67-72 Single Leaf Rear 4x4 w/ a BAG??

[72longbed]

How about this? Lifted 67-72 4x4 with a single leaf in the rear and an air bag between the frame and axle spring perch?

I've been kicking the idea around to see if it will give a 4x4 with 'lift' adjustability, and a cloud smooth ride. Huh? Cool, huh??

Ideas?

[andrewmp6]

If you mean a mono leaf set up don't do it,With a mono leaf you just have one leaf and a air bag and that single leaf will bend up in funny shapes and or break over time.

[72longbed]

My thinking is that the mono (largest bottom leaf of a pack) would act as a 'locator' for the axle, setting the fore and aft position for each side, and the air cylinder would be positioned on top of the axle, and mount between the axle and frame rail. The spring could even be a two (2) leaf for more stability. The airbag would be handling most all of the weight and load, with the ability to raise and lower the suspension, firm or soften the ride, with the bag pressure. The springs would most likely need to come from a 2" or 4" leaf pack to have the arch already set in them.

There are some bags made by firestone that I used once on a C20 in place of the rear coil spring. I forget the bag model number, but they had 2700 lb capacity each and it rode like a dream. They also gave me about 7 or 8" of height adjustability.

I guess what I am describing is basically a "poor man's 4 link", with airbags. lol!!
What do you think?

[Mr Pops]

I think you might end up with axle wrap since the leaf by itself might be too weak to keep the axle from trying to rotate with torque or braking. Especially with a leaf that isn't designed to be by itself. Axle wrap can be fixed with some form of traction bar.

[72longbed]

Good point Mr. Pops ... my idea would be more of a '3 link suspension' and adding the traction/torsion device would provide the 4th link.

I'll have to see if I can find an old 54" set of stock rear leafs to work my idea on.

It all starts with 'ideas' afterall.

Thanks.

[lowrollin70gmc]

I'll fill you in as I do this to my k20. I'm putting a later model leaf pack in and will pull a few leaves to get the rear to drop an inch or two from where I currently sit. The bags will be hooked up to a semi truck auto leveler with dump so that I can keep it at a normal ride height (1" above current location: 3" above dumped) with no worrying about adjusting for load. I need the dump feature to fit in my garage, as I currently rub my roof on the door seal and can't put on my set of 37s because of that.

I will also be running a Off Road Designs style traction bar to prevent bending leaves. Stock had 2 leaves and the Toro Flow that was in the truck bent those and I don't want that to happen with the new leaves and more powerful Cummins I currently run.

[andrewmp6]

Traction bars will just be a band aid a single leaf will break over time.If you really want to do this have custom flex springs made is the only safe way i see.

[72longbed]

I will most likely have a two (2) leaf spring pack, with the bag carrying the weight. I would also locate the traction device above the axle rather than below like the one in the pictures so far ... a 4x4 doesn't need more crap hanging down to catch stuff on as you go thru the rough stuff.

I think this idea is 'do-able' ... just need some parts (old leaf spring packs) to experiment with.

The concern about 'spring wrap' and breakage seems to come from thinking my set-up is going to be subject to hard accelerations and jackrabbit off-the-line starts. I don't do this stuff with a 4x4, so I think it will hold up well to just normal pickup truck use. Those air sleeves / bags can take a lot of weight if you get the right ones.

72

[andrewmp6]

The two leafs is still going to break or bend no matter how you drive its not designed to hold the weight its going too.Just google broke momo leaf you'll see for yourself.

[72longbed]

Andrewmp6,
you are missing a very important point. Ready ... pay attention now ... the springs WILL NOT bear the weight of the truck or the load in the bed. The bags located on top of the axle and mounted to the frame above, will carry the weight of the load. Do you follow now?

The springs will simply act as 'locators' for the fore and aft position of the axle (as they do now). That will be their new job. The airbags that I will use will have a 3000 lb capacity EACH side. This takes the concern of "breaking a spring" out of the realm of possibility, especially since I am revising my design with a double spring initially. My prediction is that I will find that only a single leaf is needed to provide the smoothest ride in back.

Can you understand the concept of weight distribution now?

Thanks.