Absolutely. Glad they are going to take care of it for you OP, & better yet Ford has realized there is a problem and addressing it. This is great for others that will have such issues
Really good news for you, so that's great.
I didn't want to create bad press with my post. I only wanted to make others aware that if they intend to run 37's there's a great chance they're going to get denied warranty if they run into this problem. Since it seems that it's impacting a lot more than just myself, I think we will see more of this in the future.
That's positive news they decided to cover it under warranty.
I thought the purpose of me replacing the UCA's, tie rods, etc was to correct the geometry with the suspension lift.
I don't think you created "bad press" I think you created "good press"...Although you went through what happens alot in this business, where a particular dealer is just not going to warranty something for reasons that likely have nothing to do w/you or your particular situation. They may already be on the "hot seat" for warranty, or the service manager simply wants to stay off the "hot seat", or a particular tech just plain doesn't want to do the job for warranty pay, and will use ANY excuses to get out of it. But your case shows that Ford is willing to do the right thing, if proper channels are followed.
Good to read!
OK, educate me here - I'm a EE not a ME... I really like this explanation, but to my pea brain, a link with Johnny Joints on both ends, should have better misalignment range in the joints than poly/rubber bushings are capable of squishing. Wouldn't that be better? Sincere question, help me understand...I want to share a simple diagram I made that illustrates the suspension bind myself and some others were talking about. Even if its not the root cause in this case, it is worth considering when looking into suspension components with compliant joints vs rigid joints. (on OEM suspension geometry)
This is not too scale, but representative of the side view (what matters here) of the Bronco rear suspension (as well as most OEM 5 link set ups).
The upper control arm and lower control arm are different lengths and not parallel. The angle between them is more relevant than the difference in length in this case. Because the arms are not parallel, (and to a lesser degree, different lengths), as the suspension moves up or down, the axle rotates forward and backward. The primary goal of this is to help counteract the forces that squat or jack the rear suspension during forward acceleration or braking. You can visualize this by imagining the torque induced at the axle by brake or driveline torque, and how it wants to lift or lower the suspension. For example, you step on the gas, the wheel torque is counter clockwise, the reaction torque at the axle is clockwise, which wants to pull the suspension down because of the angle of the links. This helps counteract the rear squat that naturally occurs as the vehicle accelerates forward and weight is transferred to the rear. The opposite is true for braking. A secondary goal of this is to help the axle pinion angle stay more aligned to the transmission or carrier bearing throughout the suspension travel. And of course beyond both of these goals there are all kinds of packaging limitations, costs, weight, durability, and NVH to consider.
Now lets look at the suspension when one side is all the way up, and the other is all the way down. (again, not to scale)
You can see that if the joints both at the frame and axle have no compliance, the axle is forced to be at a different angle between the left and right side. Axles are very strong, but when you pit it against the frame, and very robust linkages/joints, and brackets, its going to slip. If you make the axle stronger, one of those other things will give out or flex (flex may be fine but could eventually lead to fatigue failure). From the OEM perspective, the bushings themselves give. This not only helps NVH, and long term durability of the joint, it allows the axle to behave and handle well on flat surfaces as well as give the compliance needed to articulate reasonably well.
If you want to run rigid links, you either need to adjust the suspension geometry (parallel links, or triangulated) or you need to remove one of the control arms. When you remove one control arm, only the suspension arms at one side of the axle will dictate the angle of the axle (thus no binding). Meaning the torque/braking loads will be counteracted by only one side of the suspension. The side with both links. How well this could function depends on a lot of factors and probably wouldn't work well in an otherwise OEM set up. Triangulated is widely regarded as the best solution (deletes the track bar) but is also the hardest to pull off in an otherwise OEM set up. Aftermarket may offer solutions to run longer and more parallel arms (requires different frame/axle mounts) as a good solution and alternative to triangulating links or deleting a link.
Disclaimer that this is not professional advice, just take this as my observations. Much of this can be found and explained in engineering vehicle dynamics books.
Johny Joints may allow more free motion (to a limit) with respect to articulation of the linkage itself at each joint. But what is causing the binding in this case is not the articulation of the link itself but the forward and rearward rotation of the axle as one side moves up, and the other side moves down.
I have the Johnny joints on mine, and w/the coilovers unbolted the axle housing can be easily moved up, down, and articulated side to side w/no bind, almost by hand (or by hand, by a stronger fella than myself). There is no bind whatsoever
Interesting, that would hint to me then that the geometry is much more parallel than what I drew up.
