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Re: head retorquing question

To: Bullwinkle <yd3@nvc.net>, mgs@autox.team.net
Subject: Re: head retorquing question
From: Hans Duinhoven <h.duinhoven@planet.nl>
Date: Thu, 04 Sep 2003 20:19:18 +0200
I feel for your varinat Blake.
It makes sense to me.

Cheers,

Hans

----- Original Message ----- 
From: "Bullwinkle" <yd3@nvc.net>
To: <mgs@autox.team.net>
Sent: Wednesday, September 03, 2003 2:29 AM
Subject: Re: head retorquing question


> There are two types of friction: Static and sliding.  Static friction
> represents the force needed to get a stationary object moving.  Sliding
> friction is the force necessary to maintain that movement.
> 
> General science and high school physics classes teach that sliding
> friction is almost always less than static friction.  We pulled weights
> using spring balance scales to measure and test the concept.
> 
> An engineering reference shows that hard steel against hard steel has as
> static friction of 0.78 while sliding is 0.42.  That means the force
> necessary to start movement is almost twice the force necessary to
> maintain the motion.  All cylinder heads that I am aware of have steel
> washers under the nuts.  Thus it makes no difference what material
> the head is made off.
> 
> Therefor when retorqing, back off the nut using a breaker bar, or beam
> torque wrench, just until it breaks loose and no more.  You do not want
> to loosen it completely.  Then torque it back up to the recommended
> setting.  Do each nut separately and in the same sequence as recommended
> by the engine manufacturer.  That is, back off number one and retorque
> to the recommended setting.  Back off number two and retorque to the
> recommended setting, etc.
> 
> Blake

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