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Bagging Introduction


So, you want to bag your 97-04 Grand Prix, Regal, Monte Carlo, Impala, or Intrigue, huh? You've come to the right place. Over the past year or so, a ton of research, a ton of measuring and cutting, and a ton of just plain trial and error, along with getting a lot of parts fabricated, to get my car to where it is today. I also must give credit to Adam Garrett of GTXgp.com because he has done quite a bit of research as well. Our loss (money and time, among other things) is your gain though, because now you won't have to go through so much trial and error.

Truthfully, there are quite a few ways you can go about 'bagging your W-body. I will try to present the "facts" on the Pros and Cons page, which details the pros and cons of each particular setup that's available for the Grand Prix. Trust me on one thing, the "bolt on" kits you buy from most places won't get you as low as you probably want it, unless you are running a body kit or small wheels.

If you are new to the airbag scene and want to know the "basics" of air suspension, then I suggest you check out BagginIt.com. That site is an excellent resource that covers the basics and more, and has a great FAQ, among other things. Most of the stuff on there applies mainly to truck suspensions, but the "basics" carry throughout any air suspension.

OK, so here we go. After you've read the Pros and Cons, you have probably made up your mind the type of compressor you want, the size tank and valves you want, and which particular suspension setup you want to go with. Now, each of the varieties of suspension setups require different brackets or may even require custom struts to be built. These are noted in the Pros and Cons, and you should keep this in mind when planning your setup. If you can't fabricate parts on your own or just want a completely "bolt on" setup, then make sure to buy a setup that fits like this.

You might wonder, how low can I go? Well, you can check out the Bagged GP Gallery and take a look. I tried to annotate by each car what setup it was running, as best I could.

Also, many people wonder what size wheels and tires you can run before they won't tuck or won't hit the wheelwell. The largest wheel/tire combo I have seen on a bagged GP so far is Adam Garrett's rear wheels which are 19" with 225/40ZR19 tires. There is one Grand Prix running around with 20s on hydraulics but I am unsure if it rubs when laid out. The only other one I have seen with 20s on air wasn't really tucking a lot so I believe the tires may be hitting; plus that fellow was running the strutbags from AIM which do not go as low as some of the others.

One of the main questions that I get asked is how much a setup costs. Well, this really depends on a lot of factors, especially the brands and parts you decide to use. Just remember that you get what you pay for, so spend the extra couple bucks off the bat and then you won't have to redo something later on down the line. A basic F/B only setup will run you about $2000 (roughly). A FBSS setup will be about $2200-2500. You can go to a much faster setup for a little more money, along with adding compressors and more.

Courtesy of LaidGP, W-Body Suspension Moderator

Pros and Cons


Suspension Setups - Strutbags

Silver Star Customs strutbags - www.silverstarcustoms.com - $500/pair, you provide the struts
Pros: 3/8" ports, good ride quality, your choice of what brand struts to use, bolt on installation
Cons: Front lower strut mounts must be raised to get car to lay out up front, each set is made to order so you may have to wait 2/3 weeks for yours to arrive.

AIM Industries strutbags - www.truckn.com - $500/pair with Monroe Struts
Pros: Bolt on, can be bought with threaded strut bodies so that bag height is adjustable
Cons: AIM is notorious for inferior products and poor customer service. You will not be as low with these strutbags as the SSC ones, and even if you cut the mounts you will still not be able to get as low.

Air Ride Technologies strutbags - www.airride.com - $895/pair with ART struts
Pros: Bolt on, superior build quality, good customer service
Cons: Price ($900 a pair, almost twice the price of the competitors), end ride height yet to be seen since I have yet to find anyone running these.

Universal Air "Aerostrut 2" bag-overs - www.universalairsuspension.com - $250/each, you build the struts/brackets
Pros: Near universal fit, good ride, priced competitively
Cons: 1/4" ports, require custom brackets and struts to be built, bottom brackets must be cut/raised. Won't get you as low as any of the bolt-on kits will.

Air Cylinders - various sites - prices may vary - bracket fabrication required
Pros: Can dog-leg, and possibly get lower
Cons: not recommended for Macpherson strut vehicles, has been known to cause upper strut towers to crack, poor ride quality, cheaper cylinders may bend/break on potholes, seals may go out and not be able to be rebuilt, no pre-fab brackets available

Air Lift Strutbags - www.airliftcompany.com - $2375 for entire kit.

