AIR RIDE on early GM IFS

my pal Jeff Higel (GMgrunt) has been working away on his 40 Buick custom and the time had come to build the front air ride suspension. so, he asked if i would come over and lend a hand, since it was his first bag job.
Jeff had already removed the coils and installed the dropped uprights he had purchased so we got right to work fabricating the mounting points for the bags themselves.


one of the most important things that needs to be done when bagging the front of any front suspension with a coil pocket that goes inside of the frame is to open up the hole in the bottom of the frame to allow clearance for the bag. bags are typically bigger around than coils and unlike coils they also flex. [In no way shape or form is it ok for the rubber part of your bag to make contact with ANYTHING at ANY point in the travel of the suspension. if the flex member of the bag does make contact with something it is a sure recipe for a blown bag. barring any manufacturer defect or foreign object being kicked up off the road and thrust into the bag this is just about the only way an airbag will likely ever fail and it is the number one reason for airbag failure.]
a torch or plasma cutter will make quick work of this and a grinder will clean up the edges nicely. there were a couple other protrusions inside of the spring pocket that had potential to make contact with the bag so they were heated with a torch and gently (with a big hammer) massaged out of the way.







for the top mount we used what i like to call a "hat" or "cup". it is quite simple and is basicly just a length of thin wall tubing (14ga in this example) welded to a flat plate. the plate will need to have holes in it that allow the bag to be bolted to it and another (larger) hole to clear the air fitting. the tubing needs to be large enough in diameter that the fittings and bolts fit inside of it's diameter. i had a few of these plates laying around that i had made up a long time ago for just this purpose. Airlift has since changed the bolt pattern on their bags so we had to elongate the holes in order for them to work with the newer Airlift bags. Jeff is a machinist by trade and has a small mill in the shop that we used to do this work but if i were at home i would just use a burr on my die grinder and that would be sufficient.






the Buick, like many GM cars of the era, has the shock absorber incorporated into the upper control arm. Jeff plans to have them rebuilt and retained. one of the bolts that holds the body of the shock to the frame goes up through the middle of the coil pocket and also retains a small "cup" that kept the top of the coil from moving around. we will use the same concept to keep the top of our bag from moving around but we must build a bigger "cup", one that our upper bag mount will just fit over.
you can see it here:


i believe the tubing we used was 4" diameter (maybe 4.5") and in order to make the smaller piece that would snuggly fit inside of the 4" tube we simply cut a 1/4" slit out of another piece of the same diameter tube and then welded it back together. once the weld was dressed it slipped neatly inside of the other tube and was then welded to it's own plate. this plate needs only one hole but the plates we had already had holes in them. just ignore those.

 

the upper cup that once retained the coil spring inside the spring pocket was not perfectly centered in the spring pocket opening once the opening was opened up for bag clearance. in order to ensure the maximum amount of space between the bag and the opening of the coil pocket on all sides the bolt hole that will be used to retain the new cup to the frame and underside of the shock was placed slightly off center making a sort of "eccentric" allowing us a little bit of adjustability so that we could be certain the bag would have adequate room all the way around.




that takes care of our upper mount. basicly the upper "retaining cup" will bolt back into the car the same way the upper coil retainer did and the upper bag cup will bolt to the bag and then just fit snuggly around the retaining cup. the weight of the vehicle will keep this from coming out the same way the coil was held in place.
now on to the lower control arm and lower bag mounting plate...

you can see on these control arms that there is a stamped steel plate that the lower end of the coil spring sat in. these plates where held onto the cast control arms with large rivets. these rivets were ground flat on one side and marked with a center punch. they were then drilled out and the coil spring plate AND the smaller plate that held the rubber snubber in place and offered a mounting location for the sway bar was removed.



once removed we laid the two piece on a piece of 3/16" steel plate in the same relation to one another as they were when attached to the lower control arm. we then traced around them and marked the holes where the rivets had been and also for the sway bar mount. the part was then cut out (we used a bandsaw followed by clean up with the belt sander). once that was done we drilled the holes to the appropriate sizes. both the control arms and the new plates were drilled to accept the 1/2" GRADE 8 hardware that will replace the factory rivets.







once the plates were mounted to the lower control arms the whole assembly was mounted back on the car and the bag set in place. once we had the control arm at the estimated ride height we located and marked the hole in the plate that would be used to retain the bottom of the bag to the plate. these bags have a single mounting hole in the bottom center of the bag. it was then bolted up and VIOLA!
[excuse the extra long bolts, we could'nt scrounge up the correct hardware the night we did this so we mocked it up with these obscenely long bolts just to show what was going on.]






the sway bar will mount back up to our new plate just like it did on the factory piece. the stock snubber is just sitting there for reference. an aftermarket snubber with a stud in the bottom will be utilized in it's place.

 

what we did not show was that, once you have a fitting in the bag, you need to figure out where the air line will need to come through the upper cups and cut a notch or drill a large hole for the air line to pass through. just like the membrane of the bag you want to protect the plastic air line from rubbing on any sharp edges. it will not fail as quickly as a bag will but after a while you could develop a thin spot and blow a line.
i'm realy not kidding when i say that your bags can NOT touch ANYTHING EVER. i've done countless installs and made many repairs on poorly engineered and assembled systems and i've seen my share of failures. i even had to buy a pair of bags for a customer once when, after a very short time on the road (like a couple days), he had worn a hole in one bag and nearly done the same on the other. this was due to me not allowing enough room for the bag to grow when deflated. it rubbed on something and it did'nt take long to wear a hole clean through the bag.

here is Jeff's 40 Buick laid out in his garage. it'll be a very classy 40s style (think Westergard) custom running a Buick straight 8 with multiple carbs.




