another grease question: bolt threads

i still dont use a torque wrench on lug nuts most of the time. i DID buy
a torque wrench when i had to replace a head gasket. crucial tool in
that application.

valve cover, with the rubber donuts? snug is good.

 

You're right. Exclude sheared heads due to seizure.

I think this is a very realistic illustration of why determining what
torque should be applied to get the right clamping force is, bottom line,
no small amount of guesswork.

 

I reckon. I got a little persnickety about it because of a brief but
memorable period of valve cover gasket leaking. Which may have been
unrelated to the applied torque.

 

"Caroline" <> sprach im

Except for 20 years ago, never.

You learn to feel when the bolt/nut reaches the point where it suddenly
gets "tight". There's a sudden ramp-up in turning effort, and you know to
stop there.

 

This tells you nothing about whether the bolt is undertorqued.

Plus, if you're so confident in this approach, then you wouldn't be using a
torque wrench where it's accessible.

 

Your logic is unassailable, of course. And no, I don't have the confidence,
which is why I use the torque wrench where I can.

Since I'm just a driveway grease-monkey, I'm not loosening and tightening
bolts every hour of the day, so I can't get the fineness of feel that a
professional technician could.

OTOH, I haven't stripped a bolt in easily 20 years, and have never had one
come loose on me (except for a lousy Ansa exhaust system on my Corolla in
1983), so something must be going right.

I suspect that most bolts and nuts have a fair bit of a torque safety
factor built in just in case, so as long as you get it reasonably close,
you're fine. Wheel nuts, for instance. Conversely, even the pros use a
torque wrench when tightening head bolts.

 

If you lubricate bolts, torque specs will change to a lower setting.

 

Lubing spark plugs is a long practice with my first encounter being with
old VW beetles that had a pretty nasty reputation for galling block
threads due to carbon.

Torque application on spark plugs is less of a concern than bolts used
as structural fasteners.

Imagine if you will a large 1" bolt to be installed into a large block
of steel. Now, if you were to wrap you hand around the bolt shank with
a large washer under the head, and if one were to torque it to 20 ft
lbs., the pain would be much more severe if the threads were lubricated.
(Pain being used as a measure of yield).

If a manufacturer specifies a given torque value lubricated, they have
already taken all issues into consideration. Not to worry..

 

As my father once observed as I was measuring and cutting lumber for the
construction of a barn, "it's not a watch". "Measure twice, cut once" is
important, but of course one always has to consider the purpose and
materials at hand.

 

Thanks.

 

That does seem to be the consensus of this discussion.

 

I can supply you with some:

1.2 Kgf-m +/- 0.2
1.4 Kgf-m +/- 0.2
1.75 Kgf-m +/- 0.25
2.0 Kgf-m +/- 0.2
2.2 Kgf-m +/- 0.2
2.7 Kgf-m +/- 0.3
3.1 Kgf-m +/- 0.4
5.0 Kgf-m +/- 0.5
5.5 Kgf-m +/- 0.5
6.5 Kgf-m +/- 0.5
10.25 Kgf-m +/- 0.25 Steel

Note that these are transmission specs, probably taken from HES (Honda
Engineering Standards). All are for Honda (unspecified grade) steel bolts
into aluminum threads except where otherwise noted. These may or may not
apply to other applications for Honda and are meant to serve as guidelines
only. Unfortunately, I can't convert these to SAE specs, or into N-m.
Also, my $0.02 worth regarding torque of lubricated bolts.....
Oil or grease on your bolt will play havoc with accuracy of final torque. It
affects stretch as well. Many times have I seen steel bolts break off in
aluminum threads because our bolts had oil on them. How much is too much; I
couldn't say.
Doc

 

Having said all of that, what is the concensus on tightening lugnuts with
alloy rims? How many times have you had lugnuts loosen after having been
remove to service a tire? It's a common problem with Honda alloys. Even to
the point where service shops include a disclaimer in their invoices to
inform you that lugnuts on alloy rims are known to loosen up after 25 miles
or so of driving, even after having been properly torqued, and recommend
that you check them periodically. My experience tells me to lean on that
wrench; damn the rotors!
Doc

 

Thanks, Doc.