Pros: Easy bolt on that finally gets it low, new upper strut mounts, leader hoses on bags allow for easy changing of lines if necessary, adjustable struts
Cons: Rear sleeve bags are sort of wimpy, upper mount install is a bit challenging because of design


Compressors

Viair 350c - www.viaircorp.com - prices may vary - 1.48 cfm - 100% duty cycle
Fills 3 gallon tank 0-105 psi in 3 min. 24 seconds.
Fills 3 gallon tank 110-145 psi in 1 min. 35 seconds
Maximum working pressure 150 psi

Viair 450c - www.viaircorp.com - prices may vary - 1.66 cfm - 100% duty cycle
Fills 3 gallon tank 0-105 psi in 2 min. 31 seconds.
Fills 3 gallon tank 110-145 psi in 1 min. 18 seconds.
Maximum working pressure 150 psi

Viair 550c - www.viaircorp.com - prices may vary - 2.90 cfm - 100% duty cycle
Fills 3 gallon tank 0-105 psi in 1 min. 35 seconds
Fills 3 gallon tank 110-145 psi in 55 seconds
Maximum working pressure 150 psi


Valves

Ideally you want solenoid valves, no smaller than 3/8" if you want any kind of speed.

The brands I'd recommend are ODE (available from silverstarcustoms.com), SMC (available from many online retailers), Herion (only if you are running 250+ psi max), GC (available from many online retailers), or Ekstensive (available from ekstensive.com or godfathercustoms.com). Valves range in price from around $30 a piece to around $80 a piece. I personally am running 3/8" SMC valves on my car.

Remember that for each part you want to manipulate you must have an up and down valve. So if you want to do front and back only, you need 4 valves (up and down for the front, up and down for the rear). Therefore if you want to do FBSS, you need 8 valves (up/down for each corner). Complex maneuvers such as dog-legging etc may require more valves.

Ideally for optimum flow your line and line fittings should be one size up from the valve. I created a handy table below for your reference:

Valve size Line Size
1/4" 3/8"
3/8" 1/2"
1/2" 5/8"
5/8" 3/4"


Pressure Switches A pressure switch turns your compressor on and off when the air pressure in the tank reaches preset points. The most common pressure switches are 110-145, which turn the compressor on at 110 psi, and off at 145 psi. The main function of a pressure switch is safety and convenience. You won't have to cut the compressor on and off manually, and the switch will keep you from burning up your compressor or leaving it on accidentally, potentially causing a dangerous tank rupture/explosion.

Basic Components


  • Primary suspension components (strutbags/cylinders)

  • Air line (for optimal flow, step up a size from your valves, ie use 1/2" line with 3/8" valves)

  • valves (4 for front/back only, 8 for front-back-side-side)

  • compressor (yes you can run more than one)

  • pressure switch

  • tank(s)

  • fittings

  • wire

  • switches (usually momentary 3-way switches. can get SPDT or DPDT depending on how many valves you are controlling with each)

  • relay(s) for compressor power

  • Miscellaneous wire connectors, etc.

  • Air gauges (if so desired).

  • "drain" petcock for tank - optional (helps if you ever need to let air out of tanks)

  • Emergency fill valve - optional (if you ever lose a compressor you can use this to fill tank at air pump at gas station and get it home).

Please note that this is not the gospel and I am not responsible for you buying something wrong due to following this guide. Your mileage may vary, so make sure you buy what YOU need.

Install Directions


So now you are ready to start installing. This guide will be based off of a Front/Back only setup for now, as that is what I am running. If you have FBSS you will have to run twice as much line/wiring but the basic idea is the same.

First you want to locate a spot to mount your compressor(s) and tank(s). Make sure they are mounted solidly. Connect the leader hose from the compressor to the tank. Make sure to use Teflon tape or some type of thread sealer in all fittings otherwise you will get major major leaks.

Now you are probably ready to run some air line. For F/B only, you will only need to run one line to the front of the car. I recommend running it out one of the drain holes in the bottom of the spare tire well, as this is easy access and you can simply put a hole in the grommet and run the line through it. Run the line toward the driver side of the car, looping it over the sway bar and making sure it does not get close to the exhaust at any point. Run the line over to the fuel line running inside the framerail on the driver's side, and you can zip tie the air line to the fuel line to get it to the front of the car. With a F/B only setup, your line will "tee" off before it goes to the bags. I mounted my "tee" right on top of the fuel line and ran the line through the inner fenderwells and to the bags. Your method may vary, just make sure to zip tie everything in place so it doesn't flop around a lot, and keep it away from the exhaust at all costs.



Rear air line method is essentially the same. I zip-tied the "tee" to the rear sway bar and ran the line al ong the sway bar, making sure to put it along the top of the bar so it does not come close to the exhaust at any time. Make sure the line doesn't kink at any point, and make sure it's not somewhere that it is going to get pinched by moving suspension parts (trailing arms, etc).

