SOHC.co.uk Forums > CB350/400

Head + Rocker cover torques...

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K2-K6:
As ka-ja and Bryanj point out,  long term experience can encompass many of the subtle elements that are not immediately apparent to someone new to these subjects.
In addition to that,  it's the reason why flat spanners and Allen keys etc have diminishing lengths as they go down in bolt size, to in effect limit the torque applied by the user and give some semblance of feel consistent with each size when tightening.

This is effectively subverted when using a socket set with one length handle for all bolt sizes,  especially if you are using 1/2 inch drive with 10mm socket.

Even when using an appropriate rate torque wrench it seems like you aren't really tightening them enough.

I've no problem in judging without a torque wrench for non critical bolts,  but have been involved with writing manuals in which a task has to be accomplished by users with very different skill levels. It's quite a challenge to convey the correct route to such a wide range of familiarity, and end up with the same final result.

There's an old description for this " those that can do and know they can are fine, those that know they can't do and seek assistance are fine, those that can't see that they can't do are where problems exist"  :)

This thread seems to be more "behind the scenes" discussion of how the spec is affecting the final method on these engines.

To answer your last torque question Simon,  it's useful to compare the cam cover bolts to the cylinder head studs to show the difference.  The head stud has flanged nut operating on washers to reduce the torque measured from straight surface friction.  This allows it, during tightening, to pull the stud into tension within its elasticity. The resistance in torque reading will mostly come from the thread pitch lengthening on the stud coming into conflict with the nut threads which are being compressed. 
The cam cover bolts are never going to be at that level (even those size steel bolts will easily take something in excess of 10 tons of tensile load,  they'd pull the alloy threads out of the casting long before that)  so they delete the washer with the resulting torque you measure being just from friction between the underside of the bolt flange and the alloy casting. The threads really aren't being measured in this application. 

It occurred to me that the numbers quoted in the manual are not really assembly accurate figures.  They appear to be a range that "includes" torque wrench typical error figures. I.e. aim point plus or minus 10%.
That's not the same as giving the mid range figure and accepting the error of torque would do the job.  It allows,  promotes? A situation in which you can start at the extremes of error and then add some more with a torque wrench.  :o

ka-ja:
Always consider with small diameters, the lower the torque settings, the more inaccurate they become, unless you have a wrench with a very low range.

K2-K6:
Something like this

 https://www.wiggle.co.uk/x-tools-essential-torque-wrench-set/

1/4 drive and from 2nm about 1.5lb-ft

ka-ja:
Looks the part in a handy case, My smallest is 3/8 drive britool about 40 yrs old.

Nurse Julie:

--- Quote from: ka-ja on April 08, 2019, 11:49:35 AM ---Looks the part in a handy case, My smallest is 3/8 drive britool about 40 yrs old.

--- End quote ---
Trig uses the old Britool torque wrenches including the little 3/8 drive.

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