1975 Norton MK3 850 cam sprocket nut and LH worm gear nut torque
- Thread starter p400
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p400
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Per Old Britts
Oil pump worm gear/nut (06-7889), LH thread) 15 ft lb.
Camshaft sprocket nut (06-7774) 60 to 80 ft lb depending on cam metal.
Not making much sense to have worm gear at 15 ftlb
What is the "Mainshaft nut" at 40/50 flbs in my first post?
Oil pump worm gear/nut (06-7889), LH thread) 15 ft lb.
Camshaft sprocket nut (06-7774) 60 to 80 ft lb depending on cam metal.
Not making much sense to have worm gear at 15 ftlb
What is the "Mainshaft nut" at 40/50 flbs in my first post?
040023 GEARBOX MAINSHAFT NUT
marshg246
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In both cases the shafts are "turning into" the nuts. IMHO, 60-80 ft lb is WAY too much if you have a chilled iron cam (you probably do).
For a much more detailed look at torque: https://gregmarsh.com/Mc/ViewPDF.aspx?src=NCT
Updated often, including today as I learn more.
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Friction at the worm nut from the driven gear at the oil pump shaft tries to tighten the nut, which has a left hand thread, so the nut will hardly get loose by itself. Therefore, no large pretension is required.
Besides, the worm nut itself is high and wont allow thread deformation easily (generally speaking, threads deform when torquing a nut or a bolt, or both together).
- Knut
johnm
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Yes way way to much for a chilled iron camshaft. I snapped one at about 40 ft lb years ago.
I remember talking to Mike Hemmings later and he suggested 15 to 20 and some low strength loctite for the PW3 camshaft I did this and had no issues in 10 years racing.