I have seen a number of comments here on a Ford truck dilemma, bump steering. I have experienced bump steering in my Corvette, which was solved relatively, but expensively. I haven't encontered the problem with my "93 F-150 4x4, but shortly after I purchased the vehicle, I replaced all the standard bushings with polypropylene
Iam wondering,never-the-less, what causes bump steering in the Ford truck. It would seem to me the most probable cause would be worn radius arm bushings, but am not sure.
If there is someone who has experienced the problem and solved it, I would appreciate that information so that if I haven't inadvertently minimized the potential by bushing up-grade, I can make the change now before it becomes a problem with this truck
Thank you in advance for your information,
Ron

 

What the heck is it doing
making noises while turning?
In any case my opinion is this
Where the radious arm comes of of the front axle there is a upper and lower stud or bolt that hold them in place. according to the ford dealers i have talked to in the past, these either come loose or wareout.I would check this first before like myself spend alot of money for knew bushings and still have the same problem.
This is only my opinion and by no means may correct the problem but might give a place to start

 

Not sure what "bump steer" is. But now that you mention it, I recall a particular bump on I-96 here in Detroit that I hit every day on my way home while doing about 70 mph. When I hit the bump, my whole truck turns a small degree--say maybe 5 degrees--out of the direction it was tracking. Always wonder how that bump would be if the road is iced up.

 

Bump steer has nothing to do with the way a vehicles steers when it hits a bump (pothole, washboard, etc). Bumpsteer is what happens when one front tire climbs up something while the other drops down something. For example, when driving off-road, and you have to climb over some off-camber ruts. When one tire drops into the rut, and the other is driving out of it, it causes the suspension to articulate. Now, if you pay attention to the steering wheel, you will notice that have to turn the wheel in order to keep the vehicle driving straight. When the other tire climbs out of the rut, you will have to turn the wheels again to keep them straight. The reason for this is because when the tires and axles change angles, the angle from the tie rod to the steering box changes as well.
This problem is more noticable on lifted trucks with TTB. The best way that I have heard to reduce bump steer on the Fords is to install the SuperRunner steering system from Superlift. This puts the steering back in almost factory specs. However, with the design Ford uses on their TTB trucks (pre 98) bumpsteer can not be completely eliminated without changing a bunch of things.
Ford bumpsteer is not real bad, even on a lifted truck, because they use a form of cross over steering (tierod from steering box on drivers side, to the knuckle on the pass. side).
Chevy, older Dodge, and Toyota for example, have a different steering setup. There is a short draglink between the steering box and the knuckle on the drivers side. The draglink is pushed and pulled front and back. The tie rod then connects the drivers side and pass. side knuckles. Because the draglink is so short and the way it pushes and pulls, bumpsteer on these vehicles is bad, and worse on a lifted vehicle. The way to reduce bumpsteer on one of these is to install cross-over steering, which is not an easy task.
Sorry about writing a book, but I hope it helps explain.

Chris
cmercer@auxserv1.unco.edu
http://www.mountaineers4x4.org/mercer
'82 F-350, '53 Dodge PU, '85 4Runner
Proud enough to stack hay, crazy enough to eat it.

 

On another note, to cure the problem of your steering ghanging directions when hitting a bump or pothole, install a good quality steering stabilizer. However, unless you are running 38's or bigger, try to stay with a single stabilizer. Two or more will make the power steering pump and box work harder and wear out faster. Also, try to mount the stabilizer parallel to the tie rod.

Chris
cmercer@auxserv1.unco.edu
http://www.mountaineers4x4.org/mercer
'82 F-350, '53 Dodge PU, '85 4Runner
Proud enough to stack hay, crazy enough to eat it.

 

I can vouch for the steering stabilizer, I have a single rancho stabilizer on my 95. It took about 15 mins to install, and cost me $87 Canadian..
Whats that about 10-12 bucks US now,

Les

 

(from the Superlift Guide)
"Bump steer is caused by a number of alignment problems, bump steer is when a vehicle darts or wanders excessively when operated on a less that ideal driving surface.... in other words, it takes a concentrated effort to keep the vehicle in a straight line."

That of course is the generic version. In the case of the Ford Truck, if you look under the front at the Drag Link, you'll see it at an angle from the pitman arm, and the drivers side is much shorter from drag link to tie rod end then the passenger side is. These angles coupled with the lengths give the road great leverage when you hit a bump. So when one tire moves up, it changes all 4 angles and actually turns both tires, there's no real way around this.... but....

To eliminate bump steer, you have to eliminate the angle with a dropped pitman arm, and equalize the tie rod lengths, with a Superlift Superrunner Steering kit, or something similar.

Hope this helps anyone.

 

Maveric: I have a '95 F150 with stock wheels and tire size. I always thought my highway bump problem was that the light rear end was skipping sideways. Suppose I could test it after a good snowfall by loading 1000lb of snow in the back and then trying the bump again. Nonetheless, the steering stabilizer might not be a bad idea and possibly would make it wander a bit less on cross windy days?

 

My 87 Ford F250 DRW Diesel had this problem when I bought it, after replacing worn radius arm bushings, drag link and tie rods, it still did it, though not anywere near as bad, installed a rancho steering stabilizer, and that fixed it. Have not had problems since then that was 2 years ago.

Dave

http://a2ztowing.homestead.com/a2ztowing.html

 

I plan on adding a steering stabilizer soon. But I felt my rear end was skipping to, but that was before I put 3/4 Ton leaf springs on my 1/2 Ton. It handles much better now. I bit stiff, but it stays on the road more and besides, it hauls more weight before sagging.