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Slimline enclosed rear chaincase



Might seem a stupid question but I am trying to avoid potential

has anyone fitted the wider 3/8th chain with the fully enclosed rear chaincase on slimline frame ?  Currently have 3/8th chain fitted with a pattern top chain guard and would like to fit fully enclosed guard which normally would run with 1/4 chain.


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



Thanks to all. Need to do some experimenting then, especially as the chaincase needs some TLC on dents.



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