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Dommie 99 cylinder base studs

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I got a new cylinder base nut set from RGM and found that two of the nuts are 5/16, all my studs and holes in cylinder flange are 3/8, was this changed at some point?

 Thanks 

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7x 3/8"; 2 x 5/16"

Have a look at the illustration:

https://andover-norton.co.uk/en/shop-drawing/891/dommi-engine-500-600cc#

 

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1949 thru 1975 front 2 barrel holes are 3/8...., front 2 case studs are 3/8... necked down to 5/16

however during that period the nut thread pitches did change

Hello David, yes i have seen those stepped studs but because the barrel has 3/8 clearance holes all round i fitted parallel studs, unsure now whether to change them out for two stepped ones, I wonder why Norton did that?

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... to allow clearance for the spanner although a reduced hexagon might be a better solution for that.

Hello Ian don’t think it could be that, these are the two most accessible on the engine

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Barrels are iron,  cases are aluminum. putting smaller shorter diameter studs in aluminum is not smart, they can pull out easier. Putting 5/16 holes in the iron barrels is not smart, makes barrel manufacturer change drill setup.

Only one iitem is now special,  the stepped studs,   they were not stupid !

 

Hello David have ordered the stepped studs, curiously the front centre stud is short too but specified at all 3/8”!!

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Peter

Hope you ordered the early type 26 tpi through 71?  VS later UNF 24 tpi 72-75 ? IIRC

of course a 99 part should be early

 


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