Final drive Sprockets

[Robert Watson]

These have been a pet peeve of mine since I got my first Vincent twin on the road almost 40 years ago, OH Damn, Really???, anyway I found that I could never get more than a few 1000 miles from a rear sprocket, and some of the engine sprockets didn't fare too well either. After trying several suppliers I started down my own path.

First was to source ring sprockets for the engine sprocket. I took a decent used hub, machined off the worn teeth and shrunk and tack welded the ring sprockets to the old hub. The rings were made in SAE 8620 and case hardened. They take a bit of work and do cost a bit more than what is available new, but have worked well.. I have probably made 60 or 70 or so of these.

Next was the rear wheel sprocket, these I seemed to wear out at an alarming rate, some only last a few thousand miles, and when I was using the bike more than in the last few years was just a pain in the backside. Some years ago I had a local sprocket maker make me about a dozen sprockets, again in 8620 and case hardened. They did warp a bit from the heat treating but a few minutes on the press and they came out quite true. Those back in the day cost close to 2X what was available but well worth it to me as they lasted very well indeed. When I tried to order some more the price had almost quadrupled!

After trying several other options I finally gave a big sigh and gave up..... then talking to a local guru, we talked about using SAE 4340 (or equivalent) and nitriding them in a salt bath. So I took a big breath and made a batch.

This past year I finished a new project bike and it has these rears sprocket on. I rode it to the International rally in California and back. I had cause to remove the rear wheel (to redo a very poor black centre/red stripe paint job) and had a good look at the state of the sprocket. Below is a picture of the teeth, with 4500 miles on them, note this is a 520 chain, so a somewhat higher load on the teeth than a wider 530 chain.

I am pretty pleased with the result, as you can see the sprocket diameter is spot on with the rollers just touching the base of the tooth profile and showing good contact on the teeth overall.

This is just a long winded explanation of one of the small issues when re doing a bike that is going to be used as intended,..,

Cheers

and Happy new Year

 

[Peter Holmes]

I recall this is a subject that has been discussed on here before, but I don't mind that at all, I always find Roberts contributions most interesting.
I would not claim to be a high mileage rider these days, and I have always stuck with a 530 chain, simply for the reason they are on there, and I am lazy. However I am quite quite surprised how rapidly Roberts sprockets were wearing out. Years ago, on a whim, I purchased a standard rear sprocket from Conway Motors when under the ownership of Colin Jenner (I think) that sprocket was made from some sort of aluminium, maybe Duralumin (I am no metallurgist) The sprocket was manufactured by Talon, a well known supplier of sprockets, hubs and other parts, mainly for Motocross bikes.

But that sprocket has given such good service, literally thousands of miles, I am not sure how many thousands, but must be in excess of 20k, I do replace chains when they show signs of wear, and always keep them clean and well lubricated, latterly with the electronic programmable Scottoiler X System, absolutely brilliant piece of kit by the way. Sadly Talon have no records that they ever supplied sprockets for Vincent motorcycles, but they definitely did, and their trademark name is etched or stamped onto it, they will still manufacture them, but I will need to post to them my old one as a pattern, one more sprocket will definitely see me out anyway, depressing thought isn't it!

 

[vibrac]

I have used a lot of alloy sprockets on the rear over the years some on 5/8-1/4" at the ,moment the Goodwood racer uses Honda dirt bike sprockets so we can go under the Vincent limit
I am undecided whether to go for correct sized aluminium sprockets on my next road bike replacing is easy and I guess if the material works on off road bikes its pretty tough. I wonder if steel sprockets up to a certain hardness are not the best material and perhaps the elasticity or give of aluminium stops aggressive wear

 

[Vincent Brake]

This was after 75.000 km.
Original 22 teeth. Now down to 20. (You got to know when to stop)....
Same material as Robert. And nitrided. From Maughans.

 

[Peter Holmes]

Looks like a dynamo sprocket!

 

[bmetcalf]

You Yorkshiremen, take note!

