Hi,

I'm looking for a new rear chain, and am not sure about the sizes.
Manual says 5/8 by .380 91 links. 5/8 is the size between the pins?

I want to order at the Groot British Motorcycles parts, Netherlands.
He seems to have two sizes;

5/8 x 1/4 and 5/8 x 3/8

Could somebody explain the measurements?

Thanks, Menno

The first dimension is the distance between the centers of the rollers, 5/8 being approximately 16mm.

The second size is the width of the sprocket, or the distance between the plates of the chain. 0.380" is the same as 3/8, and is approximately 9.5mm.

Jan

email (option): wd.register@gmail.com

you need 91 links of 5/8 x 3/8.

Be very careful when buying replacement chains. Modern ones are far too wide with thicker side plates, which on a Matchless will rub on the back of the chaincse and eventualy wear through.

I have always stuck to Renolds chain where possible, or Jwis.

I expect there will be other opinions, they are wrong

My impression is that modern Renold is not what it was. The German Jwis (or Iwis ?) is made to correct imperial dimensions and is very good. Regina also make old-fashioned sizes. To my knowledge, no Far-Eastern manufacturers do.

If you're in the UK, Andy the chain man is useful to talk with and pops up on lots of forums.

http://www.the-chain-man.co.uk/index.html

Sprockets Unlimited are good too, have been around for Donkey's years and supply Iwis but they're usually ever so busy at shows.

http://www.sprocketsunlimited.com/

On older English bikes with countershaft gearboxes and steel chaincases, it is necessary to make sure that side plates and rivets are as narrow as possible. Chain strength if of good quality will still be more than adequate.

Thanks. The link broke. I have never seen that before...(Renolds)



But the chain is worn also, so I will buy a complete new one.
I'm in the Netherlands, and I need it quick because I'm preparing for Arhnem,
so no time to go (online) shopping in the UK

ps, when I count the pins on the chain there are 88 pins without the connection link

Hi Menno
Picking up on Ken's point about clearances, from your photo of the broken link it looks like the rivets have been rubbing on something so it may be a good idea to check clearances when you fit the new chain. You don't want to have to buy a new chaincase as well.
I know only to well having had to double check the clearance on my own G3l.
Regards
John
P.S. John and Jane at Sprockets Unlimited are, in my opinion, excellent for chains via the post and at shows

yes, something wrong there.

I'd check the back of the chaincase above the sprocket. It may be the chaincase is incorrectly fitted. Easiy done.

I've never seen a link break like that before.

I hear a lot about the latterday quality of renold chains, but speak as you find, all my bikes run on it and I have no problems.

The only thing I can surmise is that there are two standards for renold chain, one for bikes and one for industrial use.
I get mine fron a bearing and chain supplier,who will not sell it me if I say its for a bike, but if I say its for a home made agricultural machine, no problem.

It's something to do with the horsepower that can be applied; our kind of bikes wnich are rated in pony power rather than horse power are fine with the lower standard.

Industrail cahin sold by shysters as motrocycle chain seems to have kicked off the worry from Renolds.

Of course now Renold chain is made in France no doubt the EUssr [RIP] had some input.

It looks like a fatigue fracture on the spring link back plate. I don't think that it could have occurred if the cover plate was still a tight fit on the pins. Apart from loss of the spring clip, this is really the weak point of a spring link when compared with a rivetted link where the cover link is an interference fit before it is rivetted.

I'd suspect a combination of a worn re-used spring link with either sprocket misalignment or severe sprocket wear.

Personally, I keep two chains for each bike and connect them up to pull through the lubricated replacement. I can't claim to replace the spring link every time but I always check for wear on pins and plate. There is a reason that the WD toolkits included replacement parts kits for both primary and final drive chains.

I have a 1928 Sunbeam with the Sunbeam full chaincase, still happily running on its original Perry chain.

Must be a moral somewhere.

Hello Menno
Try geertshuis in rips matchless shop hè has soms in stock .
Hope to she you in Arnhem

email (option): Mgd.jansen@online.nl

Thanks for all the advice. I will check the clearance of the chaincase, good tip the end of the pins shouldn't be so shiny and smooth. I never heard it making any noise though.

The cover plate and spring were holding the chain together....
Luckily it didn't break during riding, can't imagine what the damage would be.

I bought a new Renolds chain today.

Cheers, Menno

Hope to see you there Marcel, I will send you a pm