C20 air ride suspension

[72 K20]

I was thinking the other day about possibly using an air ride system in my 72 C20.
This will be a daily driver, occaisionally hauling a load or pulling a trailer.
Can you simply replace the coil springs with air bags ? I understand how the bags work from working on big trucks with air bags.
I would like a decent ride for the majority of the time but have the ability to increase the pressure to haul a heavy load or tow a heavy trailer.
Would the system be split front to rear ? Could you set up a ride height valve like the big trucks have so loaded or unloaded you maintain the same height ?

Throw me some ideas, tips, tricks, pros, cons, etc.

Thank you in advance for your input !

Have a great day !!
Tom

[oldschool18]

with a couple of mods you can just replace the springs and yes there are valves to set ride height......I remember reading an artical awhile back and placing the bags behind the rear axel is best for towing and in front of the axel is best for ride quality. As for splitting front and rear it all depends on how you want to run it, a front/back/side/side or a FBSS would be the best so you can have control of all 4 corners of the truck. Just run the rite size bags you will want a big bag up front if you got a v8 and if its a BB then you need a bigger bag and you will have to do some measuring to make sure you get the right size bag for the rear to keep the back up when towing or hauling. If it was me and it was my every day driver and I needed more support in the rear I would put a set of leafsprings on it with a helper bag setup, if you blow a bag or a airline while out on the road or even worse towing something its not going to be fun.

[72 K20]

Old school18
Thank you for the reply !!

This truck has the very heavy duty overload "leaf springs " . They are 3 leaves,not factory .

Are the airbags for these old trucks the same quality as the ones used in the big trucks ?

It's not real often we replace them on our semi tractors.

I'm thinking onboard compresser,a couple of small air tanks,a pressure regulator for front and rear,,,,,,, What am I missing ?

Is there a website that has the different airbag dimensions ?

Have a good first monday of the week !!

[oldschool18]

the bags are differant I dont think there as thick as the bags say on a tri-axel.....I get all my air ride stuff at Airbagit.com they have 50 differant kinds of bags to choose from and I have been buying from them for over 10 years. They came out with this plug & play system a few years ago it comes with almost everything, and would save you hours or days of plumming and wiring and just make sure you get a compresser thats 100% duty. And if you want to go up faster you can always add anouther compresser and you should only need one air tank, and get atleast 1/2" air port in the front airbags or a dual 1/2 ports. Theres alot of good info on the website just research as much as possible theres alot of little things like you need a alternator atleast 100a to keep up with a big compresser so just research research research.

[72 K20]

That's a great site !! I am shooting for a comfortable ride but still be able to load the truck if needed. I'm not interested in making a frame layer or a hopper,,, I just want to maintain the hauling capacity and soften the 3/4 ton ride. Actually this truck sits at the normal rake that they did and I want to level it,, bring the front up to match the rear.

I like the kit that they offer but don't fully understand the 4 link part of the description.

Thank you for the input!!!

keep it coming !!!

[oldschool18]

the 4 link will replace the leaf springs and they might have a bolt on set but will be more money or you can get a set and fab them up yourself but will take some time and a welder and other tools and a lot of measuring. how far does the front need to come up you could always ad some leafs up front. To do a airbag setup your going to have to do a lot of work and be without your truck for awhile and I always tell people save atleast 2000 to get started. And like I said before you could get a set of helper bags for the rear....they would mount to your leafs and to the frame to give some extra support it only requires a small tank and compressor and could be put on in a day. full air ride set up you would have to find a place to mount a bigger tank and compressor, but as I said before if it was me and it was my daily driver I wouldnt do bags and when its cold it can take a little longer to get the bags moving and you get some moisture in the lines.

[72smoker]

I also put a kit form Airbagit.com on my '72. It was not the plug and play kit but if I was to do it again thats what I would do. The bags I have ride nice down the road but I will never tow anything with my truck. I think for the money it is a good place to go for the price and quallity. If you have a big block up front you will want to go bigger than they want you to. The bags I have up front are almost too small for all the extra weight I up front.

[72 K20]

the 4 link will replace the leaf springs

how far does the front need to come up you could always add some leafs up front.

This is a C20 with rear coils.

I need to bring the front end up about 3 inches.

It will be a small block .

[oldschool18]

I thought you said it had leafs in the rear...you could use spindles to raise the front end. If you you have the trailing arms in the rear then you would not need a 4 link but you might need a new panhard bar, you'll want to measure the height of your coil spring where it is right now.....lets say it's 10" now you have to figure if you want the back up any heigher......say you want 2" more lift in the rear then your at 12"......now you have to figure how your going to hook the bags to the trailing arms.....once you figure out what your using bag cups, or brackets figure out the height on them..say you weld a bag cup to the trailing arm and the cup takes up 3" then subtract that from the 12" and then figure the top out this will take some planning but if you research it on here you can find enough pics to figure it out. Just dont short yourself on the bag if you need 12" in the end you want a bag to extend more than that. the front isnt hard to do at all start the same way measure from the bottom of the lower control arm cup to the bottom of the spring perch...I always just make my own plate to bolt up to the spring perch I just use 3/16 flat steel the lower control arm you might need to weld a cup in or make a plate to cover up the spring cup since your not trying to lay frame you have less to worrie about......up front use a big bag something around 8" in dia' the bigger the bag the less air pressure you need to fill it you might have to remove some stuff from the lower control arm cause you dont want the bags rubbing on anything......alot of measuring and planning and do alot of research and ask Q? and you can try to ask in the suspention part of the board you might get them answered quicker.

[northerngmc]

Originally Posted by 72 K20

Old school18
Thank you for the reply !!

