air ride... not enough lift!

[sqweaka]

hi all, ive added a budget air ride setup to my 49 pickup, ive 6" firestone bags up front in a jag cross member and 110 sleeved firestone rears on a four bar setup, i bought a kit of ebay to operate it, 4 gallon alloy tank, single viair 444c compressor and 4 paddle switches, 2x viair twin needle gauges, the tank came with a 110/145psi pressure switch, oh and 1/4 air line.
in operation with a full tank, by putting everything in the front first till it stops lifting (120psi approx) then whats left in the rear (40 psi approx) i can get the truck up to ride hight.. just about, but in reality often there isnt enough to get it of the ground, and i have to wait till the tank refills to get clear of the ground
i had a spare 2 gallon tank which i added inline with the 4g one but to be honest it made little difference, is a higher pressure switch the answer?
the tank is rated at 200psi, but i have heard that the viair pumps are good but the check valve do fail!
any advice please

[dsraven]

post up some pics showing the air bag placement. it could be that the bags are too close to the pivot point so a lot of mechanical advantage is lost. a lot of pressure is then required to lift the vehicle. the further away from the pivot point the bag is the easier it is for the bag to lift and also the less suspension travel you get before the bag is fully extended.
anyway, post some pics and let us see the set up.

[lolife99]

A Firestone 2500 bag has a minimum height of 3".
Max height of 8".
Ride height should be around 5".

So if you have more than 3" of room between your bag mounts when your truck is air'd out,... you need to add a spacer under the bag.

[mr48chev]

I'd go along with DsRaven, post some good clear photos of your setup and how the bags are setup and one or more of the guys who know bag setups can probably give some good advice . The better the photos the easier they can tell what needs to be done.

[sqweaka]

the rear bags are mounted to the front face of the axle similar to the TCI setup, the front bags are fitted in the normal spring position on a jag xj6 crossmember, ill see if i can put up pics later but i dont think bag placement is the problem

[joedoh]

Originally Posted by sqweaka

i dont think bag placement is the problem

you should. with the geometry advantage of the front arms you should be seeing closer to 7.5 inches lift in the front with those bags. lolife is right, if you arent squishing the bag to 3 inches at full drop, you are losing lift and raising the amount of pressure you need to get up.

in the rear it can be a tough pill to swallow that you only get 5 inches of lift, I would suggest adding a spacer to keep the truck of the ground more, especially if you want to ride level and not down in the back.

there is a couple intersecting points to a bag suspension, think of it as roshambo with ride height, stance, and ride comfort. ride height is usually at the detriment to ride comfort (more lift more pressure worse ride), stance is usually at the detriment to ride height (less lift less clearance), and ride comfort is usually at the greatest detriment to stance (front up, rear down).

you need to find your triple point and set the truck up there. airbags usually (not always) ride best inflated to about half their extended height. so with a bag that has 6 inches of lift (7.5 in the front with the geometry) you need to set the bag up to squish out of air 3 inches lower than the desired ride height in the rear and 3 3/4 inches lower than the desired ride height in the front. this may hold you off the ground higher than you want when aired out, but it will RIDE GOOD and be AT THE HEIGHT YOU WANT.

if you want to lay all the way out and still hit that height, first make sure your upper and lower mounts are the min distance of the bag apart like lolife99 said. then get bags with more lift. you may need to carve out space, but how much do you want to be cool? be aware, larger bags have more volume and lower pressures, you can bottom out easier, get good gas charged shocks to go with it. in the rear you can go with a leveraged setup with the bag mounted on the bar, with it mounted halfway up the bar you will get twice as much lift, a whole 10 inches! the bags will see increased pressure at that point, and the bars and mounts will see twice the effective weight (halfway is just a talking point, you can mount it closer to the axle and scale the pressure and weight) another solution for the rear is to use sleeve bags, they do NOT lift fast, they will tear themselves up if you dont limit their travel with shocks, but they will give about 10.5 total lift (so figure 5-6 inches lift with a nice soft ride)

[sqweaka]

i maybe wrong here but ive set the bags up so at ride height (the hight i want it to ride at) the bags are half inflated... when the truck hits the ground i stop deflating the bags... so i'm not taking more air out the bags than is necessary to lay rocker.. but when fully down they are almost empty anyway, what i think is there is not enough pressure in the tank to give me the lift i need

[joedoh]

Originally Posted by sqweaka

so i'm not taking more air out the bags than is necessary to lay rocker.. but when fully down they are almost empty anyway

nope, this is the problem. if you are ok with half inflated ride height and your pressures are too high, its because you are probably not squishing your bags ALL THE WAY flat of air. if it takes 40-60 psi before the truck starts moving, you are just filling that empty space up until the truck starts lifting. thats where all that extra volume in your tank is going.

a 6" firestone bag correctly installed will lock up an s10 suspension with 80psi. I know you have a jag suspension but on an s10 locked up (upper arm hitting the frame) is about 8 inches of travel. if it takes you 120 psi to get to half extended, I would bet you probably arent squished. you need to lay the truck out without a bag in it and measure the distance between the mounts. alternatively you can just drive up on a couple 2x4 and see if you still can lay out, if the truck still goes all the way down or close to it you need to adjust your mounts.

[LCA1971]

Good info!!!

[e015475]

Squeaka, Joedoh et al-

In the interest of keeping the conversation moving (I have the same setup and am really curious about the answer) here's a picture of the Jag IFS with the 6" airbag. It is a Slam bag but should be similar enough.

