Running down I-25 in the passing lane about 80 mph in fairly heavy traffic last night after work I crossed a 90 degree{ strait across } expansion joint and all hell broke loose again only this time I almost rolled the truck, **** myself, lost a water can and did some amazing stunt driving on 2 wheels. Up until now my death wobble band aid has been twin steering stabilizers +new stock stabilizer, new ball joints, and had to reweld and beef up the drop bracket for the track bar for the 8" Pro Comp lift which broke during an earlier episode of shake rattle and shake some more. After getting home and inspecting the front end I went and purchased new ball joints for both sides upper and lower and 2 new rancho stabilizers. After a couple of years of ongoing research It seems to come down to a few things I haven't done yet. [1] Some claim that I need to adjust the caster to anywhere from 3-6 degrees positive, Is this possible and how do I go about it? [2] WCMotorsports claims that their adj trackbar and mounts $850.00 will cure my problem. [3] BD Diesel has a kit part number 1032100 that will allow up to 3 degrees + caster. Here's the 2cent question I need a million dollar answer or expert opinion for: Does any one know if these 2 fixes really work? The truck was recently aligned and the tires are rebalanced every rotation. 06 f250 8" Pro Comp lift 35x12.5x20 tires and wheels. Any insight to this problem would be greatly appreciated. As always FTE ROCKS best forum on the net. Thanks for stickin with me. Randy

 

From what I understand it has nothing to do with caster. Its the track bar bushings or something like that. Its late so words escape me, but there is a track bar on the market that doesn't use bushing abut has these sort if picitong ball joints on the ends. That's supposed to fix it.

 

I've heard that to and am looking at several brands that replace the ball joint mount with a solid mount that can be installed above or below the axle. they say to go above for lifted trucks over 4". I thought that the drop bracket brought the geometry back to stock? It's been a frustrating, time consuming and expensive process of learning way more than I wanted to about this truck. My reason for buying in 07 and justifying the cost? "It sure would be nice to have a new truck I don't have to work on". Famous last words of a forced 6.0 mechanic.

 

My truck had its first death wobble last week on Interstate, after bridge joint. After reading hundreds (if not thousands) of posts, opinions, and articles I am doing the following (in basic order) :
Inflate tires to door plate GVWR PSI. 65 in my case
Remove plow ballast weights behind rear axle (390lbs)
Reduce air pressure in front coils from plowing setting to normal (12psi)
Confirm no detectable wear in suspension components
Replace trac bar with ReadyLift bar (the ball joint on the axle side of this bar is the most recommended fix for death wobble)
Replace OEM steering damper with single Bilstein 5100.

Practically everyone that mentions caster says to increase (anywhere from 3.5 to 5+), but I read a Ford death wobble document that stated to reduce caster. I personally trust the owner's statements of increasing caster.
The death wobble condition is more predominant in gas trucks, which leads me to believe that the reduced weight on the front suspension is allowing the condition to begin. My plow counter weights take weight off the front, and I presume higher pressure air bags raise the front further. I have not been able to cause the death wobble in the same spot and varying speeds after the non hardware fixes. I am waiting on the hardware to arrive.
Good luck, and slow down

 

Scary sounding.... fortunately I've NEVER experienced anything like that in any of my fords going back to the early 80's.... but, I've also not modified the suspension on any of them other than changes wheels, tires, and shocks, so maybe I was just lucky ?

 

First off, with an 8" lift you have taken the front suspension and drivetrain way out of it's design box, so you need to engineer it yourself. Without knowing what you have already in your lift it's impossible to know what to suggest. With a lift like that you put severe compromises in the steering drag link, the pitman arm, the track bar, and the design of the radius arm that locates the front axle. Some of the "fixes" introduce their own compromises, like a dropped pitman arm for example. The typical dropped arm introduces leverage forces into the steering box that it wasn't designed for, and can introduce wear rapidly.

