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
case studs VS barrels
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
Ok
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?
It's possibley...
... to allow clearance for the spanner although a reduced hexagon might be a better solution for that.
Access
Hello Ian don’t think it could be that, these are the two most accessible on the engine
Engineering?
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 !
Ok makes sense
Hello David have ordered the stepped studs, curiously the front centre stud is short too but specified at all 3/8”!!
Which stepped studs?
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
Thread
Yes BSCY all now fitted thanks
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#