This is a 6" Slam bag sitting in the Jag spring pan. The bag sits just about half way between the inner fulcrum of the a-arm and the axis of the spindle



Here is the 6" airbag installed in the Jag IFS.



With a 26" diameter front tire, the front cross-member is 1.4" off of the floor. (the Slam bag has an internal bump-stop)

My shop compressor only goes to 100PSI, but here's the pressure vs cross member height-

0spi 1.4"
80psi 1.5"
90psi 2.1"
100psi 6.2"
110psi 9.2" (up against the bump stop -data extrapolated)

The total travel of the suspension is about 8" and the bag should be extended right about the middle of it's travel at normal ride height which is the Jag cross member sitting about 6" off the ground. I think you're going to need a spacer on your setup, as others have noted. I can't put my running boards on the pavement - there's about 3" between the running boards and the ground.

If I remember Boyle's law correctly, if you want to inflate your airbags from laid out at 0PSI to ride height (120psi) with a four gallon tank, you'll need to start with a tank at about 170psi, and even at that pressure it will be slow as the system reaches equilibrium at 120psi. I did the calculation for just the front airbags and I imagine if I added the volume of the rear airbags it'd push the pressure over 200PSI with only a four gallon tank. You need higher pressure, a bigger tank or probably both.

FWIW - I have a 4 gallon tank too, but my strategy is to 'set and forget' the ride height and I won't be 'laying it out' unless it leaks between drives, and then I suppose I'll just have to wait while it airs up.

Sqweaka - how did it ride? What did you do for front shocks?

Joedoh and the other airbag experts - how will a front airbag system ride at 100-120 PSI and the leverage ratio the Jag has? The Jag comes with a Boge gas shock. Can you recommend a brand of gas shock that works well with bags? If the rear airbags are only 50psi, how would you expect the truck to ride? Do you need more or less gas shock control at the rear where the pressure (and spring rate) is lower?

[joedoh]

Originally Posted by e015475

Squeaka, Joedoh et al-

In the interest of keeping the conversation moving (I have the same setup and am really curious about the answer) here's a picture of the Jag IFS with the 6" airbag. It is a Slam bag but should be similar enough.

This is a 6" Slam bag sitting in the Jag spring pan. The bag sits just about half way between the inner fulcrum of the a-arm and the axis of the spindle



Here is the 6" airbag installed in the Jag IFS.



With a 26" diameter front tire, the front cross-member is 1.4" off of the floor. (the Slam bag has an internal bump-stop)

My shop compressor only goes to 100PSI, but here's the pressure vs cross member height-

0spi 1.4"
80psi 1.5"
90psi 2.1"
100psi 6.2"
110psi 9.2" (up against the bump stop -data extrapolated)

The total travel of the suspension is about 8" and the bag should be extended right about the middle of it's travel at normal ride height which is the Jag cross member sitting about 6" off the ground. I think you're going to need a spacer on your setup, as others have noted. I can't put my running boards on the pavement - there's about 3" between the running boards and the ground.

If I remember Boyle's law correctly, if you want to inflate your airbags from laid out at 0PSI to ride height (120psi) with a four gallon tank, you'll need to start with a tank at about 170psi, and even at that pressure it will be slow as the system reaches equilibrium at 120psi. I did the calculation for just the front airbags and I imagine if I added the volume of the rear airbags it'd push the pressure over 200PSI with only a four gallon tank. You need higher pressure, a bigger tank or probably both.

FWIW - I have a 4 gallon tank too, but my strategy is to 'set and forget' the ride height and I won't be 'laying it out' unless it leaks between drives, and then I suppose I'll just have to wait while it airs up.

Sqweaka - how did it ride? What did you do for front shocks?

Joedoh and the other airbag experts - how will a front airbag system ride at 100-120 PSI and the leverage ratio the Jag has? The Jag comes with a Boge gas shock. Can you recommend a brand of gas shock that works well with bags? If the rear airbags are only 50psi, how would you expect the truck to ride? Do you need more or less gas shock control at the rear where the pressure (and spring rate) is lower?

nice info!

the slam specialties bags are great. It has more force/psi than the firestones which tend to spend that pressure by balooning.

the firestone 224c is the 6" bag and i was incorrect above, the bag that needs 80psi from slam specialties is the RE7, my favorite bag from any manufacturer for front setups. so e015475, it isnt a direct comparison between your RE6 and squeakas 6" firestone. the RE7 is the direct comparison to the 6" firestone

I have had a lot of airbagged vehicles, and by a lot I mean more than 12, and most of them I did the systems setup on. I remember being in squeakas position, knowing how it worked and wondering why expectations didnt meet reality.

e015475, you will quickly find you dont need as much pressure to drive as you think you do on the bench. my last truck with airbags was my 65 c10 on s10 chassis, re7 front and firestone sleeve in the rear. ride height was 60psi front and less than 20 rear. I had a 5 gallon tank and a 185psi pressure switch, running a york air conditioning compressor as an EDC. before that I had a 62 galaxie with air lift 2600 front and rear, ride height was 65psi front and less than 20 rear. once you start finding that sweet spot in the ride, you will run much less pressure.

[sqweaka]

thanks all ive been suffering with man flu this week so will check out your suggestion next week see if i can get a spacer under the front bags

as for the ride e015475 it rides pretty good, but ive nothing to compare it with, never driving the truck with anything else.. i used the standard jag shocks up front