Suspension Problems
04-26-2017, 05:39 AM
#1
Suspension Problems
I'm having two suspension problems with my truck. First off, we're talking about a 45k-mile 14 XLT screw 4x4 boost, 5.5" bed. When I bought it used at 29K-miles, it came with Ironman All Country A/T 275/65R18 tires which appear to have about half their life remaining.
And here we go
For about a year now, I've had the Hellwig anti-sway bars on both ends of the truck. I absolutely love how they help to keep the truck level in turns, but that comes at the cost of the back end feeling jittery when I encounter uneven bumps at surface-street speeds. That's problem #1.
At about the same time, I installed AirLift LoadLifter 5000 Ultimate air springs to level the truck when the bed is loaded, and calm the headlights when towing. The air spring installation includes the removal of the factory jounce bumper, because the springs have their own internal bumper. The benefit of that internal bumper is that the springs can be operated uninflated, and when doing so they have no affect on unloaded ride quality.
When I installed the air springs, I removed the rear axle blocks to get a head start on leveling the truck. I don't want to lift it, I just want it to sit unraked. With the springs at 0 PSI, the wheel wells are at at 36-5/8" and 36-7/8". Success.
Problem #2 is that if I don't slow to the barest of crawls when traversing speed bumps and similar obstacles, the rear of the truck hops pretty hard. I can't tell if the hop is happening because the jounce bumper in the air springs is too tall for the lowered axle, or if something else is causing it. If I keep 7 PSI in the air springs, the rear end calms down to almost a tolerable level. The jitter from the anti-sway bar is mitigated and the big hops are less noticeable. But then comes problem #2.5 ....the wheel wells sit at 36-1/2" front and 38-3/8" rear. The factory rake is restored. Fail.
One way to fix these problems is to remove the rear anti-sway bar and the air springs. BUT! ...I'm getting what I want from them where handling and load-leveling are concerned.
What I want is to improve ride quality. I've got it my mind that a good set of charged shocks might provide enough damping to get it done. I'm imagining something along the lines of the Fox Stage 1 kit, with shorter rear shocks to account for the lowered rear end. What do you folks think?
And here we go
For about a year now, I've had the Hellwig anti-sway bars on both ends of the truck. I absolutely love how they help to keep the truck level in turns, but that comes at the cost of the back end feeling jittery when I encounter uneven bumps at surface-street speeds. That's problem #1.
At about the same time, I installed AirLift LoadLifter 5000 Ultimate air springs to level the truck when the bed is loaded, and calm the headlights when towing. The air spring installation includes the removal of the factory jounce bumper, because the springs have their own internal bumper. The benefit of that internal bumper is that the springs can be operated uninflated, and when doing so they have no affect on unloaded ride quality.
When I installed the air springs, I removed the rear axle blocks to get a head start on leveling the truck. I don't want to lift it, I just want it to sit unraked. With the springs at 0 PSI, the wheel wells are at at 36-5/8" and 36-7/8". Success.
Problem #2 is that if I don't slow to the barest of crawls when traversing speed bumps and similar obstacles, the rear of the truck hops pretty hard. I can't tell if the hop is happening because the jounce bumper in the air springs is too tall for the lowered axle, or if something else is causing it. If I keep 7 PSI in the air springs, the rear end calms down to almost a tolerable level. The jitter from the anti-sway bar is mitigated and the big hops are less noticeable. But then comes problem #2.5
....the wheel wells sit at 36-1/2" front and 38-3/8" rear. The factory rake is restored. Fail.One way to fix these problems is to remove the rear anti-sway bar and the air springs. BUT! ...I'm getting what I want from them where handling and load-leveling are concerned.
What I want is to improve ride quality. I've got it my mind that a good set of charged shocks might provide enough damping to get it done. I'm imagining something along the lines of the Fox Stage 1 kit, with shorter rear shocks to account for the lowered rear end. What do you folks think?
04-26-2017, 08:06 AM
#2
Senior Member
You could change out the air bags for the non-jounce bumper style. The ultimate solution to this would be to increase the distance between the upper and lower mounts, but I'm guessing with a lowered suspension this is not possible. The sway bar phenomenon is normal. If you hit bumps with both tires at the same time there is no effect, but if you hit at an angle (one wheel at a time) you get the stiffness of the bar added to your existing spring rate. You could go with a lighter bar, but you'll lose some of the anti-roll/sway effect. Don't you just hate compromise ? 
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timtrace (04-26-2017)
04-26-2017, 09:18 AM
#3
Thanks, PerryB. I was also thinking that the 4x4 bags could be swapped out for the 4x2 bags, which should have a shorter jounce bumper inside them - at least, this is how it works in my mind.
That's if the jounce bumper is actually the problem. :/
Do shocks have any hope of damping anti-sway bar "jitter?" (trying to describe the truck's actions in a single word). I'm guessing "not," because the bar is tied directly to the chassis....
That's if the jounce bumper is actually the problem. :/
Do shocks have any hope of damping anti-sway bar "jitter?" (trying to describe the truck's actions in a single word). I'm guessing "not," because the bar is tied directly to the chassis....
04-26-2017, 11:08 PM
#4
Senior Member
In my case, I have Firestone bags and they have NO internal bumper. A high end set of shocks will certainly improve, but not eliminate the sway-bar jitters.