Anyway, the key is to get the suspension back as close to the stock angles and settings as you can. That means dropping the rear mount of the radius arm down so it sits very close to level again. That will bring the caster back into a stock region, and will let the radius arm suspension geometry work as designed. Dropping the chassis side track bar mount will level out the track bar, raising the axle side track bar mount will do that also but will put the track bar at a different angle than the drag link is at and will lead to steering instability. The track link and the drag bar need to be at very close to the same angle to reduce bump steer (bump steer is self-steering as the front suspension moves up and down - into bump and droop - not what happens when one wheel hits a bump). Dropping the chassis side track bar mount means using a dropped pitman arm on the steering box to keep the drag link in line with the track bar, which works but puts high loads on the steering box. The correct solution is to relocate the steering box but no one does that.

The issue with the track bar is more the stock bar having a rubber bushing at the chassis side mount. That bushing gets soft and allows a tiny amount of movement which amplifies into the wobble. Soft tires allows the amplification to happen - lots of oversize tires are not designed to run the 65 - 75 psi that Ford specifies and which does indeed do a lot to reduce wobble. I saw the caster notice from Ford as well, but I think that increasing caster to around 3 - 4 degrees is what I would do to try to reduce wobble.

Final thought - you've take the truck and redesigned it with a significant lift. Everything that is done to achieve that lift reduces the stability of the vehicle at speed. It's is no longer designed to be safe at 80 mph, so slow down a bit or put the truck back to closer to stock. The lift is basically for looks, so slow down so people can look at you...

Brian

 

The ProComp lift came with new radius arms, a drop bracket for the trackbar, a drop pitman arm, and I have recently put a new [ford reman] steering gear in as the last one was demolished when the trackbar drop bracket broke. I'm not trying to brag or show that I'm juvenile in my driving[51 yrs young] but even with the 8" lift and 37" tyres the truck was very stable and has several 400 mile trips to South Dakota averaging 85+ mph on not the best roads in the country with a fair load on the truck. I do understand your warning though and take it to heart ,but this is the way it has been driven, when I go to work is another story I'm a driller in the oilfield and I'm not nice to it. I DO a lot of maintenance work and keep it clean, this particular problem has a lot of info on it and I was looking for people that have had similar problems, how they fixed it and if the repairs held up.

 

Readylift bar 799.00 WC Motorsports trackbar kit 879.00 radius arm drop brackets 199.00-350.00 hummm ???? which one????

 

I'm going down to ford to get the seals I need to do the ball-joints. anyone actually fixed this that has stayed fixed for 20,000 miles please chime in.

 

a dual steering dampener fixed the issue in my old 2006 F-250 PSD. couldn't drive over 35 mph without getting death wobble at the first bump I hit. Installed 2 steering dampners and the issue never came back.

my lift was a 4.5" Icon with 35" BFG M/T's

how old/worn are your steering dampners? Before you spend $800+ on a fancy new piece of steel, test the dampners out. I wouldn't be surprised if they were worn out and letting the problem come back.




FYI: this is not a "lifted" or "modified" problem. this issue occurs to this very day with bone stock F-250/350 trucks. In almost all cases a simple dual stabilizer/damper setup kills the shake, rattle, and roll. Provided of course your front end components are in good repair

 

The dampeners are like 3 days old. I just got back from the Ford dealer. Its still there, wobbling down main street. So about $750+ I've got new Moog upper and lower ball joints, the track-bar ball joint, 4 seals and 2 o rings, And I still get to do the repairs with a broken rib, some times its really hard to keep luvin this truck!

 

I would get the death wobble from time to time a few years ago on a basically stock truck. The tires where worn, and once replaced the problem went away. My guess is that a broken belt was the problem.

 

Had a wobble on a late 60's Scout back in the day. That truck was a solid front axle with leaf springs. Put some angle wedges between the springs and perches to increase castor and the problem was fixed. Worn or loose parts and/or insufficient castor are the main causes of death wobble. At least that's been my experience.

 

Just a thought...do you have a really good relationship with an alignment shop? Take it there and work with the align tech to see if adjustments to the truck help or hinder the wobble....it might take a few hours of playing on and off the machine but in the end it might work out. Not saying it's going to be the end all fix but it should be better in the end.....

No offence but I think I would really slow down...2 close calls, a crap load of parts and some personal injury....seriously, rolling a truck like yours is never a good thing.....just saying.

 

no joke!

this happened 2 days ago on my current 35" rubber on the Excursion. I was going 60 MPH and it suddenly went crazy shaking
stinkin' steel belt broke