are two phenolic paper friction plates plus preload from wave washers that can be set for just short of slipping at max. electric loads. My servo motors do at least 200 W and 14 V by having a converter plus rectifier hooked on them. They would do more than 40 V unregulated so I went for the converters and not for typical motorbike regulators. Some of the common mc regulators produce a lot of heat by shorts in one phase to keep voltage in limits, not acceptable.
Vic
BMW design type ESA for Vincents, three lobes :
friction clutch on sprocket:
Your slip clutch looks much nicer than the one on the McDougalator. The only trouble with the McDougalator one is that the spring is really too stiff so you have to be very carefull about how much pressure you put on it. You have to adjust the pressure .005" at a time to get it right. Then of coarse with .005" of wear it will slip too much again.
I thought I read somewhere the Sportster chain is a different size to the Vincent one, I now wonder if they meant length, I've only just sealed my Sportster primary up or I would check. Many Sportsters did have cush drives on the engine sprocket as well, my 1979 one hasn't though.
With the 'Walkernators' which use either a 30 amp or 40 amp car alternator I use a multi vee belt, deliberately to allow a very small amount of slippage to take any shock loadings out of the system. There are about eighty of them out there and I have never heard of anyone damaging the central run of the primary chain while using one. Hopefully one would never need to use the full 30amp/600 watts or 40 amp/480 watts (more at 14 volts) so the system can certainly take both the electrical loads and shock loads from the ESA. If you do not want to move over to Vic's shock absorber then a shock absorber in the generator drive seems to be the answer.
I wonder how frequent this failure of the center row rollers actually is. Mine fell victim to it, but on the other hand that chain had been in use for 20 years. Maybe if you use a good quality one (which seems an area of some uncertainty) and replace it every 5 years, the problem will never crop up despite the ESA-induced shocks.