From: wwd@netheaven.com
Date: Sun Sep 22 2002 - 05:52:31 PDT
"Bjorn Brandstedt" <super_deuce@hotmail.com> said:
> Tested a commercial grade bolt and it
>failed at about 25 ft-lb.
?? Was it 3/16" or thinner?! 25 ft-lb is not a whole helluva lot. About
the max you would use for sparkplug into an aluminum head. About what you
get using a 4" handy-ratchet without straining. [Grade 5=commercial;
grade 3= 'hardware store']
>The grade 8 cap screw was tightened to 75
>ft-lb and came apart afterwards without any sign of failure.
>My manuals specify 45 to 50 ft-lb for grade 8 and 20 to 23 for commercial
> grade.There is a difference between wet (oiled) and dry, these numbers
>apply to dry assemblies.
>Back to the spindle on the truck, after i discovered the problem with the
> nuts, I called the Rockwell tech line (the manufacturer of the axle) and
>was told that the nuts must be grade 8 and torqued to 45 to 50 ft-lb. I
>believe that the manual calls out lock washers also, however, a properly
>torqued bolt assembly doesn't need lock washers, the tension in the bolt
>(cap screw) is what holds it together.
A new, sharp lockwasher is better for grade 5 (or 3) nuts so it can cut
into the nut and do what it is supposed to do. Also, there are different
grades of lockwashers and washers which complicates their casual use.
Better to use 'nylock' nuts for normal temperature situations or 'wrinkle'
nuts where heat could soften nylon. Then you 'know what you got' for those
critical places.
Also remember there is Locktite which comes in 3 grades: 1-regular,
2-'needs exact wrenches and exercise to get apart' and 3- 'forget about
it' (torch or grind). Loctite is our friend...
>When a lock washer is used and the assembly tightened, the lock washer
>does nothing, it only works for a while after the assembly has loosend
>up and then it's too late any way. Torquing is VERY important. Most cap
>screw assemblies on the deuce do not use lock washers.
Using a torque wrench (or those 'torque-flex-extender' abominations) is
indeed an Art. I think that K-D tools or Lyle tools should make a
wall-mounted gauge so you could do a test run with the same breaker bar in
your hand that you are going to use on the vehicle/victim. Then you could
get a pre-flight feel for just how much 'maumoo' is needed to achieve the
specified torque.
>Bjorn
Cosmo Lean [knuckledraggerus sapiens]
~~~
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