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Modifying Inner Chain Cases

Posted: Thu May 17, 2018 7:19 am
by derekmalcolm
I am building up a 57 NH basket case and with the fully enclosed rear chain, the gear box is corect with the 5mm longer shaft, but I am told that the inner chain case is for the earlier model that does not make allowance for the fully enclosed rear chain case. I suspect that the difference is associated with the height of the ridge on the rear surface that follows the chain run around the sprocket. Can anybody advise me if that that is the only change and if so is it posible to modify this to allow the fully enclosed rear chain case fit or do I need to find a later inner chain case.

Re: Modifying Inner Chain Cases

Posted: Thu May 17, 2018 10:17 am
by david.anderson
It is my understanding that the main difference is in the depth of the casting where the inner chaincase screws to the crankcase. I have seen a 57 VH with a 55VH inner chaincase packed off with a circular 5mm aluminium disc. The disc is a dougnut with 4 holes for the chaincase to crankcase screws and a large hole in the centre.
I would think that the bottom lug fixing of the chaincase to the extended gearbox pivot bolt would also need a 5mm packing washer.
So there is no actual modification to the chaincase but just the packing pieces to be made.

Re: Modifying Inner Chain Cases

Posted: Fri May 18, 2018 5:18 am
by derekmalcolm
Thanks David I will offer it up and see how it looks.

Re: Modifying Inner Chain Cases

Posted: Fri May 18, 2018 9:04 am
by Vincent.vanGinneke
Hello dnmalc, (please use a recognisable name, thanks.)

Maybe these pics show what you are looking for.

Dont mind the chromed rear chainguard in the picture,
It was a try out to make a combination between the front part from a FERC with a earlier rear chainguard.

passen FERC (2).jpg

passen FERC (5).jpg

passen FERC (3).jpg

Re: Modifying Inner Chain Cases

Posted: Fri May 18, 2018 9:14 pm
by paul.jameson
Whilst David is undoubtedly correct in the guidance he has given, I doubt that it is possible to fit the front section of the fully enclosed rear chaincase to an earlier (1954-55) chaincase inner. The shapes are very different but it was possible to buy a bike without the FERC, which is why David's advice will work without one. Inner chaincases from the VH, VB and NH are identical for 1956 - the end.

Re: Modifying Inner Chain Cases

Posted: Sat May 19, 2018 5:35 am
by johnmack
As far as I am aware the swing arm brackets attached to the leg on the drive side are different to the models with the ferc chain case and the earlier top and bottom chainguards.
John Mackintosh New Zealand.