coils V's airbags

[dr.mick]

got a GU ute with 4inch coils and interested in going airbags all round, but not to sure about what hight airbags are available? and if i'll loose any wheel travel?

any idea's???

[PGS 4WD]

Air bags on the rear are great, better articulation due to air bags retaining more consistant spring rate when compressed or decompressed, due to this though you need a sway bar or after cornering the car will continue to lean over. Also good if your load varies as you can maintain vehicle height by adding a few psi.
I wouldn't suggest them on the front due to there tendency to body roll, if you were to you'd need a 30mm front sway bar to keep the vehicle stable on the bitumen.

Joel

[dr.mick]

what about hight wise, can you get airbags to suit a 4 to 6 inch lift?
would the airbag be at it's normal ride hight at this leval?

[Freakazoid]

On the front they actually don't roll much. They handle better than the 2" OME I had in front. The problem with the airbags is that they loosen the back up so much that the front doesn't do any work. So I have to keep my swaybar attached so the front can work a bit as well. Am plannign on an X-link to loosen up the front.

At speed on washboard, nothing beats an airbag for comfort and roadholding, especially the front ones. I put Goodyear 1R8-009 in front but put a different cone/piston in. a more constant springrate. In the back the Goodyear will fit as well, but I put a Firestone in that has 14" of stroke. IF you put the Firestone or Goodyear in the back you should be able to adjust the ride by about 6-8". You can run almost on stock height but will bottom out if you fit longer shocks to make use of the travel of the bag. Full extension is just stupid. I can fully extend a Rancho 32" shock and at the same time run at stock height. The adjustability is great.

[Wooders]

Air bags on the rear are great, better articulation due to air bags retaining more consistant spring rate when compressed or decompressed, due to this though you need a sway bar or after cornering the car will continue to lean over. Also good if your load varies as you can maintain vehicle height by adding a few psi.
I wouldn't suggest them on the front due to there tendency to body roll, if you were to you'd need a 30mm front sway bar to keep the vehicle stable on the bitumen.

Joel

Not sure I'd really agree n some of that Joel....
Firstly unless you are venting the bags from one side to the other (IMHO a bad idea) then a singe air spring is more progressive rate as it is compressed the pressure increases effectively increasing the spring rate - ie not constant.
Also I would not say an air spring has more articulation - infact often an airbag will mean less because it's generally mounted at each end unlike a coil which is usually free at at least one end.
Also on the front they are fine (again assuming you are not sideways venting between the bags).

It's worth remembering the lower the air srping is run, the softer the ride & the greator the body roll - whereas when it's more inflated (within reason) the increased pressure can lessen it.

I love the airbags on my TJ. It gives acceptable wheel travel which in my opinion is very well balanced, gives a great ride on road & off and with the use of height sensors it's always at the same height regardless of load (or not) ....plus the sensors give me active susension onroad

[Suspension Stuff]

I know for the Patrol and Cruiser you can get more travel with the air bags then your coil so articulation will be improved plus if you link them you will get more pressure to the ground at full travel meaning more bite into mother earth.

I know with the Range Rover mark3 airbags the bottom bit is shaped like a cone so the spring rate is greater with less air in the bag at normal ride height therefore when pumped up say 2" you will get a softer spring rate suiting off road better. This isn't available for the Patrol yet to my knowledge and I suppose this is why Freakazoid has made his own.

As for the TJ with full air bag, I am interested in this as I have a ZJ but I have not found anyone who does bags that skinny. Wooders would your air bags fit mine and where would I find them.

Cheers
Shane

[Wooders]

Shane,
Yes they can be adapted to fit a ZJ.
PM or email me offline if you want details (we are the Aussie distributor for AiRock).

[Butt Craic]

Wooders,

I've recently been wondering whether the AiRock interface, computer and height sensors could be integrated with some of the airbags that have been developed for Patrols and Cruisers to effectively create an AiRock solution for the larger wagons and utes out there.

