<VV> FW: ANTISIEZE

[Eric Taylor]

This relates to heavy truck wheel lugs yes, (I have yet to see a car lug that needs 480 ft lbs of torque) but the relationship of torque to clamping force as it is affected by lubrication is very interesting.  I have never considered that it would make that much difference.  Of course, I am not one of the smart ones in this group, just inquisitive - which leads to the next paragraph...

So now, I guess I have to assume that torque values given in any manual should specify whether it is a dry torque or a lubricated torque?  Should it be assumed that it is dry so therefore oiling a head nut before torquing could over-torque the assembly?  Or is it the other way around that we should assume it should be oiled and therefore  we are constantly (in my garage) under clamping things by torquing them dry?
We are mostly using pretty low torques compared to this example, but concern runs along the line of 'could we be risking the breakage of bolts by not knowing this information?'  Typical bolts can run anywhere from grade 2 to 8 which have strengths that look like they will withstand the torques we use.  Noting that in simple terms, Yield strength is the point at which steel first deforms under stretching tension and Tensile is the point at which it breaks, see the table below.  It is notable that as the bolts get stronger, the yield and tensile strengths are closer together (by percentage) so the difference between stretching it and breaking it is a much smaller margin.  (see that a 1" bolt for example in grade 2 stretches at 60% of it's tensile strength, a grade 5 at 77%, and a grade 8 at 87%)
US Bolts
Head Marking 	Grade and
Material	Nominal Size Range
(inches)	Mechanical Properties 
Proof Load
(psi)	Min. Yield Strength
(psi)	Min. Tensile Strength
(psi)

No Markings	
Grade 2

Low or medium carbon steel	1/4 thru 3/4	55,000	57,000	74,000
Over 3/4 thru 1-1/2	33,000	36,000	60,000

3 Radial Lines	
Grade 5

Medium Carbon Steel, Quenched and Tempered	1/4 thru 1	85,000	92,000	120,000
Over 1 thru 1-1/2	74,000	81,000	105,000

6 Radial Lines	
Grade 8

Medium Carbon Alloy Steel, Quenched and Tempered	1/4 thru 1-1/2	120,000	130,000	150,000
And, does the finish of the bolt have a bearing on the clamping power, for example, does a plated bolt apply more clamping power than a bare steel bolt given equal torque value as a result of its plating which should make it slipperier than a bare bolt?
 
BTW, how long is that ratchet wrench to allow them to get 480 foot lbs of torque by hand????  I don't see any torque multiplier in effect here.

> Eric Taylor, '61 Corveric
> Corveric at me.com
> www.corveric.com



> On Feb 14, 2015, at 2:08 PM, James Weppelman <jweppel at hotmail.com> wrote:
> 
> Yinz guys,
> The following information is from the TIA (tire industry association) training manual. Yes,I realize its for the commercial truck market,but the principles still apply to the auto segment also.Just saying.Tried to find the video,but this is the best I could do.
> Jim Weppelman
> Pittsburgh :}
> 1961 lakewood
> 1962 700 wagon(need parts?)
> 1963 spyder rag project
> 1964 monza coupe a/c
>                                                   
> -