RE: Spark plug socket

["Davis Eichelberger" <davis@xxxxxxxxxxxxxxxxx>]

> If you use a good quality torque wrench correctly I think you will find
> that accuracy is much closer to +/- 4%.
> But that requires you know how to use the correct (as in have more than
> one) torque wrench.
> Gator in Dallas
> 
> > gator@xxxxxxxxxxxxxxx writes:

Two different issues!  Yes, a quality calibrated torque wrench used in the
proper range will measure the torque applied to within a few percent, but
the preload applied to the mating surfaces can still vary by 30%.  Why do
you think the torque for the head bolts is specified as x Nm + y deg?
Because turn of the nut applies a more consistent preload to the mating
surfaces than simply measuring the torque applied to the bolts.

Davis Eichelberger






> >  > Just my .02 but I think that is the most rediculass thing I can think
> > of.
> >
> > Hmmm, you might be surprised.   There's a table on page 1404 of
> > Machinery's
> > Handbook 25 that notes the accuracy of bolt preload methods.  They list:
> >
> > By feel +/- 35%
> > Torque Wrench +/- 25%
> > Turn-of-nut +/- %15%
> > Preload indicating washer +/- 10%
> > Strain Guages +/- 1%
> > etc.
> >
> >  > Might be a good gouge when you don't have a torque wrench, as is the
> > tool
> >  > kit when you don't have real tools..
> >
> > If the handbook is to be believed the turn-of-nut method is more
> accurate
> > than a typical torque wrench (when both are used by a typical mechanic
> :-)
> >
> > // marc

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