Slimline enclosed rear chaincase

Sorry can't answer this one but many years ago I made my own fully enclosed rear chain case.

I used 2 rotary IP2 rubber gaiters [I also had an IP2 then], cobbled together some Honda parts for the rear chain wheel and fashioned aluminium 1mm sheet to enclose the front chain sprocket. It looked ok and worked very well until one day, after maintenance, I forgot to the tighten the jubilee clips  securing both ends of each gaiter and of course the chain chewed up both. I then reattached all the bits with several puncture repair patches to return the gaiters to somewhere near their original shape and carried on. It didn't look too bad but it continued to work well. I wonder if it is still on my 1968 Mercury which is currently on SORN.

I would check if the enclosed case was listed as an option on a year model with the 3/8 system Then I would check if the case part number is the same for the earlier narrower system , usually if you try to fit a wider than std chain it fouls the gearbox casing or the back of the primary case ,   I would be interested to find out what other changes were made to accomodate the wider system ,if any?. The case is capable of catching and flipping off the spring clip if chain loose. Extra splashguards at the front  can make the case more effective and worth fitting. Combined with an automatic drip oiler chains and sprockets  seemingly last for ever.. My sprockets are orriginal 1960 and still fine. The case halves are secured by 4 whitworth thread phillips pan head set screws which must not protude to catch the tyre wall. Tyre choice may be limited to 3.50x19 old style. Stainless screws with fan washers better, Metric may fit, I will check.

Hi John

I can confirm Roberts comments.

The 4:10 x 19 rear tyre made it impractical on my 650ss with 3/8 rear chain.

If concerned about adequate clearance get some card and push it between tyre / chainguard

Or back primary case and chain to prove it. Better to destroy a piece of card than have a disaster out on the road.

Stay safe

Tim

I used to have...

The A10 front sprocket is well shielded, and the chain-guard (not case) extended downwards to shield the lower chain run from the wheel area. It was effective in keeping the chain clean.  I ran a pipe from the oil tank breather onto the chain run, and the chain needed little maintenance.

The full chain-case on Nortons was notoriously ineffective.  I hear that this is because the front sprocket is not shielded, and the case scooped crud inside causing accelerated wear.  It would be better to shield your front sprocket as a first measure, and consider adding a flat plate on the inner face of the chain-guard to keep crud off the chain lower run.  Add a chain oiler of some kind - note to self...... 

"It would be better to shield your front sprocket as a first measure, and consider adding a flat plate on the inner face of the chain-guard to keep crud off the chain lower run. Add a chain oiler of some kind"

See attached.

As Paul suggests, the 'blade' shielding the lower run is very effective. I added the both the shield to the front sprocket and the blade over 20 years ago and have no regrets. The chain oiler was this winters addition, not really run it yet to see how good it is or isn't. 

For what it's worth,  I have an 18" rear rim and have no issue with a 110/90x18 tyre on the bike. Runs close, but not touching anything.

Hope this helps,

George