Re: How are bolt torque specs arrived at?

Comboverfish wrote:
> On Sep 11, 9:50 pm, Doc <docsavag...@[EMAIL PROTECTED]
> wrote:
>> Just pondering the 9 ft/lbs specified for the rear seal housing on my
>> Cressida per the factory manual. How are bolt torque numbers
>> determined?
> 
> Basically it is a specification that has been determined by past
> testing and do***entation of the given fastener type plus engineering
> consideration of the assembly parts in question.  The two most
> im****tant things regarding the fastener are 1) it must not break/strip
> threads at this torque value and 2) it must not back out from lack of
> tension.  The makeup of the parts and their intended duty modify this
> equation as well.
> 
> In the case of a final assembly, lots of data is reviewed before
> assigning a value to a fastener.  Machining and material spec data
> publications are used by design engineers as a baseline towards
> engineering their specific requirements.
> 
> Toyota MDT in MO
>

The most im****tant thing is that the fastener is preloaded more than the 
load it will see.