...dig those skirts?? Jeff built those after seeing the tech article i wrote for Traditional Rod and Kulture doing the same treatment on my old 47 Chevy coupe. he did a damn fine job i've gotta say.

 

tits man, tits.... makes me think I should just use the stock front suspension on my '38 and bag it... hmmmm....

 

Nice work!

 

Great tech, Mike!

Wish this was out there when I bagged my Buick. Very easy to follow.

 

nice job

 

Fantastic job! Your attention to detail, especially the safety aspect, is really appreciated. I wish others had the same work ethic.

I LOVE THE BUICK!!!

 

GREAT tech! Thanks for taking the time to post it up..
Always something to learn..
Now..i think you should do one for the X-frame GM cars too so i can buy your kit and have something to look at when i install em on mine

Tony

 

Great pictures also, you did a great job getting up into the frame and taking those close ups, definitely Tech Archive material. 1953 Olds and older have this same front suspension.

 

Very nice work Mike and the 40 will be a killer. Perfect stance. Just a little question, why you don’t run Dominators instead of the older crimp ring design bags?

 

you know it is on my short list Tony. doin the body on that 63 wagon right now. my buddy won't let me tear into the suspension till the car is back together from body work. i don't blame him.

i'm almost certain it was more work to write all of this and get the pics where they needed to be than it was to do the fabrication.
...good to know about the suspension. i know my 47 Chevy was quite similar in design.

Jeff bought his kit before the DOMINATORS came out. he just ordered another kit with DOMINATORS and will likely run those up front as long as everything fits the same.

he is running sleeves in the rear but that is a whole other tech article. some clever stuff goin on back there too...

 

Awsome!
Thanks for the clarification, I'll be doing my fronts soon.

Hey, would you mind detailing how the hose is run out?

I was thinking of that, and how would you push the tube on the connector after it's bolted up there, or do you run pipe fittings up through the top and then the connector.

thanks
Thom

 

Any chance you can do a tech article on the rear? I would love to see what you ahve done. This article is very helpful as I would like to bag my 52 Caddy.

 

Yeah i know, just teasin ya. And i don't think i blame him either

 

first you want to run your air line inside of the frame heading towards the bag. make sure you have a little slack in it. now with the notches cut in the side of the cups in the right place you have a place for the air line to get to the bag fitting. the fittings are the "push to connect" type so as you are holding the bag up near the spring pocket you just push the line into the fitting making sure it is fully seated in the fitting. then you put the bag the rest of the way into position and your all set.

 

Gotcha!

 

Damn I could do that.................I think! Looks like I'm keepin my front end, putting this on the to do eventually list. Great article.

 

Cool... but be careful with those airlift bags, have seen the clamps fly the f**k off! Would swap them for Slam Specialties or Firestone.

 

whatever. i've installed more Airlift bags than i can count and have NOT ONE TIME had a crimp ring failure. i've never even heard of one "flying off"... besides, the new DOMINATOR bags are the best on the market and that is what likely will go into this car before it hits the road.

 

nice job with the pics Mike..... thanks!!

 

Nice job Mike!
You can talk to me all day long about how to do the Jetfire but until I see pics of projects, some of this never quite sinks in.

U 2 GMGrunt

 

very nice tech article. Im looking forward to starting to work on my 53

 

Is this car going to be done for the summer?? Im anxious to see it crusing the mean streets of the diamondale/charlotte area!

 

Looks great Mike. Great stance for the car. One note for those looking to add bags to a stock suspension is it cant be done on all cars with a arms. I ran across this problem helping out the local kids with their air bagged late model trucks. Where the potential problem is, is some suspensions don't lend themselves to just moving up and down with the bag. You have to be certain the bag can blow up and down as strait as possible. Even My MII front end built for air bags still mounts about 15 degrees off axis but still should handle the load at under 50 psi. A couple of local kids have asked me to help (Im the Neighbor guy with the welder and all the tools) with their bags that bend around 30-40 degrees at the top. The suspension goes up and down but it takes 150 psi to do it. Ultimatly burning up compressors from running too much.

 

some summer.

though it is ideal for it to be as straight as possible it is not absolutely imperative. i've done probably a hundred air ride setups on all types of cars and trucks. many are pushin pretty close to 100psi to get the front to full lift but i've never had a single vehicle need more than that and the compressors running too much is likely the cause of trying to fill too large a tank with too small a compressor, a cheap compressor or just plain playing with the system too much thus over working the compressor.

the way you get around having too much angle on those suspensions you refer to (the short length of the control arms is the cause) is to make a bottom "cup" that has an angle cut on the bottom edge. you make that angle so that you are sort of splitting the difference between the bag being level when deflated and the bag being level at full ride height. it's all about compromise.
it certainly is not a perfect world scenario but it can be done and i have yet to meet a suspension i could not air bag and have it work reliably. i've bagged everything from full size Ford and Chevy trucks of every vintage to a 73 Nova, countless S-10s, Toyota mini-trucks, 50-54 Chevy cars, 60s GM full size cars, MIIs, a little 62 Olds Starfire, a 70 Monte Carlo SS with a factory big block (not as easy as you might think) and even a 1 ton Dodge extended cab truck and a 1 ton GMC crew cab dually that could still haul a gooseneck trailer if it had to.

this car is actually pretty rare case in that it has a fairly long lower control arm that allows the air bag angles to be quite subdued. you don't get that lucky on most vehicle.

 

This is great tech. I hope you do a thread on the rear bags. Did you keep the stock rear suspension or change it up? I have a 4o buick special and was trying to decide if I should subframe it or not. It looks like I dont have to now.

__________________
If you cant dazzle them with brilliance, baffle em with bullshit

 

Nice Work!

 

Nice work guys! Jeff, keep up the good work.

 

would this setup be able to be used on a 47 chevy fleetline?