air bags with a big block

[texastrendz]

i have a 2000 c/k 3500 Dually. i am running slam specialties re7 bags on all four corners. the ride is horrible. i want to soften the ride, do i use a bigger bag or what. looking for any and all help guys and gals, thanks again. i have a triangulated four link in rear.

[TylerHuff]

where are your bags setup on the rear? what about your shocks? they play an important role in your ride. i have a 454 and the front rides like a dream with RE7's. the back needs a little help but thats because of my setup and bag over axle

[texastrendz]

it has a triangulated four link with the bags behind the axle. i think this may have something to do with it. the front has custom upper and lowers. when the truck is laid out the bags hardly compress. i think i am using a lot of pressure to get the lift. i think if i built a spacer between the bag mounts to take up some of the slack to compress the bag more i would get more lift a lower pressure. is this correct or am i just talking out my a$$. lol any help would be great

[edflores]

Slams should go down to 3" when fully compressed. Anything higher, and you are using more pressure, and losing lift.
And RE-7's dont belong behind the axle on any fullsize truck. Move up to some Re-8's, if you have the space, but a big sleeve style bag would probably work better.

[texastrendz]

yea i have plenty of room, is the bolt pattern on the head of the airbag the same from the re7 to the re8? that would be an easy fix if that is the problem

[colin_havens]

Originally Posted by edflores

Slams should go down to 3" when fully compressed. Anything higher, and you are using more pressure, and losing lift.
And RE-7's dont belong behind the axle on any fullsize truck. Move up to some Re-8's, if you have the space, but a big sleeve style bag would probably work better.

That is exactly what I would do. Basically they are working the same as a bag over axel setup, and while you gain better towing capacity, you lose some of the softer ride. Good shocks and a larger diameter bag or a sleeve style bag will help your ride, although you need to be sure you are using the bag in its proper useable stroke. You are definately sacraficing ride for lift if the bags barely compress. Here is a pdf of the RE-7s, and they show a max compressed height of 2.9 inches, and a max of 11. Freestanding they are 7 inches high. A spacer would help get you in the correct useable stroke of the bag, but I would still switch to an RE-8 or another bag with a larger diamater. I have also heard good things about the SS line of Slam Specalities bags if you decide you want to stay with that brand.

[cajundragger]

you guys should know your info before you post.


If you not compressing the bag all the way it wont cause an increase in pressure to lift the truck, but will take a larger amount of volume to lift the truck.

pressure=force / area.

force needed to lift the truck is a linear(probably oversimplied) function from when the truck starts to lift up to where something maxes out.

area is a constant inside the bag.

therefor the pressure to lift the truck is a linear function from when the truck starts to lift to when it maxes out. Which means for a certain height off the ground the pressure is the same(as in not enough difference to matter) no matter where the bag is in its stroke as long as its not at its absoult min or max height.

you said you want to soften the ride....so I'd put a larger bag in there.

force = pressure x area

the force is a constant right, so when you increase the area with the larger bag you can decrease the pressure.

personally I'd run re8's in the front and F2107 firestones in the back behind/over/infront of the axle.

[edflores]

Originally Posted by cajundragger

you guys should know your info before you post.

Wow..
[QUOTE=cajundragger;4263486]


If you not compressing the bag all the way it wont cause an increase in pressure to lift the truck, but will take a larger amount of volume to lift the truck.



.[/QUOTE
If he is using part of his bags stroke while the truck is still on the ground, than he is losing his amount of "lift" or stroke.
Will the same bag lift the same weight at the same psi, yes. If its not compressed though, to get to the same fender to ground height, PSI goes up. Maybe we werent on the same page.
I was giving tips based on the likely situation that he is on the upper range of the stroke of the bag, because he is not compressed, he might be using all the range the truck is capable of.
Yes, the bag at the same pressure will lift the same weight. That is a constant. What he should change is the bracketry first to put him at the proper bag height.

[edflores]

Check on slams site, but it should be the same width.
Dominator 2600's are another option, and are probably the softest double convoluted bag out there.
Over the axle like that, you should probably be running at like 25-35 psi, unless loaded, at ride hieght.

[tubbedII]

I'm pretty sure the comment about more pressure to LIFT the truck was more along the lines that he needs more pressure in his bag to be at ride height since his bag isn't fully compressed when laid.

[cajundragger]

Originally Posted by tubbedII

I'm pretty sure the comment about more pressure to LIFT the truck was more along the lines that he needs more pressure in his bag to be at ride height since his bag isn't fully compressed when laid.

and once again, that statement is completely false.

[tubbedII]

Originally Posted by cajundragger

and once again, that statement is completely false.

I'm not trying to start an argument or anything...just trying to wrap my head aroud this. So let me know where I have it wrong. I'm trying to learn here!

Let's say a bag mounted on a trailing arm's stock location and to get it at ride height (frame 5" off ground), you fill the bags to 35 psi. Let's also say that at 35 psi, the bag is 7" tall.

Now, put a set of 2" lift blocks in this set up (i know that's not possible, but follow me on this). To get the bag to the same ride height, the bag would now need to be 9" tall. Wouldn't that mean it would more than 35 psi in the bag to get it to ride height?

[cajundragger]

shouldnt.


It'd take more volume of air. As long as the force on the bag is the same the pressure is the same.

volume and pressure are related, but seperate. Pressure is caused by a restricted volume.

[texastrendz]

i have read in tech articles that sleeved bags are not really designed for heavy hauling. i will not be hauling really anything with a lot of tongue weight. just a car hauler with my 72 c-10. will a sleeve style bag handle this?

[texastrendz]

i also have some type of lowered shock on the back, i think it is a djm nitrogen filled shock. the shaft on these things are massive. i am going to replace them with a stock style shock to see if this improves the ride first.