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Java's F450 RV

bdkw1 said:
And there is your issue.



You are getting into the part of the stroke where the flat part of the curve is at. At 80PSI the spring rate is listed as 535#. That is a little light. To get the spring rate you need the pressure gets really close to the bag limits. A lager diameter bag would let you get the rate you need without pushing the limits of the bag. I realize you have space constraints which is why I pointed out the 7-1/4" bag and not the 8"which would be better.

Going to the taller bag will give your shock a little more time to make you for the flat spot in the curve.
Click to expand...

Those would require more fab and changing the brackets up, are they much better really than the convoluted? (if they are in the middle of the range?)

Ran the last 50 miles at as tall as I wanted the bags. I think it's off bumps but still a bit harsh.
 
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How much room do you have between the tire and the bag currently?

And yes, I think the convoluted bags are that much better.
 
bdkw1 said:
How much room do you have between the tire and the bag currently?

And yes, I think the convoluted bags are that much better.
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Tire isn't the issue, only 3/4 maybe on the frame side
 
So if your hacking the mounts can you move it out 1/2"?

If you move the bottom mount down, you have less chance of the tire getting into it on articulation.
 
You really need to change out your bags, will be worth getting a bag in the middle of it's weight range.

Check out a Volvo car hauler front air ride (yes, big rig) they use a narrow bag, I will look for part numbers for you.
 
bdkw1 said:
So if your hacking the mounts can you move it out 1/2"?

If you move the bottom mount down, you have less chance of the tire getting into it on articulation.
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Yes, but it would make the angles funky.
 
Grendel said:
You really need to change out your bags, will be worth getting a bag in the middle of it's weight range.

Check out a Volvo car hauler front air ride (yes, big rig) they use a narrow bag, I will look for part numbers for you.
Click to expand...

I'll have to find the specs once I'm on a computer. I'm open to that tho if the diameter works.
 
Java230 said:
I'll have to find the specs once I'm on a computer. I'm open to that tho if the diameter works.
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Model numbers posted...

They would probably need like 25 PSI in your truck :flipoff2:
 
OK on a computer now....


bdkw1 said:
Yes.

Edit: It's still perplexing to me that they are running such a small diameter bag. I also dislike the force curve on rolling bags. I think that something like these would offer way better performance.

https://www.airbagit.com/Air-Springs-Air-Bags-p/baga-26-triplex.htm
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Not rated for the weight. I am 6200lbs on the front axle.....

This one is 8.5" Diameter, and #3800lbs. https://www.airbagit.com/Air-Springs-Air-Bags-p/baga-3800.htm



Grendel said:
You really need to change out your bags, will be worth getting a bag in the middle of it's weight range.

Check out a Volvo car hauler front air ride (yes, big rig) they use a narrow bag, I will look for part numbers for you.
Click to expand...

10.12" wide, that's gonna be pushing it.
 
If you want to look at coil rates
35547bfa_c5b7_4d27_bd85_29802d386b7f_a4f8378aee6d88c3cf3d7ab92183061cfe3f99d6.jpg
 
Java230 said:
Not rated for the weight. I am 6200lbs on the front axle.....

This one is 8.5" Diameter, and #3800lbs.
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Well, if you go buy their rating method, the bags you have meow would be rated for even less. Small diameter=less load capacity. But I agree that the 8.5" bags would be better. They would just require the mounts to be modified.
 
Ideally, you want more weight rating to take less PSI and be a softer spring at your weight.
 
Grendel said:
Ideally, you want more weight rating to take less PSI and be a softer spring at your weight.
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Yes totally agree!! I'm just wondering if more volume vs larger diameter would do similar.
 
Java230 said:
Yes totally agree!! I'm just wondering if more volume vs larger diameter would do similar.
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More volume with the same sized bags (ie: ping tanks) will probably feel a little softer at higher pressures (high enough to keep it off of the bump stops), more volume with a taller bag will not hit the bump stops as much.
Not sure if either will be much softer.
Seems that Kelderman uses a taller version of that airbag in their F450 kit if I read their docs correctly.

Aaron Z
 
This pic is of a buddies 2020 F450 full air ride conversion.
You can barely see a number on the bag.
14d424969f294cfbb10860f0ea6dcd70.jpg
 
aczlan said:
More volume with the same sized bags (ie: ping tanks) will probably feel a little softer at higher pressures (high enough to keep it off of the bump stops), more volume with a taller bag will not hit the bump stops as much.
Not sure if either will be much softer.
Seems that Kelderman uses a taller version of that airbag in their F450 kit if I read their docs correctly.

Aaron Z
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Right because it's more or less the same piston size corect?

I will go look at thier docs. That looks the damn same to me. Also a taller lift, you can see the upper bracket is bigger...
 
I wouldn't say it's really lifted though, looks slightly higher than stock?
These are the kits
Edit: The link shows to be stock height for F450 but lifted for F350 which corresponds to the coil height in the Ford Spec guide.
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full drop then full height and second thought you might be right but the mount could be a 17+ difference?
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Probably the +17 yes. Does he have a build thread? The part number for the bag is on that little white sticker right at the top edge....
 
Never mind. From the Kelderman instructions for the 17+. Same bag, Firestone 5323.

50346147532_e4cf627148_c.jpg
 
Grendel said:
Ideally, you want more weight rating to take less PSI and be a softer spring at your weight.
Click to expand...

The spring rate will be more. Think of it like this, the little bag is like a coil spring that is too soft. you need a lot of preload to make it sit at the right height nut it still bottoms easy because it has a low rate. The bigger bag will take less pressure to achieve ride height but will have more resistance to bottoming. At the same ride height they are both exerting the same force but how they get there is the key.







aczlan said:
More volume with the same sized bags (ie: ping tanks) will probably feel a little softer at higher pressures (high enough to keep it off of the bump stops), more volume with a taller bag will not hit the bump stops as much.
Click to expand...

This is incorrect. Adding volume will lower the spring rate and make it bottom easier. With the curve the rolling lobe bags have, ping tanks are a really bad idea.
 
bdkw1 said:
The spring rate will be more. Think of it like this, the little bag is like a coil spring that is too soft. you need a lot of preload to make it sit at the right height nut it still bottoms easy because it has a low rate. The bigger bag will take less pressure to achieve ride height but will have more resistance to bottoming. At the same ride height they are both exerting the same force but how they get there is the key.
Click to expand...

We basically said the same thing. I use HDT truck bags in MDT trucks with less air to get a softer ride at the ride height I want, which typically matches the bag's designed ride height. That was the point I made.
 
So going to the taller bag will only make things worse if its the same diameter? But if its able to move more before bottoming (IE smaller bumpstop) wouldn't that be better? Right now I only have 2.5" of uptravel before hitting bump.
 
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