From: Bjorn Brandstedt (super_deuce@hotmail.com)
Date: Tue Jun 15 2004 - 04:04:25 PDT
Marc and list,
The interaxle removal is very important to the solution, but if your front
end is out of alignment, then it doesn't prevent cupping all by itself.
If your front leaf springs are sagging, and they most likely do after 30
plus years, the caster will be upset, which in turn changes the camber and
toe-in.
If your shocks are not worn equally, then you will have a slight shimmy at
certain speeds.
The whole formula for curing the cupping includes restoring the front
springs, and shocks to original condition and adjusting the toe-in to just
under 1/8 inch.
I also discovered that the front wheel bearings will contribute to the
toe-in and camber error if they are too loose. As a matter of fact a 1/4
turn of the adjusting nut represents 1/16 inch or more of toe-in. That's why
I suggest to tighten the nut about 1/8 inch (just check for overheating when
driving).
I measured a caster of 3 to 4 degrees on my vehicle. A camber less than 1
degree and the toe-in less than 1/8 inch. The caster is more on my driver's
side. One of my shocks is bad.
Removing the interaxle drive shaft is very important, but you must also
restore the front to original condition. Caster and camber will be right
with new springs and shocks, they are fixed at factory. The shocks do not
affect the alignment, but do control "hop" and shimmy and high frequency
vibrations while driving.
Tire pressure in the front should be increased to compensate for "high
speed" driving and near overload to 60 psi. Reduce the rear tire pressures
to 40 psi, to put more of the tread on the pavement for even wear.
Also both front tires should be worn equally and be of same brand.
I stand by my formula.
The sidewalls on bias ply tires are not thin. Radial tires have thin
sidewalls.
I appreciate feedback! Thank you.
Bjorn
>From: Marc Strangfeld <curlyjoe98@yahoo.com>
>To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
>Subject: Re: [MV] Bjorn's recipe for long front tire life (M35)
>Date: Tue, 15 Jun 2004 01:06:15 -0700 (PDT)
>
>Bjorn
>
>Good topic/debate
>
>I have to disagree with the interaxle solution to
>avoid cupping. I trashed two fronts on my trip last
>year due to cupping and the interaxle was removed. I
>assumed the majority of the problem was the camber and
>that the thin sidewalls roll under during turns. I
>did notice better driving conditions with the
>interaxle off but don't believe it helped all that
>much with tire wear. I can't argue with your turning
>radius measurements but I have two tires as proof of
>my theory. However, in hindsight I do think more than
>50 psi in the fronts might have helped.
>
>
>Marc
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