Death Wobble

[540milotalon]

If I could afford it, I would be pulling my hair out right about now.
1996 Ranger, 5.0 A/T (4R70W) 2 wheel drive and 3.73 rear diff, all from totaled 1999 Mountaineer. 63K and 3.5 years since build.
Truck developed a terrible wobble in June, like it wanted to flip over, I knew shocks had worn out but truck build included shock, brakes and new tires all around.

I have changed front springs (replaced the original 3.0 with new 4.0 coils) rear springs (rear leafs had actually sat down some) front and rear shocks. Both upper and lower ball joints and outer tie-rod ends. I replaced the passenger side spindle and front end was aligned yesterday by one of the legendary local front end techs. On the ride home last night at one particular spot (65 mph) in the road where it had happened previously, it rode good. At a second bumpy spot at 60 mph it took to wobbling. As BAD as ever.

I called front end guy today and he said he would have to ride in it but as we talked he said he remembered one other time and he heard this complaint it was a full size pickup and it was tires.
Tires are 16” Cooper on Aluminum wheels with about 30K and still look good with no obvious wear patterns.
I dunno what to do? I do have another set of name brand tires with a little more wear on the exact same wheels to try for a guess.

 

[85_Ranger4x4]

Pivot bushings?

 

[ericbphoto]

Tires, wheel bearings, pivot bushings and radius arm. Bushings are about all that’s left. I would like to assume a legendary alignment tech would have noticed bad wheel bearings.

 

[540milotalon]

I will have to look at both "pivot bushings" and radius arms. I didn't see anything noticeable but I forgot to mention that as part of the work we repacked and set the front wheel bearings replacing one set of wheel bearings.

The wobble only comes when i get into a place in the road where there is a bumby or uneven wear area and then it does it and its right scary till you slow way down and get it to quit.

It is possible that my front end guy missed something but he knew why we tore into it.
It now has parts i should have changed on the initial build like front coils but i went for the cheap.
Except for the wicked wobble it rides and steers so much nicer........until it doesn't.

 

[JoshT]

Don't get too mad at the alignment guy. Something like the bushings mentioned may not be noticable until the suspension gets unloaded like going over bumps and uneven surfaces. If he wasn't super familiar with this suspension style he wouldn't necessarily have cought it on a normal inspection.

 

[scotts90ranger]

About the only thing not mentioned is the inner joint on the drivers side steering link or the one at the box, one thing these things apparently do in rusty locations is rust around the bolts that hold the steering box to the frame so I would give everything a good spirited shake...

I've run all sorts of janky stuff on my '97, bent wheels, currently only have one functioning shock, put like 40k miles on a set of tires I never had balanced, I set the alignment with calibrated eyeballs and a tape measure and I've never once had death wobble. Not to mention all the janky issues I've had with the '90, passenger front was 1" further back than drivers side, bent a drivers beam on a rock, drove for years with blown radius arm bushings, pivot bushings aren't great, alignment adjusted itself constantly, no sway bars, all the bolts on the radius arm crossmember to the frame were loose (should have been fine thread) and again, no death wobble.

The only time I've had death wobble was on my '00 Explorer with some used tires that were scalloped and one of the outer tie rod ends had worn out, anything over 50mph was downright scary...