Smooth ride in a 1st. Gen.
 

03/05/2007
I have been playing with this idea for some time now and it has finally come together.

HOW to make my truck RIDE BETTER.

After a lot of planning and looking under big rigs and remembering what it looked like when I worked under transit coaches I finally came up with a way to make my D-350 dually fun to drive.

The roads are SO bad here in Southern California and my suspension is so tight this poor truck is beating itself to death and taking me with it. And I am getting my share of new squeaks and rattles.

I checked out some of the full air suspensions and came up with my own design for a future project but for now I will see how this works.
I just had my springs reworked hoping for a better ride and it did help some but I was not happy so I decided to modify what I already had.

My plan was to rework my existing 7-leaf pack for the softer ride and have the actual suspension handled by a set of Firestone Air Bags.

So after picking the collective brains of several spring shops I decided to remove 2 leaves from the pack and retain the overload for just incase there is ever a catastrophic failure of my air bag system. By figuring the spring rate of each leaf by removing leaf #2 & #3 it will give me a pack that is a bit heaver than a ½ ton truck would have giving me my softer ride and since my body is on the heavy side including the my usual payload the springs would actually by working Now when I add in the Air Bags to assist springs I am riding on AIR.

I checked around shops locally for the Air Bags and found prices ranging from $250.00 all the way up to $400.00 for the exact same kit so I found a dealer selling them on E-bay NEW for $234.00, he was in Florida and so I ask where they would ship from and he said they would come out of Ontario Ca. I ask and he arranged so I could pick them up and save the week delay. How nice is that?

Kit I used Firestone Ride-Rite #2071

Attachment 73695

After supporting the frame on jack stands and getting the wheels out of the way I broke down the spring packs.
This is what the stock 7-leaf pack looks like.

Attachment 73696

Springs are numbered starting at the main leaf with the bushings as #1, #2, #3, and so on what I did is remove leaf #2 and #3 clean them up and put them back together.

Attachment 73697

To make up for the thickness of the leaves I removed I cut an aluminum block 2 ½” X 6” X 1” thick and drilled a 3/8 hole in the center for the center bolt that holds them all together.

Attachment 73698

Now with the springs modified I went to work installing the Air Bags, I used the kit designed for my truck however this is quite universal and can be fitted to almost any truck if you wanted to.

Attachment 73699

With the top brackets installed I then set out to properly align the lower brackets and clamp them to the leaf pack. (You need to shim the bracket for the correct angle)

Attachment 73700

Here is what the completed modification looks like, see the air bag sits directly above the axle. When there is weight on the truck and the bags are inflated the weight of the truck is being carried from the axle to the frame on a cushion of air.

Attachment 73701

This is just the mechanical side of the install, from here I am going to design an automatic leveling system so I can pre select my ride height and have it maintained through my onboard air system yet be able to manually override the system at any time.
Also since the total volume of each air bag is so small I am installing a separate 2-gallon expansion tank and plumb in both bags to give a better ride.
I am building the control system round a pair of ASCO solenoid valves and an electronic circuit I have in my head.

Up to now this was all in my head but now was the time to try it out. As soon as I pulled out of the driveway it was MUCH softer ride, going over speed bumps before would jar your teeth but now it rolls over. It still is stiff but it is controlled.

I took it down the freeway, my big test was before if I set my cell phone on the seat beside me it would be bouncing all over the seat and within seconds it would be on the floor out of reach.

Now at 70 MPH it was still sitting pretty much where I had left it, oh it is moving around but nothing like it was.

This is with 20 PSI of air in the system; they can handle up to 100 PSI if the need arises.
They explained to me that for every 1 PSI of air in the bag equals to 40 concretive pounds of lift capacity to the system. I say concretive because the system is capable of #5000 lift.

It is now a lot more fun to drive this truck and I think it rides at least 50% better than it did before, the truck feels a lot more responsive and it is a heck of a lot quieter.

