I have a 1991 E-150 club wagon that I use as a daily driver, backroads camping vehicle, road tripping home away from home, and everything in-between. I also use a bumper hitch mounted rail type motorcycle carrrier to bring my 300 pound dirt bike with me most of the time.
I have KYB gas adjust front shocks and Im getting ready to replace the rear. What do you all like? Monroe and Gabriel make air adjustable shocks or I could use the matching KYB shocks out back and install an air-lift universal air assist kit. What's going to get me the best handling over all. If price was no object, what would you do?

 

Airbags + real shocks of your choice.

Air shocks put a substantial load on shock mounts not necessarily ready or designed to take the load.

Also, air shocks have less than ideal damping characteristics.

Might be worth upgrading springs if you carry the bigger load most of the time.

 

not true
true
the only decent options

 

Normal shocks carry absolutely no load. You can compress them easily (although slowly) by hand. The only force the shock mounts need to support with shocks like that is the force required to move the piston quickly.

Nitrogen-charged shocks carry a small amount of load, probably under 50 lbs. The pressure is there only to keep the oil from foaming, the additional force it puts, trying to extend the shock, is an unintended side effect, and not real significant.

Air shocks carry whatever extra load you are trying to get off the springs. Typically that's several hundred pounds, otherwise you wouldn't need them. Shock mounts were designed for regular and nitrogen-charged shocks, so there's no question that air shocks put forces on that the mounts weren't designed to take. That's not to say that the mounts will break if you use air shocks, but you are definitely using strength that was intended as safety factor.

Personally I'd never use air shocks. Air bags are a pretty good option. I had them on a '95 F-150 for about 9 years (Firestone Ride-Rite). They made that truck much more stable when (over)loaded. The only down-side for me was that they ended up being the limitation to my down-travel, which they weren't designed to do. I didn't flex out that truck much, but there were a couple of times I wished I had limit straps on it. The air bags held up OK, but I didn't like what I was doing to them.

 

Totally uninformed.
Ever try to move a shock QUICKLY. Ever use a shock dyno ? I have.
Go to school (I did) and learn how shocks work and you will never say they they don't carry a "load" .
They take a load in BOTH directions.
The mount has to be as strong , if not stronger, than the spring mounts.
FYI , many cars are converted to coilovers and guess what?
Yes the shock mounts handle ALL of the forces w/o any modifications.
I said the truth, not some backyard bs

 

I'm already running a heavy spring and yea, I do tend to have some weight in the back (firewood, camping stuff, car and motorcycle stuff, oil, coolant, etc...)

I guess if I were to listen to both sides of this discussion, then I would probably steer away from the air shocks and go for the LYN, which seems to have a fairly well damped ride. That said, the question would be Air Bags or Helper springs? Anyone care to delve into that?

 

I never thought of it that way before. Thanks!

 

I used to have a ford ranchero and had the air shocks on it for a as long as I had it. They were fine as I used to load the back end up with stuff and then tow a trailer with 1-2 motorcycles on it, plus water and fuel can. They worked well and even empty with minimal air pressure they were fine. I now run airbags on the pickup I took them off the old 3/4t I sold and put on the new truck. But both were scheduled for heavier loads, I also tried the coil spring monroe shocks on the 3/4T, worked ok but still not what I wanted. For your use the airb bags would probably be overkill. They used to sell a kit with coil springs and air bags inside them. Worked ok as they were only good for about 2500lbs. Mine got pinched from rock/roll due to rough road and winds and blew out! Something like these if still available might be what you want. But I think the air shocks would fit your needs since you sid you had heavy duty springs.

 

Short of replacing the rear springs in this 26 year old van........

Another option.......Timbren Rear Axle Suspension Upgrade.

I'm running them on a E350 cube van, with a 14' box, and Big improvement

 

I'm a mechanical engineer. I worked for GM (in an engine test lab, not in suspension design) for 2 years out of college, and I've worked in a small design and manufacturing company for the last 30 years. We do a lot of different things, but some are for second-tier automotive suppliers. The stuff we make still isn't used in automotive suspension, so I'm not saying I'm an automotive suspension expert, but I'm not totally uninformed, and I'm not spouting backyard BS.

What I said, and I still maintain to be true, is that shock mounts were not DESIGNED to also be spring mounts. The design engineers took into account the forces a shock absorber would put on the mounts when they designed it. They did not take into account the forces a spring would also put on it. Therefore it was not DESIGNED to also support the weight of the truck.

Are the forces a shock absorber exerts substantial compared to what a spring exerts? Definitely. But do you think an air shock doesn't need to still be a shock absorber? With an air shock the mounts need to support some of the weight of the truck while still supporting all of the forces that they were designed to support.

Will they break when asked to do this? Probably not, because, as you say, the loads from the shocks themselves are pretty high, and the mounts were designed to support those loads with safety factor. But you are using the safety factor when you put devices on that apply additional forces.

 

That said, they will handle the load Mr. Engineer.
I wish I had a dollar for every fix I had to do because an engineer didn't have real world experience and or screwed up.

 

well hold on a second here. On fords (especially) the upper shock mount tends to be the weak sister. It rusts, the rivets pop or loosed, I have even had the welded in 'bolt' or shaft snap off. I myself am looking for live load limits (thats what it would be called) for a sprung or air shock for the back of my e350 cutaway but such info is not forthcoming. I would assume, based on past experience and a 3 acre yard full of fords, that air shocks at 60-80 psi would be about the MAX and it would not help me much at 6 tons, but might at 2.5 for the OP.

Research the ford shock mounts a little more closely. This is not a 3000lb kit car converted to coil overs for the track.

 

rust is cancer
automakers don't design rust

 

there are those that would dispute that...

but returning to point, lets put it in simple terms

I want 2000lbs extra load lift of a cutaway RV. Air bags, very popular brands, are capable of 5000lbs. Any more than that and you should be looking at a respring, given that the loaded rear axle of a cutaway RV is over 8Klbs.

2000 is a fraction of 5000

if I were to take 2 good floor jacks and place on them a really large capacity bathroom scale, and a bar to connect the scale to the shaft the upper shock mount slips over, and jack it up 1000 lbs per side.

did the shaft or mount deflect upwards at all? bend? break?

I submit to you, you will not be able to perform this task. LOOK_AT_THE_PART.

what are the live load limits of the ford shock mounts? without this info, any assertion of fact is foolish.

 

reading is fundamental
I said springs or bags are best
what part don't you understand?

PS: I have real scales for weighing vehicles.