I've been thinking about what to do about ladder bars and controlling the rear end. My springs are a little saggy and I've got a Kelderman 2 bag rear coming. I did the fourlink rear before and don't want to deal with all that again. Anyway .. we had a guy come into the shop today to visit a friend and I just happen to walk down through the shop and saw a pretty nice F550. I took a look at the rear and noticed he had a Kelderman 2-bag setup but his rear leafs looked weird. As I started to nose around he came up and talked to me. He had a custom "swingarm" setup done to eliminate axle wrap and put all the ride control into the air bags. I went upstairs to my office and thought and though about it. Started to sound really cool so I drew it up quick in 'paint' just to visualize it again. Here's what is looks like. What do you guys think? I have the fab skills and resources so something like this for me to do would be very easy but I've never seen it on a truck before today. I also like to try things out and experiment with unique things. This would definitely be fun to try out.

 

61 views and not a single thought or opinion?

 

to bad you didnt snap some pics of the furd...but it looks interesting. keep me posted

brett

 

Here's a picture of how a semi's rear end works. Kind of the same idea only the kelderman system laterally positions the rear of the spring and I don't really see that happening on the semi (not saying it doesn't, I just don't see it).

 

One mistake, the pivot at the air bag. That is unless behind the airbag there is another pivot to the frame.

 

Yes behind the airback there is another pivot. I didn't draw it because it's the actual Kelderman 2-bag system and I'm not going to change that part of it.

 

It would be a lot easier to just add a couple of half leaves toward the front. The geometry is still the same. The axle control is from the front pivot point to the axle, the rest is just convenience. You would have much better side sway control with the leaves than the fabbed plate. Look at the big truck system, they still use that except for the four bag axles.

Also remember that for a smooth ride, the bags like to be low in pressure. Raise it up and the ride gets harder.

 

I'm assuming here. In your drawing you show the piece the axle connects to as being parallel with the frame. With it being parallel your up travel is limited to the frame plus what ever the length of the front mount. I would look more towards truck suspension setup. This way your not limiting travel. If you went spring under I think that would control axle wrap. Just some babeling. Good luck with it.

 

I'm not very good at drawing so I had to do it as easy as possible. It will use the stock leaf hanger locations so the swingarm will be located outboard of the frame and can pass up and down past it. Range of motion won't be any more limited than the stock leaf spring.

It will directly replace the factory spring, just not be flexible like the stock spring making all the ride quality come from the airbag instead of the spring flexing. Does that make more sense or am I thinking it clearly in my head and not writing down what I mean. I do that sometimes. lol.

 

What you are designing is that half of the rear suspension is air cushioned. That is why KW came out with the eight bag suspension, to make the front half softer. The front point of attachment regardless of how you hang it is still solid to the frame. More so as you hang it. The rear section is on air and will handle most off the road shock but it will be no softer because of the springs being replaced. Your system will handle wind up a little better than the stock, but that is easily handled with only an added half leaf toward the front as Chrysler did on performance passenger cars for years.

Not to misunderstand what I am saying, your system will work and work well. Just that you are fabbing a system that does not help cure anything except windup and that can be easier controlled just by modifying the spring. Put your geometry to work and see where you are not changing much in the ride quality. You are just connecting the air bag in a different fashion.


But hey, this is not a big thing, your design will work and do a good job. I think it is way over designed and a lot of work for little gain. jmho. Good luck with it.

 

I'm not really doing it for any other purpose than I love to fabricate things and have something unique. The air bag setup for me wasn't really to soften the ride (even though it does) but rather to keep the truck level when I put a load on it. I just figure it can do double duty and provide the spring movement as well as the ride height control. I like have a firm truck.

For me, 90% of the fun is building something. I am chopping apart a 2000 Jeep TJ just to build a buggy out of it with a 4BTA, just because I wanted to do it with a stock TJ chassis and not purchase a tube chassis. It's just fun yet functional at the same time. I just think it would be fun to build something like this but wanted to double check myself that it would actually work the way I think it will.

Not to sway me away but where do they sell half springs?

 

I can fully understand your thoughts on fabbing. I do that myself. To add half springs you pick the right length leaf and cut it off just past the U bolt area. Used to add two or three to stock classed mopars to increase the control and add traction as the foreward leaves tend to lift the rear of the car. I would end up with two leaves going all the way to the back and maybe five total. Hitting the pedal would give a noticable lift to the rear of the car. Did wonders for traction and controlled axle wind.

When I was running hotshot with the Dodge I had plans of installing the frieghtliner quarter leaf air bag system, much like the picture you posted. Of course it would only have the main quarter leaf for weight purposes.

The closer to the axle the air bag is the better the ride and handling. If it could be put over the axle that would be optimum but of course there is not room. The spring if it does not go all the way back to attach to the frame has to have a traverse rod to control side position.

Previously looking at the system, a four wheel drive Dodge might just have enough room to locate the bag on the end of the spring behind the axle if the spring were lowered so that no block is necessary.