 

[Robert Watson]

A few of us in Vancouver have run alloy sprockets (anodized) from a couple of US manufacturers, and we all came to the same conclusion. 9800 miles they look great, 10,000 miles and your rear wheel is really sparkly with all the aluminum shards adorning it. That is as good or better than all the non hardened sprockets. Holder's wouldn't tell the Spares Co what they were making them out of back in the day
I would hope for 20K from these steel ones.

Also the o ring chains, with no oiling system and just a quick lube on the road, especially if running in the rain a lot seem to be good for around 15-20k and then suddenly start to go slack, usually for a few inches in the chain where the seals have failed and pins and bushing wear very quickly, time for a new chain..

 

[CarlHungness]

This is one of those threads that make me say, "Things haven't changed". Robert Watson is one of the journeymen Vincent men in the club who has put his hands on enough parts to be able to identify most all of the bike in total darkness. I recall the day he (and a few others) assisted me in a transmission rebuild in a Minnesota parking lot on my Twin and the repair was so successful I rode the bike home. That being said, not once have I seen a Robert Watson sprocket advertised for sale (or I would have bought one, and would still buy one). Thus my complaint is the same as when I joined the club. One has to be in the 'in crowd' to know when and where some of this stuff is available. Robert did a magnificent job as editor of the MPH and I make the same suggestion to the current editor I made to him: Once a year give us a listing of some of those parts, as many as you can find that are being made that are termed 'speciality'. I've located numerous items over the years that are not highly publicized (Norman Walker's stuff for example) that the new members know nothing about. Just how is it even the veteran members are to learn of these parts that have been lovingly engineered and produced by super enthusiasts like Robert Watson. His pal Dan Smith has made some O ring suggestions that help us with stopping oil leaks, but wary be the new owner, he'll never learn about them. The MPH is the key to education and we sure need a volunteer who can compile some of these products and list, and re-list them annually to educate the plebeians. I'd buy a sprocket, don't know how much they are or if they are available, so between the editor and you small time manufacturers out there please take note.

 

[Vincent Brake]

7.5 t km and "in dutch fashion " i will turn them arround.
And so we get 15 T km on a 7075 alu or ali chain wheel.

And indeed when they go, they go quickly

 

[timetraveller]

Let me explain why I do not advertise. Carl has been very polite about some of the previous parts I have provided but this is a hobby not a business. If I advertised then people would expect me to have items in stock, to be able to provide them at short notice and be there to answer the phone or email within a day or so. My life is not like that. I design things and get professional machinists to make them. Two years ago I wanted thirty of the JE steering stems and it took over ten months for the firm which does the machining to find time from their contract work to do my jobs. I am not happy about that but realistically the work I give them will not keep a factory with twenty men in business and they have to do their contract work as a priority. There is also the problem of how much stuff to keep in stock. Several months ago I decided to get some Girdraulic lower links made. The Spares Company had been out of stock and had no idea when more would become available. These have now been made and an article in January MPH will describe what has been done. Twenty nine have gone to the Spares Company and an extra five, to suite the Greg Brillus mod are for me. Despite the fact that these are still not officially available and have not been advertised I now have orders for six of the specials when only five have been made. Clearly, I need to have more made and the good new is that the machining program is now fully developed so that will be a relatively rapid process, these are CNCd from solid. But I will have to wait until the word has got around before I know how many to order. All the standard ones will be available through the Spares Company and only the specials for the Greg Brillus mod will be available from me. The reason for this is that this project could not have gone ahead had not the Spares Company been prepared to order thirty and they can provide a normal retail experience to customers whereas I cannot. To put this into financial terms that was a £14,000 project while I recently had a delivery of thirteen JE stems which is a £5,000+ project. This might not be the retail experience which people want but I am not good with admin, am not VAT registered and could not cope with the paperwork if I was. The Spares Company do keep stock of some of my creations so that is the place to go for those who might be in a rush and are prepared to pay the extra cost which has to be incurred when a profit and VAT are charged. Let us see how the new lower links are received.

(Article will be in February MPH, we ran out of room in January - Ed)