Primary chains
- Thread starter AndyW
- Start date
Dellortoman
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- Tasmania, Australia
It's 3/8 pitch (9.525mm). Chain length is 76 pitches.
Here's a picture of the pitches. You can count 'em.
Here's a picture of the pitches. You can count 'em.
CLEMTOG
Hero member
"my clutch has 8 rubber blocks" interesting observation and correct for all triples and Breganze twins, interesting because I supect that Cam did the drawing and he is known well for his accuracy, so there must be a reason? Cam?
if you still have three rows of teeth, buy a new (triplex) chain for a Norton Commando and shorten it or get someone to shorten it.
one third the Laverda price, (in some cases) available in Regina or Reynolds, and with one of them a spring link as well (not recomeneded by me), but Commando boys do use them, and have you ever felt the torque of those 850 twins?
CLEM
if you still have three rows of teeth, buy a new (triplex) chain for a Norton Commando and shorten it or get someone to shorten it.
one third the Laverda price, (in some cases) available in Regina or Reynolds, and with one of them a spring link as well (not recomeneded by me), but Commando boys do use them, and have you ever felt the torque of those 850 twins?
CLEM
Jo
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- Cologne, NRW Germany
Steve's (BREGANZANE) website contains lot's of useful information:
Laverda primary chains
Laverda primary chains
CLEMTOG
Hero member
very interesting information by my very good pal Steve B, but I always doubted the "no longer available in suitable quality" thing for the triplex chains, moto Laverda deemed is neccesarry to fit a quadruplex chain on some of its endurance racers (a good testing ground for road bikes, condensing two or three years of road use into 24 hours) so I stick with triplex, I do not know if the Norton Commando (or TriumphtTrident) chains are recent manufacture or NOS, but mine works fine. I feel that they are newly made, but thats all it is a feeling.
Jo
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- Location
- Cologne, NRW Germany
Times changed Clem. At that time, the factory had experience with the 750 SFCs, and the quality of the available chains was different.
The quadruplex chain is very heavy. As an engineer, I once looked at the forces acting on such a chain. One part of the forces is the power to be transmitted, the other part is the centrifugal force, which is influenced by the weight of the chain, and which increases with increasing speed. Depending on the calculation model, the force resulting from the centrifugal force exceeds that of the power to be transmitted from a certain speed. Both forces add up, of course, but the higher the speed, the greater the risk of damage caused by the centrifugal forces at high speeds.
An interesting example was given by Red a few days ago. In a communication with Piero, it came out that the factory was not revving higher than 8,500 at that time (klick me). Red's racers rev 9,500 and have more than 130 horsepower on the rear wheel. Of course, Red's racers aren't long-distance racers, but I'm sure the factory would go for the Mercedes duplex chain today!
1200ts
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- USA - Riverside CA
Andy Chain told me to avoid modern Renold chains at all cost as he said it is a industrial chain made as cheap as possible. The only good Renold chains will say "MADE IN ENGLAND" on the box. If the box says "RENOLD CHAIN MANCHESTER" you are getting junk most likely made in eastern Europe or China.
I had asked him about this as I noticed a new Renold chain lasted nowhere as long as they used to.
I had asked him about this as I noticed a new Renold chain lasted nowhere as long as they used to.
Dellortoman
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- Location
- Tasmania, Australia
The reason is simple. I thought there were 6 rubbers. I had a bunch of dimensions for everything including the PCD and diameter of the rubbers, but I didn't make a note of how many rubbers there were because I thought it was obvious. Even though the primary cover was closed up by the time I did the drawing, I suppose I could have looked at a photo, but was blissfully unaware that I'd fucked up until now.
The reason for the drawing was to use it as a reference for designing a Morse type silent chain primary drive. I just wanted to see if a Morse chain would fit. The number of cush rubbers was of little importance to that exercise so I didn't give it a second thought. The Morse chain idea got shelved when Andy Fosdick (The Chain Man) came up with the Mercedes duplex chain.
GregT
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- Christchurch NZ
Keep it shelved. Morse is heavier per unit length than roller so RPM induced centrifugal loadings are much,much higher. Basically at speed they want to form a circle so batter everything they can reach. Also obtaining the correct grade is now a lottery. What was once available with generous sized pins is now downsized. A mate here races what is probably the world's quickest Honda CBX550. He's cut about five sets of cases apart when a supposedly OE Honda primary has let go. i have experience of Morse primaries in race Honda fours - big and small - and EX500 kawasaki's. We ran the latter to 13,000RPM - and changed the chain and rubbing blocks a couple of times a season.
Dellortoman
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- Location
- Tasmania, Australia
For anyone who was offended by the incorrect number of cush-drive rubber holes in my earlier drawing of the primary sprockets, I've fixed it.
I've also added a drawing of the toothed Morse type chain for anyone who's interested in the comparison.
Both chains have the same pitch, so the same number of teeth on the sprockets. But what's more interesting (although logical when you come to think of it) is that both chains have the same tooth PCD, so the chain length and shaft centre distance is exactly the same for both chains too.
The thing I find really weird is that the sprockets for the toothed chain look like they have more teeth than those for the roller chain, but they're the same (25/51). It's just an opticackle illusion. Count them doubt me.
I've also added a drawing of the toothed Morse type chain for anyone who's interested in the comparison.
Both chains have the same pitch, so the same number of teeth on the sprockets. But what's more interesting (although logical when you come to think of it) is that both chains have the same tooth PCD, so the chain length and shaft centre distance is exactly the same for both chains too.
The thing I find really weird is that the sprockets for the toothed chain look like they have more teeth than those for the roller chain, but they're the same (25/51). It's just an opticackle illusion. Count them doubt me.
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Legs
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- Location
- Adelaide Hills
Nice work.
chrisk
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- Brisbane, Australia
Shame AndyChain is off the forum these days. He was a wealth of chain knowledge.
I’ve just removed the casing from my Mirage and found the primary chain(s) are duplex. However there are 3 sprockets suggesting it should be triplex. Can anyone confirm this please? Thanks
The Sock
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- Location
- London, England
It was originally fitted with a triplex chain, but chain technology has moved on in the last forty years. An Iwis duplex, on the inboard sprockets, is more than adequate. If the provenance othe existing chain is unknown, I would advise changing it. Make sure the crankshaft sprocket nut is fully tightened.
Thanks
Dellortoman
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- Location
- Tasmania, Australia
Sorry. I can't help myself. Pedantic mode has taken control of my brain. There are definitely only two sprockets. Some (but not all) of them have 3 rows of teeth.
Jo
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- Location
- Cologne, NRW Germany
@Mirage80: I would stick with the Mercedes duplex primary chain - it's the best option you can get IMHO currently. Further I wouldn't change back to a triplex (or two simplex) if a duplex was in service for any length of thime - above link should explain it all sufficiently.