Purpose of front coil springs air bag assists, 1982 Chevy P-30

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NickD

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#1
Have no way of learning whether these were OE or added on later, but not much left of them. Front end does tip down a bit, but may level out if I ever top off the rear 100 gallon fuel tank plus the rear water and holding tanks. Have no experience with these things, do they actually raise the vehicle when filled with air?

Looked at some aftermarket bags of 70 bucks a pair, claim they are easy to install, can drink to that with the coil springs removed, just drop them in, but can see no way of removing the old bags even with the front wheels hanging. Is it suppose to be easy to remove the front springs?

Just wondered if this is something to worry about or forget about, new bags claim they come with air lines, can see no trace of the old air lines, just a tire valve sticking through a small hole in the control arm. Doesn't seem to be very accessible on the road for making adjustments.
 
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#2
I just put a set of air bags on a friend's Suburban..He pulls some pretty heavy trailers and they do raise the back of the vehicle...He seems to like them and they were real easy to put on....Jim
 

larche

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#3
I *think* the way the air bags that go inside to coils springs are suppose to work as follows.

*Before* you put the load on, you pressurise the air bag, thus helps keep the coils apart keeping your ride height.
I don't think they will raise the vehicle if you put air in while loaded.

G30 series were quite common to come with them from the factory when used for a school bus chassis.
 
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#4
I believe they come stock. The reason I believe this is because darn near everyone I have ever seen had them. Yes, the coils need to removed. I don't consider it to be an easy job. Lots of weight, make sure you have the proper jack and stands. Stock ones can be bought from GM. And are as you describe, no air line just a stem.

I have no proof of this either, but some of the guys who we have replaced them for claim they really help with the on the road sway.

Another opinion is with the age of your unit, I would suspect most of your ride height issues come from old worn out coils. I would suggest if you were to go through the trouble to R/R the coils for the air bags, it may be a good idea to install new coils.

One may think that is wasted money. But I consider suspension to be important to the safety and handling of the vehicle. And after the trans cooler line ordeal you went through on the side of the road. May want to ask what kind of trouble could I be in with a broken spring on the road?

These are just one persons opinions Nick.
 
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NickD

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#5
Well Mike, you sure know how to make a guy worry, I avoided motorhomes using nothing buy air bags for suspension as several I have looked at were sitting at a 45* angle. The springs on this thing are still rust free with black paint on them and hopefully not another problem. Know you have seen a lot more trucks than I did, but the only broken coils I have seen were also a pile of rust. But will look into the bags as this can relieve a lot of stress. Handling is pretty good, this thing likes to go and very easy to creep up to 90 mph without knowing it, ha, that would put in in jail and they would throw away the key.

I like my Douglas fir blocks, figure if they are strong enough to support a 400K pound locomotive, should be able to handle the three tons at most on the front. Get 2 by 12's, cut them off to 15" and glue and screw a 15" high stack for the base. When I pulled the AT on this thing, had blocks under both the right and left frame members where the front cross members intersected. As an added precaution, jacked up each dangling front wheel to the point where the frame wouldn't lift off the block and added more blocks under each front tire. It was as solid as a rock, also working on a flat concrete driveway on the side of my garage. Dang trailer hitch was just about hitting the driveway that verified, I could not handle a 40' motorhome. Ha, that washer and dryer was tempting in that home, but the 6 mpg was not. Same drivetrain, they really push these things.

Thanks for the tips, not sure why I purchased this thing with gas hitting $3.50 per gallon and with huge motel discounts due to the low tourist trade. Went down to Milwaukee last Tuesday during the rush hour, interstates were practically empty, couldn't believe it.
 
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#6
Concrete slab and the blocks should get it done with no problems. I have seen too many RVs on dirt and little bottle jacks.

The reason I questioned the condition of the coils was because of age and your statement about ride height. I do not know if the bags are a must have. You say your coach is riding and handling well, so I would certain;y question the need for the bags.


Oh yea, I am headed through your country today and spending the weekend in Wisc. Have some training there all weekend. Wisc is a very nice place.
 
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NickD

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#7
I like to learn the hard way, when I was 19 years old was working on my car in MS on dirt, started to rain, but too stubborn to quit, car sunk and pinned me down for three hours until help finally came, had hundreds of mosquito bites on my body.

I pitched my bottled jack stands a long time ago changing shocks on a 70 Buick, on concrete, shook the side of the car a bit too much, it slid over putting a hell of a big dent in the rear fender wheel well when it hit my knee, knee wasn't broken, but that sharp sheet metal put in quite a large slice into it, yeah it hurt. Still have traces of that scar as a reminder.

Since then have been using concrete and Douglas Fir blocks and taking the time to make sure it's secure watching the height versus width/length ratio.
 
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Omega

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#8
Go to this link for the answers to your questions:

http://www.airliftcompany.com/load_support_index.html
 
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#9
Nick, I almost learned the hard way about concrete blocks one day as a kid. Lucky I was not under the car when they gave way. Mom had called me in for dinner. I heard a loud noise and looked out to see a huge cloud of dust. Car had no tires on it and was supported by concrete blocks. It was then laying flat on the ground.
 
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NickD

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#10
Thanks for that link, Omega, read the installation instructions and they say the new bags can be installed in that bottom hole.

Suppose concrete blocks would be okay, Mike, if you fill those holes first with six bag concrete and pad both sides with Douglas fir. I already saw the consequences of using concrete blocks for lifts before I was old enough to learn the hard way, LOL. It's good we both survived.
 
