Front end alignment wiggle at 55mph

[cstarbard]

Hey guys,

I've been doing a lot of work to my 96 2.3 4x4 Ranger and one issue I have yet to resolve is that the front end, with hubs unlocked, has a strong "wiggle" that you can see in the hood (can see it shake up and down), feel it in the steering wheel. It only happens around 55, under load or coasting, it is not noticeable at 50mph and smooths out a little by 60 but is still there. If you look in the rearview mirror when the shake/wiggle happens, the rear of the truck doesn't seem to be shaking and it feels like it originates from the front end so I'm thinking it's a front end isssue, but all advice you can give me is helpful! Here's what I've done so far:

Set the toe: it was out 1/8" when I got the truck. I have it adjusted to 1/16" toe in now, that helped reduce the wiggle I'm describing but not by a lot

New wheel bearings, seated with 35ft-lbs, backed off, re tightened inner locknut with 16 in-lbs, outer locknut to 150-200ft-lbs

Front rotors turned, new pads installed

Rear pinion angle was fixed; I have a double cardan driveshaft so I set it up to have .5degrees nose down on the pinion relative to the slope of the driveshaft

I don't know how my camber/caster are right now, I want to get fully adjustable camber/caster bushings and set those as soon as I can

Haven't balanced my wheels/tires but will be doing that soon, rotate them often because of the TTB tire wear, but it hasn't seemed to matter which pair are up front or in the rear

Truck drives very smooth up to 55

Thanks

 

[4x4junkie]

That's about the speed tire imbalance (or out-of-roundness) generally shows itself. If rotating the tires isn't helping much, maybe it's possible you got two or more tires out of balance. Another possibility is a bent rear axle flange, but I would think you could tell that more from the rear though.

Have you jacked up each tire/wheel and checked for out-of-roundness? (as little as a couple millimeters out of round will induce noticeable shaking at those speeds IME).

 

[cstarbard]

Thanks for the reply as always.

I did three things yesterday, and now the vibration is totally gone!

1. I have one of those crappy transmission crossmembers with bushings outside the frame rails, they were shot, couldn't find replacements, swapped to a cross member with no bushings

2. Swapped my transfer case (which had slop) with one I rebuilt (no slop)

3. Put the transfer case counterweight on (was missing it)

Very weird, didn't think any of those things were the issue but one or all of them must have contributed to the wiggle

 

[adsm08]

Well bad transmission mount bushings and a missing vibration damper could both contribute to a whole vehicle vibration.

You should see some of the crazy vibration damper Ford has come up with over the years. Or the issues with the 3.5 LWB F-150s. They make the whole truck vibrate on takeoff. Ford was telling me that it's because the 3.5 makes power similar to a 5.4, but isn't heavy enough to dampen the vibration out of the frame.