----- Original Message -----
From: Max Power <monadnoc@crystal-mtn.com>
To: Ole Trucks <oletrucks@autox.team.net>
Sent: Tuesday, November 09, 1999 12:52 AM
Subject: Re: [oletrucks] Front end sway
>
> >
> > When I hit a bump at an angle (on the freeway or on the street),
sometimes
> > the front end will sway dangerously side-to-side. The motion is
analogous
> > to a rolling motion.
> > My first impression is that the shocks were bad, but they were new. Then
I
> > supected damaged leaf springs.
>
>
> Tom, sounds suspiciously like "bump steer", which is the dreaded curse of
a lot
> of hot rodders. It comes from changes in the steering geometry that have
> affected the steering arm radius measurements as well as front end
modifications
> that do not follow the Ackerman principle. A decent explanation is in Tex
> Smith's book of hot rod building. Suffice it to say that other than an
overhaul
> of the front end mods, rodders have tried various solutions to get around
the
> problem. Sometimes radial tires instead of bias ply will help, as will
the
> addition of a sway bar. But sometimes they are just stop-gap measures
that end
> up masking the problem. Sometimes you get lucky, and sometimes you don't.
Ping
> me off list if you'd like me to copy the section from Smith's book for
you. I
> could snail mail it if you'd like.
>
> Wally / Templeton, MA
> 53 3100
> 72 Malibu
>
>
> oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
>
Tom may be right. I have the power steering conversion that uses a new
steering arm. If its not level, you get major bump steer. I first used a
stock pitman arm from a Malibu. It put the "drag link?"at about Maybe a 10
degree angle. I could bounce the front of the truck and watch the steering
wheel move from side to side. I also had the "bump steer" on dips. I lowered
the front end a little "broken leaf " (I just took it out both sides). This
made the arm at more of an angle (in relation to....the ground), the bump
steer was worse. I was a little apprehensive about getting the pitman arm
modified but the welding shop said not a problem and seemed proud of their
work. I figured out what it would take (cutting and welding the pitman arm)
to get the steering arm level and had them do it (also had them put a 15
degree angle to match the steering box angle). It works much much better
now.
I also think when these conversions put the steering arm at the top of the
spindle instead of original (see waynes page) location, all the forces,
twisting, pushing and pulling, become more pronounced. Kinda gives it all
more leverage.
There's alot of stuff on the web about "bump steer" mostly Jeep stuff, but
it all applies. So, now you start reading about crossover steering.
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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