caster

I have an old, very beat-up pickup truck that has developed the "death
wobble" on the highway, like when it's going over 50 and hits a rough spot.
That will set off a violent shaking in the front end that won't stop untill
the truck slows way down. This is a 1994 Dodge Ram 2500 4x4 with the diesel
engine.
Death wobble is fairly common in these Dodges, which have a very underbuilt
front end. This truck spent its life getting salty in the winter; at this
point it's just about disintegrating. It's no surprise death wobble finally
hit.
Apparently, adjusting the caster can alleviate the problem (or so some say).
This brings me to my question: positive or negative caster?
Grocery shopping carts have a lot of trail (in effect, positive caster), but
are vulnerable to an effect similar to death wobble, where the caster goes
into a violent oscillation. One could naively conclude that positive caster
invites "death wobble." However, positive caster in motor vehicles enhances
high-speed stability. I presume that giving my truck a positive caster is
the right approach.
Yea or Nay?
Reply to
Michael Robinson
Loading thread data ...
Dear Michael Robinson:
I'd put in a "horizontal" shock absorber, myself. Assuming you cannot just take out the play in the steering, starting with tie rod ends and such...
David A. Smith
Reply to
dlzc
Dear Michael Robinson:
I'd put in a "horizontal" shock absorber, myself. Assuming you cannot just take out the play in the steering, starting with tie rod ends and such...
David A. Smith
Yes, I saw a comment to that effect: that death wobble is side-to-side, not up and down. You're right about replacing worn parts. I'll have to bite the bullet and shell out the bucks. I think there's a part calledthe track bar (?) that's supposed to prevent sideways movement in the axle.
Mike
Reply to
Michael Robinson
Dear Michael Robinson:
... or replace the truck.
Putting a "dampener" in there will reduce the oscillation amplitude, by disspating the energy used in destroying tires and losing control, into heating the "shock absorber". I'm sure there is a commercial product available, but not sure what it is called.
David A. Smith
Reply to
dlzc
Toe-in is likely to be the front-end geometry component that would cause this. Wear in the steering linkage and tie rod ends leads to a loss in toe-in. However most likely cause is tire balance.
-jim
Reply to
jim
I have a 1990 jeep, rear leaf springs. The worn springs were bowed up in the middle. Being fixed in front and shackeled in back, when the truck leans left, as if when I turn right, the rear left wheel will pull forward, and the rear right wheel will pull rearward, causing the rear of the vehicle to steer into the turn, causing it to lean more to the left (positive feedback). This caused a rather slow oscillation around 2 leans per second that will go caotic at about 70MPH. If felt as if the truck might roll over. Once it started rocking, I had to slow down. It was crazy! I added and replaced leaves in the back to get the bow a bit downward. Now the rear steers the back in the opposite direction. Steering feels very quick and oscillation is gone. Harry
Reply to
harryhydro

Site Timeline

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.