Lubing bolts before torquing

[Dick W.]

Re: Lubing bolts before torquing

My philosophy for years has been if it might fall off, use Loctite, if you might ever need to take it apart again, use Neverseize.

[Owen L.]

Re: Lubing bolts before torquing

When a bolt is lubricated - less torque is required to achieve bolt axial load or tension. Reduction of torques for lubricated vs. dry bolts are indicated in the table below.

No lube	0
Graphite	50 - 55
White Grease	35 - 45
SAE 30 oil	35 - 45
SAE 40 oil	30 - 40

When attaching my exhaust manifolds, I used copper anti-seize and stopped tightening when I reached the torque indicated in the assembly manual. Does this mean I over-tightened them in the range of 35-55%? Are we saying that we should be reducing the recommended torque specs by as much as 50%? Hard to believe that 15lbft if using graphite is equal to a spec'd dry 30lbft.

[Michael G.]

Re: Lubing bolts before torquing

Believe it. Realize that friction robs torque. So when you eliminate half your friction, your clamp load increases appreciably at the same torque. If you, for instance, switch your finish from Zinc (very high friction) to cadmium (extremely low friction) because you think they look alike, you may well break the bolts at the recommended torque, because you get so much more load at the recommended torque.