Now we mount our valves. Naturally you will need to install all of your fittings and whatnot first. Keep in mind that some valves are one-way so they will have one side marked "in" (SMC valves are like this, and that's one of the more common valves used). Run a line from one of the ports on your tank to the "in" side of your "up" valve. The "down" valve must come after the "up" valve so it dumps the air from the bags, and not the air from the tank (makes sense, right?). The lines you ran to the front and back that is teed are your fill lines. They need to be attached to the "up" valve. What most people do is put a "tee" on the "out" side of the "up" valve. They run the fill line off one side of the "tee" and then mount the "down" valve to the other side. Here is a pic to further illustrate what I am getting at:

Note that this picture has a fitting going to the air gauge. If you are not running gauges you will only need a 3-way "tee" in that position.

As far as mounting the valves, wherever you put them is up to you. I left them in the trunk, underneath the carpet on the sides (like behind the taillights). This way if a valve ever sticks or freezes I can get to it with relative ease to fix it.

Alright. Now your lines are run, your valves and compressor are all hooked up (except the electrical connections), and everything is mounted. Now we do some electrical connections.

For the sake of brevity I am going to cover a single compressor setup. If you run more than one compressor, there is a diagram that I will add later in the article to show how to wire it, but I will not cover that in detail here. Also, if you are running more than one tank, make sure the two tanks are linked together by air line to ensure the compressor(s) are filling the tanks to the same pressure.

Ok, first we want to install a pressure switch and relay. The pressure switch will thread into a port on your tank. Usually the pressure switch has 1/4" threads so you may need to get a reducer if your tank does not have any 1/4" ports. Again, make sure to use thread sealer and get it tight, so you don't have any leaks.

Now we get the relay. This is a standard relay, and I have a great diagram on your connections that need to be made. Here it is:



(The rocker switch is optional, if you do not wish to run a rocker switch just leave that wire intact). If you only want the compressor to be able to run while the car is cranked, make sure your power for the pressure switch (the wire with the rocker switch in the diagram) comes from an ignition-only power source (similar to a remote wire on an amp).

Alright, now that your compressor and all is wired up, make sure all your connections are tight and any unused ports on the tank are plugged. Make sure you have installed the air filter on the compressor. Crank up the car and you should hear the compressor turn on. if it turns on, you are good to go.

No we wire the valves. As you can see from the earlier pic, the valves have a positive and negative wire coming in to them. the negative wire just goes to ground. The positive wire goes to your switch. On a front/back only setup you will have two switches, one for the front and one for the back. Each switch controls two valves. Run your positive wires (one from each of the four valves) to your switches. Connect a FUSED power wire from your battery to the +12v prongs on each of your switches (usually in the middle, on the side). Connect the power wire for the "up" valve to the top prong on the switch, and the one for the "down" valve to the bottom prong on the switch. Do the same for the back valves, and now you are ready to test them out. This is best done if someone else is helping you. With solenoid valves, there is a distinct "click" when the valves are opened. Now even though you don't have much air pressure built up you should still be able to hear the click. Get someone else to click the switches while you listen for all four valves to click (individually with each switch position of course). If you have a valve wired to the wrong position on a switch, fix it now.

Alright, now we come to the fun stuff... mounting the struts.

I am assuming that whatever rig you are running, is ready to bolt up at this point. There are a few variations on the types of struts and cylinders so your methods may vary but they all mount pretty much the same. Here is a great link on strut swaps even though it has to do with springs so some of the "bolting back up" methods may be different for you with bags/cylinders.

RMCGP Strut Install Guide

Make sure before you install the strutbags/cylinders that your fittings are installed, using thread sealer and tightened down. You may need to connect your line before you mount them, depending on your setup and the location of the ports.

Once everything is put back together and ready to be set on the ground, it is a good idea to go ahead and let the compressor build up some pressure so you can check for leaks. If you can hear a leak or detect one on your air gauges, try to isolate the leak. More than likely it is a fitting. To do this, put some dishwashing liquid and water into a squirt bottle and squirt it on the fittings you think are leaking. If it is leaking, it will bubble up like mad. Once you find the leak, reseal the fitting and make sure it doesn't leak anymore. Once your leaks are fixed, and the compressor has turned off (which means you are at your preset pressure on the pressure switch) it's time to air it up a bit and get it off the jackstands/jack and set it down. (if your car is using one of the really low laying setups, you won't be able to get the jack out from under it with it laid out - trust me). Once everything is out from under the car and you are sure you have no leaks, dump out the air and admire your newly laid-out W-body.

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