I appreciate that there would likely be some custom fabrication work involved in mounting the sensors but I would think that the other numerous benefits of the AiRock integration could be enjoyed on non-Jeep vehicles out here.

Any thoughts?

[sootygu]

I am in the middle of organising a set of Firestone bags from the US for the rear of my GU CC. There are a couple of options avaialble but for you to run that lift you would require these for the rears. I am not going fronts at this stage.

Getting them from trucksprings.com

W01 358 5429
Compressed - 175mm
Extended - 566mm
Dia - 168mm

Brackets need to be fabricated to fit them to the existing spring mounts.

Cheers

[Wooders]

Wooders,

I've recently been wondering whether the AiRock interface, computer and height sensors could be integrated with some of the airbags that have been developed for Patrols and Cruisers to effectively create an AiRock solution for the larger wagons and utes out there.

I appreciate that there would likely be some custom fabrication work involved in mounting the sensors but I would think that the other numerous benefits of the AiRock integration could be enjoyed on non-Jeep vehicles out here.

Any thoughts?

Yup that's another thing we've been looking at.....dang 24 just isn;t enough hours in a day

[Freakazoid]

Hi Sootygu. that is the same spring I used in the back. Also known as the 1T14C-8. The only bracket you really need, but not necessary, is a round plate on top of the bag to interface with the upper spring mount. I can send drawing if you want. on the bottom you bolt the piston the the spring perch. You can either use the hole already in the spring perch or drill a new hole on the front edge of the spring perch. This helps the bag sit a bit straighter. You should eb able to fit it in about an hour. The biggest problem is getting the nuts on top of the upper spring mount in between the body and the mount. If you have a bit of a bodylift this should be easy. If not, you're gonna hurt yur knuckles. Getting the airline in there is also difficult.

You will definitely need a long shock,I used the Rancho RS19012. You'll also need to extend the bumpstop by 2". The rear flex is insane.

[badger]

pics

[PGS 4WD]

Air bags on the rear are great, better articulation due to air bags retaining more consistant spring rate when compressed or decompressed, due to this though you need a sway bar or after cornering the car will continue to lean over. Also good if your load varies as you can maintain vehicle height by adding a few psi.
I wouldn't suggest them on the front due to there tendency to body roll, if you were to you'd need a 30mm front sway bar to keep the vehicle stable on the bitumen.

Joel

Not sure I'd really agree n some of that Joel....
Firstly unless you are venting the bags from one side to the other (IMHO a bad idea) then a singe air spring is more progressive rate as it is compressed the pressure increases effectively increasing the spring rate - ie not constant.
Also I would not say an air spring has more articulation - infact often an airbag will mean less because it's generally mounted at each end unlike a coil which is usually free at at least one end.
Also on the front they are fine (again assuming you are not sideways venting between the bags).

It's worth remembering the lower the air srping is run, the softer the ride & the greator the body roll - whereas when it's more inflated (within reason) the increased pressure can lessen it.

I love the airbags on my TJ. It gives acceptable wheel travel which in my opinion is very well balanced, gives a great ride on road & off and with the use of height sensors it's always at the same height regardless of load (or not) ....plus the sensors give me active susension onroad

I wouldnt suggest venting from side to side either, perhaps I explained it poorly, the downforce on an extended air bag is greater than that of a coil, the compressed force on an airbag is less than a coil spring if all other things remain equal, this is why air bags are more inclined to roll and not self center. A coils rate increases to a greater degree with compression than an air bag. We use air bags a lot at PGS, personally I don't like the feel on the front, you need large sway bars to keep the vehicle upright, reduce body roll. Take the sway bars off and turn a corner and the vehicle will roll and not come back to vertical without help, like a flick of the steering.(Assuming you don't have active supension)
The air bag has an operation ride height, you can lessen the air pressure for a softer ride, this will also lower the vehicle and may take the bag out of its optimal ride height position, raising the pressure will of course do the reverse and raise the vehicle.
I'm refering to a simple bolt in kit, a 3" lift spring vs a 3" lift bag in the same location, the bag will articulate over the same distance or greater, the bag should be travel limited to stop destruction of the bag however.

