TORQUE TALK & TRASH - VW's (Bentley) Manul is inaccurate and meaningless to boot!

TORQUE TALK

In my career I have designed literally thousands of bolted joints.
All fastenings are specified as to size and grade to carry a design load with relation to the parent material.
All load bearing bolted joints must be correctly torqued, and part turned if pre-tensioned, for the grade of fastening and design load.
ALL SPECIFIED TORQUE FIGURES MUST HAVE THE CONDITION OF THE THREAD STATED
I.E.:
Dry
Lightly Oiled
Low Friction Coated - Normally MoS2.

At Butterleys we had a 'bible' with all torques specified for every grade of fastening material and thread condition.
It was mandatory to refer to this data for all drawings and manuals. Woe betide those who did not use it.
Dry joints for nuclear applications, and pre-tensioned joints, were designed individually by senior engineers.

Dry - Higher than Lightly oiled for the same effective load.
Usually only on structural joints. But. Some joints for nuclear applications were often dry because of contamination possibilities.

Lightly Oiled - Higher than Coated.
Now! Lightly oiled actually means: 'As the bolt is supplied form the manufacturer'.
In the old days boxes of bolts, nuts and washers were given a coating of thin oil to stop 'in storage' corrosion.
(I wonder if the blue/green coating on many newer VAG fastenings is an anti-corrosion coating to avoid oily hands on robots? I tried to find out what it is, and it's lubricity values, but all to no avail!)
Thread locking fluid comes under this heading. Loctite, and similar products, have the same lubricity as light oil.

Low Friction Coating - The lowest figures.


Now check out this rubbish!

Different figures for the same bolts on different pages!
No mention of thread condition! I always assume 'lightly oiled' and use Loctite blue on all threads anyway.
An instruction to 'always fit new bolts' on a not pre-tensioned joint! Unnecessary, but more money for VAG!

Finally:
The two bolts #4 in the first diagram are beautifully, and perfectly designed stretch bolts.
What a waste of time and effort.
I bet new ones cost loads o' money!?