Drop pitman arms and bump steer

[joel brodsky <travelall1974@xxxxxxxxx>]

Okay, this is now the 6th Lift I've put in a truck of
mine, and guess what?  Well, I purposely left the
front shocks off so that I could more easily
demonstrate bump steer.  I went over a speed hump in
my neighborhood, the kind that you can confortably go
about 15 over without any jarring at all.  As I
traversed the hump while holding the steering wheel
straight, the front end of the truck went down/left
and up/right in the oscillations.  This is clearly
bump steer.  The reason eludes me though.  It would
seem that the reason is that the drag link, while
being held still at the steering box, tries to get
longer in horizontal distance from the PS box as it
subscribes the arc traveling upwards.  As this
happens, it pushes the right front wheel out to make a
right turn.  then the rebound is the other way, up
gives a turn to the left.  But, the actual bump steer
is just the opposite, down and LEFT, instead of the
explano of down and right.  Anyone?

So, the solution can only be a dropped pitman arm. 
Now, with the drop and stock arms, the difference is
2.5".  The stock pitman arm radius is 9.5" and the
drop is 1.5".  The droped arm is 7" radius and 3.5
inches of drop.  So will the 2" help with the bump
steer?  I certainly hope so.  Will the steering be
affected?  Yes.  Will it matter?  I'm not so sure. 
The stock steering arm at the knuckle is 9.5" making
the ratio of steering input to wheel reaction
9.5"(input)/9.5"(output), thus it is considered to be
one to one.  The new setup is 7"/9.5" or .736842. 
Thus it runs about 3/4 as sharp as it used to.  So,
what does this mean to me/you/anyone?  Well, if the
turning circle was right at 50 feet before, now it's
35.7% bigger.  Remember that to get to 100% from
.736842 it's 1/.736842 so that 1.35714, or 35.7% more.
 So, that sounds like it sux bad!  Anyone have numbers
on steering radii for Scout 80, 800, ScoutII,
Traveler, PU, TA, Travelette, etc.?  I'm wondering if
my turning will even be close to a Scout 80, which is
atrocious on the trail anyway.

Better a wider turning circle than bump steer, I
believe.  I'm going to try the drop arm this weekend
and report back.  I have been running bump steer for
about 8 years now and no wonder I've thought these
trucks handled poorly.  Now that I understand what's
going on, I can believe that it's this bad!

Bronco II or not, there ought to be a way to get a
longer radius pitman arm, with about 4" of drop in it,
to correct a Scout steering to a place where it can
compare to the stock numbers.

Any ideas anyone?  Now, why again shouldn't I heat and
bend an stock arm to do the tests?

Thanks for your support,

JoelB
-time to get some shut-eye

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