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Discussion Starter · #1 ·
Almost done building this 71 suburban with 1 tons, 12 valve, and triple convoluted airbags. I have Rancho 9000 XL shocks on it now and it is super bouncy. It is possible that I may have blown out the shocks and that is the reason why they are not dampening much, but they really never damped it that much, to begin with.
What kind of shocks should I put on this thing?
I have been looking at the full bypass and reservoir shocks like what Bilstein, Fox, and King produces, but I am not really sure I need a super high-end shock like that for this application; however it would be nice to have the ability to adjust them. I am mostly concerned with on-road performance right now and will likely not see a huge of amount of crawling.

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Best body style ever for a Suburban, just wish they had four doors. Awesome looking rig. The Fox IPF (internal floating piston) shocks are on the cheaper end and feel just right with my 300 lbs/in. springs on the front of my SAS Suburban. They're not super stiff though and your diesel is heavier than my 5.3L. They are slightly bigger bodied than most shocks and provide nice damping.
 

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Discussion Starter · #5 ·
Thanks for the feedback.
As you probably already know air springs have a relatively low spring rate normally. My problem is exacerbated by the fact that I put some pretty large air springs on this rig.
Bags: 3B12-304 max diameter 13"; Height: max 18" min 4.8"
I normally run the bags around 23 psi at a height of 10", which according to this chart that is for this specific air spring the spring rate would be approximately 360 lb/in.
From what I have found it looks like newer diesel truck coil springs are around 780 lb/in which is over twice the spring rate
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When the bags are aired up and running a higher psi around 36-40 psi with a height around 16" then the spring rate comes up to around 460 lb/in the ride improves and the shocks are able to dampen the oscillations a bit better; however, the center of gravity is much higher.
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I did make the sway bar from solid chromoly 1 3/8" in the front and 1 1/4" in the rear. I know welding these chromoly to the mild steel arms are not that great of an idea, but it has held up thus far
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Your spring rate is not too soft. You need a shock with relatively low bleed to damp the low speed movement you're describing. Picking a softly sprung SUV application would be a good place to start. Or something that you can take apart and mess with valving. Or send to someone to valve.

And definitely try mounting the ranchos right side up, it makes a big difference.
 

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Discussion Starter · #7 ·
Thanks for the reply. I just ordered some King 2.5 smooth body reservoir shocks for all four corners. I'll put them on there out of the box and see how they perform, if they are still lacking then I'll have them re-valved.
 
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