Calculator
Torque converter
Convert Nm into kgm and lb-ft and work out the setting on the torque wrench when a spark plug spanner or hook spanner sits in line as an extension.
Result
With an extension: setting = target x L / (L + E). This applies when the extension points in the direction of the wrench. If it sits across it (90 degrees), nothing changes.
Click trainer
A torque wrench clicks once. Anyone who keeps pulling after that has gone past the value. Practise the timing: press start, the bar runs, press again at the target value.
What the calculator does
First, it converts units: newton metres, kilopond metres (old German manuals), lb-ft and lb-in (British and American manuals). Second, it works out the value you have to set on the torque wrench when an adaptor such as a spark plug spanner or a hook spanner lengthens the lever. The guide figures by property class are in the tightening torque table, the basics under understanding tightening torque.
Questions
Why does an extension change the torque?
The torque wrench measures the force times its own lever. If an adaptor sits in front of it, a longer lever acts on the part; the actual torque is greater than the value you set.
What is a kgm?
Kilopond metre, the old unit before the newton metre. 1 kgm is 9.80665 Nm. In manuals from the 1960s and 1970s the values are often given in mkg or kpm, which is the same thing.