Keith1069 said:
If you have the later taper rollers (Mk3 850) 30ft/lbs will tighten up the steering too much.
Commandos were not fitted with taper roller head bearings as standard, not even the 850 MkIII.
The standard head bearings used on Commandos (except early models) are the Norton part number 06-7604, which is a 6205 2RS 25x52x15mm type. This bearing is a = single row deep groove BALL bearing.
Doesn't seem much but I never had my tapers come undone and I never bend over the tab washer, just a drop of threadlock.
As the 6205 bearings (which maybe you do not have?) are ball bearings there is no range of adjustment, the nut is just tightened down, this clamps the top yoke/dust cover/upper bearing centre spool/spacer tube/lower bearing spool/lower yoke/lockwasher together.
Spec on post 71 is 15lbs only and the book says 40lbs for pre 71.
You appear to be quoting from the Haynes manual, however the factory manuals give the figure for '71-on as 30ft/lb. Pre-'71 models have cup and loose ball bearings with an adjuster nut and lock nut (at the upper end).
The Haynes manual says: "The bolts should be tightened to a torque setting of 40 ft lb and the steering head nut to 15 ft lb (1971 and later models ONLY)."
If that is the '40 ft lb' you are referring to, then isn't it referring to the fork cap bolts?
As the paragraph deals with reassembly as well as adjustment (although the factory manual says 30 ft/lb for those bolts -the Haynes book possibly getting that torque setting wrong by quoting the Dominator figure of '40' ft/lb?
Not sure why the difference for early to late ball types but the taper type did not come in until the Mk3 I think.
Perhaps if you do have a copy of the Haynes manual may I draw your attention to "Steering head bearings -examination and adjustment" where it says: "Pre-1971 models have ball journal bearings which can be adjusted, whereas later models have bearings of the non-adjustable type."
I have an 850 MkIII and it does not have taper head bearings, but the normal 6205 type (that are still supplied as the correct replacement parts).
Some info on Norton head bearings and conversion to taper rollers here (although I do not personally see why anyone would want to bother -not for '71-on models at least):
http://www.nortonownersclub.org/technic ... etail.html