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Posted by Keith in Washington [24.41.41.111] on Friday, August 20, 2010 at 13:41:41 :
This is OT and has not Dodge content but may be helpful. Death wobble is not restricted to any single truck brand. Death wobble is more common in lifted trucks due to changes in suspension and steering geometries. It does occur in stock trucks also. It is often due to worn steering or suspension parts but can occur in truck that are brand new off the lot.
The resolution of death wobble in my truck took a couple of weeks as we worked through it. I had a good dealer and alignment shop help in this process.
This post is a little long but I wanted to give details for people to provide some insight.
My 05 F350 1 ton dually recently developed a death wobble. The truck is totally stock with no lift. It occurred at just under 60 MPH going down hill into a right or left turn. Left turns were worse in that it occurred more often and the wobble was much more violent. Violent means that It was hard to hang onto the steering wheel and the whole truck shook badly. It never occurred on an up hill turn (weight distribution shifting weight to the front axle going down hill??). The only way to stop it was to slow down. Touching the brakes would not help it was getting down to 40 or 45 mph to stop the vibrations. Let me tell you it was scary at times when you are in a sharp corner doing 60. The truck had just over 60,000 miles on it when I started to have a problem. The truck is always fully loaded with an 11.5 ft camper on it so it is close to 12.5 K on the road. The wobble usually occurred on a 2 lane mountain hwy that is actually a good road that I can travel at 60 mph with the camper on (hwy 2 in WA State). It never occurred on the freeway. Once or twice it occurred when I hit a large pot hole at speed.
Here is what what we did to fix it: I took it to the FORD dealer to be looked at. I have to take the camper off as they can not work on it with the weight and size (a very good shop that does great work). I told them the problem and additionally my wife says I am having trouble keeping it going straight down the freeway. I actually got reported and pulled over on a recent trip. It was not bad but it was wondering.
They checked it out (I was 1 week from going out of warranty). When I got it back they had replaced the steering box as the hardened balls were failing. They said the rest of the front end was tight and with in specs. They said my front tires were worn and cupped on the edges and that was the source of any vibration which kind of made sense as the problem occurred in sharper corners where the tire would tend to roll a little. They suggested that I should have the front end alignment checked due to tire wear. They also could not duplicate the death wobble.
I took it out on the road and sure enough I could not recreate the problem with out the camper. There was minor vibration from the front tire wear. I put the camper back on and took off for the weekend. Death wobble was alive and well to say the least. So it only occurred when the truck was fully loaded. The wondering was gone.
I went back to the dealer and we had a long talk. My service guy is quite knowledgeable and also listens to me and respects my automotive knowledge. Obviously with the truck being loaded the front end steering geometry is different. They said replace the tires and have the front end aligned. I questioned them about the track bar and other front end components (known issues in some truck). They said all was within specs. They told me to take it to a shop down the road which is very good at large truck alignments and could do it with the camper on. We agreed that it needed to have the camper on during the alignment.
I stopped by the shop on the way home to make an appointment. They said they have seen this issue with some F350s before and usually requires an alignment and a new steering dampener to take care of it along with correct tire pressure. I pushed on the track bar issue and he said most likely no as it is not lifted.
I went home and installed a new steering dampener and added 5 lbs to the front tires. I could not really see much difference between the new and old dampener when pulling or pushing on them. We took off for the weekend and the death wobble was gone but still some vibrations in down hill turns. Interesting.
I had the alignment done. It was toed out and camber was off a little. The next day I had new tires put on the front end.
I just returned from Reno which was 1800 miles and a weekend trip where the death wobble was normally really bad. All problems are gone and it is silky smooth to drive in all conditions.
Death wobble is a serious problem. The final diagnosis was:. The tires were worn and cupped due to two things. First the alignment was slightly off. Secondly they were cupped from running on a 4 X 4 truck which is not uncommon. One tire was slightly worse in wear (that is why left turns were worse). Second the steering dampener was worn. What set up the death wobble was: When I went into a sharper down hill turn, usually on a 2 lane hwy, the front tires would roll slightly onto their outer edges, which is normal behavior on a fully loaded truck at 60 MPH on a sharper corner on a 2 lane hwy (no turns like that on a freeway). The tires would now be running on the cupped edges which would set up a vibration . With the steering dampener being worn slightly (weak) the vibrations would build quickly into a death wobble. So when I replaced the dampener the vibrations were still there but could not build into a death wobble. The new tires took care of the source of vibration and the alignment should solve future tire wear. I am now running at 75 psi instead of 70 psi in the front tires which will help with tire roll in corners.
The thing that bothers me is that minor cupping of the tires along with a slightly worn dampener caused the death wobble. This tells me that the steering and front suspension are on the edge and very sensitive to any wear. The F350 has a coil spring front suspension which is more complex than leaf springs. I have run tires that were cupped much worse on leaf spring front ends with out any issues (even a '99 F350 that was fully loaded with a camper). From what I have been able to find in my reading and research is that the coil spring front suspensions are much more subject to issues. The axle is not as well positionally controlled and has several bars, track and etc, that control the axle's position but are subject to wear that can cause problems much quicker and more severe than with leaf springs.
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