In a message dated 1/15/99 6:07:48 AM Pacific Standard Time,
neilc@tradesrv.com.au writes:
> There's been a big discussion on this very topic on the Healey list. I'm
> hearing two conflicting points of view there and now here! As I'm in the
> process of an Engine rebuild and will be replacing the studs, bolts, nuts
> etc I really want to know which is the right avenue to follow. Lubricate
the
> threads or not - I want to torque to what it says in the Workshop manual,
so
> how are their figures quoted - dry or lubricated? If lubricated, with what?
>
> Cheers,
> Neil.
Unless other wise stated torque spec are always given for clean lubed threads.
In all the years I have been in the automotive industry (30+) I have NEVER
seen a torque spec listed any other way.
BTW (just slightly off topic) in recent years a new type of torque spec has
come into use called torque to yield or sometimes angle torque. A spec for
this would read like
30 Ft-Lbs + 90 degrees. What happens here is that the engineer that designed
the fastener know how much effort it would take to stretch the fastener and
therefore how much clamping force would be exerted by the fastener. The first
part of the spec (30Ft-Lbs) is just to pull the slop out of the joint. The 90
degrees actually stretches the fastener and provides the clamping force for
the joint. Yes, the bolt gets longer. I have a rod bolt in my school that
was reused several times too many in class. From the parts dept. it should be
51 mm long this one mic's at 59 mm. The reason that I bring all of this up is
that in a torque to yeid fastener, Cleanliness of the fastener is secondary.
The 90 degrees stretches the bolt and provides the clamping force, no matter
how much torque is required to turn the bolt.
So now before everybody on the list sends a reply and asks <G> No I don't know
how to adapt this type of spec to LBC's. At the least it would require some
rather sophisticated calculations and probably different fasteners. I do not
know how to do these calculations, and rather than giving my brain a cramp, I
clean the threads both male and female and torque to the factory spec. I
always use new studs on a LBC head (the local parts house has a generic studs
that works great and cheap)
Two other notes on torque. Click type torque wrenches will and do go out of
calibration. I send each of mine in once a year to be recalibrated. I once
was visiting another shop where a mechanic was assembling the bottom end of an
MGB engine. I watched as he went to torque one of the main bearings. When he
got to the point of having his assistant hold the block with both hands and he
was pulling with both hands as hard as he could, I could see that something
was wrong. I went and got my torque wrench we loosened the fastener and tried
again. One hand on the wrench and one on the block and the wrench goes click.
Bottom line his wrench was WAY WAY out. Lastly when torquing a fastener
always pull the wrench in one smooth movement, do not stop at 80% and then
restart. This is because it takes more torque to Start a fastener turning
than it does to keep it turning. (one of Mr. Newton's laws).
I hope this answers some of your questions, sorry I went on for so long.
Rick Ewald
PS BTW I thought all torque specs for Healy's were the same: "Tight as it will
go plus one half turn more" <VBG>
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