1953 NH Clutch

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JohnAustin
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1953 NH Clutch

Postby JohnAustin » Sun Mar 31, 2019 6:52 pm

This sounds a pretty daft question, but as I acquired my project in bits I'm puzzled by the clutch pressure plate thrust button relative to the clutch pushrod. The pushrod is 5/16" diameter and fits fine with the GB5 gearbox etc, but the recessed hole in the thrust button in the pressure plate is 1/4" diameter (clearance). Should the pressure plate end of the pushrod run in the thrust button hole, or on what would be a 1/32" shoulder? If it should run inside, could I simply machine out the 1/4" hole to 5/16" or is the thrust button hardened? Any help would be much appreciated.

Knud.Degnbol
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Re: 1953 NH Clutch

Postby Knud.Degnbol » Sun Mar 31, 2019 8:04 pm

As far as I remember, the push rod shall be 1/4 " diameter. You can make it from silver steel with hardened ends.

Simon.Gardiner
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Re: 1953 NH Clutch

Postby Simon.Gardiner » Mon Apr 01, 2019 5:35 pm

John
Up to '52 (ie for BA or CP box) the clutch rod was 1/4" dia.
In '52 - for the GB box - the clutch rod increased to 5/16".
The pressure plate changed at the same time. Sounds like you've got a pressure plate for the earlier set-up with the smaller rod, the rod should fit inside the button.

HTH

SG
'55 Huntmaster, '56 VH, ' 51 VH, '80 R100RT, '00 Sprint ST (but all those Ariel parts can only make one running bike...)

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paul.jameson
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Re: 1953 NH Clutch

Postby paul.jameson » Mon Apr 01, 2019 8:57 pm

The early 1/4 rod operates with a ball inside the button in the centre of the pressure plate. On the later 5/16 rods there is no ball inside the button which helps the plate to lift squarely. A 5/16 pressure plate ought to be easy enough to find if you want one.
Paul Jameson
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JohnAustin
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Re: 1953 NH Clutch

Postby JohnAustin » Mon Apr 01, 2019 9:06 pm

Thanks Guys, I've ordered a 5/16" thrust button from Drags which I hope will replace the old one in the pressure plate.
Cheers, John


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