520 chain

Previously wrote:

Does anyone have a reliable source for machining a Commando 3/8" tooth rear sprocket down to 1/4" so that a 520 chain can be fitted?

Helo Chris You can By !/4 Sprockets try RGM

Go on Chris, tell us why you want to do this. Cheers, Gordon.

Hi Chris,

I've just done this conversion on my 1970 Commando but I have an early bolt up rear hub. This means that I could use Dominator brake drum and sprockets. If anybody goes down this route they will have to replace the three sleeve nuts as these are unified on the Commando and cycle on the Dominator. I was given a nearly new O ring chain and hopefully it will keep the back of the bike a little cleaner. I was suprised however, at the stiffness in the new chain.

Any machinist with a lathe big enough to take the brake drum should be able to skim down an original cush drive sprocket as they are only cast iron and should be quite nice to machine.(zero degrees top rake on the lathe tool for cast iron)

Hi Chris, Ihad my gearbox sprocketand (MK3) rear drivesprocket machined down by Norman White and he was very reasonably priced and pleasant to deal with. I fitted a 520 x ring chain and haven't regretted it as I can't remember having to adjust my chain since, and that's probably 2000 miles.

Does a 520 Xring chain fit an 88/99 without any modification?.

Previously wrote:

Does anyone have a reliable source for machining a Commando 3/8" tooth rear sprocket down to 1/4" so that a 520 chain can be fitted?

Chris

Stenor Engineering in Shropshire did mine 3 years ago and a great job they made of it. They even hardened the gearbox sprocket and it seems to be holding up well. I would probably buy a Dommie though next time.

Stenor Engineering United Kingdom 01547 540326

Here are some pic links.......

http://i424.photobucket.com/albums/pp322/keith1069/520Oringconversion003.jpg

http://i424.photobucket.com/albums/pp322/keith1069/520Oringconversion002.jpg

Previously wrote:

"Everything I read indicates that there's never much leeway when these conversions are done."

Plenty of room with the right chain. I use DID 520 'O' ring which is stiff when cold but fine hot. Max width across the spring link is 21.0mm, less than many std. 530 chains. Use their semi press fit spring clip. Mine came from Wemoto in Brighton. It takes a strong pair of mole/vise grips to squeeze in place but is extra secure. It also takes a strong flat bladed screwdriver to lever off the outer plate so on the road repairs should the chain have to be split to come off is more difficult.

Wear is minimal. I do clean every winter and use spray lubricant as I did with the 530 std. However, I rarely adjust the chain now, once a year at 3500 miles. Just looked up my notes and found it was done in Dec 07, so 12,000 miles on it now (had a year off sick in 2011).

There are special tools available to remove and replace the spring link on these modern chains. A work around is to simply drill the holes in the outer plate larger so it will simply push in to place like the ones on earlier chains did.

Colin.

Previously wrote:

Previously wrote:

"Everything I read indicates that there's never much leeway when these conversions are done."

Plenty of room with the right chain. I use DID 520 'O' ring which is stiff when cold but fine hot. Max width across the spring link is 21.0mm, less than many std. 530 chains. Use their semi press fit spring clip. Mine came from Wemoto in Brighton. It takes a strong pair of mole/vise grips to squeeze in place but is extra secure. It also takes a strong flat bladed screwdriver to lever off the outer plate so on the road repairs should the chain have to be split to come off is more difficult.

Wear is minimal. I do clean every winter and use spray lubricant as I did with the 530 std. However, I rarely adjust the chain now, once a year at 3500 miles. Just looked up my notes and found it was done in Dec 07, so 12,000 miles on it now (had a year off sick in 2011).

There are special tools available to remove and replace the spring link on these modern chains. A work around is to simply drill the holes in the outer plate larger so it will simply push in to place like the ones on earlier chains did.

Colin is probably right but I've not seen such a tool (like a small 2 leg extractor?). It is good however to have a little extra security with the press fit outer plate. http://www.wemoto.com/parts/picture/hl-600354/

These are the sort of things I was writing about:

http://customchromecatalog.com/2012/full.asp?page=850

Colin.

