hi,
you don't say how long your cheater bar is or how much you weigh..
but ...'normal' is like a 3 and 1/2 foot cheater bar with 170 lbs or so
standing on the end of it .

if you are not making it 'that kind' of tight, you are probably not getting
it tight enough.

it's unlikely, as least 'normally' that something is giving away slowly ..
you are tightening  just  inner bearing races and a spacer ..just solid
metal.
and I can't image the drum is crumbling ...but the rust I've sometimes
......wow.

probably not getting it tight enough.
Scott
www.turbovans.com
----- Original Message -----
From: "M. Jade" <tinho2010@YAHOO.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Friday, June 11, 2010 10:19 PM
Subject: Why my rear axle nuts got loose

> My rear wheels have been making rumbling noise. According to my past
> experience I know it is the axle nuts that are probably loose. So I
> finally checked them today. Sure enough they are loose. I tightened them
> until I could not turn further. I do not have a torque wrench so I am sure
> I did not apply enough torque.
>
> The questions is I did this once less than a year ago. I turned as much as
> I could until I could not turn further the nuts. I installed the cotter
> pins properly I believe. I am surprised to find that they are so loose
> today. I turned them about 30 degree each then put in new cotter pins
> again. Is there anything that may be wearing out in the axle? With the
> cotter pins in there the nuts can not possibly turn back out. Last time I
> tightened them as much as I could until I could not turn any further. But
> today I found I could turn another 30 degree further. Does this mean
> something is wearing out inside? Is there any risk if I drive it as is for
> now until maybe they get loose again?
>
> Thanks in advance for any expert tips here.