Posted by Caleb in Kansas [172.69.70.38] on Tuesday, September 24, 2019 at 13:24:25 :
In Reply to: New Fangled vehicles OT posted by Mike in Arkansas [172.69.70.38] on Monday, September 23, 2019 at 09:34:20 :
I find it mildly amusing that the mysterious phenomena we have dealt with in the modified rig world has become a major problem for the high tech cutting edge engineering of these new vehicles. My 2001 Dodge 2500 4x4 had major steering issues and was not pleasant to drive. There was ZERO play in the ball joints as the previous owner had replaced them shortly before I purchased the vehicle. It was a bit of a handful to drive and was very "darty" if that makes sense. A week after buying it, I replaced a worn pitman arm joint and then flat towed my '79 CJ sitting on 3/4 ton running gear and 37" tires out to Colorado for a Labor Day vacation. The drive out was flawless and I was averaging about 17 mpg, the trip home was a nightmare with 45mph cross winds and every rough bridge approach would nearly send me onto the left shoulder regardless of lane choice. I found that a remedy was to accelerate sharply as I hit the approach which drastically lessened the affect. When we returned home, I had an alignment done and everything was found to be in spec. Eventually it became unbearable to drive and I would not allow anyone else to drive it, including my wife. I did not have death wobble, but I did have unpredictable steering which would follow every seam in a road or get scary with a pothole or uneven lane. I did one very simple modification, I upgraded from the Y style steering to the T style which used a link set for the 2008 Ram 2500. This made the truck much more predictable, but didn't fix it. I then replaced the track bar and installed the MOOG lower bushing instead of using the softer rubber bushing and this helped much more. What really sealed the deal and got it to the point that I would allow my wife to drive it, was when I rebuilt the axles (failed pinion bearing on the front diff) I installed all new control arms and used cam bolts in the lowers which were maxed out to a 3.5° caster (may have been 4.5). Personally, I feel that the caster is the real key in combination with a small amount of additional toe-in. I have since built 3 Jeeps with multi link suspensions and the only one we haven't had issues with funky steering was the one with a triangulated 4 link and adjustable upper control arms. Anything with tires increased more that a couple of inches in size gets 4.5-5° of caster and about 3/16 of toe to start from. I ended up with 10° of total caster on my suburban and it drives just fine (to me). On my wife's Grand Cherokee, I installed a 4" lift when I replaced all of the rusted and worn suspension components that were starting to cause some wobble. I maxed out the cams on it but still felt it could have used another 2°.
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