Joel

[Freakazoid]

HI Joel, wooders. I assume the argument is based on a rolling sleeve type bag and not the bellows type. The rolling sleeve is much better for vehicle use anyway. If so the piston diameter relative to the bag diamter determines the spring rate and as you change the piston diameter from fully extended to fully compressed then you obviously change the spring rate. Most of the piston shapes are straight for about 70% of the piston and then increases fast in diameter to the fully compressed position.

I have set my normal ride height to be about 1 1/2" above this so the vehcile on road runs fairly quickly into this part of the piston when you get body roll. This makes for a much stiffer front end than my EMU's were. Offroad I inflate by about 3-4" and then I need to obviously compress quite a lot and the change in spring rate stays fairly constant.

I had a piston on the front spring that was very stiff when compressed (large dia) then had a very narrow bit (soft) and then went wider again as it increased again, like an hour glass. This was a very soft ride when the bag was in the narrow area but the roll was tremendous. It wasn't very constant either. You'd go into a turn and the body would roll very fast and then stop rolling as it hit the wide bit. A bit unnerving if you didn't know what was going on. I then changed to a straight piston and it is a really nice ride.

Then you can start messing with the piston shape if you have a half descent lathe and all of a sudden you can really outsmart yourself with spring rates and how they change.

I would say for me the biggest advantage of the air spring is that the natural frequency is down at 1-2 Hz which makes the spring a natural damper. This makes that the spring keeps a wheel on the ground far better than any coil will ever be able to.

Oh and when you inflate a air spring the only thing that changes is the volume in the spring. If the piston is straight the pressure stays the same. The pressure only changes when you either add weight to the vehicle or transfer weight from one side to the other like in body roll or cross-axle.

[Suspension Stuff]

Sounds great Freakazoid
Now we need pics and of the perfect setup. You can email them to me

[PGS 4WD]

Yep, I have a piston with parallel sides and it is a rolling sleve, everything you said makes perfect sense, often the piston shape is different with the bags designed height, I suppose ideally being stiff around ride height and compliant towards the ends of the travel would be best.

Joel

[me3@neuralfibre.com]

I'd been playing with the rate numbers on a spreadsheet for Polyairs, butthe same applies to airbags.

http://neuralfibre.com/paul/?p=280

The rate of an airbag rises exponentially with compression, unlike most springs which rise linearly. At first the rate rise is very slow, but increases dramatically toward end of travel. If your bump stops limit this travel, it dictactes where you end up on the graph, and if they will be Linear like PGS stated. If there is a larger % of stroke lenght used, then it will be highyl progressive. The graphs explain it better, so play with the numbers some.

Also, the cylinder that goes into the centre. Everyone has said the same as my first assumption, that it should be larger at the base to accomodate for rising rate. If youthink about it the rate rises anyway, dramatically toward the end. In that case you want it wide at the top and narrower at the bottom to redcue this effect somewhat - just what Rover does.

I didn't set the spreadhsset up for sleeve bags, but should be esay to adjust for any.

Paul

[beretta]

Slight hijack, but a relevent question, where do you all by air bags from, aside from airbag man?

[me3@neuralfibre.com]

www.truckspring.com

Not real helpful. so make sure you know what you want first.

Paul

[Pharb]

When you are modifying the pistons how do you clamp the bag to the new piston????

Peter H

[Freakazoid]

The pistons aren't attached to the bag. You just pull them out and put a different one in.

http://www.nissan4x4.co.za/forum/forum_ ... Freakazoid

This is my front bag with the old piston. But as you can see, sort of, the piston just sits inside the bag. Apologies for the link. i tried putting a pic in but it came out way too big.