Air Bag ride quality while empty-

[Matt400]

It may be in my head, but it sure seems like my empty ride quality is down (on bumps) with the install of rear air bags. I keep the pressure at 5 psi.



Any one else experiance this and know why with just 5 psi?

 

[jelag]

The air bags with just 5 psi will provide some lift when the truck bounces through a bump... as the body falls into the frame the bag will compress and the pressure will increase... thus a harder ride...

I have 3500 duallys with 120 gal tanks in the bed. . we hardly feel it. . with the weight of the fuel when its over 25% full. .

 

[betterthanstock]

That's why I have 2 capped off 2" PVC tubes, about 4 ft long, teed into each air line right at the bag, with high pressure hose, I think 5/8 ID. They fit under the bed sideways, hose-clamped to 2 of the structural rails under the bed floor.

It's called an expansion chamber, and reduces the spring rate.

The bags are rated for 100 psi, and the 2" pvc for at least 200.

 

[Matt400]

Interesting idea with the expansion chamber. I would suppose that would also increase sway somewhat giving and added area to compress into when carrying a load and more pressure??



My pin weight runs 1800 to 2000 and I am beginning to wonder if the bags are overkill for me cuz the truck sets pretty good with just 5 psi.



I find 25 psi is plenty for a more stable ride. Better shocks would probably accomplish the stability issue.



I didn't think 5psi would have been so noticeable unloaded.



edit I am using the PacBrake brand, their recommended 2wd single bag kit on my 4x4 as I pulled the lift blocks. I would imagine the 2wd's lower volume bag would ride more rough than the larger volume 4x4 bag.

 

[Garlic]

On my 96 I set them up to run 0 psi unloaded, and what ever pressure I set them at to level the load. The 5 psi on it DOES make a noticable ride difference, harsher. The 07. 5 has an auto leveling valve on it and maintains 0 psi with no load in the bed. I have not tried it with some pressure in it, but it does stiffen it with light loads. I have the 4wd kit and the lifting blocks are still in place. It was easy to install with basic hand tools, and the static height of the bags fit very well with 0 psi in them. The brackets on the 96 I built from the Ride-rite kit to clear the 5'er rail mounts and to place them at the static height with no air in them. No complaints on either one, the 96 has 170K on it and has towed about 70% of it's life. The auto leveling valve made all of the difference on the 07. 5 so I don't have to manually adjust the height of the truck when the 5'er is loaded. The wife really likes the loaded ride of air vs just springs.

 

[Bob4x4]

That's why I have 2 capped off 2" PVC tubes, about 4 ft long, teed into each air line right at the bag, with high pressure hose, I think 5/8 ID. They fit under the bed sideways, hose-clamped to 2 of the structural rails under the bed floor.

It's called an expansion chamber, and reduces the spring rate.

The bags are rated for 100 psi, and the 2" pvc for at least 200.

"reduces the spring rate rise under compression"

You can see the pressure rise under compression on a gauge. Has your accumulator system eliminated this or just reduced it?



With my Carli long travel bags it rides great with low psi even empty. I don't have the OEM springs or shocks so I am sure that helps as well.



Bob

 

[Matt400]

How do you "size" an accumulator for something like this? My system is the smaller 2wd single convoluted bag.



Seems there would be a fine line between spring rate reduction needed at 5psi on small bumps unloaded vs the reduced sway control at higher psi & loaded conditions.



I found this one:

KMW Performance - Air Suspension, Bags, Cylinders, Struts