Stability issue on 2015 F250

Status
Not open for further replies.
Originally Posted By: cptbarkey
Originally Posted By: Ramblejam
One. More. Time.

Let me guess...you're running 18" BFG AT KO's @ 65PSI in the front.

Donald?


I have the exact same tires on my 2000 chevy 2500 fully inflated, when unloaded they do not cause any issues like OP describes. Stop parroting internet myths.

The issue OP describes is common with all trucks from the beginning of time. Sell it and get a 300C if you want luxury.


Your truck was an IFS, the Fords have a solid front axle. The "death wobble" is all but unheard of on a IFS truck.
 
Originally Posted By: Donald
Dealer says I should to stock rims tires. The ones I have are the same size as stock however, just fancier.
Do they have some take-offs you can mount for a quick drive to see if that's the issue? I'd talk to them.
 
I'm not sure this has been summed up. Solid axle vehicles are prone to develop "death wobble" as the suspension joints develop slop and play. the process is amplified or hurried along if one adds larger wheels and tires, which push the rubber bits farther, allowing more slop to be revealed in the bushings. Basically what happens is a bump deflects a tire to steer ever so slightly, but then it begins to oscillate, like the rim is bent, with the vehicle rolling straight while the wheels roll on the inside edge, outside edge, inside...

Key things to check are caster angle and then track bar bushings. any slop allowing side-side movement is bad. Understand that the first few degrees of steering are hydraulically connected and not rigidly coupled to the steering wheel, so the steering arms can oscillate LR without being exactly replicated at the steering wheel. If the axle itself is moving L/R due to worn track bushings, it will cause/allow the wheels to pivot even if the steering system is 100% unmoving.

This plagues many 4x4s, especially with larger wheels/tires, and is aggravated by lifts which add more leverage against suspension components and/or change geometry.

All that said - it's gonna have to be put on a lift, and bushings need to be replaced, even if by hand they can't be made to budge.
 
Originally Posted By: meep
I'm not sure this has been summed up. Solid axle vehicles are prone to develop "death wobble" as the suspension joints develop slop and play. the process is amplified or hurried along if one adds larger wheels and tires, which push the rubber bits farther, allowing more slop to be revealed in the bushings. Basically what happens is a bump deflects a tire to steer ever so slightly, but then it begins to oscillate, like the rim is bent, with the vehicle rolling straight while the wheels roll on the inside edge, outside edge, inside...

Key things to check are caster angle and then track bar bushings. any slop allowing side-side movement is bad. Understand that the first few degrees of steering are hydraulically connected and not rigidly coupled to the steering wheel, so the steering arms can oscillate LR without being exactly replicated at the steering wheel. If the axle itself is moving L/R due to worn track bushings, it will cause/allow the wheels to pivot even if the steering system is 100% unmoving.

This plagues many 4x4s, especially with larger wheels/tires, and is aggravated by lifts which add more leverage against suspension components and/or change geometry.

All that said - it's gonna have to be put on a lift, and bushings need to be replaced, even if by hand they can't be made to budge.


The track bar bushing was replaced. Along with steering stabilizer. Nothing else was loose when dealer checked.

I believe the tires are stock size.
 
what if we're going down the wrong path? what if it's as simple as worn shocks allowing the tire to start bouncing?
 
Originally Posted By: meep
what if we're going down the wrong path? what if it's as simple as worn shocks allowing the tire to start bouncing?


Well the vehicle has 36k miles and the front end has been checked for wear by the dealer.

I am in contact with Ford Corporation to escalate the issue since its now out of warranty but was under warranty when the dealer last worked on the vehicle. So it should be covered but I need to not delay pursuing it.
 
It'd be great to know the alignment specs/results.
Meep and myself mentioned caster angle. If everything else has been checked out, this is a good place to look. Stock might be around +1 degree, 2 or 3 degrees would be even better. There should be some adjustability of camber and caster via the upper ball joints.

Positive caster increases straight line stability and self-centering of the steering.
 
Originally Posted By: Fsharp
It'd be great to know the alignment specs/results.
Meep and myself mentioned caster angle. If everything else has been checked out, this is a good place to look. Stock might be around +1 degree, 2 or 3 degrees would be even better. There should be some adjustability of camber and caster via the upper ball joints.

Positive caster increases straight line stability and self-centering of the steering.


The first dealer did an alignment. About 1 month ago.
 
Originally Posted By: Donald
The first dealer did an alignment. About 1 month ago.


But what are the factory alignment specs and what were your truck's measurements?

Let's say factory caster angle is +2.5 degrees +/- 1.3 degrees.

+1.2 degrees is going to handle differently than +3.7 degrees, but they would both be within spec and "aligned."
 
Originally Posted By: meep
what if we're going down the wrong path? what if it's as simple as worn shocks allowing the tire to start bouncing?


Good point.

A co-worker of mine ended up destroying both of his on his 2015 when he had to slam on the brakes. A guy pulled out in front of him and lost some PVC pipes off the top of his truck.. 1 still made it through the grill and embedded itself into the radiator. Sounds odd, but it was covered under insurance. (I had a hard time believing it..)
21.gif
 
Originally Posted By: Fsharp
Originally Posted By: Donald
The first dealer did an alignment. About 1 month ago.


But what are the factory alignment specs and what were your truck's measurements?

Let's say factory caster angle is +2.5 degrees +/- 1.3 degrees.

+1.2 degrees is going to handle differently than +3.7 degrees, but they would both be within spec and "aligned."


You make a point. But short of watching over the mechanics shoulder, not sure how to determine.
 
a bounce test would be a little harder on a 250 just because it's heavy, stiffly sprung, and your measly humanoid frame isn't going to test it much. But being solid axle setup it should be pretty easy to do - slap a couple of new ones on there and see if it improves? Bilstein, monroe reflex, gabriel ultras, all get decent talk here.
 
As to how to get the alignment numbers, maybe just ask for the alignment printouts of before and after? Everyplace I've ever had an alignment gave them to me... Not a mystery or trade secret...
 
Status
Not open for further replies.

Similar threads

N
Hellwig bushings vs Moog Thermoplastic bushings vs Energy Suspension polyurethane
Replies
5
Views
2K
Navi
C
GM truck steering gears = OEM, Reman, Redhead, Bluetop or something else?
Replies
11
Views
894
D60
OM605
Mercedes driveline rumble
2
Replies
34
Views
836
D60
C
Tie Rods, Swaybar Links, Rack, or Strut Mount?
Replies
18
Views
886
c3uo
redhat
Got an alignment help me understand
2
Replies
31
Views
2K
camrydriver111
Back
Top