Previously wrote:

There are special tools available to remove and replace the spring link on these modern chains. A work around is to simply drill the holes in the outer plate larger so it will simply push in to place like the ones on earlier chains did.

Colin is probably right but I've not seen such a tool (like a small 2 leg extractor?). It is good however to have a little extra security with the press fit outer plate. http://www.wemoto.com/parts/picture/hl-600354/

Standard chain extractors work by pushing the link pins in or out. They won't do so well if you just want to remove a sideplate as the whole plate and pin assembly needs free space to move into. Chain extractors only have room for the pin to slide through. It's probably possible to use the pin of an extractor to pushthe plate onto the pins but it would have to be moved along to get it on evenly. On the 'O' ring front these are not a problem to compress, especially with mole (vice) grips. The plate is a press fit so it stays in place once the grips are removed and the clip can be assembled with nothing trying to push it off. Then, how often would you need to remove a chain on a ride? All Commandos are QD hubs, even the early bolt ups come apart. I know littleabout Dommies etc. but do they not have bolt ups as well so in the event of a flat the wheel can be removed with chain and rear sprocket in place ?

I must say I have an issue with Colin's method of drilling a larger hole in the outer plate. This will allow the two pins to spread when under tension ie. most of the time. The removable link is probably the weakest link in the chain, so compromising its strength by making the outer plate a loose fit means all the tension is taken on fixed/ back plate in a flexing action. It won't last long doing that. I wouldn't entertain that idea. Soz!

When I wrote a larger holes, I meant ones which have about 0.001" clearance for the pins. I don't think .001" is going to excessively put all the tension on the back plate. All chains supplied with our old Nortons when they were new had chains with outer plates which could be fitted without special tools, mole grips, etc.

Colin.

Previously wrote:

I must say I have an issue with Colin's method of drilling a larger hole in the outer plate. This will allow the two pins to spread when under tension ie. most of the time. The removable link is probably the weakest link in the chain, so compromising its strength by making the outer plate a loose fit means all the tension is taken on fixed/ back plate in a flexing action. It won't last long doing that. I wouldn't entertain that idea. Soz!

So the chain might stay more clean, but if you decrease the width of the chain and sprockets by 1/3 then how much more quickly will they wear out from the decrease in load-bearing area? I know racers like 520 chain because it is a weight savings, but a 520 o-ring is not going to be much lighter than a 530.

I would rather buy new chains more often than need new sprockets more often.

' I would rather buy new chains more often than need new sprockets more often'.

As I said, 12000 miles now and no sign of any nasty 'hooking' on either sprocket. I do lube it and yes it does get ridden hard much of the time and my bike has so much torque it shears rear sprocket teeth! That happen a few years ago on an original 70's part when I noticed rough running from the rear and found I'd lost 11 teeth in three sections. The replacement drum has survived my abuse well. 520 chains are used onbikes with similaroutput to Commandos, though possiblyless torque. They seem to last OK.

Actually I don't think it's the torque to blame for teeth disappearing... When I was a peniless student, teeth started departing from the rear sprocket of my 99 and I had an increasingly worrying ride to my holiday job waiting for payday to buy new chain and sprockets. About 11 gone by payday!

Worn out chains are what ruin sprockets. The Jap bike dealers always recommend changing chain and sprockets at the same time, but I think this is just recommended to generate revenue for the dealers. In my many years of riding motor bikes, I have always found that if chains are replaced before they are really bad, then sprockets last a long time.

So if I have got this right... Standard 5/8 x 3/8 chains wear out rapidly (because Norton chainguards don't keep road spray off the chain) and then the sprockets take a hammering from the worn-out chain. Fit a 520 chain and sprockets and the chains tolerate the road spray very much better and so don't wear out anything like as fast and so give the presumably faster-wearing narrower sprockets an easier time. I find on my Atlas that chains last 2,00 to 6,000 miles (depends how much winter salt they have to tolerate) but sprockets last well over 50,000 miles. My wife's Yamaha is on original chains and sprockets as 24,000 miles. In purely financial terms, I would say that going for the 520 chain makes a lot of sense - and that's the way I will probably go in 50,000 miles time. Gordon.