Re: Bump steer question

[Steve Stegmann <stegmann@domain.elided>]

On Sat, 6 Mar 1999, Matt and Stacy Sopher wrote:

> Hi all,
> If I were to put on a steering stabilizer shock, would that help in the bump
> steer department?
> Matt Sopher
> 
Nope.  Doesn't address what causes bump steer.  Bump steer happens when
your drag link isn't level (or close) when the vehicle is at normal
suspension position. 

Let's say you have a lifted scout and the drag link drops 6 inches from
the left to right end.  Now when you hit a bump with the right side the
wheel comes up 2 inches.  Look at the drag link.  As the right wheel comes
up the drag link comes with it.  The right end of the drag link moves in
an arc, not straight up.  So... as the right end comes up, it moves a bit
to the right (remebmer it's moving in an arc).  This causes the right
wheel to point a bit more to the right and the vehicle tends to move to
the right as the wheel comes up.  And, of course to the left as the wheel
comes down.

Now, the drag link end is always going to move in an arc, can't stop that.
But...  If the link sits level when the normal load is in the vehicle you
get less lateral motion for a given vertical motion than if it starts off
with a big drop from left to right.  You can see this if you do the calcs
and draw some pictures. 

If you have a lifted Scout and have bump steer you don't like, really the
only thing I can think of to fix it is a dropped pitman arm.  You just
have to get the drag link level.  I don't think anything else will help.

Steve

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Steven A. Stegmann
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