This truck has the very heavy duty overload "leaf springs " . They are 3 leaves,not factory .

So do you have rear coils with overload leaf springs? I would like to see a picture.

My 68 C20 with rear coils rides better down the highway than my 2004 2500HD!

[72 K20]

I was wrong,,, they are not 3 leaf overloads,, they have 4 leafs.

[northerngmc]

If you are trying to improve the ride and not lower the truck have you considered removing the over load leaf springs?

Like I said above, my 68 C20 rides fairly nicely. I don't notice a lot of difference between this 68 C20 and the 69 1/2 ton I had before for ride quality.

[Whitey__62]

check out airbagit.com they have a large selection of air bag supplies. you will find different bracket you could weld to the axel and make your own airbag overload while retaining the stock suspension. they also sell conversions for the front coils
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[72 K20]

The overload springs are a couple of inches away from contacting the axle,, so they aren't really an issue until it's loaded down enough to make contact.

I have checked out the airbagit web site, and looked at the kit for this truck, and altho it looks like a quality kit, I believe I could "build " a kit for less money.

I realize that most of the folks on here that are switching to air bags are lowering their trucks,, that doesn't interest me. This will be a daily driver that will be on construction sites where the site resembles a lunar landscape,, obviously a lowered truck is out of the question.

I have 2 72 C20 trucks with rear coils and as far as I'm concerned my 72 K20 rides better than either of the 2wd trucks. But,, it's a fact of life that for all practical purposes a 2wd truck gets better mileage than a 4wd.
I got this last C20 because it's a very clean truck, very little rust, and how it's equipped,, 402 TH400 which gets me the 3:54 (?) rear end gears,,, I wanted the higher geared rear end,, the big block is coming out along with the TH400 and it will get an economy themed small block with a 700R4 .

I have always preferred the leaf spring rear over the coils,, and I thought about putting this cab and box over on a leaf spring frame that I have. Then I started thinking about an air ride system ,,,, and here I am !!!

[oldschool18]

I would run leaf springs in the rear if your going to be running around construction sites, blowing and airbag is no fun cause almost nobody has an extra one on them and just switching one out is a pain in the a**. its only going to take one piece of rebar or a metal banding strap to cut or poke a hole in the bag and you will be cursing yourself out.

[k2rm]

I am thinking about doing the same with my 70 C20 coil truck. I just removed my overload springs that bolt to the frame and rest on the trailing arms. The truck rides a little smoother, but still really rough with an empty bed. I also want it to ride at stock height with bags in the rear to ride better.

My plan is to put the overload springs back on and then replace the coils with bags. The overloads will still support the suspension in case there is a blowout.

I will probably buy these mounting brackets

http://www.newmaticsinc.com/196_72_C...s_p/231156.htm

and then get slam specialties 7 or 8" bags. I just don't know if the 8" bags would be too soft at ride height in combination with the overloads. It may be a trial and air (error experiment.

[72 K20]

My overloads don't contact the rear axle unless it has a load on it.

When I said that I would build my own kit I plan on using bags rated for a semi tractor. As you said,, it will take a little trial and error to figure out which ones to use. Obviously the dimensions will dictate a good portion of the selection. I believe I am going to go with a ride height control valve much like an air ride trailer , or semi tractor. I will figure out my desired ride height and leave it at that,, with the ride height control valves in place it should be at the same height whether loaded or empty.

[longbed67]

Just a warning on airbagit.com do some serious research on customer reviews of their products..... my experience has been very poor and when putting their bags through the paces with towing they blow before you get close to their wt rating. I have also received many pieces from them with pin holes in the bag material... After 4 sets of bad bags in a row I did a little research and found MANY MANY others out there with the same problems. Do yourself a favor and dont buy from them!

[Whitey__62]

longbed67.

good to know about the quality of their bags. any experience with the control arms and bag mounts? I have a 69 C-30 that I intended on bagging in similar fashion to 72 K20's build.
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[72smoker]

Sounds like your on the right track with you air bags. Do you have a local truck (semi) shop in your area? They might be able to send you in the right direction for the bags. Seting the ride height with a dump valve is a good idea for what you want to do with your truck. With the right bags, dump valve and fab of some brackets for the rear you will have a good setup. If Midwest Wheel is near you they might be able to get you most of what you need.

[72 K20]

There is a midwest wheel in Waterloo,,, at work we deal quite a bit with Sadler. I have plenty of time to research the available options.

For what I want to end up with I feel the ride height valve ,or dump valves would be pretty trouble free. I am hoping to get the body ready for paint by spring and maybe have a motor and trans put together by then.
There's not much body work to do,, a few small dents, the cargo/toolbox door, and 3 or 4 other small area's. All together, the 3 or 4 area's total might equal the size of a saucer.

Right now it has a 402 and a TH400,, I will end up with a 350 and a 700R4.

Have a great day !! Tom

[longbed67]

Whitey_62-- no experience with the hardware parts but I have always had nothing but amazing things to say about the quality of the parts from thorbecke bros here is there site I am now a dealer for their parts so get a little discount and am willing to pass the savings on to those on the site here to help out in any way I can.

http://*************/catalog/-63-87-fullsize-chevy-parts

[72 K20]

Finally got the air bags installed in the truck. It's not on the road yet,, more work to do !!

Went with this for the front 11431099 1973-1991 GM C30 - CoolRide Front System

and in the rear http://www.airassisted.ca/u2/metal-f...-brackets.html

With these bags http://www.airassisted.ca/u2/air-bag...-1-2-port.html

Looking forward to getting it on the road to see how it rides and handles !!