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NickD

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#11
Rather than using a hole saw, just used a utility knife to cut a hole in the bottom of the old bag using the hole as a guide. Attempting to twist the bag and pull it through the hole was difficult. My neighbor came over, one of our tough marine guys just back from Iraq struggled with it and got it out. Not much working room under there and can't seem to get the leverage. He had other things to do instead of helping me with the second bag. Has to be a better way and there was, just grabbed a slotted screwdriver, never cut the hole in the bag and using the control arm hole as a pivot, worked around the hole with a prying action, got that bag out in minutes. New bags are in the mail, nearest dealer is a hundred mile round trip, wants list price, and has to order them. Got the correct number from the Air Lift site.

The old bags had major holes worn in the sides.

Also put on new shocks yesterday, selected Monroe RV Gas Magnums, about twice the diameter of the original Delco's on there, fronts were shot, rears still worked, but the rubber grommet didn't have much left of them. Monroe is having a buy three get one free sale going on now.

Ha, wonder why I am fooling around with this old stuff, can't suck fuel from my auxiliary tank, used a mirror to see a 25 year old rubber hose with a crack in it. No problem, just have to loosen one clamp, pull off the old hose and slide on a new one. That is, after I can figure a way to empty 35 gallons of gas, and drop that tank. Last guy spliced in a new hose where the splice was hidden above the tank, thought that hose was new until I got a mirror. Did check the main tank with a mirror, that hose looks good yet.

Thought about cutting an access hole in the floor and covering that with a steel plate or something, but would have to remove half the interior to pull th carpet back, always problems.
 
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NickD

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#12
When installing Air Lift 1000 air bags please read all the instructions carefully, okay I did that.

Roll the length of the bag length wise to get all the air out, put on the cap, flatten and fold lengthwise, picture made this look like rolling pie dough, these things are as hard as a rock. Second try was warming the bags at 160*F, still as a hard as a rock.

What worked nice for me, jury rigged an air chuck to my vacuum pump, installed a Scharder valve and sucked all the air out while folding each end of the bag at the middle, as vacuum was trying to open the valve core, install the cap. They said tie a string, forget that, no way is that string going to remain on the bag when it's diameter is about 2 1/2" and you are trying to push it into a 2 1/8" diameter hole.

Definitely grind out the interior of the control arm hole and well soap it, holding the bag folded, well soaped, it won't even move in dry, work it in half way, they have a rib around the middle that gets to be a problem, I used a flat bladed screwdriver and carefully pried in that rib to get passed the hole.

With the bag near the top slide in the upper washer, did that on the first one, that hole in the washer is twice the diameter of of peg on the bag, carefully push and squeezed the bag, but it went all at once, washer caught a spring coil, fell to the side and the bag was in. I was screwed at this point.

Called tech help, one suggested removing the control arm another more experienced person said to play with it and try to work the top of the bag down, both asked me if the vehicle was jacked up, assured that is was blocked up with both wheels hanging.

After playing with the bag, it is just impossible, so I removed the shock and the lower ball joint, held it down with a bar that gave me 2 1/2 more inches, was able to work the washer in on the top, the top of the coil is buried in the upper control arm at least 3", with that extra clearance, was able to lift in the bag and insert the lower washer.

While I have a complete wedge kit for the ball joint, none of the wedges were wide enough for this thing, didn't really want to use that as sometimes it rips the boot of the ball joint, and you can't just buy a boot. On this thing, the entire control arm has to be removed and the ball joint pressed out. I tried various pullers on top of the stud, not enough space, but got my air hammer out with a blunt tip, a couple of pulls on the trigger, and the stud dropped, that was pure luck. Put that side together, bag was in, both washers, now to the next side.

Just did things a bit different, got out my glue gun and put a bead around the peg on top of the second bag, let it cool, and just enough bead so the top washer would fit snug, this time the top washer did not flip on it's side and went straight up. With the bag in, removed the valve, and just with an air blower blew some air into the Scharder to pop the bag opened. It's still impossible to get under that bag and compress it at least 2" to slide the lower washer in through the lowest spring coil. So why not just put the washer in the bottom control arm hole? Bend the washer in a U and pushed up on the bag with a finger and angled it in until it's hole was over the Scharder, needed help with a screwdriver to work in the other side, but it snapped in.

I put in 60 psi in each bag, lowered the motorhome, and it's nice and level now, raised the front at least 2 1/2", the air line kit looks nice, will put that in today so I don't have to crawl under.

Just briefly, do not see where it's possible to get out all the air from these bags by rolling it, even after warming the bags, vacuum works great, but still a very tight fit. Large hole in the lower washer is okay, let's you work the washer in through the control arm hole, forget about compressing that bag 3" so you can put it in the side of the spring. Upper hole is way too large or the peg is too small, washer is just dangling up on top and can easily fall to the side. Not sure why that center rib is on the bag, binds on the control arm hole, so it has to be carefully compressed, bit by bit until it's on the other side, then the bag can be moved up the rest of the way.
 
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NickD

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#14
Had another question for Air Lift techs, why the separate fill lines, any air shock system I have installed used a tee so both shocks would have the same pressure.

Said I could use a tee at my own risk, love that at your own risk stuff, if my vehicle is tipped to one side, could add more air to that side to straighten it out. That makes sense, but don't seem to have that problem. Big thing is going around curves, the outer bag will blow air to the inner bag and augment the tilt. Especially if I am carrying a heavy load on the roof. Said okay, thanks and hung up.

Is the latter statement really true, do air shocks also have this problem? It's not that I am going to put a 200 ton press on my roof, and while I may cruise around a 25 mph curve at 55 in my Supra, when driving a motorhome, 25 means 20!

Kicking around whether I want to add a tee or not, any comments?
 

WallysTrucks

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#15
using two lines lets you control the pressure in each bag and with air pressuer gages hooked to each you can regulate it. The nice part about separate lines is you can use the bags for levelers when you park. You can use only one air pump and a valve to switch airbags.

Wally