What is "bump steer"?

[WudreauxTWW]

Although I am very familar with the term "Bum Steer", I must admit I am a little shaky with the term "Bump Steer"... What is it? What causes it? How do you fix it?

[Crazy_Jeepman]

You are on the way to your favorite trail. You hit a pothole. The steering wheel is jerked violently left then right as the truck is heading to the side of the road. You have bump-steer!
This phenomenon is a result of modifying your tie rod and drag link geometry. The tie rod and drag link, as installed at the factory, are very close to parallel. Keeping these components parallel reduces bump-steer. Installing longer shackles, lifted springs, or a spring-over axle lift will change your tie rod and drag link angle. :D

[River Beast]

Well stated, CJM....

If your draglink is not close to parallel with your axle, at a steep angle for example like this:
http://home.off-road.com/~wagoneer/wild/misc_wagoneer/soadraglinka.jpg

When your suspension droops, your wheels will turn left and back to the right when it's compressed. This take away control from the driver... and on an off-roading excursion can be VERY dangerous in certain situations.

BTW... this is a pic of my rig just after my SOA showing the reasons behind the necessary steering mods

[WudreauxTWW]

Thanks for the info RB & Jeepman. So, if I understand this right, the lousy handling I am experiencing in my stock wag (especially at highway speeds) has nothing to do with bump steer. Instead it is likely in need of just having some of the suspension and steering components replaced. I am planning a 3 - 4" lift very soon expecting to use a kit with all new springs & shocks. Do you think this will improve the handling characteristics, or is it likely to make them worse?

[64Trvlr]

If you use a dropped pitman arm with the 4" lift you should be wander free. One thing that contributes to bad handling is low tire pressure, you might want to check that.
:cool:

[Crazy_Jeepman]

Here are the things that will contribute to hard to handle FSJ. Sloppy steering box, wore tierods, wore out drag link, spring shackle bushings wore out, bad ball joints, bad steering shaft to steering box coupler, as 64 trvlr said uneven tire pressure, or non matched tires, shocks, springs, TO MUCH BEER!! :D

[Rogue]

bumpsteer can be helped with an add on steering stabilizer ( a shock that bolts onto your steering linkage ) don't forget when you add your lift to have a competent front end shop check your alignment. the only things adjustable on a solid axle front end are toe-in and caster, caster is adjusted by placing wedge shaped shims between your springs and your axles

[River Beast]

<BLOCKQUOTE>quote:</font><HR>Originally posted by RogueStar:
bumpsteer can be helped with an add on steering stabilizer ( a shock that bolts onto your steering linkage ) don't forget when you add your lift to have a competent front end shop check your alignment. the only things adjustable on a solid axle front end are toe-in and caster, caster is adjusted by placing wedge shaped shims between your springs and your axles<HR></BLOCKQUOTE>

Just so you know... this topic has risen it's head before and you can adjust camber on our Dana 44 front axles...I just did using degreed Cosmo Shims (spindle shims)
http://www.specprod.com/PROD_DIR/prod_dynamic/prod_photos/56800.jpg
and degreed upper ball joint adjustment sleeves.
http://www.specprod.com/PROD_DIR/prod_dynamic/prod_photos/23000.jpg http://www.specprod.com/PROD_DIR/prod_dynamic/prod_illustra/23000ill.jpg

You need a "GOOD" alignmnet shop that knows what they are doing to do this right....a bit costly but can be done.

I have access to an alignment rack and did it myself... parts were only $49....

Max correction with each piece is 1.5 degrees

[ November 18, 2001: Message edited by: River Beast ]

[Rogue]

i never knew they had come out with shims for the Dana, cool man cool thanks for the info

[Bandit]

Bump steer is the change in toe (in or out) as the front wheels move through thier range of travel. As stated eariler if the drag link is not parallel, the toe can change drastically as you move over bumps and can cause a very ill handling machine. Drop pitman arm and good tie rod ends are a must!