Date:         Sun, 6 Oct 2002 12:33:15 +0100
Reply-To:     Clive Smith <clive.harman-smith@NTLWORLD.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Clive Smith <clive.harman-smith@NTLWORLD.COM>
Subject:      Re: Torque Wrench
Content-Type: text/plain; charset="iso-8859-1"

>>One other principle from aircraft mechanic school. If there is no
specified torque, use a standard torque value for the bolt size. Barring
that, go finger tight and a 1/4 turn.

Yes, yes and yes but that last sentence is just too vague. This would depend
on diameter, shank length, threads per inch and material, under many real
life situations what is finger tight? (there is a big difference between
'Gorilla fingers' and piano fingers') and 1/4 turn would barely make a
difference to a long thin bolt with a fine thread, could even be 4 turns for
such a situation.

Bolt length has been underplayed in these reply's - its very important.
Hence my earlier - 'use EYES, common sense, experience (if any) and feel' if
no troque wrench or specification. Some nuts/bolts are just there to hold
something on, not clamp it, so the criterion is simply to not come undone -
which might be accomplished by other than tightness - there is no substitute
for a little bit of thought and assessment - if knowledge and experience are
not available!

Clive
'88 Syncro Transporter


----- Original Message -----
From: "John Rodgers" <j_rodgers@CHARTER.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Sunday, October 06, 2002 2:28 AM
Subject: Re: Torque Wrench


> I personally think torque values are crucial. The specified torque
> applies the correct tension to hold what ever, and it should not back
> off once tightened. Some torque values are extremely critical and
> failure to observe them can result in a failure of a part which in turn
> may cause failure of the whole engine or whatever. Could become a safety
> issue big time.
>
> Back in my aviation school days it was hammered in that every bolt had a
> torque value that was worked out by the engineers for specific reasons,
> and those values were to be observed absolutely. There is no place in
> flight to pull an airplane over to park because some part failed or fell
> off because the correct tourque was not applied.  Aircraft bolts and
> nuts are often safety wired to prevent them from backing off. Sometimes
> that doesn't help though. I saw a case where one of the cylinders on an
> aircraft engine separated from the case because the cylinder flange hold
> down stud nuts - even though saftied - were not torqued correctly.
> Resulted in the failure of the studs, allowing the cylinder to come
> loose in flight. Bad news. So if there is a torque value given, use it.
> May save your butt.
>
> One other principle from aircraft mechanic school. If there is no
> specified torque, use a standard torque value for the bolt size. Barring
> that, go finger tight and a 1/4 turn.
>
> John Rodgers
> 88 GL Driver
>
> Marla Stelk wrote:
> >
> > So just how important is it really to use a torque wrench?  A mechanic I
spoke to once said he never uses one for tune-ups.  But the Bentley tells
you to use one for almost everything.  I've got to take the top off my
thermostat - do I really need to go buy a torque wrench to put it back on?
The buggers are pretty expensive.....
> >
> > Thanks,
> > Marla
> > '87 Westy Van "Morrison"Get more from the Web.  FREE MSN Explorer
download : http://explorer.msn.com
>