I still need to fine tune my suspension, add limiting straps and finish my control system
But this was fun.
Jim

Top notch stuff, as always, Jim:) I have been hatching a similar plan in my head for my front axle--removing leafs, adding bags and limiting straps. It's very cool to see you put into practice. Looks like you get a new thread in the sticky!

Xlent post!

Can you PM me the ebay seller.. I need to order a set.. thanks

great pix! I've been thinking about the air bags for the rear, but I hadn't contempated taking any springs out.

Great writeup. I have been considering the same type of thing. I actually have most of the kit at home. The only thing I was concerned about, with removing the leaves, would be axle wrap. With a spring over setup and all of the torque the Cummins is capable, I wonder how many leaves are needed to keep axle wrap under control?

-Steve

Great Stuff ! Got any ideas for the front ?
I wonder if anybody here has used the Kelderman (?) rear set up.It's extemely pricey .They mount the rear of the springs on a different carrier
with the air bags out back.
By the way ,you painted those springs ,Right? Up here a set of new springs with spring company paint rust in 4 weeks!

Smooth ride
 

I own a 89 W350 that my uncle purchaced new. He was in the scrap metal business and put one bad rear suspension upgrade on it. when I picked up the truck the rear sus. was not working, needless to say I had to go to the ciropractor the next day. After I found the loose wire and fixed it I pumped up the bag and boy it rode so much nicer. Now I always have it pumped up. Here are som pics. (I hope)

free89w350 that's a pretty sweet setup!

Jim look at the Air Lift company for the compressor and tank... that's what i run with my ride-rite bags. the kit i got came with compressor 115-145 pressure valve, 2 gallon tank, 0-200psi gauge, and a valve to fill them. i actually mounted the vavle to fill them in the little plate that covers where the 4x4 light would be, and if i do say so myself, it looks like it was supposed to be there!

I feel a Guiness commercial coming on after looking at those pics---Brilliant!

My set up doesn't use a air tank it has a compressor that pulls air in from th fenderwell area to fill the bag. It has a switch that will go from auto or manual (where i keep it) and another switch to raise or lower. I will try to post a pick tomorrow if your interested

Ryan

limiting strap ?/
 

[director] [director] nice job ( jim? )
why a limiting strap ?? for full droop ? or ??[dummy] [dummy]

thanks for the info ![coffee] [coffee]

I have been contemplating the same type setup in my pickup. I have the factory thick spring pack, and it gets rough, even wtih a 1200# bed on the back. I was thinking of adapting a setup like is found on semi trucks, and eliminating the springs altogether.

Nice job, Jim. free89w250- there is a TDR member with a set up similar to yours.

Daniel

My reason for installing a limiting strap is to protect the air bag in the event the truck was lifted from the body and not the axle, where it could possibly damage the bag from over-extension.

They are usually used on off road vehicles so if the truck goes airborne the the axle would not extend and be supported by the shock absorbers or other suspension components.

In the post by Free89W350 above
On the pictures of the bar in which the single air bag is mounted you see 2 straps with a hook leading under the arm, this would be to the same effect to prevent the air bag from overextending if the body was lifted and the wheels were to remain on the ground.

Since my truck never goes off road or is harshly abused I would only install them to protect the bag if some tow truck driver thought he could lift my truck.

On the subject of axle wrap I am sure this could be an issue if you were pulling something real heavy or you are excessive on the throttle but I am easy on my truck and going for a soft ride, it depends on what you are looking for.
If there was axle wrap what I would do is instead of pulling leaf #2 & #3, I would leave the longer ones and pull the shorter ones from the pack instead probably like #5 & #6 and I would also clamp the leaves midpiont for more control.
Spring shops can also build you a custom pack with a thicker main spring or you could always install a traction bar OR just put in a 4 link system.
But this I would have to experiment with if I had a problem.

Jim

Air Bags As Overloads
 

great upgrade Jim, ...my bags are similar and work well as overloads on my stock rear suspension. Mine just have Shrader air valves vrs compressor. I carried this VW Diesel almost 1000 km and with about 70psi in the bags the truck attitude was right on, headlights within spec and so on.